Assessment of myocardial viability in patients with heart failure.

The prognosis for patients with chronic ischemic left ventricular dysfunction is poor, despite advances in different therapies. Noninvasive assessment of myocardial viability may guide patient management. Multiple imaging techniques have been developed to assess viable and nonviable myocardium by evaluating perfusion, cell membrane integrity, mitochondria, glucose metabolism, scar tissue, and contractile reserve. PET, (201)Tl and (99m)Tc scintigraphy, and dobutamine stress echocardiography have been extensively evaluated for assessment of viability and prediction of clinical outcome after coronary revascularization. In general, nuclear imaging techniques have a high sensitivity for the detection of viability, whereas techniques evaluating contractile reserve have a somewhat lower sensitivity and a higher specificity. MRI has a high diagnostic accuracy for assessment of the transmural extent of myocardial scar tissue. Patients with a substantial amount of dysfunctional but viable myocardium are likely to benefit from coronary revascularization and may show improvements in regional and global contractile function, symptoms, exercise capacity, and long-term prognosis.