Long-Term Outcomes after Transcatheter Mitral Valve-in-Valve or Valve-in-Ring Procedures

Background: Redo mitral valve surgery is the standard of care for failed mitral bioprostheses or recurrence of mitral regurgitation after repair. Nonetheless, catheter-based valve-in-valve (ViV) or valve-in-ring (ViR) procedures have increasingly become viable alternatives in high-risk subpopulations. Despite reported good initial results, little is known about longer-term outcomes. Here, we report the long-term outcomes of transcatheter mitral ViV and ViR procedures. Methods: All consecutive patients (n = 54) undergoing transcatheter mitral ViV or ViR procedures for failed bioprostheses or recurring regurgitation after mitral repair in the time period between 2011 and 2021 were retrospectively enrolled. The mean age was 76.5 +/- 6.5 years, and 30 (55.6%) of the patients were male. The procedures were done using a commercially available balloon-expandable transcatheter heart valve. Clinical and echocardiographic follow-up data were obtained from the hospital's database and analyzed. Follow-up reached up to 9.9 years with a total of 164.3 patient-years. Results: A total 25 patients received a ViV and 29 patients a ViR procedure. Both groups were at high surgical risk with an STS-PROM of 5.9 +/- 3.7% in ViV and 8.7 +/- 9.0% in ViR patients (p < 0.01). The procedures themselves were mainly uneventful with no intraoperative deaths and a low conversion rate (n = 2/54; 3.7%). VARC-2 procedural success was low (ViV 20.0% and ViR 10.3%; p = 0.45), which was either driven by high rates of transvalvular pressure gradients ">5 mmHg" (ViV 92.0% and ViR 27.6%; p < 0.01) or residual regurgitation ">trace" (ViV 28.0% and ViR 82.7%; p < 0.01). ICU-stay was prolonged in both groups (ViV 3.8 +/- 6.8 days and ViR 4.3 +/- 6.3 days; p = 0.96) with acceptable hospital stay (ViV 9.9 +/- 5.9 days and ViR 13.5 +/- 8.0 days; p = 0.13). Despite 30-day mortality being acceptable (ViV 4.0% and ViR 6.9%; p = 1.00), the mean posthospital survival time was disappointingly low (ViV 3.9 +/- 2.6 years and ViR 2.3 +/- 2.7 years; p < 0.01). Overall survival in the entire group was 33.3%. Cardiac reasons for death were frequent in both groups (ViV 38.5% and ViR 52.2%). Cox-regression analysis identified ViR procedures as a predictor of mortality (HR 2.36, CI 1.19-4.67, p = 0.01). Conclusions: Despite acceptable immediate outcomes in this high-risk subpopulation, long-term results are discouraging. Transvalvular pressure gradients as well as residual regurgitations remained drawbacks in this real-world population. The indication for catheter-based mitral ViV or ViR procedures rather than conventional redo-surgery or conservative treatment must be thoughtfully considered.