Abstract
IMPORTANCE: Resting heart rate (RHR) is a widely available measure of cardiovascular fitness that has been associated with several cardiovascular outcomes. RHR has previously been associated with the risk of atrial fibrillation (AF) among individuals of European ancestry, but little is known about this association in Black adults. OBJECTIVE: To evaluate the association between RHR and incident AF in a large community-based sample of Black adults, independently of established risk factors. DESIGN, SETTING, AND PARTICIPANTS: This cohort study uses data from the Jackson Heart Study, a prospective community-based cohort in Jackson, Mississippi. Participants without prevalent AF were included and were monitored for new-onset AF during follow-up, from 2000 through 2016. Data analysis was performed from August 1 to December 11, 2023. EXPOSURE: RHR was assessed from resting 12-lead electrocardiograms performed at examination 1 (2000-2004) and examination 3 (2009-2013). MAIN OUTCOMES AND MEASURES: AF was identified from study electrocardiograms, hospitalization discharge diagnosis codes, and Medicare claims diagnosis codes. Cox regression was used to evaluate the association between baseline (examination 1) RHR and incident AF, adjusting for established AF risk factors. RESULTS: Among 4965 Black adults eligible for analysis, the mean (SD) age was 55 (13) years, 1830 (37%) were male, and the mean (SD) RHR at baseline was 65 (11) beats per minute (bpm). During a median (IQR) 14 (12-15) years of follow-up, there were 458 incident AF events, resulting in an incident rate of 7.5 per 1000 person-years (95% CI, 6.8-8.2 incidents per 1000 person-years). Each 10-bpm higher RHR was associated with a 9% higher risk of incident AF after adjustment for AF risk factors (hazard ratio, 1.09; 95% CI, 1.00-1.19). In a sensitivity analysis that excluded individuals with prior heart failure, prior myocardial infarction, and antiarrhythmic medication use at baseline, the hazard ratio was 1.14 (95% CI, 1.02-1.28). There was little evidence of effect modification of these associations by age, sex, body mass index, hypertension, or physical activity level. CONCLUSIONS AND RELEVANCE: In this large prospective cohort study of Black adults, elevated baseline RHR was associated with increased risk of incident AF, consistent with findings from previous studies of European ancestry populations. Future research should focus on determining whether RHR can be used to screen patients at high risk of AF.