Reverse redistribution of thallium-201 myocardial single photon emission tomography and contractile reserve

The present study investigated the contractile reserve of myocardium exhibi ting reverse redistribution (RRD) of thallium-201 ((TI)-T-201) after acute myocardial infarction. Forty patients experiencing their first acute myocar dial infarction underwent resting (TI)-T-201 single-photon emission compute d tomography (SPECT) and low-dose (5-10 mu g.kg(-1).min(-1)) dobutamine str ess echocardiography (DSE) within 4 weeks after the onset of infarction, Th e left ventricle was divided into 13 segments for analysis. The severity of defects in (TI)-T-201 SPECT and the extent of wall motion abnormality in D SE were visually assessed and scored. The sum of each defect score and wall motion score of infarct-related segments were defined as total defect scor e (TDS) and total wall motion score (TWM), respectively. Quantitative analy sis of (TI)-T-201 uptake was also performed. Resting (TI)-T-201 SPECT revea led RRD in 16 patients (group RRD), fixed defect (FIX) in 23 patients (grou p FIX), and redistribution in one. There was a significant difference in im provement of TWM between rest and stress in TWM in both the RRD and FIX gro ups (p<0.0001, each case). The improvement of TWM with dobutamine was signi ficantly greater in RRD than in FIX (1.6+/-1.0 vs 0.6+/-0.7, p=0.001). Ther e was a positive correlation between the magnitude of RRD and improvement o f TWM with dobutamine (r=0.48, p=0.002). Myocardium exhibiting RRD on (TI)- T-201 SPECT in patients with acute myocardial infarction has greater contra ctile reserve than that exhibiting a fixed defect.