Clinical Progress Myocardial ' Stunning ' in Man Roberto

T he progress of medicine is often driven by the development of new ideas in the experimental laboratory and their subsequent application to clinical practice. Sometimes the clinical usefulness of these ideas may not be evident when they are first formulated but becomes apparent after a period of time. The concept of postischemic myocardial dysfunction, or "myocardial stunning,"' is a classic example of these patterns. Initially described by Vatner's group in 1975 (Heyndrickx et a12), for several years this phenomenon received little or no attention among cardiologists because at that time coronary reperfusion was thought to be a rare occurrence. Postischemic dysfunction was regarded primarily as a laboratory curiosity. During the 1980s, however, the widespread use of thrombolytic therapy and other forms of interventional recanalization for the treatment of acute ischemic syndromes, coupled with the recognition that many patients with coronary artery disease experience spontaneous reperfusion after coronary spasm or thrombosis, led to a remarkable growth of interest in the phenomenon of myocardial stunning. Indeed, as shown in Figure 1, in the past decade there has been an impressive increase in the number of publications dealing with stunning at the experimental animal level, followed after a 3-5-year lag by a similar increase at the clinical level. The phenomenon of stunning is now commonly invoked by cardiologists to explain a variety of clinical observations. Decisions to revascularize hypokinetic myocardial regions are based on the presumption that the contractile dysfunction is caused by stunning. New therapies designed to prevent stunning are being investigated in preclinical studies, and soon will be tested in clinical trials. In short, the concept that the myocardium can remain reversibly depressed for extended periods of time after ischemia is changing our understanding of the pathophysiology of coronary artery disease and our approach to the management of this disorder. The purpose of this essay is to review critically -and in detail-the available information regarding the occurrence of myocardial stunning in humans and to discuss the pathophysiological and therapeutic implications of this concept in the clinical arena. The problems inherent in the recognition and differential diagnosis of