A heart attack occurs when blood flow to a section of heart muscle becomes blocked. If the flow of blood isn’t restored quickly, the section of heart muscle becomes damaged from lack of oxygen and begins to die. Cái này là định nghĩa nhé

http://en.wikipedia.org/wiki/Myocardial_infarction

Xem cái định nghĩa "Heart attack" nhé. Chọn phần tiếng việt để hiểu rõ hơn. Gd luck.