A heart attack, or myocardial infarction (MI), is when blood flow to part of the heart muscle (myocardium) is blocked and that part of the organ does not get enough blood.
When their blood supply is reduced, muscle cells in the heart get damaged and die. The more time that passes without blood flow, the greater the damage to the heart muscle. MIs are most often caused by blockages in the arteries that supply blood to the heart muscle, according to the American Heart Association (AHA). The buildup of plaque in these arteries is known as coronary artery disease (CAD), the most common type of heart disease in the U.S.
