Transcatheter aortic valve replacement in failed transcatheter versus failed surgical bioprostheses: a systematic review with exploratory meta-analysis

Background With the expanding use of transcatheter aortic valve replacement (TAVR) in younger patients, the need for reintervention on failed bioprostheses is rising. Comparative evidence between redo TAVR for failed transcatheter valves (TAV-in-TAV) and TAVR for failed surgical valves (TAV-in-SAV) is limited. Objective To systematically review and meta-analyse the clinical, haemodynamic, and safety outcomes of TAV-in-TAV versus TAV-in-SAV. Methods PubMed, Scopus, Web of Science, Cochrane CENTRAL, and Embase were searched from inception to April 2026. Studies directly comparing TAV-in-TAV with TAV-in-SAV and reporting original data with ≥10 patients per group were included. Risk of bias was assessed using ROBINS-I and the Newcastle-Ottawa Scale. Random-effects meta-analyses were performed for 30-day mortality, 1-year mortality, mean transvalvular gradient at 30 days, and new permanent pacemaker (PPM) implantation. Results Four observational studies, including 705 patients in the extracted comparative cohorts, met the inclusion criteria. Two full-text studies contributed to the primary quantitative analyses. TAV-in-TAV was not associated with a statistically significant difference in 30-day mortality compared with TAV-in-SAV (OR 0.71, 95% CI 0.25–2.00), nor in 1-year mortality (OR 1.02, 95% CI 0.47–2.18). TAV-in-TAV was associated with lower mean transvalvular gradients at 30 days (MD −2.71 mmHg, 95% CI −4.07 to −1.34). A non-significant trend toward higher new permanent pacemaker implantation was observed after TAV-in-TAV (OR 1.85, 95% CI 0.94–3.65). Conclusion Current comparative evidence between TAV-in-TAV and TAV-in-SAV remains limited and observational. No definitive mortality difference was identified, but clinically meaningful benefit or harm cannot be excluded. TAV-in-TAV shows a consistent early haemodynamic signal with lower gradients, while the possible increase in pacemaker implantation remains exploratory. These findings should be considered hypothesis-generating and require confirmation in larger prospective studies with longer follow-up. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420261369410 , PROSPERO CRD420261369410.