Usefulness and Limitation of 24 Hour Reinjection Images to Assess Myocardial Viability in Patients with Acute Myocardial Infarction

Abstract

ObjectiveThe study was performed to evaluate whether thallium reinjection RI distinguishes viable from nonviable myocardium among myocardial segments which showed persistent perfusion defect PD in patients with acute myocardial infarction AMI . Materials and Methods We studied 22 patients underwent PTCA after AMI. SPECT was performed in all patients using dipyridamole stress-4 hour redistribution RD followed by 24 hour RI protocols. Dysfunctional segs were classified into 5 groups 1 normal, 2 reversible, 3 mild to moderate PD, 4 severe PD and 5 reverse redistribution RR . All patients underwent follow up echocardiography after 4 months to assess regional wall motion WM improvement such as a criteria of viable myocardium. Results A total of 127 segs with abnormal WM was analyzed. Of 74 segs with PD, 17 23% showed enhanced uptake after 24 hour RI. Five of 17 segs 29% with PD that responded to RI with enhanced thallium uptake showed WM improvement. WM improvement were seen in the 24 of 57 segs 42% not responding to RI. All four segs 100% with RR that responded to RI showed improvement. WM improvement were not seen in the 5 of 8 segs 71% with RR not responding to thallium RI. Eleven 73% of 15 segs with mild-moderate PD after RI showed improvement, but 33% of segs with severe PD after RI did not showed improvement. Segs with mild-moderate PD after RI and fill in after RI showed improvement in comparison to segs with severe PD after RI p 0.05 . Conclusions These data indicate that because only small proportion of PD showed further perfusion improvement after RI and predictive value by the uptake after RI was low, there was limited role of RI after myocardial infarction. Usefulness of RI could be found in segs showing RR responding to RI in AMI reflects viable myocardium. Korean Circulation J 2001 ; 31 1 : 74-82 KEY WORDS Viability·Reinjection and acute myocardial infarction.