789-6 Scintigraphic Assessment of Myocardial Viability in the Late Phase (>4 weeks) of Myocardial Infarction: Comparison Between Sestamibi and Thallium-201

Abstract

This study was part of an open multicenter protocol to evaluate the value of tomographic myocardial perfusion imaging with sestamibi and thallium-201 (TI-201) in the detection of ischemic but viable myocardium in chronic stable coronary artery disease patients with left ventricular dysfunction. A series of 20 patients (pts) with > 75% coronary artery stenosis and wall motion abnormality, who were scheduled for percutaneous transluminal coronary angioplasty (PTCA) and had a > 4-week old myocardial infarction were included. All pts underwent (a) within 21 days before PTCA, a separate-day rest and stress sestamibi study, a same-day stress, redistribution and 4-hour reinjection study with TI-201, and a gated blood pool study, (bl within 4–6 weeks after PTCA, another sestamibi and gated blood pool studies. Perfusion and wall motion abnormalities were graded visually. Among the 15 pts who completed the study, left ventricular ejection fraction showed improvement after PTCA in 12 pts (39.9 ± 10.5 vs 45.3 ± 10.8, P < 0.001), while wall motion improved in 18 segments repartited into 7 pts. Among these 18 viable areas, pre-PTCA tracer uptake was normal or near-normal in 28% with sestamibi at rest, and in 56% with TI-201 at redistribution. After exercise, reversible ischemia was observed in 44% of these segments with sestamibi and in 55% with TI-201. (a) residual myocardial viability was present in nearly 50% of the pts with a < 4-week old myocardial infarct, (bl in the viable areas, at rest, sestamibi uptake was more often abnormal than TI-201 uptake.