Delayed endothelialization of watchman device identified with cardiac CT

Background: Left atrial appendage (LAA) closure with the Watchman device is increasingly used in patients with nonvalvular atrial fibrillation for stroke prevention. Though clinical trials have shown a similar combined risk of ischemic and hemorrhagic stroke, there is an increased risk of ischemic stroke in patients with a Watchman device compared with anticoagulation. Some ischemic strokes are related to a device-related thrombus (DRT), which may be attributable to delayed endothelialization of exposed fabric and metal. Methods and Results: Patients undergoing Watchman LAA occlusion between January 2016 and June 2018 were enrolled in a prospective registry. From this cohort, 46 patients who had both transesophageal echocardiogram (TEE) and computed tomography (CT) at 45 days follow-up were selected for this study. The degree of LAA occlusion and type of leak were assessed by CT and TEE. TEE identified no patients with a significant (>5 mm) peri-device leak, 27 (58.6%) with nonsignificant peri-device leak (<5 mm), and 19 (41.4%) with complete occlusion. CT identified contrast in the LAA in 28 (60%) patients. However, in 10 (21.8%) of these patients, contrast entered the LAA through the fabric rather than around the device. No DRT were identified. Conclusion: These data reveal that the Watchman device remains porous 6 weeks after implantation in a substantial percentage of patients, suggesting delayed endothelialization of the device. Cardiac CT may help to differentiate between peri-device and trans-fabric leak. Additional studies are required to test whether prolonged anticoagulation in patients with trans-fabric leak may help to reduce the risk of DRT and ischemic stroke.