Quantitative rest technetium-99m tetrofosmin imaging in predicting functional recovery after revascularization: comparison with rest-redistribution thallium-201.

OBJECTIVES This study was undertaken to 1) compare the regional myocardial tracer distributions between rest technetium (Tc)-99m tetrofosmin and rest-redistribution thallium (Tl)-201 images in patients with coronary artery disease and left ventricular dysfunction; and 2) assess the comparative values of these agents for predicting functional recovery after revascularization. BACKGROUND Tc-99m tetrofosmin is a new myocardial perfusion imaging agent, but its role for detecting viable myocardium is still unclear. METHODS Thirty-six patients with coronary artery disease and left ventricular dysfunction underwent rest Tc-99m tetrofosmin, rest-redistribution Tl-201 and gated blood pool scintigraphy. In 21 patients with successful revascularization confirmed by follow-up angiography, gated blood pool scintigraphy was repeated after revascularization. Optimal threshold cutoffs to separate reversible from irreversible dysfunction were determined by receive operating characteristic analysis. RESULTS Regional Tc-99m tetrofosimin activity highly correlated with redistribution Tl-201 activity (r = 0.93). The diagnostic performance for predicting functional recovery, as measured by the area under the receiver operating characteristic curves, measured 0.66 +/- 0.07 (mean +/- SD) for Tc-99m tetrofosmin and 0.67 +/- 0.07 for Tl-201 (p = 0.60, 96.7% power to detect difference in area of 0.10). The optimal threshold cutoffs for viability were considered to be 50% of peak activity for Tc-99m tetrofosmin and 55% of peak activity for Tl-201. The positive and negative predictive values for reversible dysfunction were, respectively, 69% and 82% for Tc-99m tetrofosmin and 69% (p = 0.99 vs. Tc-99m tetrofosmin) and 71% (p = 0.66 vs. Tc-99m tetrofosmin) by Tl-201. CONCLUSIONS The diagnostic performance of quantitative rest Tc-99m tetrofosmin imaging in predicting functional recovery after revascularization is comparable to that of rest-redistribution Tl-201.