Abstract WMP71: Atrial Fibrillation and Atrial Flutter After Ischemic Stroke in Black versus White Medicare Beneficiaries

Abstract

Introduction: Several studies suggest that black U.S. residents have a lower risk of atrial fibrillation (AF) and a similar risk of atrial flutter (AFL) compared to whites. It remains unclear whether these differences reflect screening practices or true differences in risk. Because individuals with ischemic stroke are usually screened for AF as part of standard care, this population may provide insights into racial differences in the risk of AF and AFL. Methods: We performed a retrospective cohort study using inpatient and outpatient claims between 2008-2015 from a nationally representative 5% sample of Medicare beneficiaries. We included patients of black or white race who were ≥65 years old and hospitalized with ischemic stroke, defined by validated ICD-9-CM diagnosis codes. Validated codes were used to identify the outcomes of AF and AFL. We excluded patients with AF or AFL before discharge from their first documented stroke hospitalization. We adjusted for post-stroke heart-rhythm monitoring, classified as Holter monitors, external loop recorders, implanted loop recorders, or interrogations of implanted pacemakers/defibrillators. We calculated AF and AFL incidence rates and hazard ratios (HR) using Cox proportional hazards models. Results: Among 36,624 patients with ischemic stroke and no prior AF/AFL, the 5,095 black patients were slightly younger (mean age, 76.7 versus 78.9 years) but had more hypertension, diabetes, heart failure, and chronic kidney disease. During a mean follow-up of 2.0 years, the incidence of AF was 4.5 per 100 person-years and that of AFL was 0.5 per 100 person-years. Black race was associated with a lower risk of post-stroke AF (HR, 0.86; 95% CI, 0.77-0.96) including after adjustment for demographics, vascular risk factors, and post-stroke heart-rhythm monitoring (HR, 0.88; 95% CI, 0.79-0.98). There was no association between black race and post-stroke AFL in the unadjusted model (HR, 1.04; 95% CI, 0.78-1.39) or adjusted model (HR, 1.06; 95% CI, 0.79-1.44). Conclusions: We found that black patients with ischemic stroke had a lower rate of post-stroke AF and a similar rate of post-stroke AFL compared to whites.