Assessment of viability in regional myocardium with reversed redistribution by thallium reinjection in patients with acute myocardial infarction

The aim of this study was to evaluate whether Tl-201 reinjection distinguishes viable from nonviable myocardium in patients with reverse redistribution after acute myocardial infarction. We studied 42 patients with acute myocardial infarction (age, 55±12 years). Eighteen (43%) out of 42 showed reverse redistribution on dipyridamole stress-4 hour redistribution Tl-201 single photon emission computed tomography (SPECT). Tl-201 reinjection was performed at 24 hours. Reverse redistribution was defined as worsening of perfusion defect at 4 hour delayed scan. All patients underwent follow-up echocardiography in 4 months to assess regional wall motion improvement. Tl-201 uptake on reinjection images were analyzed for the prediction of myocardial wall motion improvement. Of 36 segments with reverse redistribution, 17 segments showed normal wall motion on echocardiography, while 19 segments showed wall motion abnormalities. Of 19 the segments with reverse redistribution, 11 (58%) showed enhanced uptake after 24 hour reinjection. Myocardial wall motion was improved in 10 of 11 segments (90%) wth enhanced uptake on reinjection. Wall motion improvement was not seen in 5 of 8 segments (63%) without enhanced thallium uptake. When myocardial viability was assessed by the uptake on reinjection image, nine of 10 segments (90%) with normal or mildly decreased uptake showed improved wall motion. Wall motion was not improved in 5 of 9 segments (56%) with severely decreased uptake. In patients with acute myocardial infarction, Tl-201 reinjection imaging on myocardial segments with reverse redistribution has a high positive predictive value in the assessment of myocardial viability