All these current mode of treatments help the heart by increasing the blood flow to the area of the heart muscle not receiving adequate blood supply. Once the blood supply is increased towards normal the patient's chest pain will be decreased or eliminated and his exercise tolerance will improve.
During IECP hearts natural mechanism of forming new vessel is increased which markedly increase the blood supply to the heart muscle. IECP also tends to improve your endothelial cell function that lines your coronary arteries, which determine your chance of getting heart attacks.