Abstract 9945: Concomitant Early Repolarization Increases Occurrences of Ventricular Fibrillation in Patients with Acute Myocardial Infarctions

Abstract

Background: Previous studies demonstrated that there is an increased prevalence of electrocardiographic early repolarization among patients with a history of idiopathic ventricular fibrillation (VF). Early repolarization is also associated with life threatening ventricular tachyarrhythmias in patients with chronic coronary artery disease. However, no studies have clarified whether or not there is an association between electrocardiographic early repolarization and the VF occurrences after the onset of acute myocardial infarction (AMI). Methods: This study included 220 consecutive patients with AMIs (69±11 years; 57 females) in whom 12-lead ECGs before the AMI onset could be evaluated. The patients were classified based on the VF occurrence within 48 hours after the AMI onset. Sustained VF was defined as that lasting longer than 30 seconds or that required electrical cardioversion. Early repolarization was electrocardiographically defined as an elevation of the QRS-ST junction of >0.1 mV from baseline in at least 2 inferior or lateral leads, manifested as QRS slurring or notching. Results: Twenty-one (10%) patients experienced an episode of VF within 48 hours of AMI onset. Compared to the patients without VF, the VF patients had a higher prevalence of early repolarization (p<0.001) and male gender (p<0.05), a shorter duration from onset to admission (p<0.05), and a greater number of diseased coronary arteries (p<0.05) and Killip class (p<0.001). A multivariate analysis revealed that early repolarization (odds ratio [OR]=6.45; 95% confidence interval [CI]= 2.07-20.40; p<0.01), a time from onset to admission less than 180 minutes (OR=3.54; 95% CI=1.08-11.53; p<0.05), and a Killip class greater than I (OR=11.43; 95% CI=3.22-40.59; p<0.001) were independent predictors of VF occurrences. Conclusion: The presence of early repolarization increases the risk of VF occurrences within 48 hours after the AMI onset.