Impact of effective regurgitant orifice area on outcome of secondary mitral regurgitation transcatheter repair.

Objectives: To assess the value of effective regurgitant orifice (ERO) in predicting outcome after edge-to-edge transcatheter mitral valve repair (TMVR) for secondary mitral regurgitation (SMR) and identify the optimal cut-off for patients' selection.
Methods: Using the EuroSMR (European Registry of Transcatheter Repair for Secondary Mitral Regurgitation) registry, that included patients undergoing edge-to-edge TMVR for SMR between November 2008 and January 2019 in 8 experienced European centres, we assessed the optimal ERO threshold associated with mortality in SMR patients undergoing TMVR, and compared characteristics and outcomes of patients according to baseline ERO.
Results: Among 1062 patients with severe SMR and ERO quantification by proximal isovelocity surface area method in the registry, ERO was < 0.3 cm ² in 575 patients (54.1%), who were more symptomatic at baseline (NYHA class ≥ III: 91.4% vs. 86.9%, for ERO < vs. ≥ 0.3 cm ² ; P = 0.004). There was no difference in all-cause mortality at 2-year follow-up according to baseline ERO (28.3% vs. 30.0% for ERO < vs. ≥ 0.3 cm ² , P = 0.585). Both patient groups demonstrated significant improvement of at least one NYHA class (61.7% and 73.8%, P = 0.002), resulting in a prevalence of NYHA class ≤ II at 1-year follow-up of 60.0% and 67.4% for ERO < vs. ≥ 0.3 cm ² , respectively (P = 0.05).
Conclusion: All-cause mortality at 2 years after TMVR does not differ if baseline ERO is < or ≥ 0.3 cm ² , and both groups exhibit relevant clinical improvements. Accordingly, TMVR should not be withheld from patients with ERO < 0.3 cm ² who remain symptomatic despite optimal medical treatment, if TMVR appropriateness was determined by experienced teams in dedicated valve centres.