Subannular repair or transcatheter edge-to-edge repair for secondary mitral regurgitation? More data for international guidelines

Study protocol for an international registry observational study evaluating clinical outcomes of transcatheter versus standard surgical mitral valve operation for secondary mitral regurgitation: the TEERMISO study

BACKGROUND

Secondary mitral regurgitation (SMR) is a condition affecting the left ventricle (LV) rather than the mitral valve (MV). If the MV remains structurally unchanged, enlargement of the LV or impairment of the papillary muscles can occur. Several mechanical interventions are available to dictate the resolution of MR. However, there is a lack of robust data to compare MV replacement, MV repair (including subvalvular repair) and transcatheter mitral valve procedures (TMVp). This study aims to compare the effectiveness and clinical outcomes of TMVp using the edge-to-edge mitral valve repair technique and standard surgical mitral valve procedures in patients with SMR.

METHODS AND ANALYSIS

Five cardiac surgery centres from four European countries and Japan have collaborated to create a multicentre observational registry (TEERMISO). The registry will enrol consecutive patients who underwent mechanical intervention for SMR between January 2007 and December 2023. The investigators assessed the difference between replacement and repair for both the standard surgical approach and the transcatheter procedure. The main clinical outcome will be the degree of LV remodelling as assessed by the Left Ventricular End-Diastolic Volume Index at 10 years. The study will measure several secondary endpoints, including all-cause mortality as the primary endpoint, followed by functional status, hospitalisation, neurocognition, physiological measures (echocardiographic assessment), adverse events and reoperation.

ETHICS AND DISSEMINATION

Ethics approval was obtained in Montpellier University Hospital on 24 May 2022 (Institutional Review Board Approval Number: IRB-MTP_2022_05_202201143). The results of the main study and each sub-analysis will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT05090540.

A Protocol Investigation Comparing Transcatheter Repair with the Standard Surgical Procedure for Secondary Mitral Regurgitation

Background: Secondary mitral regurgitation (SMR) is characterized by a pathological process impacting the left ventricle (LV) as opposed to the mitral valve (MV). In the absence of structural alterations to the MV, the expansion of the LV or impairment of the papillary muscles (PMs) may ensue. A number of technical procedures are accessible for the purpose of determining the optimal resolution for MR. Nevertheless, there is a dearth of rigorous data to facilitate a comparative analysis of MV replacement, MV repair (including subvalvular repair), and transcatheter mitral valve interventions (TMV-Is). The objective of this investigation is to evaluate and compare the efficacy and clinical outcomes of transcatheter mitral valve repair (TMV-r) utilizing the edge-to-edge mitral valve repair (TEER) procedure in comparison to conventional surgical mitral valve interventions (S-SMVis) in patients with secondary mitral regurgitation. Methods and analysis: A consortium of five cardiac surgery institutions from four European states and Japan have joined forces to establish a multicenter observational registry, designated TEERMISO. Patients who underwent technical procedures for SMR between January 2007 and December 2023 will be enrolled consecutively into the TEERMISO registry. The investigation team evaluated the comparative efficacy of replacement and repair techniques, utilizing both the standard surgical methodology and the transcatheter intervention. The primary clinical outcome will be the degree of left ventricular remodeling, as assessed by the left ventricular end-diastolic volume index, at 10 years. The forthcoming research will assess a variety of secondary endpoints, among which all-cause mortality will be the primary endpoint. Subsequent assessments will be made in the following order: functional status, hospitalization, neurocognition, physiological measures (echocardiographic assessment), occurrence of adverse clinical incidents, and reoperation. Ethics and dissemination: The multicenter design of the database is anticipated to reduce the potential for bias associated with institutional caseload and surgical experience. All participating centers possess an established mitral valve protocol that facilitates comprehensive follow-up and management of any delayed mitral complications following replacement surgery or surgical repair of the secondary mitral regurgitation. The data collected will provide insights into the impact of diverse surgical approaches on standard mitral valve surgery and TEER. This will facilitate the evaluation of LV remodeling over the course of long-term post-procedural follow-up. Trial Registration: ClinicalTrials.gov ID: NCT05090540; IRB ID: 202201143.

Atrial functional mitral regurgitation in cardiology and cardiac surgery

Functional or secondary mitral regurgitation (MR) is a clear and present danger to cardiovascular health, with heightened morbidity and mortality rates. Secondary MR is caused by an imbalance between two sets of forces. There are two forces at play here. One keeps the mitral leaflets tethered, while the other closes them. The evidence clearly shows inadequate coaptation. Functional MR (FMR) is the typical form of MR. It is almost always caused by dysfunction and alterations of the left ventricle (LV) geometry. It occurs in both ischemic and non-ischemic disease states. Atrial FMR (AFMR) is a disease that has only recently come to be acknowledged. This phenomenon arises when mitral annular enlargement is caused by left atrial enlargement. This preserves the geometry and function of the LV. AFMR is most frequently encountered in individuals with chronic atrial fibrillation or heart failure, in whom a normal ejection fraction is present. Published studies and ongoing research vary in their definition of AFMR, but there is no doubt that AFMR exists. This review definitively explains the pathophysiology of AFMR and demonstrates the necessity of a common working standard for the definition of AFMR. This is essential to warrant cohesiveness in the data reported and to drive forward the much-needed research into the outcomes and treatment strategies in this critical field. A number of high-quality studies have demonstrated that restrictive mitral annuloplasty and transcatheter procedure based on edge-to-edge repair are effective in reducing MR and alleviating symptoms. The pathophysiology, echocardiographic diagnosis, and treatment of AFMR are thoroughly reviewed in this comprehensive review.

Assessing emerging causes of mitral regurgitation: atrial functional mitral regurgitation

Functional or secondary mitral regurgitation is linked to increased cardiovascular morbidity and mortality. From a mechanical perspective, secondary mitral regurgitation occurs due to an imbalance between the forces that tether the mitral leaflets and those that close them. This results in incomplete coaptation. Most commonly, functional mitral regurgitation, which occurs in both ischaemic and non-ischaemic disease states, is usually caused by dysfunction and changes in the left ventricle. Atrial functional mitral regurgitation (AFMR) is a disease state that has been more recently recognized. It occurs when mitral annular enlargement is associated with left atrial dilatation, preserving left ventricular geometry and function. AFMR is typically seen in patients with chronic atrial fibrillation or heart failure who have a conserved ejection fraction. Published reports and ongoing investigations vary in how they define AFMR. This publication examines the pathophysiology of AFMR and highlights the importance of having a common working standard for the definition of AFMR to ensure consistency in the data reported and to drive forward the much needed research into the outcomes and treatment strategies in this area. Several studies have reported that restrictive annuloplasty and transcatheter edge-to-edge repair can reduce mitral regurgitation and improve symptoms. This narrative review will explore the pathophysiology, echocardiographic diagnosis and treatment of AFMR.

Interpapillary muscle distance independently predicts recurrent mitral regurgitation

OBJECTIVE

Ischaemic secondary mitral regurgitation (ISMR) after surgery is due to the displacement of papillary muscles resulting from progressive enlargement of the left ventricle end-diastolic diameter (LVEDD). Our aim was to prove that if the interpapillary muscle distance (IPMD) is surgically stabilized, an increase in LVEDD will not lead to a recurrence of ischaemic mitral regurgitation (MR).

METHODS

Ninety-six patients with ISMR, who underwent surgical revascularisation and annuloplasty, were randomly assigned in a 1:1 ratio to undergo papillary muscle approximation (PMA). At the 5-year follow-up, we assessed the correlation between PMA and echocardiographic improvements, the effect size of PMA on echocardiographic improvements, and a prediction model for recurrent MR using inferential tree analysis.

RESULTS

There was a significant correlation between PMA and enhancements in both the α and β angles (Spearman's rho > 0.7, p < 0.01). The α angle represents the angle between the annular plane and either the A2 annular-coaptation line or the P2 annular-coaptation line. The β angle indicates the angle between the annular plane and either the A2 annular-leaflet tip line or the P2 annular-leaflet tip line. PMA led to substantial improvements in LVEDD, tenting area, α and β angles, with a large effect size (Hedge's g ≥ 8, 95% CI ORs ≠ 1). The most reliable predictor of recurrent MR grade was the interpapillary distance, as only patients with an interpapillary distance greater than 40 mm developed ≥ 3 + grade MR. For patients with an IPMD of 40 mm or less, the best predictor of recurrent MR grade was LVEDD. Among the patients, only those with LVEDD greater than 62 mm showed moderate (2+) MR, while only those with LVEDD less than or equal to 62 mm had absent to mild (1+) MR.

CONCLUSION

Prediction of recurrent ischaemic MR is not independent of progressive LVEDD increase. PMA-based surgical procedure stabilises IPMD.

Impact of Mitral Regurgitation Recurrence on Mitral Valve Repair for Secondary Ischemic Mitral Regurgitation

OBJECTIVES

The current guidelines still do not include specific recommendations on the use of subvalvular repair (SV-r) for treatment of ischemic mitral regurgitation (IMR). Therefore, the objective of our study was to evaluate the clinical impact of mitral regurgitation (MR) recurrence and ventricular remodeling on long-term outcomes after SV-r combined with restrictive annuloplasty (RA-r).

METHODS

We performed a subanalysis of the papillary muscle approximation trial, studying 96 patients with severe IMR and coronary artery disease undergoing restrictive annuloplasty alongside subvalvular repair (SV-r + RA-r group) or restrictive annuloplasty alone (RA-r group). We analyzed treatment failure differences, the influence of residual MR, left ventricular remodeling, and clinical outcomes. The primary endpoint was treatment failure (composite of death; reoperation; or recurrence of moderate, moderate-to-severe, or severe MR) within 5 years of follow-up after the procedure.

RESULTS

A total of 45 patients showed failure of the treatment within 5 years, of which 16 patients underwent SV-r + RA-r (35.6%) and 29 underwent RA-r (64.4%, p = 0.006). Patients with significant residual MR presented with a higher rate of all-cause mortality at 5 years compared with trivial MR (HR 9.09, 95% CI 2.08-33.33, p = 0.003). MR progression occurred earlier in the RA-r group, as 20 patients in the RA-r group vs. 6 in SV-r + RA-r group had a significant MR 2 years after surgery (p = 0.002).

CONCLUSIONS

RA-r remains a surgical mitral repair technique with an increased risk of failure and mortality at 5 years compared with SV-r. The rates of recurrent MR are higher, and recurrence occurs earlier, with RA-r alone compared to SV-r. The addition of the subvalvular repair increases the durability of the repair, thus extending all of the benefits of preventing MR recurrence.