Abstract 14795: Oral Anticoagulation Associated With Lower Risk of Stroke in Patients With Post-operative Atrial Fibrillation

Abstract

Introduction: Recent studies showed post-operative atrial fibrillation (POAF) is associated with increased stroke risk - even approaching that of unprovoked AF. This raises the question of whether patients with POAF should receive anticoagulation. We aim to compare different anticoagulation strategies in patients with POAF after cardiac and non-cardiac surgeries. Methods: Using a large national administrative database (OptumLabs Data Warehouse), we identified 33,981 patients with POAF between 1/1/2013-9/30/2019. Patients were divided to four groups based on the initial treatment within 30 days of POAF: (1) no anticoagulation (N=28,807) (2) apixaban (N=2178) (3) rivaroxaban (N=1320) (4) warfarin (N=1676). Follow up started at the 30 th day after POAF to exclude patients who died shortly after surgery and minimize immortal time bias. The follow up continued until patients changed treatment strategies, insurance, or died. 1:1 propensity score matching was performed between each anticoagulant to no treatment to balance on 86 baseline characteristics. Results: The mean age was 71.1±11.2 yr; mean CHA 2 DS 2 -VASc was 4.1±1.8; 29.1% received cardiac surgeries; 15.2% received anticoagulation within 30 days of POAF. The event rate per 100 person years was 1.58 for stroke in no-anticoagulation group, and 1.29 for anticoagulation group; 2.86 for major bleeding in no-anticoagulation group and 4.50 for anticoagulation group. After matching, apixaban and rivaroxaban were associated with a lower risk of stroke, but a higher risk of major bleeding; warfarin was not associated with a lower risk of stroke, but a higher risk of major bleeding (Figure). The effect was consistent across subgroups, e.g., age and surgery type. Conclusions: In patients with POAF, the stroke rate was lower than what was typically observed in clinical AF. Treatment with apixaban and rivaroxaban immediately after POAF was associated with a reduced risk of stroke but an increased risk of major bleeding.