Coronary artery disease (CAD) is a common heart condition that affects the coronary arteries, which supply blood to the heart. It is caused by the buildup of plaque (fats, cholesterol, and other substances) on the artery walls, leading to narrowed arteries and reduced blood flow to the heart. CAD typically develops over time and can cause symptoms like chest pain and shortness of breath. A complete blockage of blood flow may result in a heart attack.