Real-world spatial distribution of peri-device leaks on cardiac CT after WATCHMAN implantation

Background The WATCHMAN device requires post-implant imaging to assess peri-device leak (PDL) and device-related thrombus, typically with transesophageal echocardiography (TEE). Cardiac CT has emerged as a non-invasive alternative, offering high-resolution views of left atrial appendage (LAA) anatomy. However, real-world data on CT-based leak localization are limited, and standardized methods to describe leak distribution are lacking. Purpose To evaluate the spatial distribution of PDLs using gated cardiac CT at first follow-up post-WATCHMAN implantation and to apply a reproducible clock-face framework for anatomical mapping. Methods Patients undergoing WATCHMAN FLX or FLX Pro implantation were enrolled in a prospective multicenter registry and followed per local standard of care. Gated cardiac CT was performed first follow up (45-90 days) and interpreted by a central imaging core laboratory. PDLs were defined as contrast opacification within the LAA and categorized by minimum width: <3 mm or ≥3 mm. Leak locations were mapped using a 12-point clock-face centered on the LAA ostium, with 12:00 representing anterior and 6:00 posterior, following standard axial CT orientation. Results Among 676 patients with post-implant CT imaging, 41 (6.1%) had core lab–adjudicated PDLs with defined anatomical location and size. A total of 42 leaks were recorded, including one patient with two distinct sites. Among 30 patients with leaks ≥3 mm, 7:00 was the most common site (9/30; 30%), followed by 6:00, 8:00, and 11:00 (each 4/30; 13.3%). Among 11 patients with leaks <3 mm, the most frequent sites were 1:00 (4/11; 36.4%) and 11:00 (4/11; 36.4%), followed by 12:00 and 2:00. Leaks were less frequently observed at lateral positions (3:00 and 9:00). (Figure) Conclusion At first follow-up, CT-identified peri-device leaks were most frequently located in the posterior-inferior region of the LAA ostium, particularly for larger leaks. Smaller leaks tended to occur more anteriorly. Clock-face mapping offers a reproducible and intuitive framework for spatial assessment of PDLs and may improve procedural planning, cross-modality comparisons, and device refinement.