Risk of Ischemic Bowel Disease in Patients With Atrial Fibrillation Receiving Warfarin or Non-vitamin K Antagonist Oral Anticoagulants

Background: Although atrial fibrillation (AF) is a risk factor for ischemic bowel disease, data regarding the incidence of ischemic bowel disease in patients with anticoagulated AF were limited. Methods: The present study used the Taiwan NHIRD and included newly diagnosed patients with AF aged ≥ 20 years without ischemic bowel disease from 2012 to 2018. A total of 69,549 patients taking warfarin or non-vitamin K antagonist oral anticoagulants (NOACs) constituted the final study group. We aimed to study the incidence of ischemic bowel disease in patients with AF receiving warfarin or NOACs. Secondary endpoints were also analyzed, including ischemic stroke, systemic embolism, myocardial infarction, mortality, intracranial hemorrhage (ICH), major bleeding, and composite adverse events (ischemic bowel disease or ICH or major bleeding). Results: There were 43,787 patients taking NOACs and 25,762 patients taking warfarin. The overall incidence rate of ischemic bowel disease was 0.036% per year and increased with the CHA₂DS₂-VASc scores [0.013% for patients with a CHA₂DS₂-VASc score of 0 (men) or 1 (women), 0.022% for those with a CHA₂DS₂-VASc score of 1 (men) or 2 (women), and 0.039% for those with a CHA₂DS₂-VASc score ≥ 2 (men) or ≥ 3 (women)]. The risk of ischemic bowel disease was similar between NOAC and warfarin groups (0.036%/year vs. 0.037%/year; adjusted hazard ratio 0.802, p = 0.430), whereas the NOAC group had a significantly lower risk of secondary endpoints compared to the warfarin group. Conclusion: We reported the incidence of ischemic bowel disease in patients with anticoagulated AF from a nationwide cohort database and observed a positive correlation between the increase of CHA₂DS₂-VASc scores and the incidence rate. Moreover, NOAC was as effective as warfarin for the risk of ischemic bowel disease.