Beyond stroke: atrial fibrillation and the broader burden of thromboembolic events in the population-based EpiHealth study

OBJECTIVES: To investigate the distribution and risk of thromboembolic events (TEs) among adults with and without atrial fibrillation (AF), and to assess oral anticoagulant (OAC) use over time. DESIGN: This population-based longitudinal cohort study included EpiHealth participants recruited between April 2011 and December 2016 and followed through linkage to Swedish health data registers from baseline until the first TE, death, or December 31, 2016. RESULTS: At baseline, 873 of 22,616 participants (3.9%) had AF and 297 developed incident AF during follow-up. 484 participants experienced at least one TE during 70,587 person-years. Participants with AF had higher TE incidence (68 events, 5.9%; p < 0.001), predominantly arterial (73.5%), with 94% of arterial events involving the cerebral circulation. Approximately one quarter of TEs among participants with AF occurred outside the cerebral circulation and comprised both venous and non-cerebral arterial events. Although participants with incident AF represented less than one quarter of participants with AF, they accounted for 40% of TEs in the AF group. OAC use increased from 39.0% to 50.4%, with a shift from predominantly warfarin to direct oral anticoagulants.In time-dependent Cox regression adjusted for age, sex, and prior arterial thromboembolism, untreated AF was associated with increased thromboembolic risk compared with no AF (HR 2.53), whereas OAC use was associated with lower risk. CONCLUSIONS: AF was associated with substantially increased thromboembolic risk, predominantly arterial in nature. One in five TEs among participants with AF coincided with newly diagnosed AF, suggesting potential opportunities for earlier AF detection and timely initiation of anticoagulant treatment.