Quantitative thallium-201 and technetium 99m sestamibi tomography at rest in detection of myocardial viability in patients with chronic ischemic leftventricular dysfunction

Background. This study was designed to determine the most effective quantit ative threshold for thallium-201 and technetium 99m sestamibi uptake on tom ographic imaging after rest injection for the detection of myocardial viabi lity in patients with chronic myocardial infarction. Methods and Results, Thallium and sestamibi cardiac tomography at rest was performed in 43 patients with chronic myocardial infarction and impaired le ft ventricular (LV) function undergoing coronary revascularization, In all patients, echocardiography and radionuclide angiography were performed at b aseline and repeated 12 months later to evaluate recovery of regional LV fu nction and LV ejection fraction, respectively, Optimal threshold cutoff poi nts to separate reversible from irreversible dysfunction were determined by receiver operating characteristic analysis, When all dysfunctional segment s were considered, the best cutoff point in the identification of reversibl e LV dysfunction for both thallium and sestamibi activity was 67%. When onl y akinetic or dyskinetic segments were considered, the best cutoff point in the identification of reversible LV dysfunction was 58% for thallium and 5 5% for sestamibi, In these segments, the area under the receiving operating characteristic curves constructed for thallium and sestamibi activity were 0.74 +/- 0.05 and 0.75 +/- 0.04, respectively (P = not significant), LV ej ection fraction was 33% +/- 7% at baseline and increased to 37% +/- 7% afte r revascularization (P < .0001). A significant relation between the number of akinetic or dyskinetic but viable myocardial segments and revascularizat ion-induced changes in LV ejection fraction was observed for both thallium (r = 0.60, P < .0001) and sestamibi (r = 0.64, P < .0001) imaging, Conclusions. In patients with chronic myocardial infarction, quantitative a nalysis of thallium and sestamibi activity on tomographic imaging at rest p redicts recovery of regional and global LV dysfunction after revascularizat ion procedures. The most effective quantitative threshold for detecting rev ersible LV dysfunction is comparable for thallium and sestamibi tomographic imaging, However, the optimal cutoff point is different for both tracers w hen all dysfunctional segments are considered or when the analysis is focus ed only on segments with more severe functional impairment (ie, akinetic or dyskinetic segments).