Early Repolarization Is an Independent Predictor of Occurrences of Ventricular Fibrillation in the Very Early Phase of Acute Myocardial Infarction

BACKGROUND: Recent evidence has linked early repolarization (ER) to idiopathic ventricular fibrillation (VF) in patients without structural heart disease. However, no studies have clarified whether or not there is an association between ER and the VF occurrences after the onset of an acute myocardial infarction (AMI). METHODS AND RESULTS: This study retrospectively included 220 consecutive patients with an AMI (57 female; mean age, 69±11 years) in whom the 12-lead ECGs before the AMI onset could be evaluated. The patients were classified on the basis of a VF occurrence within 48 hours after the AMI onset. Early repolarization was 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. Twenty-one (10%) patients had a VF occurrence within 48 hours of the AMI onset. A multivariate analysis revealed that ER (odds ratio OR, 7.31; 95% confidence interval CI, 2.21-24.14; P<0.01), a time from the onset to admission of <180 minutes (OR, 3.77; 95% CI, 1.13-12.59; P<0.05), and a Killip class greater than I (OR, 13.60; 95% CI, 3.43-53.99; P<0.001) were independent predictors of VF occurrences. As features of the ER pattern, a J-point elevation in the inferior leads, greater magnitude of the J-point elevation, notched morphology of the ER, and ER with a horizontal/descending ST segment, all were significantly associated with a VF occurrence. CONCLUSIONS: The presence of ER increased the risk of VF occurrences within 48 hours after the AMI onset.