Abstract
BACKGROUND: Coronary access and neosinus washout are critical considerations following transcatheter aortic valve replacement (TAVR). However, the impact of transcatheter heart valve (THV) pathology on these factors remains unexplored.
OBJECTIVES: The aim of this study was to assess THV frame obstruction due to fibrotic tissue ingrowth and its potential impact on coronary access and neosinus flow.
METHODS: Thirty-four SAPIEN platform and 10 Evolut/CoreValve (EV/CV) platform explanted THVs were evaluated for frame cell obstruction. Patient data and clinical imaging were reviewed to assess relationships with frame fibrosis. Cannulation feasibility was assessed using 6-F catheter passage. Redo-TAVR was modeled using a SAPIEN 3 device implanted at EV/CV node 5. Histologic staining was performed to analyze endothelial-like cells, activated platelets, and fibrotic remodeling.
RESULTS: Across all explanted THVs, 79.5% of frame exhibited fibrotic ingrowth, with implant duration correlating with obstruction severity (P = 0.003). Fibrotic ingrowth was more commonly seen in the upper and lower regions of EV/CVs and in the upper cells adjacent to commissures in SAPIEN THVs. Fibrotic ingrowth prevented cannulation with a 6-F catheter in 13.0% of cells in areas of likely cannulation to achieve coronary access. Greater fibrotic ingrowth was associated with damage to native structure at THV explantation. Redo-TAVR models had reduced accessibility, with up to 76% unable to be fenestrated by a 6-F catheter. Frame adhesions were not detectable by standard clinical imaging. Histologic analysis demonstrated progressive granulation tissue formation, which became more organized in later explantations, with a median thickness of 0.5 mm.
CONCLUSIONS: Fibrotic THV frame ingrowth is a common phenomenon that may complicate THV explantation and impede neosinus washout and coronary access after TAVR.