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Background: Transcatheter aortic valve replacement (TAVR) pushes aside the diseased native aortic valve and creates a native neo-sinus bordered by the aortic root wall and the displaced native valve. There are limited data on the progression of native valve disease post-TAVR and no previous analysis of the native neo-sinus., Methods: Native aortic valves and native neo-sinus explants obtained post-TAVR were evaluated histologically (hematoxylin and eosin, Movat pentachrome, and Martius Scarlet Blue stains) and by immunohistochemistry (TGF-β1 [transforming growth factor-beta 1], FAP [fibroblast activation protein], and ALP [alkaline phosphatase]) to assess disease mechanisms., Results: Native aortic valves were obtained from 20 patients from 0 to 2583 days (7.08 years) post-TAVR. Native leaflets showed persistent calcific aortic stenosis-like disease activity with positivity for ALP and FAP. Native valve remodeling was observed as changes in architecture evident in explants >1.5 years, which was observed as crumpling of the leaflets. Disease activity was also present in native neo-sinuses with transcatheter heart valve implant durations >1 year with positive staining for TGF-β1, FAP, and ALP. Extensive native neo-sinus remodeling occurred with replacement and filling-in of this space with contiguous extracellular matrix, calcific deposits, and microvessels., Conclusions: Following TAVR, there is ongoing calcific aortic stenosis-like disease with architectural changes to native leaflets and extensive remodeling of the native neo-sinus, evidenced by replacement and contiguous filling-in of the native neo-sinus blood pool space with increasing implant duration. The dynamic nature of these tissues has potential implications for neo-sinus flow, valve degeneration, and re-intervention., Competing Interests: Dr Meier has received an institutional grant from Edwards Lifesciences. Dr Sellers is a consultant for Edwards Lifesciences, Medtronic, and Anteris, and received research support from Edwards Lifesciences, Medtronic, Vivitro Labs, and HeartFlow. H. Gill is supported by the Canadian Institutes of Health Research CGS-D award. Dr Webb is a consultant to Edwards Lifesciences, and received research support from Edwards Lifesciences, Boston Scientific, and Abbott. Dr Seidman is a consultant for Baylis Medical Technologies. J. Sathananthan has been a consultant to Edwards Lifesciences, Anteris, Medtronic, and is an employee of Boston Scientific. Dr Khan is a proctor for Edwards Lifesciences and Medtronic and has equity in Transmural Systems, and received educational grants from Abbott, Boston Scientific, Edwards Lifesciences, Medtronic, and Philips. The other authors report no conflicts.

Background: When a balloon-expandable transcatheter heart valve (THV) is chosen to treat a failed balloon-expandable THV, there is a risk of underexpansion with a potential impact on performance., Aims: We aimed to assess the impact of pre- and post-dilatation on the expansion of balloon-expandable THVs after redo-transcatheter aortic valve implantation (TAVI)., Methods: Redo-TAVI was performed on the bench with a 23 mm SAPIEN 3 (S3) implanted within a 23 mm SAPIEN XT (SXT) or a 23 mm S3, both of which served as the "failed" THVs. Pre- and/or post-dilatation was performed using a 23 mm non-compliant TRUE balloon. Expansion of the index and redo-THVs were assessed before and after pre-/post-dilatation using microcomputed tomography (micro-CT), and THV hydrodynamic testing was conducted., Results: Without pre- or post-dilatation, the S3 was underexpanded, for all combinations, particularly in the mid-portion of the THV (18.6 mm and 19.7 mm representing 81% and 86% of the nominal diameter inside the SXT and S3, respectively). Pre- and post-dilatation had an additive effect on diameter expansion of the redo-THV, which remained constrained in most combinations. The only combination to achieve nominal expansion was the S3 in S3 when both pre- and post-dilatation were performed. The S3 remained underexpanded inside the SXT despite pre- and post-dilatation (93% in the mid-portion). Improved redo-THV expansion was accompanied by 2.7 mm (12%) overexpansion of the index THV. While all samples had acceptable hydrodynamic performance, the underexpanded samples had worse leaflet pinwheeling., Conclusions: When performing redo-TAVI with a 23 mm S3 inside a 23 mm SXT or S3, only the S3 in S3 with the use of pre- and post-dilatation reached full expansion. This underlines the importance of CT assessment of THV expansion and the role of pre-/post-dilatation.

Background: Bioprosthetic valve fracture (BVF) can be used to improve transcatheter heart valve (THV) haemodynamics following a valve-in-valve (ViV) intervention. However, whether BVF should be performed before or after THV deployment and the implications on durability are unknown.  Aims: We sought to assess the impact of BVF timing on long-term THV durability., Methods: The impact of BVF timing was assessed using small ACURATE neo (ACn) or 23 mm SAPIEN 3 (S3) THV deployed in 21 mm Mitroflow valves compared to no-BVF controls. Valves underwent accelerated wear testing up to 200 million (M) cycles (equivalent to 5 years). At 200M cycles, THV were evaluated by hydrodynamic testing, second-harmonic generation (SHG) microscopy, scanning electron microscopy (SEM) and histology., Results: At 200M cycles, the regurgitant fraction (RF) and effective orifice area (EOA) for the ACn were 8.03±0.30%/1.74±0.01 cm 2 (no BVF), 12.48±0.70%/1.97±0.02 cm 2 (BVF before ViV) and 9.29±0.38%/2.21±0.0 cm 2 (BVF after ViV), respectively. For the S3 these values were 2.63±0.51%/1.26±0.01 cm 2 , 2.03±0.42%/1.65±0.01 cm 2 , and 1.62±0.38%/2.22±0.01 cm 2 , respectively. Further, SHG and SEM revealed a higher degree of superficial leaflet damage when BVF was performed after ViV for the ACn and S3. However, the histological analysis revealed significantly less damage, as determined by matrix density analysis, through the entire leaflet thickness when BVF was performed after ViV with the S3 and a similar but non-significant trend with the ACn.  Conclusions: BVF performed after ViV appears to offer superior long-term EOA without increased RF. Ultrastructure leaflet analysis reveals that the timing of BVF can differentially impact leaflets, with more superficial damage but greater preservation of overall leaflet structure when BVF is performed after ViV.