Hydrodynamic Assessment of Explanted Degenerated Transcatheter Aortic Valves: Novel Insights Into Noncalcific and Calcific Mechanisms.

Background: The etiology of transcatheter aortic valve (TAV) degeneration is poorly understood, particularly noncalcific mechanisms.
Objectives: The authors sought to investigate noncalcific and calcific mechanisms of TAV degeneration and evaluate their impact on leaflet function by bench testing, imaging, and histology.
Methods: TAV explants were obtained from the EXPLANT THV registry and clinical institutions. Hydrodynamic assessment was performed using a heart valve pulse duplicator system under physiological conditions. Micro-computed tomography, high-resolution photography, high speed video, and hematoxylin and eosin staining were used to evaluate the morphological appearance, leaflet kinematics, and calcium burden of TAVs.
Results: A total of 14 explants were evaluated: 10 self-expanding CoreValve/Evolut TAVs (Medtronic), 3 balloon-expandable SAPIEN 3 TAVs (Edwards Lifesciences), and 1 mechanically expandable Lotus TAV (Boston Scientific). The median patient age at explantation was 73.0 years (Q1-Q3: 64.5-80.0 years), with a time to explantation of 4 years 1 month (1 year 5 months to 4 years 11 months). Six TAV explants were found to have leaflet calcification (162.4 mm ³ ; 58.8-603.0 mm ³ ), and 8 had no calcification detectable by micro-computed tomography and histology. All samples had impaired leaflet kinematics. There was no significant difference in the hydrodynamic mean gradient between calcified (47.2 mm Hg; 26.6-74.1 mm Hg) and noncalcified (27.6 mm Hg; 15.2-36.7 mm Hg; P = 0.28) TAVs. Leaflet calcification had a weak but nonsignificant association with the hydrodynamic mean gradient (r = 0.42; P = 0.14).
Conclusions: TAV function can be severely impacted by noncalcific and calcific mechanisms of tissue degeneration. Importantly, functional stenosis can occur in TAVs in the absence of obvious and significant calcification.
Competing Interests: Funding Support and Author Disclosures This work was supported by Medtronic, USA, and the Cardiovascular Translational Laboratory, Canada. Dr Sathananthan is the chief medical officer for Interventional Cardiology Therapies from Boston Scientific; a consultant to Medtronic and Edwards Lifesciences; has received speaking fees from Edwards Lifesciences, and NVT; and has received research support from Medtronic, Edwards Lifesciences, and Vivitro Labs. Mr Nigade, Dr Spencer, and Mr Navarro are employees and shareholders of Medtronic. Dr Meier has received an institutional grant from Edwards Lifesciences. Dr Pirelli is a consultant and receives speakers honoraria from Medtronic and Edwards Lifesciences. Dr Webb is a consultant to and has received research funding from Edwards Lifesciences, Abbott, and ViVitro Labs. Dr Wood is a consultant and receives unrestricted grant support from Medtronic, Edwards Lifesciences, and Abbott Vascular. Dr Lutter is a consultant to Medtronic, Edwards Lifesciences, and Abbott. Dr Puehler is a consultant to Abbott. Dr Tang has received speaker honoraria and served as a physician proctor, consultant, advisory board member, TAVR publications committee member, APOLLO trial screening committee member and IMPACT MR steering committee member for Medtronic, has received speaker honoraria and served as a physician proctor, consultant, advisory board member and TRILUMINATE trial anatomic eligibility and publications committee member for Abbott Structural Heart, has served as an advisory board member for Boston Scientific and JenaValve, a consultant and physician screening committee member for Shockwave Medical, a consultant for NeoChord, Peija Medical and Shenqi Medical Technology, and has received speaker honoraria from Siemens Healthineers. Dr Fukuhara is a consultant for Medtronic, Terumo Aortic, and Artivion. Dr Sellers is a consultant for Medtronic, Edwards Lifesciences, and Anteris; and has received research support from Medtronic, Edwards Lifesciences, Vivitro Labs, and HeartFlow. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)