Three types of ischemic abnormalities portend differential responses to medical therapy (such as b-blockade) and revascularization. These include: (1) reversible ischemic myocardium; (2) hibernating, or viable myocardium, a state in which segments of the myocardium exhibit abnormalities of contractile function; and (3) nonviable myocardium. In theory, these types of myocardium behave differently. Ischemic myocardium is likely to improve function after revascularization (> 80% likelihood), and hibernating and viable myocardium states are less likely (40%-50% likelihood) to improve measured according to segmental wall motion. A body of evidence supports the concept that patients with reversible segments experience the best clinical and functional outcomes after surgical revascularization, followed by those with hibernating/viable segments. As such, the presence of reversible or viable myocardium might affect the decision to proceed to a revascularization procedure, but will not be the sole determining factor.