Myocardial stunning: an experimental act with a large clinical audience.

Myocardial stunning, a prolonged post-ischemic contractile dysfunction following single or multiple brief episodes of myocardial ischemia, was a fortuitous laboratory observation. Several years later it is obvious that myocardial stunning is a ubiquitous clinical finding and occurs whenever ischemia and reperfusion are present. Reperfusion, by restoring oxygen supply, which is beneficial and protective for the ischemic myocardium, induces at the same time a burst of oxygen free radicals complicated with intracellular Ca2+ overload, which is harmful for the contractile proteins. If it is a one-time episode, stunning is a benign condition which usually does not need treatment. If repetitive, it may lead first to chronic stunning and later to hibernating myocardium, characterised by permanent cellular injury and cell death through apoptosis with secondary reduction in myocardial perfusion. Patients with severe left ventricular dysfunction on the basis of hibernating myocardium carry an unfavourable prognosis when not revascularized. Further insight into molecular and genomic adaptation to ischemia and reperfusion will undoubtedly help improve our ability to fight ischemic heart disease.