The data presented above suggest that assessment of myocardial viability after MI, particularly in those patients with severe LV dysfunction, is important for the identification of those with the highest risk, in whom revascularization can be of clinical benefit. There is growing and consistent evidence that patients with relatively large areas of dysfunctional but viable myocardium after MI have improved function, symptoms, and survival with prompt revascularization compared with medical therapy alone. Most importantly, long-term survival with revascularization in these patients is comparable with that achieved with cardiac transplantation. There are several methods available to the clinician with which to investigate the presence of tissue viability, and the evidence suggests that the scintigraphic approaches are the most sensitive. These observations suggest that noninvasive investigation of the amount of ischemic myocardium should be an important component of the diagnostic evaluation of patients with severe LV dysfunction after MI. This approach will likely enhance the often difficult process of selecting patients with poor cardiac function in whom revascularization will likely improve both the quality and quantity of life.