Risk of Atrial Fibrillation in Black Versus White Medicare Beneficiaries With Implanted Cardiac Devices

Background Black individuals in the United States experience higher rates of ischemic stroke than other racial groups but have lower rates of clinically apparent atrial fibrillation ( AF ). It is unclear whether blacks truly have less AF or simply more undiagnosed AF . Methods and Results We performed a retrospective cohort study using inpatient and outpatient claims from 2009 to 2015 for a 5% nationally representative sample of Medicare beneficiaries. We included patients aged ≥66 years with at least 1 documented Current Procedural Terminology code for interrogation of an implantable pacemaker, cardioverter-defibrillator, or loop recorder and no documented history of AF , atrial flutter, or stroke before their first device interrogation. Kaplan-Meier statistics and Cox proportional hazards models were used to examine the association between black race and the composite outcome of AF or atrial flutter while adjusting for age, sex, and vascular risk factors. Among 47 417 eligible patients, the annual incidence of AF /atrial flutter was 12.2 (95% CI , 11.5-13.1) per 100 person-years among blacks and 17.6 (95% CI , 17.4-17.9) per 100 person-years among non-black beneficiaries. After adjustment for confounders, black beneficiaries faced a lower hazard of AF /atrial flutter than non-black beneficiaries (hazard ratio, 0.75; 95% CI , 0.70-0.80). Despite the lower risk of AF , black patients faced a higher hazard of ischemic stroke (hazard ratio, 1.37; 95% CI , 1.22-1.53). Conclusions Among Medicare beneficiaries with implanted cardiac devices capable of detecting atrial rhythm, black patients had a lower incidence of AF despite a higher burden of vascular risk factors and a higher risk of stroke.