Science and Education Publishing American Journal of Medical Case Reports 2374-216X 3 5 2015 05 07 All Target Specific Anticoagulants are not Created Equal 153 154 EN Mohammad Umar Farooq Internal Medicine, Easton Hospital, Easton, Pennsylvania, USA Daniel Mascarenhas AJMCR20153510 10.12691/ajmcr-3-5-10 2015 04 24 2015 04 29 2015 05 07 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.