Heart attack. Computer artwork of the head and body of a human skeleton that is having a heart attack (myocardial infarction). The major arteries (red lines) and veins (blue lines) are shown. The heart is seen within the rib cage. 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) that supply the 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.