Heart Attack

A heart attack, also called a myocardial infarction (MI), refers to a sudden event in which a portion of the heart muscle stops working because it no longer receives blood, usually due to a blockage in the coronary artery. Generally, a heart attack occurs when plaque (fat, cholesterol, and calcium) builds up and then ruptures in the coronary artery, creating a place where a blood clot can form (thrombus). Eventually, this blood clot totally blocks the coronary artery. This stops blood flow, so the heart tissue beyond the point of the blockage does not get any blood and oxygen. If there's no blood flow to the tissue, the tissue dies, and the heart's muscle becomes damaged and unable to function. This causes serious consequences to the patient, and the degree to which the patient is affected depends upon the location and size of muscle damage.

A recent study— Multi-center Automatic Defibrillator Implantation Trial II (MADIT II)—found that people who have survived a heart attack, yet who have extensive muscle damage, may be at risk for sudden cardiac arrest due to the heart’s inability to pump enough blood. For many of these patients, physicians are recommending an implantable cardioverter defibrillator (ICD), which can deliver therapy that, in essence, restarts the heart if it stops beating.