It is interesting that you report your father died and came back!. Was the near death experience prior to the stent implant? Has there been any symptoms subsequently?
Due to the stent, there should be adequate blood flow to the heart muscle and if no permanent heart damage has occurred, it should all return to normal again. It sounds as though his heart attack was severe, and he was lucky that Doctors managed to bring him back. Does he have any known permanent heart tissue damage?
Anti cholesterol medication is one measure, but isn't he on aspirin also? this is vital to lower the risk of another severe heart attack. You also don't mention beta blocker medication, perhaps this is a sign he has no long term damage?
As stated your husband's underlying problem is due to occluded vessel(s), but if there are medical problems subsequent and asscoiated to the heart attack, there can be medical conditions such as an enlarged heart, poor contractility with reduced cardiac output, etc. that present symptoms such as shortness of breath, chest pains, muscle fatigue, etc.
The medication taken is to help control or prevent further ischemia due to occluded vessels.
Cardiac ischemia is the name for lack of blood flow and oxygen to the heart muscle.
It's the term given to heart problems caused by narrowed heart arteries. When arteries are narrowed, less blood and oxygen reaches the heart muscle. This is also called coronary artery disease and coronary heart disease. This can ultimately lead to heart attack.
Ischemia often causes chest pain or discomfort known as angina pectoris.
Coronary artery disease is atherosclerosis of the coronary arteries, producing blockages in the vessels which nourish the heart itself. Atherosclerosis occurs when the arteries become clogged and narrowed, restricting blood flow. Without adequate blood flow from the coronary arteries, the heart becomes starved of oxygen and vital nutrients it needs to work properly.