Computed Tomography Scan Evidence for Left Atrial Appendage Short‐Term Remodeling Following Percutaneous Occlusion: Impact of Device Oversizing

BACKGROUND: The interrelationships between left atrial appendage (LAA) dimensions and device following implantation are unknown. We aimed to analyze the impact of Watchman device implantation on LAA dimensions following its percutaneous closure and potential predictors of remodeling. METHODS AND RESULTS: All consecutive LAA closure procedures performed at 2 centers between November 2017 and December 2020 were included in the WATCH‐DUAL (Watchman 2.5 Versus Watchman FLX in a Dual‐Center Left Atrial Appendage Closure Cohort) registry. This study included patients who had pre‐ and postintervention computed tomography scan analysis. The LAA and device dimensions were measured in a centralized core lab by 3‐dimensional computed tomography scan reconstruction methods, focusing on the device landing zone. This analysis included 104 patients (age, 76.0 [range, 72.0–83.0] years; 72% men; 53% Watchman FLX; 47% Watchman 2.5). The baseline characteristics were comparable between Watchman 2.5 and Watchman FLX groups, except for the higher use of oversizing in the latter group. The median delay for computed tomography control was 49 (range, 43–64) days. The landing zone area (median, 446 [range, 363–523] versus 290 [222–366] mm(2); P<0.001) and minimal diameter (median, 23.0 [range, 20.7–24.8] versus 16.7 [14.7–19.4] mm; P<0.001) significantly increased after implantation. The absolute (median, 157 [range, 98–220] versus 85 [18–148] mm(2), P<0.001) and relative (median, 50% [range, 32%–79%] versus 26% [4%–50%]; P<0.001) increases in landing zone area were more pronounced in patients with oversized device. Baseline LAA dimensions were smaller, landing zone eccentricity larger, and oversized device more frequent in patients with significant overexpansion compared with the others. CONCLUSIONS: LAA dimensions increased at the site of the Watchman prosthesis after implantation, suggesting a local positive remodeling after the procedure. This phenomenon was more pronounced in the case of oversized devices.