When a coronary artery is healthy and has no blockages, blood flows through easily. Healthy arteries can easily supply the oxygen-rich blood your heart needs.
Coronary artery disease begins when damage to the artery lining leads to the buildup of fat-like substances and cholesterol along the artery wall. This is called plaque. This damage could be caused by things like high blood pressure or smoking. This plaque buildup begins to narrow the arteries carrying blood to the heart. This is called atherosclerosis.
As more plaque builds up, your artery has trouble supplying blood to your heart muscle when it needs it most, such as during exercise. You may not feel any symptoms when this happens. Or you may feel angina – pressure, tightness, achiness, or pain in your chest, jaw, neck, back, or arm.
A piece of plaque may break off and completely block the artery. Or a blood clot may plug the narrowed artery. When this happens, blood flow is blocked from reaching the heart. Without oxygen-rich blood, part of the heart muscle becomes damaged and stops working. You may feel crushing pressure or pain in or around your chest. This is a heart attack (acute myocardial infarction, or AMI) and is a medical emergency.