The tissue death (infarct) of a section of the heart muscle, usually as a result of reduced blood flow to the heart, which can be caused by blood clots, especially in arteries narrowed by arteriosclerosis. Commonly referred to as a heart attack. Symptoms include chest pain (often radiating into the left arm) and shortness of breath. Electrocardiograms, or EKG/ECGs are often used to diagnose MIs, which are then treated with thrombolytic (clot-dissolving) drugs, angioplasty, or even coronary bypass surgery. Myocardial infarctions are serious, life-threatening occurences, and while there is a genetic predisposition for them, the vast majority could be prevented simply by eating right, not smoking, and getting regular exercise.

For more information, I recommend:
HeartInfo -
Infarct Combat Project -