Why does the heart have a separate circulatory system and what circulatory system is effected by a heart attack?

The heart. doesn't have a circulatory system that is truly separate,but it is a muscle, and like any muscle or organ,has its own blood supply derived from the main circulatory system.The coronary arteries extend from the aorta and supply the heart. In a heart attack,one or more coronary arteries become narrowed or blocked, and without enough oxygenated blood(ischemia), the supplied tissue may die(infarct)
Coronary arteries. The coronary arteries deliver oxygen-rich blood to the heart (myocardium).