The impact of residual mitral regurgitation after MitraClip therapy in functional mitral regurgitation

Aims MitraClip therapy for the treatment of functional mitral regurgitation (FMR) is an increasingly used intervention for high-risk surgical patients. The aim of this observational study was to assess the impact of residual mitral regurgitation (rMR) at discharge on long-term outcome after MitraClip therapy in patients with FMR. Methods and results Overall, 458 patients (mean age 73.8 +/- 8.9 years) underwent MitraClip implantation between September 2008 and December 2017. The impact of rMR <= 1+ at discharge (n= 251) was retrospectively compared to patients graded as rMR 2+ (n= 173) and rMR >= 3+ (n= 34) at discharge. Median follow-up time was 5.09 years (5.00-5.26) with maximum follow-up of 10.02 years. The primary outcome was survival, and Kaplan-Meier analyses revealed significant differences among all rMR subgroups with highest survival rates for rMR <= 1+ patients. This was further confirmed by composite outcome analyses (P < 0.02). The inferior outcomes of rMR 2+ and rMR >= 3+ at discharge were confirmed by increased adjusted hazard ratios when rMR 2+ (1.54,P= 0.0039) and rMR >= 3+ (2.16,P= 0.011) were compared to rMR <= 1+. Moreover, patients with stable rMR <= 1+ grades within 12 months showed significantly higher survival rates compared to patients with rMR <= 1+ at discharge and rMR >= 2+ at 12-month follow-up or rMR >= 2+ at discharge and 12-month follow-up (P= 0.029). Conclusions Patients with optimal and durable rMR <= 1+ at discharge and 12-month follow-up showed better outcome compared to patients with rMR 2+ and rMR >= 3+. Treatment success and durability characterized by rMR <= 1+ at discharge and 12 months seem to be important factors for long-term outcomes, which has to be further confirmed by prospective randomized trials.