What is a coronary heart attack?Are you at the risk of a coronary heart attack?Here are some insights to help you...A heart attack happens when the blood supply to part of the heart muscle itself (the myocardium) is severely reduced or even stopped entirely.The medical term for a heart attack is myocardial infarction.The reduction or stoppage of blood supply happens when one or more of the coronary arteries supplying blood to the heart muscle is blocked.This may be caused by the buildup of plaqu.