Mohammad Umar Farooq^1,, Daniel Mascarenhas²

Background: New target specific anticoagulants (TSOACs) are convenient to use and effective management in the prophylaxis against thromboembolic sequela of atrial fibrillation (AF). However, without a test to monitor therapeutic efficacy, non-responders may not be detected until they suffer complications. We present a case where one year of dabigatran treatment failed to prevent development of a left atrial clot in the setting of AF. Case: An 84-year-old male with persistent atrial fibrillation presented with anemia of unknown etiology. Workup revealed no acute sources of bleeding, but he was on oral anticoagulation with dabigatran for greater than one year. Anticoagulation had to be discontinued for planned endoscopy. Thus, patient was electrically cardioverted to sinus rhythm. However, 3 days later he presented with a clot in the left femoral artery requiring embolectomy and was back in atrial fibrillation. He was switched to rivaroxaban for anticoagulation. Transesophageal echocardiogram (TEE) 4 weeks later revealed no clot. He was started on the antiarrhythmic amiodarone, then electrically cardioverted to sinus rhythm without complication. Discussion: TEE should be performed prior to electrical cardioversion for patients on TSOACs in case patient is a non-responder. Non-responders, should be placed on a TSOAC with an alternative mechanism of action. Conclusion: Switching TSOACs may be effective management for certain patients with failure of anticoagulation.

atrial fibrillation, target specific anticoagulants, novel oral anticoagulants, failure of anticoagulation