That is the mechanism responsible for that massive heart attack-induced death. Now, what causes the ventricular fibrillation? Indeed, it can be a heart attack, but there are other causes as well. Heart attack refers to a blockage of blood flow in one of the arteries nourishing the heart. You must remember the heart is a muscle and needs blood flow like your biceps or your triceps needs blood flow with nourishment, oxygen and so on.