The heart is a muscle about the size of a fist located behind the breastbone. It pumps blood through the body through two coronary arteries that encircle the heart. Coronary artery disease occurs when fatty deposits build up in the arteries and reduce blood flow, which can lead to chest pain, heart attack, or heart failure. Risk factors include high blood cholesterol, high blood pressure, smoking, obesity, and lack of exercise. Treatment may involve lifestyle changes, medication, procedures like angioplasty to clear blockages, or bypass surgery.