Healing dynamics, residual flow and WATCHMAN FLX Pro device integrity after concomitant PFA and LAAC: insights from serial CT and micro-CT imaging in a canine model

Abstract Background The procedural synergy of PVI and LAAC in a single session is increasingly adopted in clinical workflows. However, the acute tissue response to PFA may influence LAAC device sizing and LAA complete seal. This preclinical study investigated healing dynamics, residual flow mechanisms, and structural device integrity using serial contrast CT and post-mortem micro-CT following combined PFA or RFA with WATCHMAN FLX Pro implantation. Methods Nine healthy canines underwent PVI using either PFA (n=6) or RFA (n=3), followed by LAAC in the same setting. Serial TEE and contrast-enhanced CT scans were acquired at baseline, post-procedure, and on days 7, 14, 28, and 45. All animals received DAPT for the duration of follow-up. Hypoattenuated Thickening (HAT) was evaluated to characterize healing and potential thrombus formation. Residual contrast patency was classified by source (e.g., uncovered trabeculations vs. trans-fabric flow). At terminal sacrifice, micro-CT imaging was performed with 35μm resolution and 1120×1120 pixel image size. CTvox software enabled 3D rendering of the devices, which were evaluated for grossly visible structural abnormalities, including fractures, disconnections, tangles, or other surface defects. Results All animals achieved successful LAAC with no acute complications. No device dislodgement was observed on imaging. At day 45, 5 animals (3 PFA, 2 RF) exhibited residual contrast patency. In 3 of these (1 PFA, 2 RF), the source was trans-fabric flow, suggesting incomplete endothelialization of the device fabric. The remaining 2 cases (both PFA) showed contrast patency due to small PDLs (