Recovery of myocardial function in the hibernating heart.

Impaired contractile performance at rest is not necessarily due to irreversible tissue damage but may relate to the "hibernating" myocardium. Hibernating myocardium has been defined as potentially reversible, chronic contractile dysfunction during prolonged, painless ischemia. The extent and time course of functional recovery after restoration of flow is of major importance for clinical decision making. The existence of hibernating myocardium was first documented in patients following bypass surgery. Angiographic studies in patients undergoing coronary angioplasty revealed immediate recovery of global and regional systolic, as well as diastolic, function after revascularization. Subgroup analysis showed an improvement in patients without previous myocardial infarctions and in those with non-Q-wave infarctions, but a benefit was not consistently seen in patients with transmural infarctions. A further improvement of systolic function after 15 weeks suggests a biphasic course of recovery. Prospective studies must clarify whether the potential for improvement in function constitutes an indication for revascularization independent of clinical symptoms.