Background: Mitral transcatheter edge-to-edge repair (M-TEER) carries a risk for iatrogenic stenosis, particularly in patients with small native mitral valves.
Methods: Impact of native and residual mitral valve orifice area (MVOA) on overall survival was analyzed in 482 patients undergoing M-TEER. MVOA was assessed using 3D planimetry and patients were stratified according to native MVOA (≤ 3.5 vs. >3.5 cm2) as well as residual MVOA (≤1.5cm2 vs. >1.5cm2).
Results: 13.3% (n=64) of patients presented with small native MVOA <3.5cm2 (mean MVOA: 2.9±0.5 vs. 5.7±1.7 cm², p<0.01). These patients were significantly elder (81{76.3-85.0} vs. 79.0{72.0-84.0} years, p=0.02), more often female (78.1 vs. 40.0%, p<0.01) and had smaller body surface area (1.7{1.5-1.8} vs. 1.8{1.7-2.0}m², p=0.01). Degenerative mitral regurgitation (MR) was equally frequent in both groups (45.3 and 36.8%, p=0.32).
Preprocedural MR was more severe in patients with larger MVOA (Grade IV: 30.2 vs. 52.5%, p<0.01). Fewer devices were implanted (1.1±0.2 vs.1.4±0.6, p<0.01) in patients with small MVOA, yet MR reduction was equally effective (Residual MR ≤I: 90.6 vs. 86.8%, p=0.40).
In patients with small native MVOA, postprocedural MVOA were significantly smaller (1.7±0.5 vs. 2.4±0.8cm², p<0.01) and postprocedural transmitral gradients were significantly higher (4.3±2.0 vs. 3.2±1.5mmHg, p<0.01). Residual MVOA ≤1.5cm² was observed in 45.9% of patients with small native MVOA compared to only 7.7% in patients with large native MVOA (p<0.01).
During follow-up, patients with small native MVOA presented with similar probability of survival compared to patients with larger MVOA (65.0 vs. 68.5%, p=0.18). In multivariable Cox regression analysis adjusted for covariates, etiology of MR as well as residual MR, small native MVOA ≤ 3.5cm² showed a trend towards increased mortality (HR: 1.73, 95% CI: 0.97-3.11, p=0.06). Post-procedural MVOA ≤1.5cm² was found to independently increase mortality (HR: 1.94, 95% CI: 1.01-3.72, p=0.046).
Conclusion: M-TEER effectively reduces MR in patients with small MVOA. Notably, more than half of these patients do not develop postprocedural stenosis. However, their risk of experiencing relevant stenosis is substantially higher and associated with increased mortality. Patients with small MVOA require careful device selection and alternative transcatheter treatments such as transcatheter valve replacement should be considered.
