When the oxygen-rich blood is unable to flow to a section of heart muscle and the heart can’t get oxygen then the heart face an attack. This is known as heart-attack. If the flow of blood is not restored quickly, that particular section of heart muscle begins to die. Heart attack happened because coronary arteries which supply blood flow to the heart muscle, slowly becomes narrow because of fat, cholesterol and other substances called plague. This blood clot may block the flow of blood through heart muscle.