Should we shift warfarin to non-vitamin K antagonist oral anticoagulants for patients with atrial fibrillation staying well on warfarin for years?

Abstract Funding Acknowledgements Type of funding sources: None. Background Non-vitamin K antagonist oral anticoagulants (NOACs) are recommended over warfarin for stroke prevention for patients with atrial fibrillation (AF) in 2020 ESC guidelines. However, whether warfarin should be shifted to NOACs for patients who stayed very well with warfarin for years remains unknown. Methods From 2007 to 2010, a total of 167,176 newly-diagnosed AF patients aged ≥20 years were identified from the Taiwan National Health Insurance Research Database. Among these patients, 83,604 were alive to June 1st, 2015 and 54,803 of them who did not experience ischemic stroke or intra-cranial hemorrhage (ICH) have constituted the study population. Among the study population, 8,007 patients who continuously received warfarin and survived for at least 90 days after June 1st, 2015 were defined as the "original warfarin cohort". These patients were then categorized into 2 groups according to the stroke prevention strategies they received after June 1st, 2015; that is, staying on warfarin (n = 6,635) and shifting to NOACs (n = 1,372). Results Compared to patients staying on warfarin, the risk of ischemic stroke was lower for patients who were shifted NOACs (aHR 0.886; p=0.002). Also, the risk of major bleeding was lower for shifting to NOACs (aHR 0.849; p<0.001)(Figure). Compared to staying on warfarin, NOACs use was associated with a lower composite risk of ischemic stroke or ICH (aHR 0.842; p<0.001) and ischemic stroke or major bleeding (aHR 0.880; p<0.001). Conclusions Even for patients staying well on warfarin for years, shifting to NOACs was still associated with better clinical outcomes.