The role of coronary arterial spasm in ischemic heart disease

With the arteriographic demonstration of coronary arterial spasm, fundamental questions have been raised concerning the role of spasm in myocardial ischemia and infarction. It is now clear that coronary arterial spasm is the cause of Prinzmetal's variant angina pectoris in patients with and without coronary atherosclerosis. In most patients with coronary heart disease, major ischemic events frequently result from increased myocardial oxygen demand or coronary thrombosis. However, recent evidence suggests that coronary arterial spasm may initiate or contribute to the development of unstable angina pectoris, acute myocardial infarction, and sudden death in these patients. Thus, episodes of myocardial ischemia and infarction are induced by factors, acting singly or in combination, that augment myocardial oxygen demand or diminish myocardial oxygen supply, and the latter alteration can result from thrombotic coronary occlusion or a dynamic increase in coronary arterial tone (that is, coronary arterial spasm).