Racial differences in the incidence of atrial fibrillation after cryptogenic stroke

Background: The incidence of atrial fibrillation (AF) is lower in nonwhites than in whites despite a higher burden of AF risk factors. However, the incidence of new AF after cryptogenic stroke in minorities is unknown.

Objective: The purpose of this study was to determine the incidence of AF after cryptogenic stroke in different racial/ethnic groups.

Methods: We retrospectively analyzed 416 consecutive patients undergoing insertable cardiac monitor implantation at our hospital from 2014 through 2019. Incidence of AF was identified through the review of device monitoring, including adjudication of AF episodes for accuracy, and compared by race.

Results: The mean follow-up time was 1.5 ± 1.1 years. The predominantly nonwhite cohort included 244 (59%) blacks and 109 (26%) Hispanics, and 45% (n=189) were male. The mean age was 62 ± 12 years; Blacks and Hispanics had more hypertension, diabetes, and chronic kidney disease and higher body mass index than did whites. In blacks and Hispanics, the cumulative incidences of AF at 1, 2, and 3 years were 14.1%, 19.9%, and 24% and 12.9%, 18.3%, and 20.9%, respectively. By comparison, the incidence in whites was significantly higher: 20.8%, 34.3%, and 40.3%. In a Cox proportional hazards model adjusting for common AF risk factors, blacks (hazard ratio 0.49; confidence interval 0.26-0.82; P = .03) and Hispanics (hazard ratio 0.39; confidence interval 0.18-0.83; P = .01) were less likely to have incident AF than whites.

Conclusion: In patients with an insertable cardiac monitor after cryptogenic stroke, the incidence of newly detected AF is approximately double in whites compared with both blacks and Hispanics. This has important implications for the investigation and treatment of nonwhites with cryptogenic stroke.