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Background: In hospital-based studies and in studies of participants with pre-existing conditions, African Americans have a higher risk of in- and out-of-hospital sudden cardiac death (SCD) compared with Whites. However, the risk of SCD of African Americans and Whites has never been compared in large-scale community-based cohort studies.Objective: To compare the risk of SCD among African Americans and Whites, and to evaluate the risk factors that may explain racial differences in incidence.Methods: Cohort study of 3,838 African Americans and 11,245 Whites participating in ARIC. Race was self-reported. SCD cases were defined as a sudden pulseless condition from a cardiac cause in a previously stable individual and adjudicated by an expert committee. Mediation effect of covariates was calculated using boot-strapping method. Cox proportional hazards models were adjusted for demographics, social economic status, cardiovascular (CVD), and electrocardiographic risk factors.Results: The mean (SD) age was 53.6 (5.8) for African Americans and 54.4 (5.7) years for Whites. During 25.3 years of follow-up, 215 African Americans and 332 Whites experienced SCD. Inmultivariable-adjusted models, the HRs (95% CI) for SCD comparing African Americans and Whites were 1.70 (1.37, 2.10) overall, 2.00 (1.40, 2.84) in women, and 1.46 (1.10, 1.92) in men (p-value for race by sex interaction 0.02; Table). CVD and electrocardiographic risk factors explained 36.6% (21.4, 51.8%) of the excess risk of SCD in African Americans, with a large proportion of racial differences unexplained.Conclusions: The risk of SCD in community-dwelling African Americans was significantly higher than in Whites, particularly among women. CVD risk factors, including higher prevalence of obesity, diabetes, hypertension and LV hypertrophy in African Americans, explained only a small fraction of this difference. Further research is needed to identify factors responsible for race differences in SCD and to implement prevention strategies in high-risk minorities.