Radionuclide viability testing: should it affect treatment strategy in patients with cardiomyopathy and significant coronary artery disease?

Background Ischemic heart failure is a significant source of morbidity and mortality, yet it has an unclear treatment strategy. The assessment of viable myocardium by nuclear imaging studies has shown promise in predicting improvements in ejection fraction and symptoms. However, the relationship of viability to long-term mortality has not been fully established. Methods A number of studies have addressed long-term mortality with nuclear viability imaging in patients with impaired left ventricular function and significant coronary artery disease. These studies were analyzed to determine differences in design, results, trends, and limitations. They were then evaluated by use of qualitative criteria established for prognostic studies. Results Fourteen studies met our criteria. Although the conclusions differed, it appears that patients with viability who undergo revascularization have the highest survival rate, whereas patients with viability who are treated medically have a much lower survival rate. Patients without viability have an intermediate survival rate, regardless of treatment. Several limitations were identified, including a lack of randomization, small sample size, inadequate follow-up, and extensive study protocol and design differences. Conclusions The use of viability testing in patients with heart failure and significant coronary artery disease has shown promise in predicting the long-term mortality rate with treatment allocation. However, there is a need for further study involving larger cohorts with a randomized design, longer periods of follow-up, improved study designs, and identification of referral bias and viability prevalence.