Heart attack. Conceptual computer artwork representing a heart attack (myocardial infarction). Heart attacks occur due to the sudden death, or necrosis, of part of the heart muscle. This commonly results from a blockage in one of the coronary arteries on the surface of the heart. These arteries supply the heart muscle with blood. The most frequent cause of blockage is atherosclerosis, in which fatty plaques develop in the lumen of the arteries, restricting the blood flow. Heart attacks cause sudden severe pain in the centre of the chest, and around half are fatal within days.