Coronary heart disease, also called “coronary artery disease” or “heart disease,” is the most common cause of death in the United States. It usually occurs due to atherosclerosis, a process in which fat, cholesterol, and other materials form small “bumps,” called plaques in the inner lining of the arteries in the heart. As atherosclerosis builds up, the flow of blood and oxygen to the heart is gradually blocked. In some cases, plaques rupture, causing a blood clot to form in the artery. This plugs the artery, resulting in a heart attack.

Atherosclerosis normally begins in childhood and slowly progresses throughout life. Symptoms often do not occur until late stages. The most common symptom is chest pain (called angina pectoris), which is often described as a tight or crushing pressure in the chest. In some cases, patients describe the feeling as if “someone is sitting on my chest.” The pain may also spread to the arms, neck, back, or upper stomach.

Other common symptoms of a heart attack include shortness of breath, profuse sweating, nausea, vomiting, and headache.

Women, older individuals, and persons with diabetes may experience different symptoms during a heart attack. Instead of chest pain, they may experience shortness of breath, nausea, and vomiting, or jaw or back pain. It is important to be aware of these alternative symptoms so that medical care is not delayed.

Risk Factors

• Increasing age
• Male gender
• Family history
• Hypertension
• Cigarette smoking
• Dyslipidemia
• Obesity
• Diabetes
• Sedentary lifestyle

Coronary Heart Disease: Control of Major CHD Risk Factors

Several diet-related conditions, including obesity, high blood pressure, elevated blood sugar, and elevated blood cholesterol, increase the risk for heart disease.

• Preventing excess weight gain can lower the risk for coronary artery disease. Numerous studies have shown that obesity is a predictor of heart attacks. In particular, abdominal fat is strongly associated with the severity of atherosclerosis.
• Controlling blood pressure reduces the risk for coronary artery disease. Reducing blood pressure to optimal levels can prevent nearly 40 percent of heart attacks events in men and more than 50 percent in women.
• Controlling blood sugar levels reduces the risk for coronary artery disease. Chronically elevated blood sugar increases risk for coronary disease, even in persons without diabetes. Among those with diabetes, improved control of blood sugar has been shown to reduce the risk of cardiovascular disease.
• Regular exercise lowers the risk for developing atherosclerosis and coronary artery disease. Regular exercise reduces death due to heart disease, particularly if the activity is sufficiently intense. Current recommendations suggest a minimum of 30 minutes of moderately vigorous physical activity every day.

Survival and Prognosis After Coronary Events

A low-fat vegetarian diet reduces the risk for repeated heart attacks.

In a 12-year study of patients who had already experienced heart attacks, those who followed a low-fat (< 10 percent of calories) vegetarian diet had an absence of repeated heart attacks. Diet interventions that have also included exercise, stress reduction, and smoking cessation appear to cause reversal of atherosclerosis.

Coronary Heart Disease: Diagnosis and Treatment

Diagnosis

• The first step is noting the patient’s history and performing a physical examination.
• Blood testing: No blood test can definitively diagnose atherosclerosis. However, studies have shown that high blood levels of cholesterol, fibrinogen, homocysteine, C–reactive protein, and some other molecules in the blood are associated with atherosclerosis and risk for heart disease. Other tests are used to measure the levels of cardiac enzymes in the blood to diagnose a heart attack.
  
• Electrocardiogram (EKG): The pattern of electrical activity on an EKG can be used to diagnose a heart attack.
  
• Stress testing: Stress testing is used to evaluate an individual’s risk for heart attack. Patients exercise on a treadmill under close supervision of a physician. The doctor is able to see how the blood vessels in the heart respond to physical stress. If patients experience chest pain, shortness of breath, or EKG abnormalities while exercising, they may be at high risk for a heart attack and may require immediate preventive treatment.
  
  Patients who cannot exercise on a treadmill can have a pharmacologic stress test, in which medications are administered to speed up the heart, mimicking exercise.
• Cardiac catheterization is the most accurate way to assess the arteries of the heart and determine the risk for heart attack. A doctor will insert a small catheter into an artery in the leg and then advance it to the heart, where a dye is injected into the coronary arteries. A picture is taken which will show the locations and severities of atherosclerosis, if present. If a blockage is found, the doctor can use an angioplasty procedure (see Treatment section, below) to widen the artery to improve blood flow to the heart.

Treatment

• Diet and lifestyle changes to modify risk factors are the cornerstone of treatment. Prevention strategies include control of blood pressure, reduction of cholesterol, smoking cessation, dietary changes, and exercise. Unfortunately, many patients are not properly counseled regarding the importance of diet and exercise in the prevention of heart disease.
• Many common medical drugs work by decreasing the workload of the heart, thereby decreasing its oxygen requirements. These include nitrates (e.g., nitroglycerin), beta–blockers (e.g., propranolol, atenolol, and metoprolol), and calcium–channel blockers (e.g., diltiazem, verapamil, nifedipine, and amlodipine).
• Other important cardiac drugs, such as aspirin and clopidogrel, work to “thin” the blood, which decreases the risk of artery blockages.
• Cholesterol–lowering medications include “statins” (e.g., Lipitor), cholestyramine, gemfibrozil, and ezetimibe.
• In high–risk patients, surgical intervention may be necessary. This may include angioplasty, in which a small balloon is inflated within a narrowed artery to widen the area of blood flow and a stent is placed to hold the artery open.

Coronary Heart Disease: Nutritional Considerations

A modified diet, particularly if combined with regular exercise, can prevent, delay, or even reverse the progression of atherosclerosis and development of coronary artery disease, and reduce the risk for heart attack. 

• Decreasing intake of saturated fat and cholesterol lowers blood cholesterol levels. Saturated fats and cholesterol in the diet increase levels of cholesterol in the blood, particularly low density lipoprotein (LDL, or “bad”) cholesterol. Following a diet low in saturated fat and cholesterol can help reduce atherosclerosis.
  
  The National Cholesterol Education Program has recommended moderate reductions in total fat (≤ 30 percent of calories), saturated fat (≤ 7 percent of calories), and cholesterol (< 200 mg/day) intake. In clinical trials, such changes reduce LDL cholesterol concentration by about 5 percent. Studies suggest that low–fat vegetarian and vegan regimens are significantly more effective, reducing LDL cholesterol approximately 15 to 30 percent. Because such regimens have also been shown to reduce body weight and blood pressure, and to reverse atherosclerosis, they provide much more clinical benefit. From the patient’s standpoint, they are often preferred, provided that individuals receive basic diet instruction.
• Increasing dietary fiber can reduce blood cholesterol. Soluble fiber, which is found in oats, barley, and beans, is particularly helpful for reducing cholesterol in the blood. Sources of soluble dietary fiber and pectin, found mainly in fruits and vegetables, have also been shown to reduce the progression of atherosclerosis.
• Soy products can reduce cholesterol. Both population–based and clinical studies have shown that soy products (e.g., soymilk and meat substitutes) may reduce CHD risk. In addition to reducing total cholesterol, soy has cardioprotective effects, such as lowering LDL and blood pressure.
  
  Clinical trials have combined these lipid–lowering strategies. A vegetarian diet emphasizing a “portfolio” of cholesterol–lowering foods (including oats, soy foods, nuts, and sterol/stanol margarines) appears to be particularly effective, lowering LDL cholesterol concentration approximately 30 percent, an effect similar to that of treatment with statin medications.

• Increasing intake of antioxidants can improve functioning of the blood vessels. Dietary antioxidants, folate, magnesium, and other substances in foods may improve the functioning of blood vessels and may also reduce blood pressure.
• Fruits and vegetables can help reduce the risk for CHD. Fruits and vegetables can help reduce atherosclerosis and lower risk for CHD, particularly if the diet is low in saturated fat. However, the benefits of these foods go beyond their having no cholesterol and very little saturated fat, and their high fiber content. Other heart protective components in fruits and vegetables include vitamin C, antioxidant flavonoids, and folic acid.
  
  Several studies have shown that higher dietary intakes of carotenoid–containing fruits and vegetables are associated with a decreased risk of coronary artery disease. Others have found that lower blood levels of carotenoids are associated with a higher risk for CHD.
• Dietary intake can reduce inflammation in the blood vessels. Inflammation plays a large role in the process of atherosclerosis. There are several ways to decrease inflammation, including weight loss, reduced intake of saturated fat (which is primarily found in animal products), reduction of partially hydrogenated vegetable oils (known as trans fats), and increasing omega–3 fat intake from healthy sources (e.g., walnuts, flax seeds, flaxseed oil, and canola oil).
  
  Some studies have looked at the addition of omega–3 fatty acids in either foods or supplements. Several researchers have found that these fats can decrease inflammation and atherosclerosis. In addition, they have other heart protective properties, including “thinning” the blood and reducing the risk for arrhythmias.
  
  However, fats or oils that provide omega–3 fatty acids do contain as many calories as other fats and are mixtures of various fat types. Fish oils, for example, include significant amounts of saturated fat (15 to 30 percent of total fat content) and cholesterol. People who include fatty fish in their diets as a means of increasing omega–3 intake will also increase total and saturated fat intake, and may experience elevated cholesterol and weight gain. Moreover, fish are often contaminated with dangerous pollutants such as mercury.
• Whole grains are associated with lower risk for heart disease. In epidemiological studies, whole grain consumption is associated with a lower risk of heart disease, as is frequent consumption of nuts. In addition to providing the lipid–lowering benefit of dietary fiber, these foods provide magnesium and vitamin E, both of which may be related to a lower risk for coronary heart disease. Nuts are high in fat and calories, however, and may influence body weight. 
• Alcohol consumption should not be used as a means of preventing heart disease. Although alcohol is often said to be protective for heart disease, no controlled clinical trials have examined the effect of alcohol intake on cardiovascular endpoints. Regular alcohol consumption also contributes to several medical conditions, including serious diseases of the liver, pancreas, central nervous system, and cardiovascular system. Alcohol also increases the risks for some cancers, notably gastrointestinal and breast cancers.