Myocardial infarction (heart attack) is a leading cause of death worldwide and is responsible for approximately 42 percent of all deaths from cardiovascular disease. Heart attacks occur when the blood supply to an area of the heart is blocked by a blood clot or atherosclerosis (fatty deposits or plaques lining vessel walls), causing heart tissue to die.  Rapid diagnosis and treatment to restore blood flow through the affected vessel are vital to save as much of the heart tissue as possible.