EFFECTS OF DELAYED RECANALIZATION OF AN OCCLUDED ACUTE MYOCARDIAL INFARCTION-RELATED ARTERY USING CORONARY ANGIOPLASTY ON LATE POTENTIALS

Background: Recent evidence suggests that late reperfusion of an occluded infarct-related artery after an acute myocardial infarction may reduce the frequency of subsequent arrhythmic events. Late mechanical reperfusion by percutaneous transluminal coronary angioplasty (PTCA) under these circumstances has a high success rate. The present study was performed to test the hypothesis that the late mechanical restoration of anterograde flow in an occluded infarct artery after an acute myocardial infarction causes a resolution of late potentials. Methods: Twenty subjects (10 men, one woman; aged 32-77 years) suffering a first acute myocardial infarction, with signal-averaged electrocardiographic (EGG) recordings and a severely occluded infarct-related artery, were prospectively identified. Results: Eighteen patients underwent successful PTCA of the occluded artery 6-32 days after a first acute myocardial infarction. Late potentials were observed in 14 patients 5-22 days after the infarction. A follow-up signal-averaged ECG was performed 1-8 days later. In the subgroup of 12 patients with successful reperfusion and an abnormal signal-averaged ECG before PTCA, seven (58.3%) showed resolution of the late potentials at follow-up; in these patients the filtered QRS duration showed a significant reduction (112.1+/-14.2 to 96.7+/-12.7 ms, P=0.02), the root-mean-square voltage increased (9.8+/-6.5 to 33.1+/-15.5 mu V, P=0.017), and the duration of low-amplitude signals <40 mu V decreased after angioplasty (46.3+/-11.0 to 28.5+/-6.5 ms, P<0.022). In contrast, two patients with late potentials before PTCA and unsuccessful reperfusion had no significant changes in signal-averaged EGG. Conclusions: In some patients with an acute myocardial infarction, late mechanical reperfusion of the culprit vessel may reduce the incidence of abnormalities on the signal-averaged EGG. Whether this will improve long-term survival has yet to be confirmed in a large trial.