Natural History of the Early Repolarization Pattern in a Biracial Cohort: CARDIA (Coronary Artery Risk Development in Young Adults) Study

Objectives The objective of this analysis was to determine the natural history and prospective association of cardiovascular risk factors with early repolarization (ER). Background ER is common and has been suggested to increase risk for cardiovascular mortality in middle-aged adults. Data are sparse regarding the natural history of ER from young adulthood to middle age. Methods We examined 5,069 participants (mean age 25 years at baseline; 40% black) from the CARDIA (Coronary Artery Risk Development in Young Adults) cohort over 20 years. Electrocardiograms were recorded at years 0 (Y0), 7 (Y7), and 20 (Y20) and coded as either definite, probable, possible, or no ER. Logistic regression was used to determine the association of cardiovascular risk factors with the presence of ER cross-sectionally and prospectively. Results A total of 941 of the 5,069 participants (18.6%) had definite ER at baseline, and only 119 of 2,505 participants (4.8%) at the Y20 examination still demonstrated the presence of ER. Younger age, black race, male sex, longer exercise duration and QRS duration, and lower body mass index (BMI), heart rate, QT index, and Cornell voltage were associated cross-sectionally with the presence of ER. Predictors of maintenance of ER from Y0 to Y20 were black race (odds ratio [OR]: 2.62; 95% CI; 1.61 to 4.25), BMI (OR: 0.62 per 1 SD; 95% CI: 0.40 to 0.94), serum triglyceride levels (OR: 0.66 per 1 SD; 95% CI: 0.45 to 0.98), and QRS duration (OR: 1.68 per 1 SD; 95% CI: 1.37 to 2.06) at baseline. Conclusions The prevalence of ER was significantly higher than previous estimates among asymptomatic young adults, and the majority of ER regressed by middle age. Black race, lower BMI, lower serum triglyceride levels, and longer QRS duration were independently associated with maintenance of ER over time. (J Am Coll Cardiol 2013;61:863-9) (c) 2013 by the American College of Cardiology Foundation