Dysfunction in collateral-dependent myocardium. Hibernation or repetitive stunning?

Jt is now well established that myocardial dysfunction, once thought to be indicative of irreversible tissue damage, is in many cases reversible. This has led to the concepts of myocardial "stunning"1'2 and "hibernation."3 In both of these conditions, myocardial function is reversibly compromised; in stunning, myocardial function is decreased in response to a previous ischemic insult, and blood flow is normal or nearnormal, whereas in hibernation, function is reduced in response to a continuing flow deficit. However, as reviewed in detail recently,2 in the clinical environment, a sharp distinction between stunning and hibernation may not always be feasible because in a patient with resting flow abnormalities, any increase in demand due to normal daily activities would be expected to lead to ischemia and postischemic dysfunction. Thus, stunning may be superimposed on hibernation. In this issue of Circulation, Vanoverschelde et a14 provide further in-