Fibrotic Tissue Ingrowth of Transcatheter Heart Valve Frames

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.