What is a heart attack? A heart attack, or myocardial infarction, is a life-threatening condition in which the heart tissue does not receive enough oxygen. This lack of oxygen causes serious damage (infarction) to the heart muscle (myocardium) and its ability to function effectively. Coronary artery disease, more commonly referred to as heart disease, is the most common cause of heart attack and the leading cause of death for both men and women in the United States, according to the Centers for Disease Control and Prevention (Source: CDC). The heart is a muscle that requires a steady supply of oxygen in order for it to pump blood effectively to the rest of body. Oxygen is supplied to the heart by blood that flows through the coronary arteries. Heart attacks are most commonly due to the buildup of plaque on the coronary artery walls (atherosclerosis). Atherosclerosis can lead to the formation of a blood clot that blocks blood flow to the heart. The area of the heart that is damaged in a heart attack and the severity of a heart attack vary depending on which coronary artery is blocked, how long the blockage lasts, and other factors. Damage to the heart can become permanent within minutes and result in the death of the affected heart tissue (myocardial necrosis or infarction) and death. Angina is a type of chest pain that occurs when the heart is not getting enough oxygen. Having angina may mean that you are at increased risk for a future heart attack or that a heart attack may occur soon. A heart attack is an immediately life-threatening condition that can rapidly lead to cardiac arrest and death. Immediate emergency heart attack treatment best minimizes the risk of these and other serious complications, such as heart failure and disability. Seek immediate medical care (call 911) if you, or someone you are with, have heart attack symptoms, such as chest pain and difficulty breathing, which may be combined with dizziness, sweating, fainting and anxiety.