RADIONUCLIDE IMAGING AFTER THROMBOLYTIC THERAPY OR EMERGENCY PTCA IN ACUTE MYOCARDIAL-INFARCTION

The aim of our study was to compare the short-term outcome of angiogra phically successful emergency PTCA and acute thrombolytic therapy afte r acute myocardial infarction by stress- and redistribution-201-thalli um-chloride-SPECT. Radionuclide imaging using SPECT is highly specific and sensitive for the determination of reperfusion and infarction siz e after an acute myocardial infarction. This technique allows to disti nguish between three different groups of SPECT-results: irreversible d efects without any redistribution of the radiotracer suggesting mainly scar tissue, partial or complete redistribution suggesting ischemic m yocardium potentially combined with scar tissue, and normal tracer acc umulation without signs of infarction or ischemia. The following inter ventions were performed in 79 patients (60 males, 19 females, mean-age : 55.4 +/- 9.1 years) with acute myocardial infarction: emergency PTCA in 42 patients and thrombolytic therapy with either streptokinase or rt-PA in 37 patients. Within 4 weeks after intervention the patients w ere examined by 201-thallium-chloride-SPECT immediately following exer cise and 5 hours later. Only 9 patients had no evidence of ischemia or scar tissue in the infarction area. The ECG at rest and under stress did not show any typical signs of ischemia or scar tissue in these pat ients either. Irreversible defects without redistribution in the zone of infarction were seen in 50 patients, defects with partial or comple te redistribution in 20 patients. The most successful method in avoidi ng ischemic changes determined by SPECT was emergency PTCA (85.7% with out reversible defects, thrombolysis: 62.2%). The least irreversible d efects without redistribution were found after thrombolysis (48.6%, em ergency-PTCA: 76.2%). These irreversible defects may indicate scar tis sue. We conclude that there are only small differences between both te sted methods with respect to non-pathologic SPECT-results. Significant differences (p < 0.05) were observed with respect to redistribution i n SPECT indicating ischemic reaction of viable myocardium in the zone of infarction. This reaction was rare after emergency PTCA (14.3%). Th e cases with suspicion of ischemia in SPECT after primary successful i ntervention had an angiographically confirmed restenosis of the infarc t vessel. The higher rate of irreversible defects after emergency PTCA (76.2%, thrombolysis: 48.6%, p < 0.05) may indicate a higher rate of scar development.