The presence of myocardial viability is an important determinant of functional recovery after revascularization. Radionuclide and echocardiographic techniques are highly valuable in the identification of viable myocardium. Several clinical studies have compared the two modalities. Dobutamine echocardiography appears to have a higher specificity and a lower sensitivity in comparison with single-photon emission computed tomographic imaging. Importantly, both myocardial perfusion and inotropic reserve are capable of identifying the patients with the large increments in ejection fraction after successful revascularization.