Effect of reperfusion time on inducible ventricular tachycardia early and spontaneous ventricular arrhythmias late after ST elevation myocardial infarction treated with primary percutaneous coronary intervention

Background Prompt thrombolytic reperfusion reduces postinfarct ventricular electrical instability after ST elevation myocardial infarction (STEMI). Objective The purpose of this study was to examine the relationship between reperfusion time and inducible ventricular tachycardia (VT) early and spontaneous ventricular arrhythmias (VAs) late after primary percutaneous coronary intervention (PCI) for STEMI. Methods Consecutive patients were recruited if they (1) had no prior coronary disease, (2) had been reperfused with primary PCI, (3) had postinfarct ejection fraction ≤40%, and (4) had undergone cardiac electrophysiologic study (n = 128). Three groups were compared according to reperfusion time: early (≤3 hours, n = 26), intermediate (>3–5 hours, n = 45), or delayed reperfusion (>5 hours, n = 57). Spontaneous VA was a composite endpoint of sudden death or defibrillator-treated VA. Results Mean ejection fraction (33% ± 5%, 31% ± 6%, and 31% ± 7%, P = .41) and peak creatinine kinase ( P = .37) were similar between groups. VT was inducible in 11.5%, 17.8%, and 36.8% of patients in the early, intermediate, and delayed reperfusion groups, respectively ( P = .003). At 2 years, the incidence of spontaneous VA was 0%, 8.9%, and 14% in the early, intermediate, and delayed reperfusion groups, respectively ( P = .025). By multivariable analysis, delayed reperfusion conferred a sixfold increase in the odds of inducible VT ( P = .01). Although inducible VT was the strongest predictor of spontaneous VA (hazard ratio 14.31, P = .001), delayed reperfusion conferred a threefold increase in risk when inducible VT was excluded from the multivariable model ( P = .035). Conclusion Reperfusion time is a critical determinant of postinfarct ventricular electrical instability early and late after STEMI treated with primary PCI.