Early mitral valve repair surgery versus active surveillance in patients with asymptomatic severe primary mitral regurgitation; insights from the Dutch AMR registry
Authors: El Mathari S , Hart E , Jansen R , Wind A , Schaap J , Cramer M J , Bots M L , Streukens S A J , Wagenaar L , Boekholdt S M , Kluin J , Chamuleau S A J 
Published: November 2023

Abstract

Background
Management of asymptomatic patients with severe mitral regurgitation (MR) and preserved left ventricular function is still a challenging clinical entity. According to international guidelines, early mitral valve repair (MVR) surgery and active surveillance with facilitated surgery are both possible treatment strategies. Conflicting evidence is available on the number of patients that reach an indication for facilitated surgery during follow-up in the active surveillance strategy group [1, 2]. In the multicenter Dutch AMR registry, asymptomatic MR patients were allocated to either strategy according to the heart team decision [3]. In this registry there was a low threshold to perform additional testing (i.e. cardiac magnetic resonance imaging, holter monitoring and/or cardiopulmonary exercise testing).

Purpose
To prospectively assess the percentage of MR patients undergoing facilitated surgery during a long-term active surveillance strategy.

Methods
Since 2013, 99 patients with severe primary MR were included in the Dutch AMR Registry in 5 medical centers. Enrollment for early surgery or active surveillance was based on ESC guidelines and heart team decision. During long term follow-up, we assessed primary endpoints for both groups; occurrence of atrial fibrillation, cerebrovascular accident, heart failure, MVR surgery and cardiovascular/non-cardiovascular death. In particular, we assessed the number and timing of patients that underwent facilitated surgery in the active surveillance group.

Results
In total, 71 patients were allocated to the active surveillance and 28 to the early surgery group. 39 Patients in the active surveillance group reached a primary endpoint including 3 deaths (2 cardiovascular and 1 non-cardiovascular) (Figure 1). In the early surgery group, 4 patients reached a primary endpoint including 2 cardiovascular deaths. Over a mean follow-up time of 4.4 years, 36 patients (51%) of the active surveillance population underwent facilitated surgery due to either symptomatic or asymptomatic triggers (Table 1).

Conclusions
In the Dutch AMR registry, 51% of MR patients under active surveillance needed facilitated surgery within 4.4 years. Approximately half of these patients were still asymptomatic when developing an indication for surgery. Cardiovascular mortality rates were similar between the two treatment strategies. This result shows that active surveillance can be safely accomplished in asymptomatic severe MR patients. The Dutch AMR registry will further elucidate 1) whether MR patients can be stratified at baseline to either strategy based on additional testing and 2) whether facilitated surgery is non-inferior to early surgery in terms of surgical outcome, quality of life and long-term survival. For now, the current results support an active surveillance strategy in selected asymptomatic MR patients based on guidelines since half of patients are still free of symptoms without guideline indications for surgery.Figure 1Table 1