Elsevier

Heart Rhythm

Volume 18, Issue 6, June 2021, Pages 847-852
Heart Rhythm

Clinical
Atrial Fibrillation
Racial differences in the incidence of atrial fibrillation after cryptogenic stroke

https://doi.org/10.1016/j.hrthm.2021.01.027Get rights and content

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.

Introduction

Atrial fibrillation (AF) is the most common sustained arrhythmia and the most common cause of embolic stroke.1,2 Despite a higher prevalence of conventional risk factors for the development of AF in blacks and Hispanics,3, 4, 5, 6, 7, 8 whites have more AF than do blacks and Hispanics.9, 10, 11, 12 Oral anticoagulation is the preferred method of stroke prevention in AF in those with stroke risk factors.1 However, after cryptogenic stroke (CS), it is only after subsequent diagnosis of AF that anticoagulation is recommended. The Cryptogenic Stroke and Underlying AF (CRYSTAL AF) trial investigators reported a 12.4% rate of detection of AF at 1 year in patients undergoing implantation of an insertable cardiac monitor (ICM) after CS. However, as this study was performed in a predominantly white population, with only 3% blacks and fewer than 1% Hispanics,13 the incidence of newly diagnosed AF after CS in nonwhites remains unknown. We hypothesized that the rate of detection of AF would be lower in black and Hispanic patients than in white patients after implantation of an ICM for CS.

Section snippets

Methods

We performed a retrospective review of our electronic medical record to identify consecutive patients undergoing implantation of an ICM for CS at our urban medical center from July 2014 to December 2019. The diagnosis of CS was made by the referring neurologist, and the extent of diagnostic testing performed before ICM was at the discretion of the referring neurologist. Patients were excluded if they had any history of AF or atrial flutter, even if this was an isolated postoperative diagnosis.

Results

A total of 454 patients during the study period were identified as having received ICMs for the detection of AF after CS. In total, 38 patients were excluded: 23 patients (5%) who were lost to follow-up immediately after ICM implantation before any device interrogation, 4 patients (0.8%) who required removal within 2 weeks of implantation because of concern for infection and in whom no device interrogation data were documented, 3 patients (0.4%) who were found to have AF or atrial flutter

Discussion

In a retrospective analysis of all patients referred to our racially and ethnically diverse urban tertiary care hospital for ICM implantation after CS over a 5-year period, we compared the incidence of newly detected AF by race and ethnicity. We found that blacks and Hispanics had a significantly lower incidence of AF detection after CS than did whites, despite a higher burden of AF risk factors. Although whites comprised only 15% of patients in our study, which is markedly different from the

Conclusion

In patients undergoing implantation of an ICM after CS, the incidence of newly detected AF in whites is approximately double the incidence of that found in blacks and Hispanics. This difference persisted over 3 years of follow-up, despite a higher prevalence in blacks and Hispanics of most cardiovascular and AF risk factors. This has important implications for the investigation and treatment of nonwhites with CS.

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    Funding sources: The authors have no funding sources to disclose.

    Disclosures: The authors have no conflicts of interest to disclose.

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