Abstract 12403: Interval that Estimates Overlap between Depolarization and Repolarization Helps to Discriminate between Benign and Malignant Early Repolarization in Black Men
Background: An association has been reported between sudden cardiac death (SCD) and the early repolarization (ER) ECG phenomenon. However, ER ECG in black men is usually associated with a benign prognosis. The goal of this study was to identify a subgroup of black men with ER at an increased risk of SCD.
Methods: We analyzed baseline resting digital 12-lead ECGs of 1332 black men, participants of the prospective community-dwelling the Atherosclerosis Risk In Communities cohort. Individuals with coronary heart disease (CHD), heart failure, or QRS > 120 ms at baseline were excluded. ER was diagnosed if the elevation of the J-point ≥ 0.1 mV was detected in at least two lateral leads (I, aVL, V5, V6). The inverse Dower transformation was applied to construct the vectorcardiogram (VCG). JJ interval that estimates overlap between depolarization and repolarization was measured by custom Matlab software as the time epoch between J-on-ECG-point defined as the end of QRS complex on ECG (onset of repolarization) and J-on-VCG-point, defined on VCG as the origin point where QRS loop has completely returned to the baseline (end of depolarization).
Results: During a median follow-up of 14 years, 46 cases of SCD, 51 non-sudden fatal CHD and 249 non-CHD deaths occurred. ER in lateral leads was diagnosed in 85 (6.4%) black men. SCD was twice as frequent in men with vs. without ER [7(8.2%) vs. 39(3.1%); P=0.013]. JJ interval in ER was half as long in black men with SCD (14.0±12.8 vs. 28.3±23.8 ms; P=0.026). ER in lateral leads with JJ interval ≤ 13 ms predicted SCD with 11% sensitivity, 98% specificity, 15% positive predictive value, and 97% negative predictive value. In multivariable competing risks regression analysis, ER in lateral leads with JJ interval ≤ 13 ms was significantly associated with SCD after adjustment for study center, age, body mass index, history of diabetes mellitus and hypertension (subHR 5.6; 95% CI 2.8-13.8; P≤0.0001), but was not associated with non-CHD death.
Conclusion: A short JJ interval characterizes the subgroup of asymptomatic middle-aged black men with ER ECG on lateral ECG leads at a higher risk of SCD. Further studies of JJ interval in other cohorts are needed to replicate findings.
- © 2013 by American Heart Association, Inc.