What causes myocardial infarction?

As explained above, myocardial infarction is caused by one or more of the arteries supplying the heart becoming blocked. The blockage is usually caused by coronary artery disease. Arteries are like pipes with blood flowing through them. In coronary artery disease, the arteries become narrowed, usually because of a build-up of fatty deposits, cholesterol and other substances with a fibrous layer on top. This process is known as atherosclerosis and the deposits are collectively known as atheroma. Sometimes this fibrous layer breaks or becomes damaged and roughened, and platelets (blood cells) can stick to this damaged area and form a blood clot. This clot can completely block the blood flow through the coronary artery, causing myocardial infarction.