Background Major randomized trials assessing non-vitamin K antagonist oral anticoagulants ( NOAC s) for stroke prevention in atrial fibrillation generally excluded patients with hemoglobin <10 g/dL. This study evaluated the safety and effectiveness of NOAC s in patients with atrial fibrillation and anemia. Methods and Results A cohort study based on electronic medical records was conducted from 2010 to 2017 at a multicenter healthcare provider in Taiwan. It included 8356 patients with atrial fibrillation who had received oral anticoagulants (age, 77.0±7.3 years; 48.0% women). Patients were classified into 2 subgroups: 7687 patients with hemoglobin ≥10 g/ dL and 669 patients with hemoglobin <10 g/ dL . A Cox regression analysis was performed to assess the risks of ischemic stroke/systemic embolism, bleeding, and death associated with NOAC versus warfarin in both subgroups, respectively. In patients with hemoglobin ≥10 g/ dL , NOAC (n=4793) was associated with significantly lower risks of ischemic stroke/systemic embolism, major bleeding, and gastrointestinal tract bleeding than warfarin (n=2894); there was no difference in the risk of death. In patients with hemoglobin <10 g/ dL , NOAC (n=390) was associated with significantly lower risks of major bleeding (adjusted hazard ratio, 0.43; 95% CI, 0.30-0.62) and gastrointestinal tract bleeding than warfarin (n=279), but there was no difference in the risk of ischemic stroke/systemic embolism (adjusted hazard ratio, 0.79; 95% CI , 0.53-1.17) or death. Subgroup analyses suggested that NOAC was associated with fewer bleeding events, irrespective of cancer or peptic ulcer disease history. Conclusions In patients with atrial fibrillation with hemoglobin <10 g/ dL , NOAC was associated with lower bleeding risks than warfarin, with no difference in the risk of ischemic stroke/systemic embolism or death.
Keywords: anemia; anticoagulation; atrial fibrillation; bleeding; outcome.