Overview of Heart Attack
The heart is a complex, highly specialized, muscular organ in the chest that maintains the circulation of blood throughout the body. Heart attack, or acute myocardial infarction, is the death of heart tissue caused by a complete blockage in one of the arteries that supply blood to the heart (coronary arteries), resulting in an interruption in the blood supply to the heart. Anyone who experiences heart attack symptoms or witnesses a person experiencing a heart attack should seek immediate medical attention (i.e., call 9-1-1).
When heart tissue is deprived of blood-borne oxygen for longer than 30 minutes (called ischemia), it begins to die. Ischemia causes electrical instability within the chambers of the heart, preventing the heart from adequately pumping blood throughout the body (called ventricular fibrillation). Permanent brain damage and death can occur when the brain is deprived of blood flow for longer than 5 minutes.
In most cases, blockage occurs as a result of coronary heart disease (CHD), also called atherosclerosis, a condition in which plaques (deposits of cholesterol and fatty material) build up in the arteries and partially or completely block blood flow. When the surface of a plaque tears or ruptures, a blood clot (thrombus) can form and completely block the flow of blood in the artery.
Sudden cardiac arrest (SCA), also called sudden cardiac death, occurs when the heart develops an abnormal rhythm (arrhythmia; e.g., ventricular fibrillation) that causes it to stop beating suddenly. In as many as 95% of cases, a person who experiences SCA dies, usually within minutes.
Incidence and Prevalence of Heart Attack
According to the American Heart Association, coronary heart disease (CHD) is the leading cause of death in the United States; and, in adults, heart attacks cause 1 out of every 5 deaths. According to the National Institutes of Health (NIH) more than 1.2 million heart attacks occur each year in the United States and about 460,000 of these are fatal. Approximately 300,000 people die annually from heart attacks before they can receive medical treatment.
According to the World Health Organization (WHO), coronary heart disease accounts for about 17 million (approximately 30%) deaths annually throughout the world. It is estimated that by the year 2010, heart disease will be the leading cause of death in the world.