Effects of late (1 to 30 days) reperfusion after acute myocardial infarction on the signal-averaged electrocardiogram

Abstract Early reperfusion (4 to 6 hours) after acute myocardial infarction reduces mortality and reduces the incidence of late potentials on a signal-averaged electrocardiogram (SAECG). Recent reports suggest that reperfusion accomplished after >6 hours also may reduce mortality. The effect of such later reperfusion on the SAECG is not known. We hypothesized that reperfusion by angioplasty accomplished >24 hours after onset of infarction would reduce late potentials and improve the parameters on the SAECG. Forty-one patients with a totally occluded infarct-related artery 12 ± 8 days after infarction underwent attempted angioplasty. SAECG, echocardiography and thallium-201 imaging were performed before and 1 month after attempted angioplasty. Angioplasty resulted in successful reperfusion in 32 patients and was unsuccessful in 9. No change in the incidence of late potentials occurred after successful reperfusion (13 of 32 patients before and 13 of 32 patients 1 month later) or after unsuccessful reperfusion (6 of 9 patients before and 5 of 9 patients 1 month later). Among patients with successful reperfusion, no significant change occurred in the QRS duration or the terminal signal duration