Abstract 9624: Concomitant Early Repolarization is the Independent Predictor for the Occurrence of Sustained Ventricular Tachyarrhythmias or Sudden Death in the Chronic Phase of Acute Myocardial Infarction

Abstract

Background: We recently demonstrated that the presence of early repolarization (ER) increased the risk of ventricular fibrillation (VF) ccurrences in the early phase of acute myocardial infarction (AMI). However, it is unknown whether there is an association between ER and VF occurrences in the chronic phase of AMI. Methods: This study included 1001 patients with AMI (67±12 years; 762 male; 239 female) who underwent successful percutaneous coronary intervention. The primary endpoint was occurrence of sustained ventricular tachyarrhythmias (VT/VF) or sudden death more than 14 days after AMI onset. We evaluated the presence of ER from the ECG recorded at pre-discharge. ER was defined as a QTS-ST junction elevation of >0.1mV from baseline in at least 2 leads. We also analyzed the localization (inferior or lateral leads), amplitude, morphology (notching or slurring), and ST segment characteristics (upsloping or horizontal/descending) of ER to evaluate the significance of the ER pattern. Results: After a mean follow-up of 27.7±17.3 months, 16 (1.6%) patients had an episode of VT/VF or sudden death. The patients with VT/VF or sudden death had a greater prevalence of a left anterior descending culprit artery (75% vs. 45%; p<0.05) and lower left ventricular ejection fraction (39±11% vs. 54±11%; p<0.001) than those without. Furthermore, with the 12-lead ECG analysis recorded pre-discharge, ER was found in 7 (44%) of the patients with VT/VF or sudden death, which was more prevalent than in those without (11%; p<0.01). A multivariate Cox regression analysis revealed that ER (hazard ratio [HR] 6.14; 95% confidence interval [CI] 2.24-16.83; p<0.001) and a left ventricular ejection fraction lower than 35% (HR 15.77; 95% CI 5.69-43.73; p<0.001) were independent predictors of the occurrence of VT/VF or sudden death. As features of the ER pattern, a J-point elevation in the inferior leads, notched morphology of the ER, and ER with a horizontal/descending ST-segment, all were significantly associated with VT/VF or sudden death occurrences. Conclusions: The presence of ER increases the risk for VT/VF or sudden death occurrences in the chronic phase of AMI, and may become a useful tool for deciding an indication for an implantable cardioverter defibrillator.