Denerved myocardium detected by I-123 metaiodobenzylguanidine myocardial imaging following successful percutaneous transluminal coronary thrombolysis

I-123 metaiodobenzylguanidine (MIBG) is taken up by sympathetic nerve endings. Thirteen patients with acute myocardial infarction, in whom reperfusion was achieved with percutaneous transluminal coronary thrombolysis (PTCR), MIBG and Tl-201 (Tl) images 14 days after PTCR which were simultaneously performed were studied. In the late stage, Tl myocardial stress test was also performed to detect ischemia. The extent of myocardial defect was estimated as percent defet. Wall motion was assessed by echocardiography. Ejection fraction (EF) was assessed in the chronic phase using left ventriculography. In nine of the 13 patients, the denerved myocardial regions having the MIBG defects were noted using a Tl uptake. A percent defect noted in MIBG images was 25±6% and was greater than those (6±6%, p<0.01) in Tl images. During the convalescent phase, the wall motion of the denerved region was restored (2, normal; 4, mild hypokinesis; 3, moderate hypokinesis) and in the chronic phase, EF was well preserved (61±14%). Ischemic regions noted in stress images coincided with denerved regions. In four patients without the denerved myocardium, EF was 46±3% (p<0.05) and wall motion of defect areas was akinetic. Both EF and myocardial viability were more preserved in cases with denerved region; i.e., PTCR was successfully performed in these cases. It was suggested that the denerved region was the area of severe ischemia during the acute phase and that it was salvaged by PTCR. The sympathetic nerve was damaged by severe ischemia, and depressed sympathetic function persisted long after the recovery of both myocardial perfusion and the wall motion. With denerved regions, the myocardium salvaged by PTCR could be evaluated by MIBG images and patients with extensive denerved regions might be candidates for PTCR and/or CABG. Thus, MIBG imaging proved clinically useful. (author)