Development of fatty plaque is due partly to excessive intake of cholesterol and animal fats in the diet (see Nutrition, Human). A sedentary life-style is thought to promote atherosclerosis, and evidence suggests that physical exercise may help prevent heart disease (see Physical Fitness). A striving, perfectionist temperament referred to as Type A personality has also been associated with increased risk of heart attacks (see Stress-Related Disorders), as has cigarette smoking. The occurrence of the heart attack itself is much more likely in persons who have high blood pressure (see Hypertension). The actual event precipitating the attack may involve products secreted by platelets in the blood. This has led to clinical studies testing whether persons who have had a heart attack will be protected from a second infarction if they take drugs that block the action of platelets (see Blood).
Many persons having severe angina because of atherosclerotic disease can be treated with drugs, such as propranolol and nitrates, which enable the heart to work more efficiently. Those who do not obtain relief with pharmacologic means can often be treated by a form of surgery called coronary bypass. In this procedure, which became established in the 1970s, a section of vein from the leg is sewn into the blocked coronary artery to form a bridge around the atherosclerotic region. In most recipients the operation relieves the pain of angina and in many persons it prevents a fatal heart attack. By 1986 more than 225,000 patients were undergoing these procedures each year in the U.S.