Stroke risk in women with atrial fibrillation

Background and Aims — Female sex is associated with higher rates of stroke in atrial fibrillation (AF) after adjustment for other CHA2DS2-VASc factors. This study aimed to describe sex differences in age and cardiovascular care to examine their relationship with stroke hazard in AF.

Methods — Population-based cohort study using administrative datasets of people aged >65 years diagnosed with AF in Ontario between 2007 and 2019. Cause-specific hazard regression was used to estimate the adjusted hazard ratio (HR) for stroke associated with female sex over a 2-year follow-up. Model 1 included CHA2DS2-VASc factors, with age modelled as 66–74 vs. ≥ 75 years. Model 2 treated age as a continuous variable and included an age–sex interaction term. Model 3 further accounted for multimorbidity and markers of cardiovascular care.

Results — The cohort consisted of 354 254 individuals with AF (median age 78 years, 49.2% female). Females were more likely to be diagnosed in emergency departments and less likely to receive cardiologist assessments, statins, or LDL-C testing, with higher LDL-C levels among females than males. In Model 1, the adjusted HR for stroke associated with female sex was 1.27 (95% confidence interval 1.21–1.32). Model 2 revealed a significant age–sex interaction, such that female sex was only associated with increased stroke hazard at age >70 years. Adjusting for markers of cardiovascular care and multimorbidity further decreased the HR, so that female sex was not associated with increased stroke hazard at age ≤80 years.

Conclusion — Older age and inequities in cardiovascular care may partly explain higher stroke rates in females with AF.