Nuclear cardiology and echocardiography for the assessment of myocardial viability

The review aims to make a comparative analysis of the nuclear cardiology and echocardiographic approaches for the assessment of myocardial viability on the basis of the most recent literature. Preliminarily the most extensively used methods are described: 1) metabolic tracers, especially as regards FDG-F18 (quantitative uptake; mismatch FDG uptake/perfusion); 2) sarcolemmal integrity tracers (201Tl- with stress-redistribution-reinjection or with rest-redistribution protocols; rest MIBI 99mTc); 3) low dose dobutamine stress echocardiography (LDDSE) for the detection of residual contractility reserve. Global sensitivity values of thallium studies are reported to be similar to those of LDDSE, but in selected patients populations with akinetic or severely hypokinetic segments the LDDSE sensitivity seems to be significantly lower, when metabolic viability assessed by FDG studies is assumed as gold standard. According to the Authors' opinion thallium study with a protocol including a rest injestion can be considered at the moment the first choice for myocardial viability assessment because of its convenience, reproducibility, possibility of technical and interpretative standardization, amount of clinical and experimental validations. Anyway further clinical trials with adequate follow-up are necessary in order to define the scintigraphic and echocardiographic patterns that provide the best accuracy in the prediction of the post-revascularization clinical outcome.