Redo-TAVI with SAPIEN 3 in SAPIEN XT or SAPIEN 3-impact of pre- and post-dilatation on final THV expansion

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 expan-sion 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.