Resolution (and Late Recurrence) of WATCHMAN Device–Related Thrombus Following Treatment with Dabigatran

The WATCHMAN left atrial (LA) appendage closure system is an alternative therapy for stroke prevention in patients with atrial fibrillation who are intolerant to chronic oral anticoagulation with warfarin. Infrequently, LA device–related thrombus (DRT) has been suspected. Optimal treatment of DRT is not known, and the efficacy of novel oral anticoagulants (NOAC) in this setting has not been previously described. A 69‐year‐old woman with permanent atrial fibrillation underwent WATCHMAN device placement. A transesophageal echocardiogram (TEE) performed 45 days following implant revealed a well‐seated device. A 1‐year follow‐up TEE revealed a 1.2 × 0.8 cm sized DRT on the LA aspect of the WATCHMAN device. She was prescribed dabigatran 150 mg po BID for 3 months and she remained on aspirin 325 mg per day. She returned approximately 4 months later (and several weeks after completing her 3‐month course of dabigatran) for a repeat TEE, which revealed complete resolution of the DRT. A TEE was performed approximately 8 months later and revealed a new DRT measuring 1 cm in diameter on the LA aspect of the device. This is the first report of successful WATCHMAN DRT treatment with a NOAC, and the first report of late DRT recurrence following treatment to resolution with an anticoagulant. This case report demonstrates that (1) WATCHMAN DRT may form late following implantation, (2) DRT resolution is possible with NOACs, specifically dabigatran, and (3) late recurrence of DRT is possible, even after treatment to initial resolution with systemic anticoagulation.