Favorable outcomes despite small neo-left ventricular outflow tract area in valve-in-valve transcatheter mitral valve replacement
I Magana, J Mesnier, A Cailliau, N El Beze, C Delhomme, N Groshenry, A Souquet, M Benamer, G Ducrocq, B Iung, G Suc, M UrenaAbstract
Introduction
Left ventricular outflow tract (LVOT) obstruction is a serious complication of transcatheter mitral valve replacement (TMVR). Current guidelines suggest a predicted neo-LVOT area < 200 mm² as a threshold to reconsider the procedure. However, this cut-off is largely derived from TMVR in native valves or rings, and its applicability to valve-in-valve (ViV) TMVR remains debated.
Purpose
To evaluate the post-procedural neo-LVOT area using computed tomography (CT) and to assess the clinical and hemodynamic impact of a small neo-LVOT following ViV TMVR.
Methods
We included patients who underwent successful ViV TMVR at a high-volume tertiary center between 2014 and 2025 and had a post-procedural CT. Neo-LVOT was defined as the smallest area in the LVOT between the stent frame and the interventricular septum, measured at end-systole. Patients were dichotomized by neo-LVOT size (< 200 mm² vs. ≥ 200 mm²). The primary outcome was significant hemodynamic LVOT obstruction, defined as a maximal LVOT gradient ≥ 30 mmHg on the first post-procedural transthoracic echocardiogram. Secondary outcomes included 30-day functional status and a composite of all-cause mortality or mitral re-intervention at the end of follow-up. A sensitivity analysis was performed for patients with a neo-LVOT < 100 mm².
Results
A total of 97 patients were analyzed. Following ViV TMVR, the median neo-LVOT area was 170 (IQR: 105–305) mm², with 57 patients (58.8%) presenting a neo-LVOT < 200 mm². Patients with a reduced neo-LVOT were more likely to be female (82.5% vs. 45.0%, p < 0.001) with a higher left ventricular ejection fraction (59.3 ± 9.2% vs. 55.1 ± 10.4%, p = 0.04). Two cases of LVOT obstruction occurred, both in patients with a neo-LVOT < 200 mm² (169 mm² and 87 mm²), but neither had clinical consequences. One of these cases occurred in a woman who had undergone alcohol septal ablation prior to ViV TMVR, with complete regression of the LVOT gradient at 3 months. A neo-LVOT < 200 mm² was not associated with worse 30-day functional outcomes (73.7% in NYHA class I/II vs. 60.0% in the ≥ 200 mm² group, p = 0.42). Over a mean follow-up of 2.7 ± 2.4 years, 22 (22.7%) composite events (death or mitral re-intervention) occurred, with no significant difference between groups (HR 1.74, 95% CI 0.69–4.38, p = 0.24). Results were similar in the 23 (23.7%) patients with a neo-LVOT < 100 mm².
Conclusion
Post-procedural neo-LVOT areas < 200 mm² are common after ViV TMVR, occurring in nearly 60% of patients. However, this finding is infrequently associated with significant hemodynamic LVOT obstruction and does not negatively impact long-term clinical outcomes. Even a neo-LVOT < 100 mm² (present in a quarter of patients) showed no adverse impact on long-term outcomes. These findings suggest the conventional 200 mm² threshold may be overly restrictive for ViV TMVR candidates.