MI: Commonly used abbreviation for myocardial infarction, otherwise known as a heart attack.
The term "myocardial infarction" focuses on the heart muscle, which is called the myocardium,and the changes that occur in it due to the sudden deprivation of circulating blood. This is usually caused by arteriosclerosis with narrowing of the coronary arteries, the culminating event being a thrombosis (clot). The main change is death (necrosis) of myocardial tissue.
The word "infarction" comes from the Latin "infarcire" meaning "to plug up or cram." It refers to the clogging of the artery.