Showing posts with label Disease. Show all posts
Showing posts with label Disease. Show all posts

Sunday, March 2, 2014

Overview

Despite recent declines in age-adjusted mortality, in 2005, cardiovascular disease (CVD) was the primary cause in 864,480 deaths (35.3% of total) and the secondary cause in another 507,520 deaths in the United States.[1] In fact, CVD has been the leading cause of death in the United States for the past 100 years, except for 1918.[1] While CVD age-adjusted death rates are reportedly declining in the United States, they are increasing in many developing countries. These developing countries and emerging market economies are succumbing to the epidemiologic transition that afflicted the United States (CVD-related mortality), posing a major challenge to these regions as they undergo social and economic development as emerging market economies.[2, 3, 4]

The most preventable form of CVD is coronary heart disease (CHD). In the United States, CHD annually results in 502,000 deaths, of which 185,000 are due to myocardial infarction (MI); 1.2 million MIs, of which 700,000 are first infarctions; and an economic burden of $133 billion.

An American Health Association policy statement concluded that costs will rise to more than $1 trillion annually in the United States by the year 2030, thus suggesting the great need for preventative measures.[5]

Currently, 16.8 million Americans (8.7 million men, 8.1 million women) have documented CHD.[4] Asymptomatic disease is even more prevalent. By the year 2020, CHD is estimated to become the leading cause of death and disability worldwide. Despite this high prevalence, evidence increasingly suggests that the atherosclerotic process can be greatly slowed and its consequences markedly reduced by preventive measures. Primordial prevention usually refers to healthy lifestyle choices to prevent the development of coronary risk factors.[6] Primary prevention deals with delaying or preventing the onset of cardiovascular disease (MeSH definition).

Many countries where CHD is on the rise have instituted counselling and educational methods to encourage people to reduce their risks for developing heart disease. A review examined 55 trials intended to reduce multiple risk factors; the trials lasted between 6 months and 12 years and were conducted in several countries over the course of 4 decades. The review suggested that intervention results in small reductions in risk factors, including blood pressure, cholesterol, and smoking, but has little or no impact on the risk of CHD mortality or morbidity.[7] This demonstrates that a different approach to behavior change is needed, particularly in developing countries where cardiovascular disease rates are rising.

A study by Pande et al suggests millions of US adults with peripheral arterial disease (PAD) are not receiving secondary prevention therapies.[8] PAD was defined as an ankle-brachial index of 0.90 or less. Of 7458 eligible participants aged 40 years or older, weighted PAD prevalence was 5.9±0.3%, corresponding to approximately 7.1 million US adults with PAD. Treatment with multiple therapies (statins, ACE inhibitor/angiotensin receptor blockers, and aspirin) is associated with reduced all-cause mortality.

Secondary prevention relies on early detection of disease process and application of interventions to prevent progression of disease (MeSH definition). This article summarizes the guidelines for the primary and secondary prevention of CHD.

NextRisk Assessment and Primary PreventionRisk Factors and Risk Scores

Primary prevention reduces MI and heart failure, decreases the need for coronary revascularization procedures, and extends and improves the quality of life. The American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines, in a 2010 report on cardiovascular risk assessment in asymptomatic adults, recommends obtaining global risk scores (eg, Framingham Risk Score[9] ) and a family history of cardiovascular disease for cardiovascular risk assessment.[10]

The Framingham Heart Study first introduced the term risk factor into modern medical literature; the term is generally applied to a parameter that is predictive of a future cardiovascular event. Broadly, risk factors are arbitrarily divided into 3 major categories:

Table 1. Basic Categories of Risk Factors for Future Cardiovascular Event (Open Table in a new window)

Category Risk Factors Nonmodifiable risk factorsAge, sex, family history, geneticModifiable risk factorsSmoking, atherogenic diet, alcohol intake, physical activity, dyslipidemias, hypertension, obesity, diabetes, metabolic syndromeEmerging risk factorsC-reactive protein (CRP), fibrinogen, coronary artery calcification (CAC), homocysteine, lipoprotein(a), and small, dense LDL

Adapted from ATP III Final Report 2002, ATP III Update 2004: Implications of Recent Clinical Trials for the ATP III Guidelines[11]

Several risk scores have been developed to help predict an individual's risk of future cardiovascular events. For example, the Framingham Heart Study developed a coronary risk estimate using some of the following major traditional risk factors:

AgeGenderFamily history of premature CHD (first-degree male relative Elevated total or LDL cholesterol levelReduced HDL cholesterol levelSmokingHypertensionDiabetes mellitusObesitySedentary lifestyle

Using these risk factors, a Framingham score can be computed that helps assess the 10-year risk of CHD for individuals with risk factors. The American Heart Association suggests childhood obesity is likely to lower the age of onset and increase the incidence of cardiovascular disease worldwide.[12]

Berry et al suggest that differences in risk-factor burden result in marked differences in the lifetime risk for cardiovascular disease. They also conclude that these differences are consistently noted across both race and birth cohorts.[13]

The following tables are adapted from NHLBI Web site.[9] Note that diabetes is excluded because it constitutes coronary artery disease risk equivalent.

NCEP/Framingham Estimate of 10-Year Coronary Heart Disease Risk in Men

Table 2. Framingham Point Scores by Age Group in Men (Open Table in a new window)

AgePoints20-34-935-39-440-44045-49350-54655-59860-641065-691170-741275-7913

Table 3. Framingham Point Scores by Age Group and Total Cholesterol in Men (Open Table in a new window)

Total CholesterolAge 20-39Age 40-49Age 50-59Age 60-69Age 70-7900000160-19943210200-23975310240-27996421280+118531

Table 4. Framingham Point Scores by Age and Smoking Status in Men (Open Table in a new window)

Age 20-39Age 40-49Age 50-59Age 60-69Age 70-79Nonsmoker00000Smoker85311

Table 5. Framingham Point Scores by HDL level in Men (Open Table in a new window)

HDLPoints60+-150-59040-4912

Table 6. Framingham Point Scores by Systolic Blood Pressure and Treatment Status in Men (Open Table in a new window)

Systolic BPIf UntreatedIf Treated00120-12901130-13912140-15912160+23

Table 7. 10-Year Risk by Total Framingham Point Scores in Men (Open Table in a new window)

Point Total10-Year Risk01%11%21%31%41%52%62%73%84%95%106%118%1210%1312%1416%1520%1625%17 or more≥30%NCEP/Framingham Estimate of 10-Year Coronary Heart Disease Risk in Women

Table 8. Framingham Point Scores by Age Group in Women (Open Table in a new window)

AgePoints20-34-735-39-340-44045-49350-54655-59860-641065-691270-741475-7916

Table 9. Framingham Point Scores by Age Group and Total Cholesterol in Women (Open Table in a new window)

Total CholesterolAge 20-39Age 40-49Age 50-59Age 60-69Age 70-7900000160-19943211200-23986421240-279118532280+1310742

Table 10. Framingham Point Scores by Age and Smoking Status in Women (Open Table in a new window)

Age 20-39Age 40-49Age 50-59Age 60-69Age 70-79Nonsmoker00000Smoker97421

Table 11. Framingham Point Scores by HDL level in Women (Open Table in a new window)

HDLPoints60+-150-59040-4912

Table 12. Framingham Point Scores by Systolic Blood Pressure and Treatment Status in Women (Open Table in a new window)

Systolic BPIf UntreatedIf Treated00120-12913130-13924140-15935160+46

Table 13. 10-Year Risk by Total Framingham Point Scores in Women (Open Table in a new window)

Point Total10-Year Risk91%101%111%121%132%142%153%164%175%186%198%2011%2114%2217%2322%2427%25 or more≥30%

Prevalence of coronary risk factors in the United States are as follows:

LDL cholesterol >130 mg/dL – 46%HDL cholesterol 40 mg/dL – 26%Prehypertension – 22%Hypertension – 25%Tobacco use – 25%Diabetes mellitus – 8%Overweight or obese – 65%Physically inactive – 38%Metabolic syndrome – 24%

Considerable clinical benefit can be derived from the management of 3 major modifiable coronary risk factors: hypercholesterolemia, hypertension, and cigarette smoking.

According to the Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research (EISNER), the addition of CAC scanning to conventional risk factor modification has been associated with superior coronary artery disease risk factor control without increasing downstream medical testing.[14]

Every 1 mmol/L (38.7 mg/dL) decline in LDL cholesterol results in a 21% decrease in cardiovascular events.[15] A decrease in systolic blood pressure by 10 mm Hg can decrease cardiovascular mortality by 20-40%.[16, 17, 18] Similarly, the risk of acute MI increases by 5.6% for every additional cigarette smoked per day.[19]

Hypercholesterolemia/dyslipidemia

Screening should include a full fasting lipid profile including total cholesterol, HDL, and triglycerides measurements. The ratio of total or LDL cholesterol to HDL appears to be a powerful risk predictor.[20] The Adult Treatment Panel III NCEP guidelines, published in 2001, include initiation of lifestyle and drug management with the following goals.

A primary goal of reducing LDL cholesterol level is as follows:

20% 10-year Framingham risk

Secondary goals are as follows:

If LDL goals are achieved and triglyceride levels are >200 mg/dL, the goal for non-HDL cholesterol level should be set at 30 mg/dL higher than the LDL cholesterol level. In response to the recent trial results, the NCEP has recommended lowering of the LDL target goals to [21] The value of intensive cholesterol reduction is best documented for patients with CHD in the recent IVUS, ASTEROID, and PROVE-IT trials, studying atherosclerosis progression and coronary events, respectively. Their statement acknowledges that the recent trials have failed to demonstrate an LDL cholesterol level below which coronary risk does not decrease. Measurement of HDL cholesterol should be used as part of the initial cardiovascular risk assessment but should not be used as a predictive tool of residual vascular risk in patients who are treated with potent high-dose statin therapy to lower LDL cholesterol.[22] The extended follow-up of the Heart Protection Study (HPS) assessed the long-term efficacy and safety of lowering LDL cholesterol with statins, and found that prolonged LDL-lowering statin treatment produces larger absolute reductions in vascular events. The benefits of long-term continuation of statin treatment persisted for at least 5 years without any evidence of developing risks.[23] On the basis of the JUPITER trial, European health authorities have suggested that when LDL cholesterol levels do not require pharmacologic treatment, 20 mg of rosuvastatin significantly reduces major cardiovascular events in primary prevention patients with elevated high-sensitivity C-reactive protein who have high global cardiovascular risk (10-year Framingham risk score >20%).[24] The Multi-Ethnic Study of Atherosclerosis (MESA) studied eligible participants from the JUPITER trial to assess whether or not coronary artery calcium (CAC) might further stratify risk. The results suggest that in the patients eligible for JUPITER, CAC could be used to target subgroups of patients who are expected to derive the most, and the least, absolute benefit from statin treatment.[25] Secondary causes of dyslipidemia

Before therapy is initiated, the following potential secondary causes of dyslipidemia should be considered based on the associated dyslipidemia:

High LDL: Hypothyroidism[26, 27] , nephrotic syndrome, primary biliary cirrhosis[28] , and anorexia nervosa[29, 30] Hypertriglyceridemia: Diabetes mellitus[31] , chronic kidney disease, alcoholism, pregnancy[32] , hypothyroidism[26, 27] Low HDL: Diabetes mellitus, cigarette smoking[33, 34] , obesity[35]

Table 14. Proposed Modifications of ATP III LDL-Cholesterol Goals and Cut Points for Therapeutic Lifestyle Changes and Drug Therapy in Different Risk Categories[36] (Open Table in a new window)

Risk CategoryLDL GoalLDL level at which to Initiate Therapeutic Lifestyle ChangesLDL level at which to Consider Drug

Therapy§

High risk  - CHD or CHD risk equivalent (10-y risk >20%)***≥100 mg/dL║≥100 mg/dL,¶Moderate-high risk  - 2 or more risk factors (10-y risk 10-20%)†††≥130 mg/dL≥130 mg/dL; 100-129mg/dL consider drug options#Moderate risk - 2 or more risk factors (10-year risk ≥130 mg/dL≥160 mg/dLLower risk  - 0-1 risk factor‡≥160 mg/dL≥190 mg/dL; 160-189 mg/dL consider drug options* Heart disease risk equivalents include noncoronary forms of atherosclerotic disease (peripheral arterial disease, abdominal aortic aneurysm, and carotid artery disease) and diabetes. Ten-year risk defined by modified Framingham risk score.

† Risk factors that modify LDL goals include cigarette smoking; hypertension (BP ≥140/90 mm Hg or on antihypertensive medications); low HDL cholesterol (
‡ Almost all people with 0-1 risk factor have a 10-year risk of less than 10%; thus, 10-year risk assessment in people with 0-1 risk factor is not necessary.

§ When LDL-lowering drug therapy is given, the intensity of therapy should be sufficient to achieve at least a 30-40% reduction in LDL levels.

â•‘ Any individual at high or moderately high risk who has lifestyle-related risk factors (eg, obesity, physical inactivity, hypertriglyceridemia, low HDL cholesterol [
¶ If baseline LDL is
# For moderately high-risk persons with LDL of 100-129 mg/dL at baseline or after lifestyle changes, initiation of an LDL-lowering drug to achieve an LDL of less than 100 mg/dL is an option.

** Very high risk favors the optional LDL goal of
†† Optional LDL goal of
Triglycerides

Data on the impact of triglycerides on CHD events is not as clearly evident. However, meta-analyses data suggest that elevated triglyceride levels are an independent risk factor for CHD[37, 38] , and data on the benefits of reducing triglyceride levels were demonstrated by using the drug gemfibrozil (fibric acid derivative) in a population with low HDL level ([39, 40]

Non-HDL cholesterol

In patients with mixed dyslipidemia (elevated LDL cholesterol and triglyceride levels), non-HDL cholesterol is a useful measurement. Non-HDL cholesterol represents very LDL cholesterol plus LDL cholesterol, both of which are apo B-100–containing atherogenic lipoprotein fractions. In hypertriglyceridemic individuals, non-HDL cholesterol goals are 30 mg/dL higher than the corresponding LDL goals, representing a triglyceride goal of 150 mg/dL. Non-HDL cholesterol can be measured in a nonfasting state. Non-HDL cholesterol was found to be more predictive of future CV events than LDL in several trials, probably because it measures both of the atherogenic apo B–containing fractions.[41, 42] LDL and total cholesterol/HDL cholesterol ratios are also strongly predictive of CVD risk.[20]

Secondary prevention

When drug therapy is indicated for reducing LDL cholesterol, statins are generally initiated as first-line therapy. Exceptions include pregnancy, hepatic disease, or history of myositis while on these agents. Resins, nicotinic acid, or ezetimibe can be added if LDL cholesterol level is not reduced to goal. Pharmacologic therapy for triglyceridemia includes fibrates, nicotinic acid, and omega-3 fatty acids. Fibrates and nicotinic acid are also effective in raising low HDL, particularly when high triglycerides are present.

In mixed dyslipidemias, a statin may be combined with nicotinic acid or a fibrate. As described earlier, non-HDL cholesterol is a useful parameter to monitor therapy results in mixed dyslipidemia. When using combined therapy, particularly statins plus fibrates, the risk of myositis increases and, therefore, patients should be educated about muscle symptoms. To minimize the risk of statin myopathy, the statin dose should be kept as low as possible to achieve the LDL goal, and it may be helpful to separate the dosing of statins and fibrates to evening and morning, respectively.

Varespladib methyl 500 mg once daily may be an effective antiatherosclerotic agent.[43]

Compared with placebo or statin monotherapy, evacetrapib as monotherapy or in combination with statins increased HDL-C levels and decreased LDL-C levels. However, further investigation is warranted.[44]

Blood Pressure Control

Hypertension is a well-established risk factor for adverse cardiovascular outcomes, including CHD. Systolic blood pressure is at least as powerful a coronary risk factor as the diastolic blood pressure. Isolated systolic hypertension is now established as a major hazard for CHD. Compelling data from meta-analyses indicate that a reduction of diastolic blood pressure by 5-6 mm Hg results in a reduction of stroke risk by 42% and CHD events by 15%.[45]

The self-management of hypertension, which includes self-monitoring of blood pressure and self-titration of antihypertensive drugs, along with telemonitoring of home blood pressure measurements, is an important new addition to the control of hypertension in primary care. Patients who self-manage hypertension have experienced a decrease in systolic blood pressure compared to those who sought usual care.[46] The Clinical Evaluation of Remote Notification to Reduce Time to Clinical Decision (CONNECT) trial found that wireless remote monitoring with automatic clinician alerts significantly reduced the time to a clinical decision in response to clinical events as well as reduced the length of hospital stay.[47]

In patients with mild hypertension (systolic 140-159 mm Hg or diastolic 90-99 mm Hg), the following is noted:

Despite side effects and cost of antihypertensive medications, the beneficial effects of treatment may outweigh the risks, even in low-risk patients. Treatment, if necessary, is initiated with a low-dose of a once-a-day antihypertensive drug in an attempt to minimize future cardiovascular risk after a prolonged trial of nonpharmacologic therapy. One such antihypertensive medication that is used worldwide is hydrochlorothiazide (HCTZ). A daily dose of 12.5-25 mg was measured in head-to-head studies using ambulatory blood pressure measurement and was shown to be consistently inferior to all other drug classes. Because data is lacking for dosing, HCTZ is an inappropriate first-line drug for the treatment of hypertension.[48]

In individuals with high-normal blood pressure (systolic 130-139 mm Hg and/or diastolic 85-89 mm Hg), the following is noted:

These persons have an increased risk of cardiovascular events over time compared with those who have optimal blood pressure.Antihypertensive drug therapy should be considered among such patients if diabetes or end-organ damage is present.Treatment, particularly with an angiotensin-converting enzyme (ACE) inhibitor or, if not tolerated, an angiotensin-II receptor blocker, is also warranted in patients with renal insufficiency, diabetes mellitus, or heart failure to slow the progression of the underlying disease. Diet

Two types of dietary guidelines exist.

The first type recommends specific quantities of macronutrients, such as [49, 50]

A second type recommends the consumption and exclusion of specific foods, often in combination. An example is the recommendation to eat the following foods to lower cholesterol: stanol/sterol ester margarines, soy products, soluble fiber, and almonds or walnuts. This specific food portfolio recommendation has been found to lower LDL cholesterol more than an AHA Step 2 approach (29% vs 8%, respectively). The reductions were, in fact, equivalent to those of lovastatin 20 mg.[51] Total allowed daily fat ranges from 25-35% of total daily calories provided that saturated fats and trans-fatty acids are kept low.

A diet containing stanol-enriched margarine, soy pA diet containing stanol-enriched margarine, soy products, high-fiber foods, and almonds reduced LDL cholesterol and CRP more than an NCEP diet. The reductions were equivalent to lovastatin 20 mg.

The Third ATP of the NCEP further modified its dietary recommendations to include a more intense and effective eating plan than previously advocated. Specific recommendations are as follows: 1) Saturated fat,

In general, diets containing unsaturated fats, whole grains, fruits, vegetables, fish, and moderate alcohol are optimal for preventing heart disease.[52] The revised AHA guidelines place emphasis on foods and an overall eating pattern, rather than on percentages of food components such as fat.

One meta-analysis studied the effect of a Mediterranean diet on metabolic syndrome.[53] The diet is characterized by high consumption of monounsaturated fatty acids, primarily from olives and olive oil, and encourages daily consumption of fruits, vegetables, whole grain cereals, and low-fat dairy products; weekly consumption of fish, poultry, tree nuts, and legumes; a relatively low consumption of red meat, approximately twice a month; as well as a moderate daily consumption of alcohol, normally with meals. Adherence to the diet was associated with reduced risk of metabolic syndrome and reduced HDL-cholesterol levels and triglycerides levels. The results are of considerable public health importance because this dietary pattern can be easily adopted by all population groups and various cultures and is cost-effective.

A separate meta-analysis performed by Nordmann et al found that the Mediterranean diet had more favorable changes in weighted mean differences of body weight, body mass index, systolic blood pressure, diastolic blood pressure, fasting plasma glucose, total cholesterol, and high-sensitivity C-reactive protein than low-fat diets.[54]

Of note, in a recently published prospective study, dietary supplementation with marine n−3 fatty acids (eicosapentaenoic acid [EPA], docosahexaenoic acid [DHA] and the plant-derived alpha-linolenic acid [ALA]) did not significantly reduce the rate of cardiovascular events among patients with a prior myocardial infarction.[55]

Alcohol

Moderate alcohol consumption (1-2 drinks per d) is associated with a reduced overall and CHD-related mortality compared with both abstinence and heavy drinking.[56, 57]

Alcohol raises HDL (by stimulating the hepatic production of apo A-I and A-II)[58, 59, 60] , stimulates fibrinolysis[61, 62, 63] , reduces fibrinogen levels[64, 65] , reduces inflammation[66] , and inhibits platelet activation[67] .

In the United States, additional antioxidant effects have been attributed to red wine, but the consumption of other alcoholic beverages is associated with a somewhat lower or similar reduction in CHD risk[68, 69] , and the pattern and amount of alcohol intake appears to be more important than the type.

Antioxidants

Although several observational studies and 1 randomized, controlled secondary prevention trial (CHAOS)[70] found reduced CVD in those taking large amounts of antioxidant vitamins, the HOPE[71] GISSI-Prevention[72] , and Heart Protection Studies (HPS) found no benefit for 400 and 300 IU/d of vitamin E, respectively.[11]

A current meta-analysis of available data suggests no benefit for antioxidant vitamins.[73]

Herbals

An estimated 40% of Americans use herbal remedies, and at least $15 billion is spent annually in North America on alternative forms of health care. Inquiry about the use of herbals is a component of good medical care, especially in cardiovascular medicine.

Alternative medicine approaches to cholesterol lowering include garlic, policosanol, gugulipid, and red rice yeast extracts, the latter of which contains HMG-CoA reductase inhibitors. Garlic modestly lowers cholesterol (approximately 3%) and may lower BP and inhibit platelet aggregation. Fermented red rice yeast extracts contain statins and lower cholesterol 13-26%.[74] Ephedra-containing herbals, often used as anorexics, are associated with hypertension and stroke and have been banned in the United States.[75, 76]

Summary of General Nutritional Recommendations

Achieve and maintain ideal body weight by limiting foods high in calories and low in nutrition, including those high in sugar, such as soft drinks and candy.

Eat a variety of fruits; vegetables; legumes; nuts; soy products; low-fat dairy products; and whole grain breads, cereals, and pastas.

Eat baked or broiled fish at least twice per week.

Choose oils and margarines low in saturated fat and high in omega-3 fat, such as canola, soybean, walnut, and flaxseed oils, including those fortified with stanols and sterols.

Avoid foods high in saturated and trans - fats, such as red meat, whole milk products, and pastries.

Limit alcohol consumption to no more than 2 drinks per day for a man or 1 drink per day for a woman.

Eat less than 6 g of salt or

Physical Activity

Reduced physical activity is a major risk factor for CVD. In elderly individuals, the risk of MI is reduced by as much as 50% by walking 30 minutes daily.[77, 78] A study of the associations between physical activity and risk of cardiovascular disease among 44,551 middle-aged men found vigorous- and moderate-intensity activity were associated with lower risk of disease.[174] On the other hand, the Cooper Center Longitudinal Study found that low fitness in mid-life was associated with higher lifetime risk for CVD death.[79]

Abnormal heart rate recovery (HRR) has been shown to predict mortality. A study by Jolly et al to determine whether HRR could be improved with cardiac rehabilitation suggests it can improve after patients with abnormal HRR at baseline normalize HRR with exercise. The mortality rate was similar to that of individuals with baseline normal HRR.[80]

The following general principles need to be considered in recommending increased physical activity:

Increased physical activity begins with increasing lifestyle activities, such as walking.A complete exercise program includes aerobic exercise, resistive training, and stretching.More frequent exercise, optimally daily, provides more benefit.More strenuous exercise, such as jogging, provides more benefit. A good goal is 75% of age-predicted maximal heart rate (220 - age of individual). Excellent benefit can be derived from 30 minutes of daily exercise.Studies have also shown that even 15 minutes a day or 90 minutes a week of moderate-intensity exercise may be beneficial.[81] The most recent scientific statement from the American Heart Association provides recommendations on implementing the most efficacious and effective physical activity and dietary strategies in adults.[82] European studies suggest that elevated waist circumference and physical inactivity are associated with an increased risk of coronary heart disease.[83] Smoking

Of all the lifestyle modifications recommended to prevent CVD, smoking cessation is the most important. Tobacco use prematurely kills 435,000 Americans annually. Smoking cessation is the most cost-effective preventive measure, estimated at $220 per year of life saved. Individuals aged 30 years gain 3-5 years of life by stopping smoking and the mortality benefit was equally impressive in elderly populations.[84, 85] The most effective smoking cessation programs involve programmatic and/or group support and the use of nicotine substitutes and antidepressants, such as bupropion. Varenicline is a recent addition to the armamentarium and has been found to be superior to bupropion in this respect.[86, 87, 88]

Smoking is a risk factor for CVD in women and men; however, a systemic review and meta-analysis by Huxley and Woodward suggests that in some countries, smoking by women is on the rise; the study suggests that proper counseling and nicotine addiction programs should focus on young women.[89]

Smoking cessation counseling with supportive contact after a patient with acute myocardial infarction is discharged is potentially cost-effective and may reduce the incidence of smoking and further adverse health events.[90]

Secondary prevention (after development of CHD)

Table 15. Smoking Cessation and Mortality After MI[91] (Open Table in a new window)

StudyPatients Studied (No.)5-Year Mortality RateQuittersSmokersSparrow, 1978365 (269 men, 96 women)12%25%Aberg, 1983

Daly, 1983

983 (men only)

498 (men only)

16%

20%

22%

30%

Johansson, 1985

Perkins, 1985

156 (women only)

119 (90 men, 29 women)

15%

21%

27%

47%

Hedback, 1987305 (258 men, 47 women)16%31%

Several large observational studies, all of which had at least 5 years of follow-up and a meta-analysis including these studies, showed a substantial reduction in mortality [RR: 0.64 (I: 0.58-0.71)] in patients with a history of MI, CABG, angioplasty, or known CHD, who quit smoking compared with patients who continued to smoke.[92] The overall mortality risk of smokers who quit decreases by 50% in the first couple of years and tends to approach that of nonsmokers in approximately 5-15 years of cessation of smoking.

Primary prevention should start with lifestyle modification, including weight management, diet, physical activity, and smoking cessation. Hormone therapy increases cardiovascular events in postmenopausal women. Estrogen alone increases stroke, but it does not alter CHD events.

Aspirin

Two recently published meta-analyses showed that aspirin use (75-162 mg/d) decreases the occurrence of primary MI by 25-33% and has also been shown to decrease death due to vascular causes; these benefits are not gender specific.[93, 94] However, all benefits have to be balanced against the risk of GI bleeding. Low-dose aspirin therapy (75 mg/d) is therefore recommended for primary prevention in individuals with a 10-year Framingham coronary risk estimate greater than 10%, outweighing risks of gastrointestinal hemorrhage and hemorrhagic stroke.[95] Aspirin has been shown to be similarly efficacious in secondary prevention of MI, stroke, and death secondary to vascular causes.[96, 97] However, a study by Berger et al suggests aspirin has only modest benefit in patients without clinical cardiovascular disease and this benefit is offset by its risk.[98]

PreviousNextClassification of Recommendations

Recommendations made herein are based largely on major practice guidelines from the National Institutes of Health and ACC/AHA. The information presented is adapted from recent statements by the AHA/ACC, which involved the process of partial adaptation of other guideline statements and reports and supplemental literature searches.[99]

The American College of Cardiology Foundation (ACCF) and the American Heart Association (AHA) have produced guidelines for the procedures of detection, management, or prevention of disease.[100]

Classification of recommendations and level of evidence

Classification of recommendations is as follows:

Class I - Conditions for which there is evidence and/or general agreement that a given procedure or treatment is beneficial, useful, and effective Class II - Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment Class IIa - Weight or evidence/opinion is in favor or usefulness/efficacyClass IIb - Usefulness/efficacy is less well established by evidence/opinion Class III - Conditions for which there is evidence and/or general agreement that a procedure/treatment is not useful/effective and in some cases may be harmful

Level of evidence is as follows:

Level of evidence A - Data derived from multiple randomized clinical trials or meta-analysesLevel of evidence B - Data derived from single randomized trial or nonrandomized studiesLevel of evidence C - Only consensus opinion or experts, case studies, or standard-of-care

Table 16. Applying Classification of Recommendations and level of Evidence (in ACC/AHA format) (Open Table in a new window)

Size of Treatment Effect Class I

Benefit >>> Risk

Procedure / treatment

should be

performed / administered.

Class IIa

Benefit >> Risk

(Additional studies with focused objectives needed)

Performing procedure / administering treatment is reasonable.

Class IIb

Benefit ≥ Risk

(Additional studies with broad objectives needed; additional registry data would be helpful)

Procedures / treatment may be considered.

Class III

Risk > Benefit

(No additional studies needed)

Procedure / treatment should not be performed / administered since it is not helpful and may be harmful.

Estimate

of

Certainty

(Precision)

of

Treatment

Effect

level A

Multiple (3-5) population risk strata evaluated*

General consistency of direction and magnitude of effect

Recommendation that procedure or treatment is useful/effective

Sufficient evidence from multiple randomized trials or meta-analyses

Recommendation in favor of treatment or procedure being useful/effective

Some conflicting evidence from multiple randomized trials or meta-analyses

Recommendation's usefulness / efficacy less well established

Greater conflicting evidence from multiple randomized trials or meta-analyses

Recommendation that procedure or treatment is not useful/effective and may be harmful

Sufficient evidence from multiple randomized trials or meta-analyses

level B

Limited (2-3) population risk strata evaluated*

Recommendation that procedure or treatment is useful / effective

Limited evidence from single randomized trial or nonrandomized studies

Recommendation in favor of treatment or procedure being useful / effective

Some conflicting evidence from single randomized trials or nonrandomized studies

Recommendation's usefulness / efficacy less well established

Greater conflicting evidence from single randomized trial or nonrandomized studies

Recommendation that procedure or treatment is not useful/effective and may be harmful

Limited evidence from single randomized trial or nonrandomized studies

level C

Very limited (1-2) population risk strata evaluated*

Recommendation that procedure or treatment is useful/effective

Only expert opinion, case studies, or standard-of-care

Recommendation in favor of treatment or procedure being useful/effective

Only diverging expert opinion, case studies, or standard-of-care

Recommendation's usefulness / efficacy less well established

Only diverging expert opinion, case studies, or standard-of-care

Recommendation that procedure or treatment is not useful/effective and may be harmful

Only expert opinion, case studies, or standard-of-care

Suggested phrases for writing recommendationsShould

Is recommended

Is indicated

Is useful / effective / beneficial

Is reasonable

Can be Useful / effective / beneficial

Is probably recommended or indicated

May/might be considered

May/might be reasonable

Usefulness / effectiveness is unknown / unclear / uncertain or not well established

Is not recommended

Is not indicated

Should not

Is not useful / effective / beneficial

May be harmful

*Data available from clinical trials or registries about the usefulness/efficacy in different subpopulations, such as gender, age, diabetes, history of prior MI, history of heart failure, and prior aspirin use. PreviousNextSecondary Prevention Goals and Management

Patients covered by these guidelines include those with established coronary and other atherosclerotic vascular disease, including peripheral arterial disease, atherosclerotic aortic disease, and carotid artery disease. Treatment for patients whose only manifestation of cardiovascular risk is diabetes will be the topic of a separate AHA scientific statement.

The AHA/ACCF Secondary Prevention and Risk Reduction Therapy for Patients With Coronary and Other Atherosclerotic Vascular Disease: 2011 Update: A Guideline From the American Heart Association and American College of Cardiology Foundation has been released.[101]

Smoking cessation

The goal is complete cessation and no exposure to environmental tobacco smoke.

Ask the patient about tobacco use status at every visit. I (B)Advise every patient who uses tobacco to quit. I (B)Assess the patient’s willingness to quit using tobacco. I (B)Assist the patient by counseling and developing a plan for quitting. I (B)Arrange follow-up, referral to special programs, or pharmacotherapy (including nicotine replacement and bupropion). I (B)Urge the patient to avoid exposure to environmental tobacco smoke at work and home. I (B)Blood pressure control

The goal is BP

For all patients, initiate or maintain lifestyle modification, weight control, increased physical activity, alcohol moderation, sodium reduction, and increased consumption of fresh fruits, vegetables, and low-fat dairy products. I (B)

For patients with BP ≥140/90 mm Hg (or 130/80 mm Hg for individuals with chronic kidney disease or diabetes), as tolerated, add BP medication, treating initially with beta-blockers and/or ACE inhibitors, with addition of other drugs, such as thiazides, as needed to achieve goal blood pressure. I (A)

Diet

Diets that include nonhydrogenated unsaturated fats as the predominant form of dietary fat, whole grains as the primary form of carbohydrate, fruits and vegetables, omega-3 fatty acids (from fish, fish oil supplements, or plant sources) offer significant protection against coronary heart disease.

Light-to-moderate alcohol consumption (5-25 g/d) has been significantly associated with a lower incidence of cardiovascular and all-cause mortality in patients with cardiovascular disease. A meta-analysis by Costanzo et al found J-shaped curves for alcohol consumption and mortality, with a significant maximal protection against cardiovascular mortality with consumption of approximately 26 g/d and maximal protection against mortality from any cause in the range of 5-10 g/d.[102]

Lipid management

The goal is LDL cholesterol

The following measures should be taken for all patients:

Start dietary therapy. Reduce the intake of saturated fats (to I (B)Adding plant stanol/sterols (2 g/d) and viscous fiber (>10 g/d) will further lower LDL cholesterol level.Promote daily physical activity and weight management. I (B)Encourage increased consumption of omega-3 fatty acids in the form of fish or in capsule form (1 g/d) for risk reduction. (Pregnant and lactating women should limit their intake of fish to minimize exposure to methylmercury.) For treatment of elevated triglyceride levels, higher doses are usually necessary for risk reduction. IIb (B)

Assess fasting lipid profile in all patients and within 24 hours of hospitalization for those with an acute cardiovascular or coronary event. For hospitalized patients, initiate lipid-lowering medication as recommended below before discharge according to the following schedule:

LDL cholesterol level should be I (A)Further reduction of LDL cholesterol level to IIa (A)If baseline LDL cholesterol level is 100 mg/dL, initiate LDL-lowering drug therapy. I (A)If the patient is on treatment and LDL cholesterol is 100 mg/dL, intensify LDL-lowering drug therapy (may require LDL-lowering drug combination [standard dose of statin with ezetimibe, bile acid sequestrant, or niacin]). I (A)If baseline LDL cholesterol level is 70-100 mg/dL, treating to LDL cholesterol level of IIa (B)If triglyceride levels are 200-499 mg/dL, non-HDL cholesterol level should be I (B)Further reduction of non-HDL cholesterol level to IIa (B)

Therapeutic options to reduce non-HDL cholesterol level are as follows:

More intense LDL cholesterol-lowering therapy, I (B)Niacin (after LDL cholesterol–lowering therapy), IIa (B)Fibrate therapy (after LDL cholesterol–lowering therapy), IIa (B)

If triglyceride levels are 500 mg/dL, therapeutic options to prevent pancreatitis are fibrate or niacin before LDL-lowering therapy, and treat LDL cholesterol level to goal after triglyceride-lowering therapy. Achieve non-HDL cholesterol level of I (C) (Patients with very high triglycerides should not consume alcohol. The use of bile acid sequestrant is relatively contraindicated when triglycerides are >200 mg/dL.) (The combination of high-dose statin plus fibrate can increase risk for severe myopathy. Statin doses should be kept relatively low with this combination. Dietary supplement niacin must not be used as a substitute for prescription niacin.)

In 2011, The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health stopped a clinical trial studying a blood lipid treatment that was adding high-dose, extended-release niacin to statin treatment in people with heart and vascular disease.[103] The study was stopped because the treatment did not reduce the risk of cardiovascular events, including heart attacks and stroke. The AIM HIGH study selected patients at risk for cardiovascular events despite well-controlled LDL ("bad cholesterol"). Participants who took high-dose, extended-release niacin and statin treatment had increased HDL cholesterol and lower triglyceride levels compared with participants who took a statin alone; however, but the combination treatment did not reduce fatal or nonfatal heart attacks, strokes, hospitalizations for acute coronary syndrome, or revascularization procedures to improve blood flow in the arteries of the heart and brain.

Further, The AIM HIGH investigators concluded that patients with atherosclerotic cardiovascular disease and LDL cholesterol levels of less than 70 mg/dL (1.81 mmol/L) experienced no incremental clinical benefit from the addition of niacin to statin therapy, despite significant improvements in HDL cholesterol and triglyceride levels.[104]

A study by Mills et al suggests intensive statin dosing reduces the risk of nonfatal events (coronary heart disease and nonfatal myocardial infarction ) and may have a role in reducing mortality.[105] However, the benefits of high-dose statins must be weighed against the risk of myopathy, including rhabdomyolysis, at high doses.

When LDL-lowering medications are used, obtain at least a 30-40% reduction in LDL cholesterol levels. If LDL cholesterol 50% in LDL cholesterol levels by either satins or LDL cholesterol-lowering drug combinations.

RVX-208, the first oral agent designed to enhance apolipoprotein (apo) A-I synthesis, has shown to increase apoA-I, HDL-C, and concentration of large HDL particles, as well as increase in liver enzymes.[106]

Lowering LDL cholesterol with statin regimens may have an effect in people with moderate-to-severe kidney disease.[107] The Study of Heart and Renal Protection (SHARP) Trial suggests simvastatin (20 mg) plus ezetimibe (10 mg) daily safely reduces the incidence of major atherosclerotic events in a wide range of patients with advanced chronic kidney disease.

Secondary prevention trials in older persons with CAD and hypercholesterolemia have demonstrated that statin drugs reduced all-cause mortality, cardiovascular mortality, coronary events, coronary revascularization, stroke, and intermittent claudication. Statin therapy significantly decreases cardiovascular events and all-cause mortality in both women and men.[108]

Raal et al found that lipid-lowering therapy is associated with delayed cardiovascular events and prolonged survival in patients with homozygous familial hypercholesterolemia.[109]

Physical activity

The goal of physical activity is 30 minutes, 7 days per week (minimum 5 d/w). The US guidelines for physical activity suggest low, moderate, and high activity levels. A meta-analysis by Sattlemair et al attempted to quantify these amounts and found that "some physical activity is better than none" and "additional benefits occur with more physical activity."[110]

For all patients, assess risk with a physical activity history and/or an exercise test to guide prescription. I (B)For all patients, encourage 30-60 minutes of moderate-intensity aerobic activity (eg, brisk walking) on most, preferably all, days of the week, supplemented by an increase in daily lifestyle activities (eg, walking breaks at work, gardening, household work). I (B)Encourage resistance training 2 days per week. IIb (C)Advise medically supervised programs for high-risk patients (eg, recent acute coronary syndrome or revascularization, heart failure). I (B)Weight management

The goal of weight management is body mass index of 18.5-24.9 kg/m2 and waist circumference of [111]

Assess body mass index and/or waist circumference on each visit and consistently encourage weight maintenance or reduction through an appropriate balance of physical activity, caloric intake, and formal behavioral programs when indicated to maintain or achieve a body mass index between 18.5 and 24.9 kg/m2. I (B)If waist circumference (measured horizontally at the iliac crest) is 35 inches in women and 40 inches in men, initiate lifestyle changes and consider treatment strategies for metabolic syndrome as indicated. I (B)The initial goal of weight loss therapy should be to reduce body weight by approximately 10% from baseline. With success, further weight loss can be attempted if indicated through further assessment. I (B)

According to The Aerobics Center Longitudinal Study, maintaining or improving fitness is associated with a lower risk of all-cause and CVD mortality in men. Health care providers should encourage men to exercise regularly, regardless of age, as it is important for longevity regardless of BMI change.[112]

Diabetes management

The goal of diabetes management is to maintain glycosylated hemoglobin (HbA1c) concentration of

Initiate lifestyle and pharmacotherapy to achieve near-normal HbA1c level. I (B)Begin vigorous modification of other risk factors (eg, physical activity, weight management, BP control, and cholesterol management) as recommended above. I (B)Coordinate diabetic care with the patient's primary care physician or endocrinologist. I (C)Antiplatelet agents and anticoagulantsStart aspirin 75-162 mg/d, and continue indefinitely in all patients unless contraindicated. I (A)  For patients undergoing coronary artery bypass grafting, aspirin should be started within 48 hours after surgery to reduce saphenous vein graft closure. Dosing regimens ranging from 100-325 mg/d appear to be efficacious. Doses higher than 162 mg/d can be continued for up to 1 year. I (B)Start and continue clopidogrel 75 mg/d in combination with aspirin for up to 12 months in patients after acute coronary syndrome or percutaneous coronary intervention with stent placement (at least 1 month, but ideally 12 months, for bare metal stent; at least 12 months for drug-eluting stents). I (B)  Patients who have undergone percutaneous coronary intervention with stent placement should initially receive higher-dose aspirin at 162-325 mg/d for 1 month for bare metal stent, 3 months after sirolimus-eluting stent, 6 months after paclitaxel-eluting stent, after which daily long-term aspirin use should be continued indefinitely at a dose of 75-162 mg.[113] I (B)Manage warfarin to international normalized ratio of 2.0-3.0 for paroxysmal or chronic atrial fibrillation or flutter, and in post–MI patients when clinically indicated (eg, atrial fibrillation, left ventricular thrombus). I (A)Use of warfarin in conjunction with aspirin and/or clopidogrel is associated with increased risk of bleeding and should be monitored closely. I (B)A nationwide cohort study suggests NSAID treatment duration in patients with prior myocardial infarction, whether short term or long term, is associated with increased risk of death and recurrent myocardial infarction in patients with prior myocardial infarction and is not recommended for this population.[114] NSAID use should be limited from a cardiovascular safety point of view. Renin, angiotensin, and aldosterone system blockers

Consider the following with ACE inhibitors:

Start and continue indefinitely in all patients with left ventricular ejection fraction ≥40% and in those with hypertension, diabetes, or chronic kidney disease, unless contraindicated. I (A)Consider for all other patients. I (B)Among lower-risk patients with normal left ventricular ejection fraction in whom cardiovascular risk factors are well controlled and revascularization has been performed, use of ACE inhibitors may be considered optional. IIa (B)

Consider the following with angiotensin receptor blockers:

Use in patients who are intolerant of ACE inhibitors and have heart failure or have had an MI with left ventricular ejection fraction ≤40%. I (A)Consider in other patients who are intolerant of ACE inhibitors. I (B)Consider use in combination with ACE inhibitors in systolic dysfunction heart failure. IIb (B)

Aldosterone blockade are used in post-MI patients without significant renal dysfunction (creatinine should be >2.5 mg/dL in men and > 2.0 mg/dL in women) or hyperkalemia (potassium should be [115] I (A)

Beta-blockersStart and continue indefinitely in all patients who have had MI, ACS, or LV dysfunction with or without heart failure symptoms, unless contraindicated. l (A)Consider chronic therapy for all other patients with coronary or other vascular disease or diabetes, unless contraindicated. lla (C)Influenza vaccination

Patients with cardiovascular disease should have an influenza vaccination. I (B)

PreviousNextWomen and Coronary Artery Disease

In the United States, CHD is the leading cause of death in both men and women, claiming more lives than cancer, accidents, and diabetes combined.[116, 117] Although breast cancer may be more feared, age-adjusted death rates from CVD in women are 4 times higher in white women and 6 times higher in black women than the death rates for breast cancer.

The 2010 ACCF/AHA report on assessment of cardiovascular risk in asymptomatic adults includes the recommendation that for all adult women and men, global risk scoring should be performed and a family history of cardiovascular disease should be obtained for cardiovascular risk assessment.[10]

Compared with men, LDL cholesterol is lower and HDL cholesterol is higher in women before menopause. Although women have lower rates of hypertension and cigarette smoking than men, rates for obesity and diabetes mellitus are higher. Diabetes mellitus is a particularly serious risk factor in women, tripling the risk of cardiovascular death and causing diabetic women to have the same frequency of CVD as diabetic men.[118, 119, 120] HDL cholesterol and triglyceride levels are more predictive of CVD in women than in men.[121] Women have been noted to have similar or slightly higher prevalence of stable angina as compared to men.[122]

It is now known that women tend to present more commonly with unstable angina as compared to men, the reverse of which is true for MI. However, when women do present with MI, they are more likely to have Q wave rather than non-Q wave.[123, 124] Mortality rates of MI and CABG are about 50% higher in women, mostly related to older age of onset. Lipid lowering has shown similar efficacy in women and men in the angiographic progression and event trials. Cardioprotective agents, including aspirin, beta-blockers, and ACE inhibitors, appear to have similar efficacy in men and women.[125, 126, 127]

Hormone therapy is no longer recommended to prevent coronary events in postmenopausal women with or without established CHD. Although hormone therapy improves LDL and HDL cholesterol levels[128, 129] , it also increases coagulation and inflammation (as measured by C-reactive protein [CRP]) and decreases LDL particle size.[130, 4] Treatment rates for risk factors in women tend to be even lower than in men, as are rates for coronary angiography and coronary artery revascularization following presentation with chest pain.

Women who may have had radiotherapy through the mid-1980s to treat breast cancer are also at an increased risk of mortality from cardiovascular disease. The concern is even greater if the woman was treated for a left-sided breast cancer with contemporary tangential breast or chest wall radiotherapy.[131]

Finally, it must be emphasized that while the guidelines detailed above represent best practice, their formulation is often a blend of science and art. Therefore, guideline interpretation should always occur alongside good clinical judgment.

Previous Contributor Information and DisclosuresAuthor

Tamam N Mohamad, MD  Fellow, Department of Cardiology, Wayne State University, Detroit Medical Center
Tamam N Mohamad, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians-American Society of Internal Medicine, American Medical Association, Michigan State Medical Society, and National Arab American Medical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Luis C Afonso, MD  Assistant Professor, Department of Internal Medicine-Cardiology, Program Director of Cardiology Fellowship Program, Wayne State University; Director of Echocardiography Laboratory, Harper University Hospital
Luis C Afonso, MD is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Medical Association, and American Society of Echocardiography
Disclosure: Nothing to disclose.

Pretti Ramappa, MD  Fellow, Department of Cardiology, Detroit Medical Center, Wayne State University
Pretti Ramappa, MD is a member of the following medical societies: American College of Cardiology and American College of Physicians
Disclosure: Nothing to disclose.

Pawan Hari, MD, MPH  Resident Physician, Department of Internal Medicine, Wayne State University School of Medicine
Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Medscape Salary Employment

Brian Olshansky, MD  Professor of Medicine, Department of Internal Medicine, University of Iowa College of Medicine
Brian Olshansky, MD is a member of the following medical societies: American College of Cardiology, American Heart Association, Cardiac Electrophysiology Society, and Heart Rhythm Society
Disclosure: Guidant/Boston Scientific Honoraria Speaking and teaching; Medtronic Honoraria Speaking and teaching; Guidant/Boston Scientific Consulting fee Consulting; BioControl Consulting fee Consulting; Boehringer Ingelheim Consulting fee Consulting; Amarin Consulting fee Review panel membership; sanofi aventis Review panel membership

Amer Suleman, MD  Private Practice
Amer Suleman, MD is a member of the following medical societies: American College of Physicians, American Heart Association, American Institute of Stress, American Society of Hypertension, Federation of American Societies for Experimental Biology, Royal Society of Medicine, and Society of Cardiac Angiography and Interventions
Disclosure: Nothing to disclose.

Chief Editor

Yasmine Subhi Ali, MD, MSCI, FACC, FACP  President, Nashville Preventive Cardiology, PLLC; Assistant Clinical Professor of Medicine, Vanderbilt University School of Medicine
Yasmine Subhi Ali, MD, MSCI, FACC, FACP is a member of the following medical societies: American College of Cardiology, American College of Physicians, American Heart Association, American Medical Association, National Lipid Association, and Tennessee Medical Association
Disclosure: Nothing to disclose.

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Saturday, February 15, 2014

Background

In patients with peripheral arterial disease, obstructing plaques caused by atherosclerotic occlusive disease commonly occur in the infrarenal aorta and iliac arteries. Atherosclerotic plaques may induce symptoms either by obstructing blood flow or by breaking apart and embolizing atherosclerotic and/or thrombotic debris to more distal blood vessels. If the plaques are large enough to impinge on the arterial lumen, reduction of blood flow to the extremities occurs. Several risk factors exist for development of the arterial lesions, and recognition of these factors enables physicians to prescribe nonoperative treatment that may alleviate symptoms as well as prolong life.

Surgical treatment of aortoiliac occlusive disease (AIOD) has been well standardized for many years, and the outcomes are quite good. However, the additional techniques of percutaneous transluminal angioplasty (PTA) and stenting have offered more alternatives to open surgery and offer successful techniques to patients who may have been considered at an unacceptably high risk for conventional open surgical repairs. Catheter-based endovascular treatments for aortoiliac occlusive disease (AIOD) offer the advantages of less morbidity, faster recovery, and shorter hospital stays. In fact, most endovascular interventions today are simply performed as outpatient procedures. This chapter reviews the risk factors for development of atherosclerotic occlusive disease of the aorta and iliac arteries and describes the natural history, diagnosis, and treatment of the disease.

An image depicting atherosclerosis can be seen below.

Type I atherosclerosis with occlusive disease limiType I atherosclerosis with occlusive disease limited to the infrarenal aorta and common iliac arteries.

For excellent patient education resources, visit eMedicineHealth's Cholesterol Center. Also, see eMedicineHealth's patient education articles High Cholesterol and Cholesterol FAQs.

NextHistory of the Procedure

Before prosthetic grafts for aortic bypasses became available, the first direct surgical reconstructions on the aorta were performed using the technique of thromboendarterectomy (TEA), first described by Dos Santos of Lisbon in 1947.[1] The initial procedure was performed on a patient with superficial femoral artery (SFA) obstruction, and Dos Santos termed the procedure disobliteration. Edwin J. Wylie, MD, adapted this technique to the aortoiliac region and, in 1951, performed the first aortoiliac endarterectomy in the United States.[2] With the discovery of suitable prosthetic graft materials for aortic replacement in the 1960s, surgical treatment of aortoiliac occlusive disease (AIOD) became available to even more patients.

In 1964, Dotter first performed percutaneous iliac angioplasty using a coaxial system of metal dilators.[3] This procedure proved to have limited application due to the cumbersome nature of the device. However, Dotter's early work paved the way for Grüntzig, who, in 1974, developed a catheter with an inflatable polyvinyl chloride balloon that could be passed over a guidewire.[4] This device became the cornerstone for the percutaneous treatment of arterial occlusive lesions today. In 1985, Julio Palmaz introduced the first stent that helped to improve the results of angioplasty for arterial occlusive disease.[5] Since the advent of angioplasty and stenting, the technology has evolved at an astronomical rate. The design and quality of endovascular devices, as well as the ease and accuracy of performing the procedures, have improved. These improvements have led to improved patient outcomes following endovascular interventions for aortoiliac occlusive disease (AIOD).

PreviousNextProblem

Aortoiliac occlusive disease (AIOD) occurs commonly in patients with peripheral arterial disease (PAD). Significant lesions in the aortoiliac arterial segment are exposed easily by palpation of the femoral pulses. Any diminution of the palpable femoral pulse indicates that a more proximal obstruction exists. Obstructive lesions may be present in the infrarenal aorta, common iliac, internal iliac (hypogastric), external iliac, or combinations of any or all of these vessels. Occasionally, degenerated nonstenotic atheromatous disease exists in these vessels and may manifest by atheroembolism to the foot, the "blue toe" or "trash foot" syndrome.

Aboyans et al found that patients with aortoiliac peripheral arterial disease (PAD) have a poorer general prognosis than those with more distal PAD. Their review of 400 patients with PAD showed that after adjustment for age, sex, cardiovascular disease history and risk factors, critical leg ischemia status, and treatments, proximal PAD was significantly associated with a worse prognosis (hazard ratio [HR] for death, nonfatal myocardial infarction or stroke, and coronary or carotid revascularization: 3.28; HR for death ratio: 3.18, p [6]

PreviousNextEpidemiologyFrequency

At least half of patients with peripheral arterial disease (PAD) have no symptoms, and, therefore, the exact incidence and prevalence of the condition is unknown. However, the incidence of PAD is known to increase with advancing age so that, by age 70 years, as many as 25% of the US population is affected. Occlusive disease involving the aortoiliac arterial segment occurs commonly in patients with peripheral arterial disease (PAD) and is second only to occlusive disease of the SFA in frequency.

PreviousNextEtiology

Atherosclerosis is the most common etiology of occlusive plaques in the aorta and iliac arteries. Several risk factors exist for the development of atherosclerotic plaques in the aortoiliac arterial segment. Cigarette smoking and hypercholesterolemia are observed more commonly in patients with aortoiliac occlusive disease (AIOD) as compared with infrainguinal occlusive disease. In addition, patients with aortoiliac occlusive disease (AIOD) tend to be younger and less likely to have diabetes.

An uncommon cause of aortic obstruction is Takayasu disease, a nonspecific arteritis that may cause obstruction of the abdominal aorta and its branches. The etiology of Takayasu disease is not known. For the purpose of this chapter, only occlusive lesions caused by atherosclerosis are considered.

PreviousNextPathophysiology

Atherosclerosis is an extraordinarily complex degenerative disease with no known single cause. However, many variables are known to contribute to the development of atherosclerotic lesions. One popular theory emphasizes that atherosclerosis occurs as a response to arterial injury. Factors that are known to be injurious to the arterial wall include mechanical factors such as hypertension and low wall shear stress, as well as chemical factors such as nicotine, hyperlipidemia, hyperglycemia, and homocysteine.

Lipid accumulation begins in the smooth muscle cells and macrophages that occur as an inflammatory response to endothelial injury, and the "fatty streak" begins to form in the arterial wall. The atheroma consists of differing compositions of cholesterol, cholesterol esters, and triglycerides. Some plaques are unstable, and fissures occur on the surface of the plaque that expose the circulating platelets to the inner elements of the atheroma. Platelet aggregation then is stimulated. Platelets bind to fibrin through activation of the glycoprotein (Gp) IIb/IIIa receptor on the platelets, and a fresh blood clot forms in the area of plaque breakdown. These unstable plaques are prone to atheromatous embolization and/or propagation of clot that eventually can occlude the arterial lumen.

If the atheroma enlarges enough to occupy at least 50% of the arterial lumen, the flow velocity of blood through that stenosis can significantly increase. The oxygen requirements of the lower extremity at rest are low enough that even with a moderate proximal stenosis, no increase in blood flow velocity occurs. During exercise, however, the oxygen debt that occurs in ischemic muscle cannot be relieved because of the proximal obstruction of blood flow; this results in claudication symptoms. In more advanced cases, critical tissue ischemia occurs, and neuropathic rest pain or tissue loss ensues. However, critical limb ischemia is seldom, if ever, caused by aortoiliac occlusive disease (AIOD) alone. Commonly, in patients with critical limb ischemia, multiple arterial segments are involved in the occlusive atherosclerotic process.

PreviousNextPresentation

The most common symptom of patients with hemodynamically significant aortoiliac disease is claudication. The word claudication stems from the Latin word claudicatio, to limp. The symptom complex of claudication is defined as muscle cramps in the leg(s) that occur following exercise and are relieved by resting. In any individual patient, the exercise distance at which claudication occurs is quite constant. Claudication usually occurs first in the calf muscles, although thigh, hip, and buttocks muscles also can be affected when more extensive proximal lesions are present. Location of the muscle pain (ie, calf vs thigh) does not necessarily correlate with the level of arterial obstruction. However, more proximal symptoms (ie, buttocks or thigh claudication) are generally associated with severe aortoiliac occlusive disease.

Symptoms of buttock claudication can occur in association with erectile dysfunction in patients with absent femoral pulses. This constellation of symptoms is termed Leriche syndrome, named for the surgeon who described the condition in 1923. Leriche syndrome occurs when either preocclusive stenosis or complete occlusion of the infrarenal aorta is present due to severe aortic atherosclerosis. Due to the chronic nature of the occlusive process leading to development of rich collateral vessels that supply the lower extremity, limb-threatening ischemia seldom occurs.

PreviousNextIndications

Treatment of patients with peripheral arterial disease (PAD) has 2 goals. The first and foremost goal is to reduce the risk of vascular events (myocardial infarction, stroke, vascular death) that occur at an alarmingly high rate in patients with PAD. About 30% of patients with peripheral arterial disease (PAD) die within 5 years, and death is usually due to an ischemic coronary event.

The second goal of treatment is to improve symptoms in those patients with claudication and prevent amputation in patients with critical limb ischemia. Critical limb ischemia is present when patients have symptoms of ischemic rest pain, nonhealing foot ulcers, or gangrene, and its presence mandates urgent evaluation with aortography and endovascular and/or surgical revascularization to prevent limb loss.

At least half of patients with peripheral arterial disease (PAD) are asymptomatic and are diagnosed only by physical examination and/or measurement of the ankle/brachial index (ABI). An ABI less than 0.9 clearly is abnormal and confirms the diagnosis of peripheral arterial disease (PAD). An abnormal ABI should alert the clinician to the fact that this group of patients is at risk for early mortality from cardiovascular causes, ie, myocardial infarction, stroke, other vascular death. The goal for treatment of asymptomatic patients is to reduce the risk of subsequent vascular events.

PreviousNextRelevant Anatomy

Three distinct arterial segments distal to the visceral bearing portion of the abdominal aorta may become diseased by atherosclerosis. Type I atherosclerosis involves the infrarenal aorta and common iliac arteries only. This pattern of atherosclerosis is present in about 5-10% of patients with peripheral arterial disease (PAD) and occurs more commonly in women. The vessels distal to the common iliac arteries usually are generally normal or only minimally diseased. Type II atherosclerosis involves the infrarenal aorta, common and external iliac arteries, and may extend into the common femoral arteries. This pattern is observed in 35% of patients with peripheral arterial disease (PAD). Type III atherosclerosis is the most severe form and, unfortunately, also the most common. This pattern of atherosclerosis involves the infrarenal aorta, iliac, femoral, popliteal, and tibial arteries.

Diabetes mellitus is a risk factor that results in a characteristic pattern of atherosclerotic lesions in patients with peripheral arterial disease (PAD). The proximal inflow (aorta, iliac) arteries tend be normal. However, the femoropopliteal segment (including the profunda femoris artery), and especially the proximal tibial arteries, are usually severely diseased. Fortunately, the distal tibial and plantar vessels may be normal, enabling successful arterial reconstruction for limb-threatening ischemia.

PreviousNextContraindications

At least 50% of patients with peripheral arterial disease (PAD) may be asymptomatic. Because natural history data are poor for iliac stenosis, surgical and/or endovascular intervention should not be considered if patients truly are asymptomatic. Surgical intervention for limb-threatening ischemia is accepted universally, unless the limb is deemed nonviable. Determining whether or not to intervene in a patient with mild claudication may not be as straightforward.

An important role exists for conservative therapy in patients with aortoiliac occlusive disease (AIOD). Although surgical therapy usually alleviates symptoms, the patient must be apprised of the operative risk of mortality (2-3%) as well as anticipated outcomes over time. Since the advent of catheter-based treatments for aortoiliac occlusive disease (AIOD), asymptomatic patients are often treated prophylactically with either angioplasty or stenting of iliac arterial lesions that are discovered during coronary angiography. This practice of drive-by angioplasty should not be recommended.

PreviousProceed to Workup , Aortoiliac Occlusive Disease

Tuesday, February 11, 2014

Overview

The 2 primary modalities for revascularization are coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI). This article briefly discusses the history, indications, applications, and current status of these revascularization procedures. Rapid advances are being made in both PCI and surgical revascularization, and such advances are likely to continue in the years to come.

Completely bioabsorbable stent struts are being developed.[1] Bioabsorbable magnesium stents are being evaluated.[2, 3] The advantages of biodegradable polymers include high drug-loading capacity, controlled long-term drug release, and full degradation of the polymer over a defined period, resulting in full release of the drug during a well-controlled time interval.[3]

Thromboresistant polymer coatings based on biologic substances such as fibrin, collagen, hyaluronic acid, and biologic oils are being tested. These polymers serve as drug delivery reservoirs for drugs that inhibit neointimal hyperplasia through suppression of platelet activation and the inflammatory response and through inhibition of smooth muscle cell migration and proliferation.

The effect of variable dose and release kinetics of drugs on neointimal hyperplasia is also being studied.[4] Multiple drugs may be delivered at timed intervals through newly designed stents.

Gene-eluting stents[5] are undergoing experimental and clinical trials; these will be usable either alone or in conjunction with other drug-eluting stents (DESs) and may further reduce in-stent restenosis (ISR). The ABSORB trial studied the safety of the bioabsorbable everolimus-eluting stent.[6] At 2 years, the stent was bioabsorbed, with vasomotion restored and restenosis prevented, and was clinically safe, suggesting freedom from late thrombosis.

The TRITON-TIMI 38 trial[7] showed that in patients with acute coronary syndromes with scheduled PCI, prasugrel therapy was associated with significantly reduced rates of ischemic events, including stent thrombosis, but with an increased risk of major bleeding, including fatal bleeding. Overall mortality did not differ significantly between treatment groups. Prasugrel has been approved by the US Food and Drug Administration (FDA). Other antithrombotics are in the pipeline.

Most acute coronary syndromes are caused by rupture of unstable plaques of mild-to-moderate stenosis ([8] Stenting of such vulnerable lesions might result in stabilization and prevention of plaque rupture. Likewise, rapid advances have been made in surgical techniques. In the future, PCI and CABG may come to be seen as complementary techniques for myocardial revascularization.

NextSurgical Revascularization

In 1953, William Mustard performed the first direct surgical approach to the coronary circulation: a carotid-to-coronary bypass in a patient in Toronto. In 1962, the first surgical myocardial revascularization procedure, the patch graft technique, was performed to repair an obstruction of the left main trunk coronary artery.[9] Subsequently, saphenous vein graft (SVG) interposition became the dominant approach.

Shortly thereafter, coronary artery bypass grafting (CABG) became the most commonly performed surgical procedure in the United States. Subsequently, advantages of using the left internal mammary artery (LIMA) were demonstrated.[10] Better long-term patency rates and improved late survival were achieved by using the LIMA than by using SVGs.

Since 1986, the LIMA has been used in more than 90% of CABG procedures. Less frequently, the right internal mammary artery (RIMA) is used. However, a large study found that the RIMA is as good as the LIMA for CABG and better than either radial arteries or veins. Radial artery grafts have about the same 1-year patency rates as SVGs.[11]

Use of both the RIMA and the LIMA raises concerns about possible impaired sternotomy healing and infection, but it may be considered if the risk of not using both vessels outweighs the 2.5% risk of infection (eg, if the patient does not have good vein conduits and the LIMA is not sufficient for the number of bypass touchdown sites needed).[12] Most CABG operations involve placement of 1 or more SVG grafts in addition to use of the LIMA.

Indications

In 2004, the American College of Cardiology (ACC) and the American Heart Association (AHA) published guidelines for CABG, which divide indications into 3 classes.[13]

Class I indications are as follows:

Left main coronary artery disease (LMCAD) with 50% or greater narrowingAnatomically equivalent LMCAD with 70% or greater narrowing in both the proximal left anterior descending (LAD) coronary artery and the left circumflex artery 3-vessel coronary artery disease (CAD), particularly in the setting of an impaired left ventricular ejection fraction (LVEF)

Class II indications are as follows:

Proximal LAD coronary artery stenosis (impaired LVEF becomes a class I indication)1-vessel or 2-vessel CAD that does not involve the proximal LAD coronary artery if a moderate area of viable myocardium is at risk

Class III indications are as follows:

1-vessel or 2-vessel CAD that does not involve the proximal LAD coronary artery1-vessel or 2-vessel CAD that does not involve the proximal LAD coronary artery with only a small area of viable myocardium

The expected benefit from surgery must be weighed against its morbidity and mortality. Improvements in operative techniques and technologies have allowed surgical treatment of more difficult cases.

Early studies comparing CABG with coronary intervention for multivessel disease demonstrated that the 2 strategies had similar mortalities but that there was an increased need for repeat procedures in the angioplasty and bare-metal stent (BMS) arms.[14, 15] Some studies have demonstrated improved mortality in diabetic subgroups that undergo surgical revascularization, though those findings have not been universal.

Before the widespread use of drug-eluting stents, the main advantages of CABG over percutaneous coronary intervention (PCI) included a lower rate of repeat procedures, greater success with chronically occluded coronary arteries, and protection of the entire vessel proximal to the distal anastomosis of a mammary graft. The primary disadvantage of CABG is the higher rate of upfront risks and complications.

Drug-eluting stents have improved PCI results, particularly with regard to repeat revascularization, and there is hope that a decrease in restenosis with drug-eluting stents (DESs) will reduce the need for repeat procedures in patients with multivessel disease that was treated with PCI. Large clinical trials comparing surgery and PCI with DESs (eg, SYNTAX, CARDIA, FREEDOM, and VA CARDS)[16, 17, 18] should provide more data on this critical issue.

Results from the SYNTAX trial showed that the rates of major adverse cardiac or cerebrovascular events at 12 months were significantly higher in the PCI group (17.8% vs 12.4% for CABG), in large part because of an increased rate of repeat revascularization (13.5% vs 5.9%).[16] At 12 months, the rates of death and myocardial infarction (MI) were comparable in the 2 groups; stroke was significantly more likely to occur with CABG (2.2% vs 0.6% with PCI).

Minimally invasive coronary artery bypass grafting

Advances in CABG have enabled surgeons to avoid having to perform a median sternotomy, thereby reducing pain and respiratory complications and preventing the large scar associated with this incision. Minimally invasive CABG includes surgical techniques that allow access to the heart through small thoracotomy incisions with endoscopic robotic surgery using a computer-enhanced telemanipulation system.[19, 20, 21]

Off-pump CABG (OPCABG) usually involves a medial sternotomy but avoids cardiopulmonary bypass (CPB), thus perhaps reducing bleeding and the frequency of renal failure. Minimally invasive direct CABG (MIDCABG) can be performed with or without CPB.

Robotic CABG

In robotic CABG, the surgeon, seated at a computer console, introduces instruments through small incisions in the chest and manipulates them with robotic arms. Early results of robotic coronary endoscopic surgery were successful on anterior vessels, and this success led to the development of complete multivessel endoscopic CABG.[19, 20, 21]

Minimally invasive direct CABG

In MIDCABG without CPB, the LIMA is harvested under direct visualization through a small left anterior thoracotomy incision or via an endoscopic approach through a small porthole incision. One end of a free segment of the inferior epigastric artery, the radial artery, or the saphenous vein is attached in an end-to-side fashion to the LIMA (which is anastomosed to the left anterior descending [LAD] artery), and the other end extends the bypass to other accessible coronary arteries (eg, diagonal or circumflex branches), in the form of a T or Y graft.[22]

Small thoracic incisions substantially reduce the morbidity related to median sternotomy and offer a quicker recovery, though wound complications occur in as many as 9% of patients.[23] Although other arteries can be accessed, the anterior MIDCABG approach is best suited for the anterior coronary vessels.

MIDCABG without CPB is primarily performed in the following circumstances:

For anterior lesions (lesions of the LAD in particular) when PCI is unsuitable for technical or other reasonsFor patients in whom traditional bypass cannot be performed safely because of major comorbidities associated with high surgical risk[24] For reoperation, when sternotomy or CPB is contraindicated because of the risk of jeopardizing bypass grafts, cardiac structures adherent to the sternum, previous sternal wound infection, mediastinal radiation therapy, or a calcified or diffusely atherosclerotic aorta[25, 26]

MIDCABG to the LAD in conjunction with PCI of the right coronary artery or left circumflex artery is also performed.[27, 28] This procedure is done off the pump through a small anterior thoracotomy. Typically, MIDCABG offers access only to the LAD and diagonal coronary arteries. Hybrid MIDCABG is not widely used, because of limited exposure and the increased difficulty of harvesting the mammary artery. Furthermore, thoracotomy may cause more pain than sternotomy.

When MIDCABG is done through a limited anterior thoracotomy with CPB, antegrade and retrograde cardioplegia is delivered to produce optimal myocardial protection. The empty decompressed heart is still and bloodless. This approach offers enhanced myocardial protection, better access, and greater freedom to manipulate and expose the entire heart, which is necessary for multivessel CABG.

Off-pump CABG

OPCABG is performed via a conventional median sternotomy, which facilitates harvest of the internal mammary artery and access to all coronary arteries. Specialized cardiac retraction and myocardial stabilization platforms improve the accuracy and ease of distal anastomosis on the beating heart,[29, 30] facilitating the achievement of complete standard anastomoses. Temporary endovascular shunts are used to limit myocardial ischemia.

In the Surgical Management of Arterial Revascularization Therapies (SMART) trial, 197 patients were randomly assigned to either OPCABG or conventional CABG performed by a single surgeon; a mean of 3.2 grafts per patient were placed.[31] Rates of death, stroke, MI, recurrent angina, and revascularization at 30 days and 1 year were similar. The quality of life was comparable in the 2 groups, and the cost of care was modestly reduced with OPCABG.

The main advantage of OPCABG is that it prevents complications of artificial perfusion and CPB, including reductions in inflammatory response, postoperative infection, and atrial fibrillation.[32, 33]

The Society of Thoracic Surgeons database revealed that CABG without CPB (ie, beating-heart surgery) represented 10% of all CABG procedures in the United States from 1998 to 1999.[34] This number increased to approximately 25% of isolated CABG procedures in 2001.[35]

In a single-center randomized trial, 308 patients undergoing CABG were randomly assigned to OPCABG and CPB; no difference was found between groups with respect to the combined endpoint of death, MI, further revascularization (surgery or angioplasty), or stroke at 5-year follow-up.[36]

Port-access CABG

In port-access CABG, the grafting is performed through small incisions, but with conventional CPB. The connections to the bypass machine are made through the femoral vessels rather than through the open chest. This approach is time-consuming, technically difficult, and potentially risky for patients with lower-extremity arterial or venous insufficiency. Consequently, it has not been widely applied.

PreviousNextPercutaneous Coronary Intervention

In 1977, Andreas Grüntzig performed the first coronary angioplasty as a nonsurgical method for coronary artery revascularization.[37] In 2005, more than 600,000 percutaneous coronary intervention (PCI) procedures were performed in the United States. Originally, angioplasty was performed only in stable patients with a single discrete, noncalcified, proximal, concentric lesion in a single vessel; currently, such patients constitute a minority of those undergoing PCI.

Balloon angioplasty and coronary stenting are the mainstays of PCI. Other technologies include devices that ablate plaque (atherectomy), devices that remove clots from vessels (thrombectomy), and devices that capture and remove embolic debris (embolic protection).

Indications

Class I indications for PCI are as follows[38] :

Patients with class II-IV angina or acute coronary syndrome with 1 or more significant lesions in 1 or more coronary arteries suitable for PCI Patients with acute ST-segment elevation myocardial infarction (STEMI) who can undergo angioplasty of the infarct artery within 12 hours of symptom onset or patients who have recurrent ischemia or infarction (rescue PCI) Patients older than 75 years who develop cardiogenic shock within 36 hours of an acute STEMIPatients with early ischemia (usually within 30 days) after CABG

Class II indications for PCI are as follows:

Patients with focal saphenous vein graft (SVG) lesions or multiple stenosis who are poor candidates for reoperationThe presence of 1 or more lesions with reduced likelihood of success, or vessel or vessels subtending a less-than-moderate area of viable myocardium Patients with STEMI in whom thrombolytic therapy is contraindicatedPatients with STEMI who experience cardiogenic shock or hemodynamic instability after thrombolysisPatients with ischemia occurring 1-3 years postoperatively and preserved left ventricular function with discrete lesions in graft conduits Patients with disabling angina secondary to new disease in a native coronary circulation

Class III indications for PCI are as follows:

Patients with no evidence of myocardial injury or ischemia on objective testing who have not undergone a trial of medical therapy, who have a small amount of salvageable myocardium, or who are at high risk of procedural success or morbidity or mortality Patients with insignificant coronary stenosisPatients with significant left main coronary artery disease (CAD) who are candidates for coronary artery bypass grafting (CABG)Patients who opt for elective PCI of a non–infarct-related artery at the time of myocardial infarction (MI)Patients with no evidence of myocardial ischemia after 12 hours of MI or routine PCI of the infarct artery after thrombolytic therapy Patients with total vein graft occlusions

A large multicenter cohort study evaluating data from patients 65 years or older who underwent elective PCI procedures suggests that same-day discharge can be considered for select patients who have low-risk clinical features, successful procedures without prolonged postprocedure use of parenteral antithrombotic agents, and adequate social support.[39]

Balloon angioplasty

The original technique of balloon angioplasty involved advancing a balloon-tipped catheter to an area of coronary narrowing, inflating the balloon, and then removing the catheter after deflation. Balloon angioplasty can reduce the severity of coronary stenosis, improve coronary flow, and diminish or eliminate objective and subjective manifestations of ischemia. To refine PCI techniques, medications and devices that replace or serve as adjuncts to the balloon catheter continue to be developed.

The mechanism of balloon angioplasty action involves 3 events: plaque fracture, compression of the plaque, and stretching of the vessel wall.[40] These lead to expansion of the external elastic lumina and axial plaque redistribution along the length of the vessel.

Coronary stenting

Coronary stents are metallic scaffolds that are deployed within a diseased coronary artery segment to maintain wide luminal patency (see the first image below). They were devised as permanent endoluminal prostheses that could seal dissections, create a predictably large initial lumen, and prevent early recoil and late vascular remodeling so as to improve on both the early and the late results of balloon angioplasty (see the second image below).

Metallic stent. Metallic stent. Deployment of stent in area of significant stenosiDeployment of stent in area of significant stenosis.

Stents have become the most important development in interventional cardiology since the development of the balloon and the steerable guide wire systems. The first human coronary stent implants occurred in 1986 in France. The stent was an interwoven, helical, self-expanding design (Wallstent). A wire coil stent was used in 1987 in the United States. Stents were first applied to treat arteries that become acutely occluded after angioplasty.

Drug-eluting stents (DESs) elute medication to reduce restenosis within the stents (see the image below). Local release of rapamycin and its derivatives or of paclitaxel from a polymer matrix on the stent during the 30 days after implantation reduces inflammation and smooth muscle cell proliferation within the stent, decreasing in-stent late loss of luminal diameter from the usual 1 mm to as little as 0.2 mm. This dramatically lowers the restenosis rate after initial stent implantation or after secondary implantation of a DES for an in-stent restenosis.[41]

TAXUS Express paclitaxel-eluting coronary stent. TAXUS Express paclitaxel-eluting coronary stent.

A meta-analysis of 16 randomized trials suggested that sirolimus-eluting stents are superior to paclitaxel-eluting stents in terms of a significant reduction in the risk of reintervention and stent thrombosis. The risk of death was not significantly different between the 2 DESs, but there was a trend toward a higher risk of MI with paclitaxel-eluting stents, especially in the first year after the procedure.[42]

Everolimus is a derivative of sirolimus and has immunosuppressive and antiproliferative properties. The SPIRIT III trial randomly assigned 1002 patients with 1 or 2 de novo coronary artery lesions to everolimus-eluting low-profile, thin-strut stents or to paclitaxel-eluting polymer-based stents.[43] The everolimus stents yielded significantly better event-free survival rates at 2-year follow-up, with evidence of continued divergence of hazard curves for target vessel failure and major adverse cardiac events between 1 and 2 years.[43]

The ENDEAVOR II trial randomly assigned almost 1200 patients to the zotarolimus-eluting stent or the same bare-metal stent (BMS) without the drug; at 9 months, target lesion revascularization was significantly lower with the zotarolimus stent (4.6 vs 11.8%). The above 4 stents are presently the approved DESs in the United States, although additional DESs are in the pipeline.

In the ZEST trial, Park et al observed that zotarolimus-eluting stents had similar rates of major adverse cardiac events (ie, death, myocardial infarction, ischemia-driven revascularization) at 12 months as compared with sirolimus-eluting stents and lower rates of such events as compared with paclitaxel-eluting stents.[44]

Clinical trials have found DESs to be superior to BMSs for preventing in-stent restenosis and target vessel revascularization. In most studies, DESs reduced the need for repeat revascularization by more than 50% (to less than 5%) as compared with BMSs.[45, 46, 47] This is the chief reason for the reduction in major adverse cardiac events in the first 2 years after PCI in patients receiving DESs as opposed to BMS.[48] Clinical introduction of DESs correlates with a decline in referrals for CABG.[49]

Some reports have questioned the safety of DESs, suggesting that these devices are more frequently associated with stent thrombosis.[41, 50, 51] However, extended follow-up of patient cohorts to 4 years confirms the sustained benefit of DESs in decreasing the need for repeat revascularization without excess death or MI.[41, 52, 53]

A meta-analysis by Lee et al suggests that DESs have advantages over BMSs in SVG interventions.[54] In a comparison of the 2 stent types that involved 19 studies including 3,420 patients, target vessel revascularization was less frequently performed in patients who had undergone intervention with a DES, and the incidence of MI was lower. No differences were found in the risk of death or stent thrombosis.

Concern are still being raised that subsets of patients may be at increased risk for stent thrombosis if DESs are used in higher-risk off-label indications (eg, bifurcations, long lesions, small-diameter vessels, vein grafts, or restenotic disease). Hence, larger and longer follow-up studies of patients incorporating standard definitions of stent thrombosis and close monitoring of antiplatelet therapy compliance are needed.[55]

An analysis based on the database of the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry concluded that even among patients with off-label indications, the use of DESs was not associated with a higher risk of death or MI than the use of BMSs but was associated with a lower rate of repeat revascularization at 1 year.[56] Various clinical trials have revealed that results of stent implantation depend on the patient’s risk profile, lesion characteristics, and other components of the coronary anatomy.

An important issue that remains to be resolved is the duration of dual antiplatelet therapy after DES implantation. Current guidelines recommend the administration of clopidogrel 75 mg/day to all post-PCI patients receiving a stent. Clopidogrel 75 mg/day should be given for at least 12 months if the patient is not at high risk for bleeding after receiving a DES.

For post-PCI patients receiving a BMS, clopidogrel should be given for a minimum of 1 month and ideally for as long as 12 months (unless the patient is at increased risk for bleeding, in which case the drug should be given for a minimum of 2 weeks). However, the optimal duration of clopidogrel therapy after 1 year has not been established and should depend on the risk–benefit ratio for the individual patient.

An open discussion about the need for and risks of dual antiplatelet therapy before placement of stents, especially DESs, should be undertaken by the physician. When patients are unwilling to or unable to comply with prolonged dual antiplatelet therapy, a BMS is preferred to a DES. See the images below.

Angioplasty versus stenting

In 1989, 2 randomized trials, the Stent Restenosis Study (STRESS) and the Belgium Netherlands Stent (BENESTENT) Study, compared stenting with balloon angioplasty, and their findings led to the approval of coronary stents.[57, 58] The superiority of stents in these trials was, at best, marginal. They reduced restenosis of the coronary artery without improving clinical outcome, at the cost of a higher rate of sudden coronary thrombosis and a marked increase in hemorrhagic complications resulting from drugs administered to prevent stent thrombosis.

Subsequent refinements in stent strategies improved clinical results dramatically. High-pressure poststent balloon inflations to provide complete expansion of stent devices[59] and replacement of warfarin by a thienopyridine (first ticlopidine, then clopidogrel) reduced stent thrombosis and hemorrhagic complications.

Compared with angioplasty, current BMSs reduce the frequency of restenosis and the need for a repeat revascularization procedure by approximately 50% (from 20-30% to 10-15%). Emergency coronary bypass rates have been brought down below 0.5%, coronary occlusion occurs less now with stents than it did with balloon angioplasty, and vascular complications arise less commonly than ever before. The improvement in outcomes with stents resulted in rapid transition from the traditional balloon angioplasty to PCI with stenting.

Currently, coronary stents are used in about 90% of interventional procedures. Stent-assisted coronary intervention has now replaced CABG as the most common revascularization modality in patients with coronary artery disease (CAD) and is used in patients with multivessel disease and complex coronary anatomy.

Other technologies

Atherectomy

The directional coronary atherectomy (DCA) catheter was first used in human peripheral vessels in 1985 and in coronary arteries in 1986.[60] In this procedure, a low-pressure positioning balloon presses a windowed steel housing up against the lesion; any plaque that protrudes into the window is shaved from the lesion by a spinning cup-shaped cutter and trapped in the device’s nose cone.

The Coronary Angioplasty Versus Excisional Atherectomy Trial (CAVEAT) demonstrated that atherectomy led to a higher rate of early complications, increased cost, and provided no apparent clinical benefit after 6 months of follow-up observation.[61] By 1994, stenting produced results similar to those of DCA, with fewer complications. Coronary DCA is rarely performed at present.

Rotational atherectomy uses a high-speed mechanical rotational stainless steel burr with a diamond chip–embedded surface. The burr is attached to a hollow flexible drive shaft that permits it to be advanced over a steerable guide wire with a platinum coil tip. The drive shaft is encased within a Teflon sheath through which flush solution is pumped to lubricate and cool the drive shaft and burr. A compressed air turbine rotates the drive shaft at 140,000-200,000 rpm during advancement across the lesion.

Rotational atherectomy is used in fewer than 5% of patients with PCI but is invaluable in patients with heavily calcified blockages, particularly those in which a balloon cannot be inflated.

Laser ablation

In laser ablation, an intense light beam travels via optical fibers within a catheter and enters the coronary lumen. After the target lesion is crossed with the guide wire, the laser catheter is advanced to the proximal end of the lesion. Blood and contrast medium are removed from the target vessel by flushing with saline before activating the laser. In view of their substantial cost and the lack of clinical benefit in comparison with other mechanical therapies, ablative laser techniques have not entered mainstream practice.

Mechanical thrombectomy

Intracoronary thrombi may be treated with mechanical thrombectomy devices (including rheolytic, suction, and ultrasonic thrombectomy devices). Although demonstrating the efficacy of such devices in randomized trials is difficult, dramatic results are often obtained in individual cases.

In rheolytic thrombectomy, high-speed water jets create suction via the Bernoulli-Venturi effect. The jets exit orifices near the catheter tip and spray back into the mouth of the catheter, creating a low-pressure region and intense suction. This suction pulls surrounding blood, thrombus, and saline into the tip opening and propels particles proximally through the catheter lumen and out of the body.

The catheters used for suction thrombectomy act via manual aspiration. They are advanced over a wire to the intracoronary thrombus, then passed through the thrombus while suction is applied to a hole in the catheter tip. Large intact thrombus fragments can be removed by means of this technique.

Ultrasonic thrombectomy involves the use of ultrasonic vibration to induce cavitation that can fragment thrombus into smaller components. The efficacy of this technique remains unproven and is under investigation.[62]

Embolization protection

Balloons and stents dislodge fragments of friable plaque or thrombus. Particle embolization appears to be one of the main causes of no-reflow and elevation of cardiac enzyme levels during SVG intervention.[63, 64] Several devices have been developed, undergone clinical trial evaluation, and gained regulatory approval for trapping such embolic material and removing it from the circulation (see the image below).

Emboli captured during saphenous vein graft (SVG) Emboli captured during saphenous vein graft (SVG) intervention. FilterWire EZ system reduces major adverse events associated with SVG interventions.

The Saphenous Vein Graft Angioplasty Free of Emboli Randomized (SAFER) trial was the first large trial that demonstrated the beneficial effect of protection devices on clinical outcomes.[65] Currently, use of these devices is a class I recommendation when PCI is being performed on SVGs.[38]

PreviousNextAdjunctive PharmacotherapyAspirin

Aspirin should be administered before undergoing any coronary revascularization procedure. Pretreatment with 75-325 mg of aspirin is recommended in patients undergoing either percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). For long-term treatment, aspirin 75-325 mg/day is recommended. For long-term treatment after PCI in patients who receive antithrombotic agents such as warfarin, lower dosages (eg, 75-100 mg/day) are advised.[66]

Thienopyridines

Patients who undergo pretreatment with clopidogrel before PCI have better 30-day outcomes than patients who are not treated; the rate of death and myocardial infarction (MI) is reduced by nearly 39%.[67]

Currently, 12 months of dual antiplatelet therapy is recommended for all patients who receive a drug-eluting stent (DES)[68] unless there is a high risk of bleeding. The benefits and indications for treatment with dual antiplatelet therapy beyond 1 year in patients with a DES are the subject of ongoing studies. Low-dose aspirin should be continued indefinitely.

For patients with clinical features associated with stent thrombosis (eg, renal insufficiency, diabetes, or procedural characteristics such as multiple stents or treatment of a bifurcation lesion), extended dual antiplatelet therapy beyond 1 year may be reasonable. The risk of stent thrombosis must be balanced against the risk of other medical conditions and nonmedical factors that might affect the risk-benefit ratio of dual antiplatelet therapy as compared with other therapies.

Unfractionated heparin

Unfractionated heparin (UFH) administered to achieve a target activated clotting time (ACT) longer than 200 seconds is recommended when a glycoprotein (GP) IIb/IIIa inhibitor is used. In patients who do not receive a GPIIb/IIIa inhibitor, the target ACT should be 250-350 seconds. Administration of additional anticoagulation to low-molecular-weight heparin depends on the timing of the last dose.

Low molecular weight heparin

The STEEPLE study[69] randomly assigned 3528 patients who underwent PCI to receive enoxaparin or UFH adjusted for ACT. In the setting of elective PCI, a single intravenous (IV) bolus of enoxaparin 0.5 mg/kg is associated with reduced rates of bleeding, and a dose of 0.75 mg/kg yields rates similar to those for unfractionated heparin, with more predictable anticoagulation levels.

Glycoprotein IIb/IIIa inhibitors

In patients with acute coronary syndrome who are undergoing PCI without clopidogrel, a GPIIb/IIIa inhibitor in addition to heparin is a class I indication. Administration of these inhibitors is reasonable in patients with acute coronary syndrome who have undergone clopidogrel pretreatment and in those who have undergone elective PCI with stent placement. The greatest advantage of GPIIb/IIIa inhibitors is their ability to reduce periprocedural MI.

The 3 GPIIb/IIIa inhibitors are the following:

The monoclonal antibody abciximabThe nonpeptide tyrosine derivative tirofibanThe cyclic heptapeptide eptifibatide

Significant pharmacologic differences exist. For example, the platelet-bound half-life is long for abciximab and shorter for eptifibatide and tirofiban. The relative clinical efficacy of abciximab, tirofiban, and eptifibatide at the recommended doses is still uncertain.

Abciximab and tirofiban were compared in the TARGET trial, in which 4809 patients undergoing nonemergent stent-based PCI were randomly assigned to one agent or the other immediately before revascularization.[70] At 30 days after revascularization, tirofiban offered less protection from major ischemic events than abciximab did. However, by 6 months’ follow-up, there was no significant difference between the 2 drugs with respect to the combined endpoint or the individual endpoints.[71]

The only benefit from abciximab in TARGET appeared to be a reduction in procedure-related MI, primarily in patients with an acute coronary syndrome.[71] Although the exact reason for this is not known, a likely possibility is that more potent GPIIb/IIIa blockade occurred with abciximab at the doses used in the trial.

Direct thrombin inhibitors

The Acute Catheterization and Urgent Intervention Triage Strategy Timing (ACUITY) trial revealed that bivalirudin plus a GPIIb/IIIa inhibitor was not inferior to heparin plus a GPIIb/IIIa inhibitor at 30 days. The Randomized Evaluation in PCI Linking Angiomax to Reduced Clinical Events (REPLACE-2) trial revealed that bivalirudin with provisional GPIIb/IIIa blockade was not inferior to heparin plus planned GPIIb/IIIa blockade during PCI and was associated with less bleeding.[72]

Therefore, bivalirudin can be used as an alternative to heparin both in patients who are not treated with GPIIb/IIIa antagonists and as an adjunct to GPIIb/IIIa antagonists in patients at high risk for bleeding.

In subgroups of patients with high-risk acute coronary syndrome (eg, the troponin-positive group), an increase in ischemic events was seen in the bivalirudin arm if subjects were not pretreated with clopidogrel. Bivalirudin can be used as an alternative to heparin in patients with acute coronary syndromes.

Even in patients with ST-segment elevation MI (STEMI) who are undergoing primary PCI, anticoagulation with bivalirudin alone, as compared with heparin plus GPIIb/IIIa inhibitors, was shown to result in significantly reduced 30-day rates of major bleeding and net adverse clinical events in the HORIZONS-AMI study.[73]

Parodi et al compared bivalirudin and UFH plus protamine in patients undergoing elective percutaneous transluminal coronary angioplasty (PTCA) who were pretreated with clopidogrel and aspirin; less major bleeding and fewer ischemic complications were observed in the patients who received bivalirudin than in those who received UFH plus protamine.[74]

PreviousNextComplicationsPercutaneous coronary intervention

Complications of percutaneous coronary intervention (PCI) have been categorized as major (eg, death, myocardial infarction [MI], stroke, and emergency repeat revascularization)[75, 76] or minor (eg, transient ischemic attack, access-site complications[77] , renal insufficiency[78] , and adverse reactions to radiographic contrast).

Additional specific complications include intracoronary thrombosis, coronary perforation, tamponade, and arrhythmias. Bleeding is an increasingly worrisome complication because of the more common use of potent antithrombin and antiplatelet agents.[79] Late subacute thrombosis was observed in some series, particularly in patients who received drug-eluting stents (DESs).[80]

Coronary artery bypass grafting

Stroke and other neurologic complications are the most feared morbidity of coronary artery bypass grafting (CABG); the incidence of clinically obvious stroke is 0.8-5.2%.[81] Although coronary bypass surgery without cardiopulmonary bypass (CPB) may be associated with a lower risk of stroke, no randomized trial has demonstrated a lower incidence of stroke after off-pump surgery.

Deep sternal wound infection occurs in 1-4% of patients after CABG[82] and carries a mortality of nearly 25%. It is associated with obesity, diabetes, reoperation, use of both internal mammary arteries, and longer procedures.

Another common complication is postoperative renal dysfunction, defined as either a serum creatinine concentration of 2 mg/dL or higher or an increase of 0.7 mg/dL or more in comparison with preoperative values. MI can occur as a perioperative complication in 4-5% of patients.[83]

In-hospital mortality is approximately 1% for the lowest-risk elective patients and 2-5% for all patients. Risk varies in accordance with the presence or absence of comorbid conditions, the surgeon’s skill and experience, and the hospital’s volume of CABG procedures. Low albumin and age are strong predictors of adverse outcomes. Mortality may be as high as 20% if mitral valve surgery is needed in addition to CABG.[84]

PreviousNextOutcome Comparisons

Randomized clinical trials have assessed the outcomes of patients treated with medical therapy, percutaneous coronary intervention (PCI), and coronary artery bypass grafting (CABG). However, relatively few have been performed since the advent of drug-eluting stents (DESs).

CABG versus medical therapy

By the early 1980s, researchers had observed an improved quality of life, a decrease in the rate of myocardial ischemia, and an increase in the survival rate after CABG (compared with medical therapy) in selected subsets of patients (eg, those with left main coronary artery obstruction or 3-vessel disease, particularly those with a proximal left anterior descending (LAD) artery obstruction).[85]

In 1994, Yusuf et al[86] published a meta-analysis of 10-year results from randomized clinical trials in patients with stable angina, of whom 1324 were assigned to CABG and 1325 to medical treatment, and found that CABG conferred a survival benefit. The analysis demonstrated that a CABG improved survival compared with medical therapy (with crossover to surgery as needed) for patients with left main disease or 3-vessel disease with reduced ventricular function, and, possibly, 3-vessel disease with normal left ventricular function.

The meta-analysis showed that the CABG patients lived longer during a follow-up period of 10 years than those initially assigned to medical therapy.[86] A high crossover rate from medical therapy to surgery was observed (25% at 5 years and 41% at 10 years). Other data suggest that patients with 2-vessel disease with proximal LAD involvement may also derive a survival advantage with CABG.[87]

However, the medical therapy administered to patients randomized to the medical therapy arms of these trials predated the routine use of aspirin, beta blockers, statins, angiotensin-converting enzyme (ACE) inhibitors, angiotensin-receptor blockers, and calcium blockers, all of which improve survival, reduce angina, or both. Surgical therapy has also improved since these trials; the left internal mammary artery (LIMA) was used in only 14% of the patients enrolled in the trials.

With all of the improvements in medical and surgical therapy taken into account, CABG is still favored for patients with multivessel disease and reduced ventricular function. However, CABG has not been shown to be superior to complete revascularization with DESs.

Results of a randomized trial by Velazquez et al showed no significant difference in the death rate between patients with heart failure and coronary artery disease who underwent medical therapy alone and patients with the same conditions who underwent medical therapy plus CABG.[88]

In this study, 1212 patients with an ejection fraction of 35% or less and coronary artery disease (CAD) amenable to CABG were randomized to receive either medical therapy alone or medical therapy plus CABG. The primary outcome, death from any cause, occurred in 244 (41%) of the patients in the medical therapy group and 218 (36%) of those in the medical therapy plus CABG group. However, patients who underwent CABG, as opposed to those who received medical therapy only, had lower mortalities from cardiovascular causes.[88]

In a substudy of these patients, investigators assessed myocardial viability using single-photon emission computed tomography (SPECT), dobutamine echocardiography, or both; they were unable to identify a survival benefit from CABG as compared with medical therapy alone.[89]

The BARI 2D randomly assigned 2368 patients with both type 2 diabetes and heart disease to undergo either prompt revascularization with intensive medical therapy or intensive medical therapy alone and to undergo either insulin-sensitization or insulin-provision therapy. Primary endpoints were the rate of death and a composite of death, myocardial infarction, or stroke (major cardiovascular events).[90]

In the CABG stratum of this study (n = 763), the rate of major cardiovascular events was significantly lower in the revascularization group (22.4%) than in the medical-therapy group (30.5%). The death rate did not differ significantly between the revascularization group and the medical therapy group in either the CABG arm or the PCI arm.[90]

PCI versus medical therapy

Stable angina

The COURAGE trial[91] randomized 2287 patients with objective evidence of myocardial ischemia and stable CAD to an initial management strategy of either PCI plus optimal medical therapy or optimal medical therapy alone. PCI did not reduce the risk of death, myocardial infarction, or other major cardiovascular events when added to optimal medical therapy.

An initial strategy of PCI added to optimal medical therapy relieved angina and improved self-assessed health status to a greater extent than an initial strategy of optimal medical therapy alone for approximately 24 months. A greater benefit from PCI was observed in those patients with more severe and more frequent angina.[92]

Thus, patients with chronic CAD may expect relief from angina with either treatment strategy, and both strategies can have a profoundly positive effect on patients’ health status. The roles could be complementary, and some experts have suggested that optimal medical therapy might be considered first-line therapy, with PCI reserved for patients who do not have a response or who have severe baseline symptoms.

In COURAGE patients who underwent serial myocardial perfusion SPECT, adding PCI to optimal medical therapy resulted in greater reduction of ischemia than optimal medical therapy alone did. Rates of death or MI were directly proportional to the extent and severity of ischemia on the 6- to 18-month myocardial perfusion SPECT study.[93]

Acute coronary syndromes

A meta-analysis of 8 randomized controlled trials concluded that in acute coronary syndromes, an invasive strategy is beneficial in men and high-risk women for reducing the composite endpoint of death, MI, or rehospitalization with acute coronary syndrome. In contrast, the data supported a conservative strategy in low-risk women.[94]

In the guidelines published by the American College of Cardiology (ACC) and the American Heart Association (AHA), an early invasive strategy is indicated for those who have refractory angina or hemodynamic or electrical instability (without serious comorbidities or contraindications to such procedures) and in initially stabilized patients who have an elevated risk for clinical events.[95]

This recommendation is in accord with findings from other major contemporary trials (including FRISC-2,[96] TACTICS-TIMI18,[97] and RITA-3[98] ), which indicated that the greatest benefit from an invasive strategy was achieved in high-risk patients, particularly those with refractory angina, elevated cardiac troponin levels, dynamic ST-segment changes, and diabetes mellitus.

ST-segment elevation MI

The 2 types of reperfusion therapy are PCI capability and pharmacologic reperfusion. The DANish trial in Acute Myocardial Infarction (DANAMI) found that patients treated at facilities without interventional cardiology capabilities had better outcomes with transfer for PCI within 2 hours of presentation than with pharmacologic reperfusion treatment at the local hospital.[99]

However, when PCI capability is available, the best outcomes are achieved by offering this strategy 24 hours per day, 7 days per week.[100] In hospitals without PCI capability, immediate transfer for primary PCI is a treatment option when the expected door-to-balloon time is within 90 minutes of first medical contact.[101]

Better outcomes with primary PCI should not undermine the importance of fibrinolytic therapy. This is particularly relevant in that many hospital systems cannot consistently meet the time goal for primary PCI.[102] The aim with fibrinolytic therapy is to deliver the drug within 30 minutes of the time that the patient presents to the hospital. In these settings, transfer protocols need to be in place for arranging rescue PCI when clinically indicated.[103]

The fundamental concept is that faster times to reperfusion and better systems of care are associated with important reductions in morbidity and mortality rates in patients with ST-segment elevation MI (STEMI).

Another strategy that once appeared promising but has fallen out of vogue is facilitated PCI, a strategy of planned immediate PCI after an initial pharmacologic regimen (eg, full-dose fibrinolysis, half-dose fibrinolysis, a glycoprotein (GP) IIb/IIIa inhibitor, or a combination of reduced-dose fibrinolytic therapy and a platelet GPIIb/IIIa inhibitor). A planned reperfusion strategy using full-dose fibrinolytic therapy followed by immediate PCI is not recommended and is a class III recommendation according to the ACC/AHA guidelines.[104]

Facilitated PCI using regimens other than full-dose fibrinolytic therapy might be considered as a reperfusion strategy (class IIb recommendation) when the following are true:

Patients are at high riskPCI is not immediately available within 90 minutesBleeding risk is low (because of younger age, absence of poorly controlled hypertension, and normal body weight)

The Occluded Artery Trial (OAT) tested the hypothesis that mechanical opening of a persistently occluded infarct-related artery at a time too late for myocardial salvage would improve long-term outcome.[105] It randomized patients to a strategy of medical therapy or routine PCI for total occlusion of the infarct-related artery 3-28 days after acute MI. The composite endpoint included death, reinfarction, or New York Heart Association (NYHA) class IV heart failure.

Contrary to the hypothesized benefit, the study showed high rates of procedural success with PCI and sustained patency but no clinical benefit with respect to death, reinfarction, or heart failure during an average 3-year follow-up.[105]

CABG versus PCI

Several clinical trials have compared CABG and percutaneous transluminal coronary angioplasty (PTCA), including the Coronary Angioplasty Versus Bypass Revascularization Investigation (CABRI), the Randomized Intervention Treatment of Angina (RITA) trial, the Emory Angioplasty versus Surgery Trial (EAST), the German Angioplasty Bypass Surgery Investigation (GABI), and the Bypass Angioplasty Revascularization Investigation (BARI).

Analyzed separately and together, these studies demonstrated that in patients with multivessel disease, the rates of death and MI during 1 to 10 years’ follow-up was similar when initial PTCA was compared with initial CABG. However, results of the 2 treatment modalities differed in that patients who underwent angioplasty required additional revascularization procedures much more commonly than did patients who underwent CABG because of the recurrence of symptoms (most commonly restenosis).

Patients who underwent CABG had longer initial hospitalizations and a longer period of convalescence but typically enjoyed greater relief of angina. A meta-analysis that compared 8 trials of CABG with angioplasty demonstrated no differences in hospital stay, mortality, or MI rate at 1 year[106] ; the main difference was in the number of repeat procedures.

Five randomized trials compared CABG with PCI in patients with multivessel disease in whom bare-metal stents (BMSs) were routinely placed during the PCI procedure. As in the CABG-versus-PTCA trials mentioned above, the frequencies of death and MI were similar in the 2 arms during the follow-up periods. Repeat revascularization was more common for those treated with stents than in those treated with CABG. The death and MI frequencies were half those observed in the older balloon angioplasty comparison trials.

In a meta-analysis of 23 randomized controlled trials,[107] 5019 patients randomly assigned to undergo PCI were compared with 4944 patients randomly assigned to undergo CABG. CABG was more effective than PCI in relieving angina and led to fewer repeated revascularizations but had a higher risk for procedural stroke. Survival to 10 years was similar for both procedures.

Although current ACC/AHA guidelines recommend CABG for the treatment of patients with unprotected left main CAD, that recommendation is based on clinical trials demonstrating a survival advantage for CABG as compared with medical therapy.

A meta-analysis by Lee et al suggests that PCI using a DES is safe in this patient population and could represent a good alternative to CABG in selected cases.[108] At 1-year follow-up in 2,905 patients from 8 clinical studies, no significant difference was noted in risk of death, MI, or stroke between the CABG and PCI groups, although the risk for target vessel revascularization was significantly lower in the CABG group.

Similarly, in 5-year results from the MAIN-COMPARE (Revascularization for Unprotected Left Main Coronary Artery Stenosis: Comparison of Percutaneous Coronary Angioplasty Versus Surgical Revascularization) registry, stenting and CABG showed similar rates of death and of the composite endpoint of death, Q-wave MI, or stroke in patients with unprotected left main CAD. Rates of target vessel revascularization were higher with stenting, however.[109]

Comparisons of current medical therapy, catheter intervention, and bypass surgery show that patients whose disease is well controlled by medical therapy do not gain a survival benefit from PCI or CABG and that those whose disease is not adequately controlled by optimal medical therapy have similar outcomes regardless of whether they undergo PCI or CABG.

An early invasive strategy is recommended for those patients who have refractory angina or hemodynamic or electrical instability or acute presentation and elevated risk for clinical events, preferably via quick access to a 24/7 intervention service.[110]

Enrollment is under way for several large randomized trials comparing CABG and DESs.

Previous, Comparison of Revascularization Procedures in Coronary Artery Disease