<p>Coronary artery disease (CAD) is the most common type of heart disease. It is the leading cause of death in the United States in both men and women.</p> <p>CAD happens when the arteries that supply blood to heart muscle become hardened and narrowed. This is due to the buildup of <a href="https://medlineplus.gov/cholesterol.html">cholesterol</a> and other material, called plaque, on their inner walls. This buildup is called <a href="https://medlineplus.gov/atherosclerosis.html">atherosclerosis</a>. As it grows, less blood can flow through the arteries. As a result, the heart muscle can't get the blood or oxygen it needs. This can lead to chest pain (<a href="https://medlineplus.gov/angina.html">angina</a>) or a <a href="https://medlineplus.gov/heartattack.html">heart attack</a>. Most heart attacks happen when a <a href="https://medlineplus.gov/bloodclots.html">blood clot</a> suddenly cuts off the hearts' blood supply, causing permanent heart damage. </p> <p>Over time, CAD can also weaken the heart muscle and contribute to <a href="https://medlineplus.gov/heartfailure.html">heart failure</a> and <a href="https://medlineplus.gov/arrhythmia.html">arrhythmias</a>. Heart failure means the heart can't pump blood well to the rest of the body. Arrhythmias are changes in the normal beating rhythm of the heart. </p> <p class="">NIH: National Heart, Lung, and Blood Institute</p>