The blockage usually is caused by atherosclerosis, the build-up of plaque in the artery walls, and/or by a blood clot in a coronary artery. A slow buildup of this plaque may almost block one of your coronary arteries. The cause of the heart is not always known. Heart attacks may occur when you are resting or asleep, after a sudden increase in physical activity, or severe emotional or physical stress. Heart attack risk factors include age, men who are 45 or older and women who are 55 or older are more likely to have a heart attack
The blockage usually is caused by atherosclerosis, the build-up of plaque in the artery walls, and/or by a blood clot in a coronary artery. Sometimes, a healthy or atherosclerotic coronary artery has a spasm and the blood flow to part of the heart decreases or stops. Why this happens is unclear, but it can result in a heart attack.
The longer the artery remains blocked during a heart attack, the more damage will be done to the heart. If the blood supply is cut off severely or for a long time, muscle cells suffer irreversible injury and die. This can be fatal to the sufferer.
About one-fifth of all heart attacks are silent, that is, the victim does not know one has occurred. Although the victim feels no pain, silent heart attacks still can damage the heart.
The outcome of a heart attack also depends on where the blockage is, whether the heart rhythm is disturbed, and whether another coronary artery supplies blood to that part of the heart. Blockages in the left coronary artery usually are more serious than in the right coronary artery. Blockages that cause an arrhythmia, an irregular heartbeat, can cause sudden death.
Heart attacks generally are caused by