The coronary arteries may become blocked by a build-up of fatty material, caused by certain kinds of 'bad' cholesterol. As the fatty material increases, one or more coronary arteries narrow, and can become blocked.
If a blockage builds up, the amount of oxygen reaching the heart muscle is reduced. A person will develop chest pain, and if left untreated, a heart attack is the result. This can cause damage to, or death of the heart muscle. Part of the heart muscle, or the whole heart, will die.