The term "heart disease" refers to several types of heart conditions. The most common type of heart disease in the United States is coronary artery disease, which affects the blood flow to the heart. Decreased blood flow can cause a heart attack. A heart attack, also called a myocardial infarction, occurs when a part of the heart muscle doesn’t receive enough blood flow. The more time that passes without treatment to restore blood flow, the greater the damage to the heart muscle. Every year, about 735,000 Americans have a heart attack among them 525,000 are the casses of first heart attack whereas, 210,000 happen to people who have already had a first heart attack.