A heart attack happens when blood flow to an area of heart muscle suddenly becomes blocked and an area of heart muscle is damaged.
Most heart attacks occur as a result of coronary artery disease. The coronary arteries supply blood and oxygen to the muscle of the heart. Coronary artery disease is a condition in which the coronary arteries become narrowed by inflammatory fatty deposits called atherosclerotic plaque. These plaques build up over time and can decrease the amount of oxygen reaching your heart.
If a plaque suddenly ruptures, a blood clot can form and block the blood supply to an area of the heart. This stops oxygen from reaching the heart muscle and begins to cause permanent damage to the tissue. This is called a heart attack or myocardial infarction. The amount of damage depends on the size of heart muscle supplied by that artery and the amount of time that passes before treatment. Without treatment, a heart attack can cause serious health problems or death. A heart attack can increase the future risk for heart failure or abnormal heartbeats called arrhythmias.