Clinical Outcomes of the Allegra Transcatheter System in Bioprosthetic Aortic Valve Failure: A Multicentre Valve-in-Valve Registry

Introduction
The prevalence of bioprosthetic aortic valve failure is increasing due to the broader use of bioprosthetic valves, both surgical and transcatheter, and an ageing population. Registry data indicate a higher risk of coronary obstruction and elevated gradients following valve-in-valve transcatheter aortic valve implantation (TAVI). We report outcomes of the Allegra transcatheter heart valve system in valve-in-valve TAVI.

Methods
In this retrospective multicentre cohort study, all patients undergoing valve-in-valve TAVI with the Allegra system between 2019 and 2025 at five UK centers were included. The combined primary outcomes were technical success, device success, and early safety at 30 days, as per the VARC-3 (Valve Academic Research Consortium-3) criteria. A key secondary outcome was all-cause mortality at the longest documented follow-up.

Results
A total of 106 patients underwent valve-in-valve TAVI. The mean age was 79 ± 6 years, with 57.5% being female. Almost half of the patients had an index valve ≤ 21 mm, with an STS (Society of Thoracic Surgery) score of 7.1% (5.1–12.0). The post-implant aortic valve mean pressure gradient was 12 ± 6 mmHg, and the mean valve area was 1.7 ± 0.5 cm2. The combined primary outcomes were technical success of 86.8% (CI 80.3%–93.2%), device success of 75.5% (CI 67.3%–83.7%), and early safety of 86.8% (CI 80.3%–93.2%). All-cause mortality at 30 days was 0%. All-cause mortality occurred in 6.6% at a median follow-up of 15 months.

Conclusions
The Allegra TAVI system demonstrates promising technical and device success rates, with early safety and good post-implant haemodynamic performance in high-risk patients undergoing valve-in-valve TAVI. Larger randomized trials are needed to confirm these results.