Coronary heart disease—often simply called heart disease— occurs when the arteries that supply blood to the heart muscle become hardened and narrowed due to a buildup of plaque on the arteries’ inner walls. Plaque is the accumulation of fat, cholesterol, and other substances. As plaque continues to build up in the arteries, blood flow to the heart is reduced. Heart disease can lead to a heart attack. A heart attack happens when an artery becomes totally blocked with plaque, preventing vital oxygen and nutrients from getting to the heart. A heart attack can cause permanent damage to the heart muscle