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Heart attack and acute coronary syndrome

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of heart attack.

Alternative Names

Acute coronary syndrome; Myocardial infarction

Prognosis

Each year, an estimated 650,000 Americans will suffer a first heart attack, and 450,000 will have a recurrent episode. Currently, half of the men and 63% of the women who died of heart disease had no warning prior to their fatal attacks.

Predicting the Severity of a Heart Attack

Heart attacks may be rapidly fatal, evolve into a chronic disabling condition, or lead to full recovery. The long-term prognosis for both length and quality of life after a heart attack depends on its severity and the preventive measures taken afterward.

About 88% of patients under age 65 who experience a heart attack can expect to return to work. About 12,600,000 Americans who have had heart attacks, angina, or both are alive today. However, within 6 years of a heart attack, 18% of men and 35% of women have a recurrent attack. And, about 22% of men and 46% of women develop heart failure.

Although no tests can absolutely predict whether another heart attack will occur, experts estimate that up to 30% of fatal attacks, and many follow-up surgeries, could be avoided with healthy lifestyle changes and adherence to medical treatments. Two-thirds of patients who have suffered a heart attack, however, do not take the necessary steps to prevent another.

Higher Risk Individuals. A heart attack is always more serious in certain people:

• Elderly (particularly those who are thinner)
• People with a history of heart disease or risk factors for heart disease
• People with heart failure
• People with diabetes
• People on long-term dialysis

Women are more likely to die after a heart attack than men. The risk is highest in younger women (although in the younger population, the risk for having a first heart attack and then dying from it is very low). It is still unclear why heart attacks are more severe in this group.

Factors Occurring at the Time of a Heart Attack That Increase Severity. The presence of other conditions during a heart attack can contribute to a poorer outlook:

• Arrhythmias (disturbed heart rhythms). A dangerous arrhythmia called ventricular fibrillation is a major cause of short-term death from heart attack. Such arrhythmias are more likely to occur within the first 4 hours and are associated with a high mortality rate. Patients who are successfully treated, however, have the same long-term prognosis as those who do not experience such arrhythmias.
• Signs of severe physical damage to the heart may indicate a poorer outlook.
• Shock. This very dangerous condition is associated with very low blood pressure, reduced urine levels, and cellular abnormalities. Shock occurs in about 7% of heart attacks. The incidence has not declined over recent years, although its survival rates have improved.
• Heart block, also called atrioventricular (AV) block, is a condition in which the electric conduction of nerve impulses to specialized muscles in the heart is slowed or interrupted. Although heart block is dangerous, it can be treated effectively with a pacemaker, and it rarely causes any long-term complications in patients who survive it.

Risk for Stroke

Heart attacks and acute coronary syndrome pose a high risk for stroke. According to a major 2002 study, the risk for stroke after heart attack is 2.5% in the first 6 months and 5% per year thereafter. In the study, patients with a higher risk (about 4%) for stroke within 6 months of a heart attack were older (over age 75), African American, had a history of stroke, atrial fibrillation, hypertension, diabetes, or peripheral artery disease. Most people who fall into these categories have more than one of these risk factors.

• Review Date: 4/15/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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