Heart disease is indiscriminate — it's the No. 1 killer of men, women and people of most races and ethnicities in the U.S. Coronary artery disease, the most common type of heart disease, is especially brutal. It accounts for about 55% of those yearly deaths. When plaques made of cholesterol, fat, calcium and other waste build up in the vessels of the heart — what we call atherosclerosis — coronary heart disease develops. It's the primary cause of heart attacks, which occur when those vessels become completely closed off by a growing plaque, or one that's shaken loose, and stops blood supply to the heart. It happens to someone in the U.S. once every 40 seconds.