Impact of Angiographically Detected Residual Trabeculation After Left Atrial Appendage Closure Using the WATCHMAN Device: Insight From the OCEAN-LAAC Registry

Background: Research on the impact of angiographically detected residual trabeculation after left atrial appendage closure (LAAC) is limited. Objectives: To investigate the incidence, characteristics, and clinical implications of angiographically detected residual trabeculation after LAAC using the WATCHMAN device. Methods: We analyzed 1350 consecutive patients with atrial fibrillation undergoing LAAC using the WATCHMAN device from the OCEAN-LAAC registry, which is a prospective ongoing, multicenter Japanese registry. The inclusion criteria comprised patients who successfully underwent LAAC and whose presence or absence of residual trabeculation can be confirmed using a contrast medium. The clinical outcomes were compared between patients with and without angiographically detected residual trabeculation. Results: Residual trabeculation was angiographically detected in 5.6% (75/1350 patients). At the procedure, the proportion of peri-device leak (PDL) was significantly higher in the residual trabeculation group than in the non-residual trabeculation group (20% vs. 5.1%, p < 0.001). However, the PDL and device-related thrombosis at 45 days and 1 year were comparable between the two groups (37% vs. 23%, p = 0.24; 28% vs. 31%, p = 0.84; 2.1% vs. 1.4%, p = 0.50; 6.9% vs. 6.0%, p = 0.69, respectively). The 3-year cumulative incidence of ischemic stroke, all cardiovascular death, and all-cause death were comparable between the two groups (5.7% vs. 5.5%, log-rank p = 0.96; 7.7% vs. 8.9%, log-rank p = 0.34, 31.4% vs. 22.3%, log-rank p = 0.71, respectively). Conclusion: The angiographically detected residual trabeculation rate was 5.6%, and this population had a significantly higher prevalence of PDL at the procedure. However, the presence of residual trabeculation did not contribute to PDL or device-related thrombosis at follow-up or affect the clinical outcomes.