1. the first thing in the process is plaque builds up in the arteries, which narrows the artery
2. Then is a piece of this plaque breaks off, it bleeds and causes a clot to form
3. After which the clot travels along until it comes to an artery that is too narrow for it to pass through
4. Last thing that happens is that this cuts the blood supply off to that area and the area dies. A heart attack has occurred.