Clinical Electrophysiology -> Atrial Fibrillation & Atrial Flutter: -> Left Atrial Appendage Closure D-PO01 - Featured Poster Session (ID 11) Poster

D-PO01-036 - Histologic Failure To Endothelialize Watchman And Watchman FLX LAAO Devices At Autopsy (ID 55)


Background: LAA occlusion (LAAO) with Watchman or Watchman FLX is associated with device related thrombi (DRT) and subsequent embolic events. Post implant drug regimen assumes adequate endothelium formation beyond 3-6 months, allowing transition to aspirin as monotherapy. Little is known about the course or degree of human endothelium formation on LAAO devices at autopsy.
Objective: Evaluate gross and histologic appearance of the endoluminal surface on Watchman or Watchman FLX 6-24 months post-implant for the presence of endothelium.
Methods: Three patients followed at Vanderbilt Medical Center underwent analysis. Watchman case 1 died suddenly 9 months post LAAO (72yr M, CHADS2Vasc score 5), Watchman case 2 underwent CABG with excision of the LAA and the device implanted 2 years prior (86yr M, CHADS2Vasc 4). A Watchman FLX patient died from a DRT related embolic stroke with hemorrhagic conversion 6 months post implant (68yr M, CHADS2Vasc 4).
Results: All patients had complete seal of the LAA with no peri-device leak by TEE or CTA at 6-12 weeks post implant. This was confirmed at autopsy. Specimens were evaluated by gross inspection, H and E stain, Exakt sectioning and scanning electron micrography (SEM). No case had complete endothelial layering, and in all three, histology confirmed 20-35% of luminal surface area was completely bare PTFE fabric. Example Figure 1 (Case 1): Panel A-gross inspection; B-Exakt section with H and E, C-SEM region showing endothelium, D-SEM with bare PTFE.
Conclusion: Incomplete luminal endothelium on Watchman or Watchman FLX devices may account for late embolic events and sudden death from DRT. This appears independent of complete LAA occlusion by the device.