Coronary artery disease develops slowly, usually over a period of decades. Plaque, which is composed of fat, cholesterol, calcium and other substances, builds up on the artery walls over time. Coronary artery disease can be hereditary, or it can develop over time from a poor diet and lack of exercise. Eventually the flow of blood becomes severely restricted, causing shortness of breath and chest pain. When the artery becomes completely blocked, a heart attack can occur.Symptoms can include: chest pain or pressure (angina), which feels as if someone is standing on your chest, shortness of breath or a heart attack. Symptoms of a heart attack typically include a crushing pressure on your chest, pain in your shoulder or arm and in women, nausea and back or jaw pain. However, a heart attack may occur without any symptoms at all in cases of coronary artery disease, especially when it is associated with diabetes.