Radionuclide imaging for the assessment of myocardial viability in chronic LV dysfunction

Clinical decision making for the selection of patients with coronary artery disease and depressed left ventricular (LV) function for coronary revascularization is very critical but at times difficult. There is strong evidence of an increased event rate (myocardial infarction, death, unstable angina) in one fourth of patients with viable myocardium who are treated medically compared with only one sixteenth after revascularization. Documentation of the presence of viable myocardium best allows identification of patients who are most likely to benefit from coronary revascularization as evident by postoperative improvement in LV systolic function, exercise capacity, quality of life, or survival. On the other hand, identifying patients who would not demonstrate significant improvement is equally important in view of the high morbidity and mortality rates associated with surgery in such patients. Noninvasive imaging to determine the presence and extent of viable myocardium has become an important component of the assessment of patients with coronary artery disease and depressed LV function. About 40% of such patients have the potential for significant improvement after successful surgical revascularization. This review summarizes the role of radionuclide myocardial perfusion imaging for the assessment of viable myocardium.