Possible Factor Xa Resistance in a Patient Who Failed Apixaban and Rivaroxaban.

This article aims to discuss the literature on switching to an anticoagulant with a different mechanism of action in case of treatment failure. We present a patient with atrial fibrillation who incurred an embolic stroke despite adequate anticoagulation with apixaban and developed a new symptomatic ischemic stroke during the same admission after switching to rivaroxaban, a factor Xa inhibitor with a similar mechanism of action. He had no new events at 3-months after switching to dabigatran, a direct thrombin inhibitor. We identified no apparent reason for anticoagulation failure in our patient. The literature on switching anticoagulants in case of failure is inconclusive with no strong supportive evidence. More research is needed to define anticoagulation failure and identify cases with factor Xa inhibitor resistance, in which switching to a different mechanism of anticoagulation may be appropriate.