Background: 

A growing number of patients are currently treated for severe mitral regurgitation (MR) using a transcatheter mitral valve repair (TMVr). In clinical routine, the potential risk of elevated post-procedural mitral valve pressure gradient (MVPG) may prohibit optimal MR reduction driven by the avoidance of additional clip implantations. Thus, the unfavorable impact on survival and functional outcome of increased MVPG in patients undergoing TMVr is currently debatable.

Methods

In this single-center, retrospective study, we analyzed the survival and functional outcome of 780 consecutive patients with severe MR undergoing TMVr in our center between September 2008 and January 2020. Eighty-nine patients were excluded due to an unsuccessful procedure and 15 patients were lost to follow-up. Therefore, data of 676 patients with a median follow-up time of 5.26 (5.11, 5.51) years were analyzed. MVPG was determined by transthoracic echocardiography at discharge. Following multivariate adaptive regression spline analysis to calculate the optimal MVPG cut-off, MVPG was considered elevated in excess of 4.5 mmHg at discharge. Kaplan-Meier analysis, as well as Cox regression models, were performed and correlated with MVPG. The primary outcome measure was a combined endpoint consisting of death or rehospitalization for heart failure.

Results: 

Among 676 high-risk patients undergoing TMVr (mean age 74.6 ± 8.5 years, 59.0% male, median STS Score 3.9 [interquartile range 2.5; 6.0]), 179 (26.4%) patients showed elevated MVPG >4.5 mmHg. Functional MR was present in 426 (63.0%) patients. In the overall patient cohort, Kaplan-Meier and Cox Regression analyses could not demonstrate significant differences for the combined endpoint (p=0.99). In contrast, subgroup analysis according to MR etiologies (degenerative MR [DMR] vs. functional MR [FMR]) indicated a significant adverse influence of elevated MVPG on the combined endpoint as well as functional outcome in patients with DMR, but not with FMR. After adjustment, multivariate Cox Regression analysis showed an inferior prognosis in patients with DMR and elevated MVPG > 4.5 mmHg (hazard ratio 1.77 [1.16, 2.68], p=0.0076).

Conclusions:

TMVr-patients with DMR and measurable elevated post-procedural MVPG face an inferior prognosis and reduced functional outcomes compared to patients with FMR.