Incidence, Determinants, and Outcomes of Predicted vs. Measured Prosthesis–Patient Mismatch After TAVR in Sievers Type 1 Bicuspid Aortic Valve: Insights from the AD-HOC Registry

Background: Bicuspid aortic valve (BAV) is the most common congenital heart defect and a frequent cause of severe aortic stenosis (SAS), particularly in younger patients increasingly treated with transcatheter aortic valve replacement (TAVR). Anatomic features characteristic of BAV may predispose to prosthesis–patient mismatch (PPM), yet its prognostic significance after TAVR remains uncertain. Moreover, PPM assessment differs across studies, with measured effective orifice area (mEOA) predominating in TAVR but subject to hemodynamic and measurement variability, while predicted effective orifice area (pEOA) has only recently been applied to TAVR and has not been clearly linked to outcomes. In this context, evidence regarding prosthesis–patient mismatch (PPM), measured (mPPM) and predicted (pPPM), after transcatheter aortic valve replacement (TAVR) in bicuspid aortic valve (BAV) stenosis remains limited. Aim of the study: This study aims to evaluate the incidence, predictors, and prognostic implications of mPPM and pPPM in patients with Sievers type 1 BAV undergoing TAVR. Methods: The AD-HOC registry is a retrospective, multicenter study including 781 patients with SAS and Sievers type 1 BAV, treated with TAVR between 2016 and 2023 across 24 centers. Measured PPM (mPPM) was based on echocardiographic indexed effective orifice area (EOA), and predicted PPM (pPPM) on reference values for each transcatheter heart valve (THV) type and size, both defined per VARC-3 criteria. Primary outcome was all-cause mortality at longest follow-up, whereas secondary outcomes included cardiovascular mortality, heart failure (HF) hospitalization, bioprosthetic valve dysfunction, and stroke/transient ischemic attack. Results: Moderate-to-severe mPPM was more frequent than pPPM (22% vs 8%; p<0.001). Balloon-expandable valves were independently associated with both mPPM and pPPM, while smaller valve size and supra-annular sizing predicted only pPPM. During a mean follow-up of 621±470 days, neither mPPM nor pPPM was associated with mortality in the overall cohort. Among patients with a small annulus (≤430 mm²; n=145), pPPM occurred was significantly higher (19% vs 5.5%; p<0.001) and was associated with increased all-cause mortality, but not with cardiovascular mortality. Conclusions: In patients with Sievers type 1 BAV undergoing TAVR, pPPM occurred less frequently than mPPM and was predominantly driven by anatomic characteristics and sizing strategies. Although pPPM was associated with increased all-cause mortality among patients with small annuli, this association did not extend to cardiovascular mortality and should be considered hypothesis-generating. Further prospective investigations are warranted to better delineate the impact of anatomic constraints on clinical outcomes in this anatomically challenging subset.

Presupposti dello studio: Le evidenze relative al mismatch protesi-paziente (PPM), sia misurato (mPPM) sia predetto (pPPM), dopo sostituzione valvolare aortica transcatetere (TAVR) nella stenosi aortica su valvola aortica bicuspide (BAV) rimangono limitate. Scopo dello studio: Valutare l’incidenza, i predittori e le implicazioni prognostiche del mPPM e del pPPM nei pazienti con BAV di tipo 1 secondo Sievers sottoposti a TAVR. Materiali e metodi: Il registro AD-HOC è un registro multicentrico retrospettivo che include 781 pazienti con stenosi aortica severa e BAV trattati mediante TAVR tra il 2016 e il 2023 in 24 centri. Il PPM è stato definito secondo i criteri del Valve Academic Research Consortium-3 (VARC-3). L’endpoint primario era la mortalità per tutte le cause. Risultati: Il mPPM moderato-severo è risultato più frequente rispetto al pPPM (22% vs 8%; p<0,001). Le valvole balloon-expandable sono risultate indipendentemente associate sia al mPPM sia al pPPM, mentre le dimensioni protesiche minori e il sizing sopra-annulare sono risultati predittori esclusivamente del pPPM. Durante un follow-up medio di 621±470 giorni, né il mPPM né il pPPM sono risultati associati alla mortalità nella coorte complessiva. Tra i pazienti con anulus piccolo (≤430 mm²; n=145), il pPPM è risultato significativamente più frequente (19% vs 5,5%; p<0,001) ed è risultato associato a un aumento della mortalità per tutte le cause, ma non della mortalità cardiovascolare. Conclusioni: Nei pazienti con BAV di tipo 1 secondo Sievers sottoposti a TAVR, il pPPM si è verificato meno frequentemente rispetto al mPPM ed è risultato prevalentemente determinato da caratteristiche anatomiche e strategie di sizing. Sebbene il pPPM sia risultato associato a un incremento della mortalità per tutte le cause nei pazienti con anulus piccolo, tale associazione non si è estesa alla mortalità cardiovascolare. Sono comunque necessari ulteriori studi prospettici per meglio delineare l’impatto delle limitazioni anatomiche sugli outcome clinici in questo complesso sottogruppo.