Statin Use and Stroke Rate in Older Adults With Atrial Fibrillation: A Population‐Based Cohort Study

BACKGROUND: Atherosclerotic disease is an important contributor to adverse outcomes in patients with atrial fibrillation (AF). There is limited recognition of the association between statin use and stroke rates in AF. We aimed to quantify the association between statin use and stroke rate in AF. METHODS AND RESULTS: Using linked administrative databases in Ontario, Canada, we conducted a population‐based retrospective cohort study of patients, aged ≥66 years, diagnosed with AF between 2009 and 2019. We used cause‐specific hazard regression to determine the association of statin use with stroke rate. We developed a second model to further adjust for lipid levels in the subset of patients with available measurements in the year before AF diagnosis. Both models adjusted for age, sex, heart failure, hypertension, diabetes, stroke/transient ischemic attack, vascular disease, and P2Y12 inhibitors at baseline, plus anticoagulation as a time‐varying covariate. We studied 261 659 qualifying patients (median age, 78 years; 49% women). Statins were used in 142 834 (54.6%) patients, and 145 673 (55.7%) had lipid measurement(s) in the preceding year. Statin use was associated with lower stroke rates, with adjusted hazard ratios of 0.83 (95% CI, 0.77–0.88; P<0.001) in the full cohort and 0.87 (95% CI, 0.78–0.97; P=0.01) when adjusting for lipid data. Stroke rates increased in a near‐linear manner as low‐density lipoprotein values increased >1.5 mmol/L. CONCLUSIONS: Statins were associated with lower stroke rates in patients with AF, whereas higher low‐density lipoprotein levels were associated with higher stroke rates, highlighting the importance of vascular risk factor treatment in AF.