Procedural Outcomes of a Self-Expanding Transcatheter Heart Valve in Small Annuli

Background: Self-expanding transcatheter valves (THV) seem superior to balloon-expanding valves in regard to the incidence of prosthesis–patient mismatch (PPM). Data on the occurrence of PPM with the ACURATE neo/neo2 system as a representative of self-expanding prostheses in very small annuli, even below the applicable instructions for use (IFU), are scarce. Methods: Data from 654 patients with severe native aortic stenosis treated with the smallest size ACURATE neo/neo2 valve (size S, 23 mm) at two German high-volume centers from 06/2012 to 12/2021 were evaluated. We compared clinical and hemodynamic outcomes among patients with implantation in adherence to the recommended sizing (on-label n = 529) and below the recommended sizing range (off-label n = 125) and identified predictors for PPM in the overall population. BMI-adjusted PPM was defined according to VARC-3 recommendations. Results: Post-procedure, the mean gradient (10.0 mmHg vs. 9.0 mmHg, p = 0.834) and the rate of paravalvular leakage (PVL) ≥ moderate (3.2% vs. 2.8%, p = 0.770) were similar between on-label and off-label implantations. The rate of moderate to severe PPM (24%) was comparably low in ACURATE neo/neo2 S, with a very low proportion of severe PPM whether implanted off- or on-label (4.9% vs. 3.8%, p = 0.552). Thirty-day all-cause mortality was higher among patients with off-label implantations (6.5% vs. 2.3%, p = 0.036). In the subgroup of these patients, no device-related deaths occurred, and cardiac causes did not differ (each 5). Besides small annulus area and high BMI, a multivariate analysis identified a greater cover index (OR 3.26), deep implantation (OR 2.25) and severe calcification (OR 2.07) as independent predictors of PPM. Conclusions: The ACURATE neo/neo2 S subgroup shows a convincing hemodynamic outcome according to low mean gradient even outside the previous IFUs without a relevant increase in the rate of PVL or PPM. In addition to known factors such as annulus area and BMI, potential predictors for PPM are severe annulus calcification and implantation depth. Nevertheless, the ACURATE neo/neo2 system seems to be a reliable option in patients with very small annuli.