Sex Differences and 2‐Year Mortality in Patients With Atrial Fibrillation Diagnosed After Stroke and Known Atrial Fibrillation: A Register‐Based Study in Sweden

BACKGROUND: The objective of this study was to determine associations between atrial fibrillation diagnosed after stroke (AFDAS) and known atrial fibrillation with 2-year mortality among men and women. METHODS AND RESULTS: This longitudinal, register-based study included patients with ischemic stroke admitted to 3 hospitals in Gothenburg, Sweden, between November 1, 2014 and June 30, 2019. The exposures were known atrial fibrillation and AFDAS detected at the stroke units. The outcome was all-cause mortality 2 years after stroke. Cox-regression analyses were conducted to assess sex differences in relation to the adjusted mortality risk. Of 5468 patients with ischemic stroke, 2583 (47%) were women, and the mean age was 74 years (SD 14). Overall, 19% had known atrial fibrillation, and 10% had AFDAS. Women were older and had more severe strokes compared with men. Within the first month, women with AFDAS did not have an increased risk of mortality compared with women with no atrial fibrillation (hazard ratio, 0.93 [95% CI, 0.46-1.88]), in contrast to men with AFDAS who had an increased risk (hazard ratio, 2.14 [95% CI, 1.07-4.26]). Men and women with AFDAS had an increased risk of long-term mortality (31 days to 2 years) compared with those with no atrial fibrillation. Known atrial fibrillation was associated with the highest poststroke mortality irrespective of sex and time interval. CONCLUSIONS: Our findings suggest that underlying sex differences exist in the association between the occurrence of AFDAS and poststroke mortality. Sex differences related to the timing of atrial fibrillation diagnosis should be considered when developing preventive measures and medical care after stroke.