Risk of stroke in male and female patients with atrial fibrillation in a nationwide cohort.

Female sex has been suggested as a risk modifier for stroke in patients with atrial fibrillation (AF) with comorbid prevalent stroke risk factors. Management has evolved over time towards a holistic approach that may have diminished any sex difference in AF-related stroke. In a nationwide cohort of AF patients free from oral anticoagulant treatment, we examine the time trends in stroke risk overall and in relation to risk differences between male and female patients. Here we show that among 158,982 patients with AF (median age 78 years (IQR: 71 to 85); 52% female) the 1-year thromboembolic risk was highest between 1997-2000 with a risk of 5.6% and lowest between 2013-2016 with a risk of 3.8%, declining over the last two decades. The excess stroke risk for female vs male patients has also been declining, with risk-score adjusted relative risk estimates suggesting limited sex-difference in recent years.