Transseptal or Transapical Transcatheter Valve-in-Valve Implantation Versus Redo Surgical Replacement for Degenerated Mitral Bioprostheses

Background Bioprosthetic mitral valve degeneration can be problematic as redo surgical mitral valve replacement (Redo-SMVR) is associated with a high morbidity and mortality. Valve-in-valve transcatheter mitral valve replacement (TMVR) has emerged as an alternative for high-risk patients, but comparative data is lacking. Objectives We aimed to evaluate the outcomes of Redo-SMVR vs. TMVR, using either transapical (TA) or transseptal (TS) approach. Methods and Results A total of 415 patients (69% rheumatic) were included between January 2014 to May 2023 (Redo-SMVR=239; TA-TMVR=84; TS-TMVR=92). Patients in the Redo-SMVR group were younger (51.7±12.3, 64.3±10.5, 73.7±10.9, respectively for Redo, TA and TS; p<0.001) with a lower median STS score (2.9 [1.7 – 5.1], 6.6 [3.9–10.5], 6.5 [4.2–10.0]; p<0.001). 30-day mortality was significantly higher for both Redo-SMVR and TA-TMVR vs. TS-TMVR (14.2%, 15.5%, 4.3%; p=0.030) and procedural success was lower (52.5%, 64.9%, 88%; p<0.001). There was no difference in terms of 1-year mortality rate across the groups (Log-rank p=0.222). Reduced preprocedural left ventricular ejection fraction, higher right ventricular systolic pressure (RVSP), and the presence of coronary artery disease were independently associated with 30-day mortality, while transseptal approach was protective. At 1-year follow-up, the predictors of mortality remained consistent, with significant tricuspid regurgitation replacing RVSP (all with p<0.05). Conclusions In high-risk patients with dysfunctional mitral bioprosthesis and most with rheumatic etiology, TS-TMVR was associated with higher procedural success and better short-term outcomes, including all-cause mortality, despite higher risk characteristics. In the mid-term follow-up, there were no significant differences in mortality across the groups.