Measured Versus Predicted Prosthesis–Patient Mismatch after TAVR in Sievers Type 1 BAV: Incidence, Determinants, and Outcomes From the AD-HOC Registry

Background: Evidence regarding prosthesis-patient mismatch (PPM), measured (mPPM), and predicted (pPPM), after transcatheter aortic valve replacement in bicuspid aortic valve stenosis remains limited. This study sought to evaluate the incidence, predictors, and prognostic implications of mPPM and pPPM in patients with Sievers type 1 bicuspid aortic valve undergoing transcatheter aortic valve replacement. Methods: The AD-HOC registry is a retrospective, multicenter study including 781 patients with severe aortic stenosis and bicuspid aortic valve treated with transcatheter aortic valve replacement between 2016 and 2023 across 24 centers. PPM was defined according to Valve Academic Research Consortium-3 criteria. The primary outcome was all-cause mortality. Results: Moderate-to-severe mPPM was more frequent than pPPM (22% versus 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 occurrence was significantly higher (19% versus 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 bicuspid aortic valve undergoing transcatheter aortic valve replacement, 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.