Who watches the WATCHMAN™? A case of incomplete endothelialization at 3 years after device implantation.

WATCHMAN™ is a left atrial appendage (LAA) occlusion device used to prevent thromboembolism in patients with atrial fibrillation. Endothelialization of the device is required to completely occlude the LAA. Prior to endothelialization, the device is thrombogenic. The duration of dual-antiplatelet therapy after device insertion is based on animal studies demonstrating endothelialization at 3 months. A 73-year-old man presented with symptomatic severe mitral regurgitation 3 years after the WATCHMAN device was implanted. During mitral valve repair, we found that the WATCHMAN device was not endothelialized. The device was removed and the LAA was ligated after repair of the mitral valve. The long-term incidence and clinical significance of incomplete endothelialization after LAA-occlusion must be investigated. Postimplantation and perioperative antiplatelet and anticoagulation protocols require re-evaluation. The potential role of thoracoscopic epicardial LAA clipping must be considered.