Translocated anterior mitral leaflet sparing is a viable treatment option for both degenerative and functional mitral valve disease

Introduction

Several studies have documented the early (1-4) and late (5-7) haemodynamic advantages of retaining the subvalvular apparatus of the mitral valve (MV) during mitral valve replacement (MVR). While some researchers (5,8,9) have addressed the issue of complete versus partial chordal preservation retrospectively, this question has not been rigorously investigated in the clinical setting with extended follow-up in both degenerative, restrictive and infectious MV disease. As a result, because of concerns about increased technical complexity, prolonged operation time, potential interference with mechanical leaflet motion, the need to undersize the MV prothesis, and the possibility of creating left ventricular (LV) outflow tract obstruction (10-12), many surgeons continue to preserve only the posterior leaflet chordae tendineae. Furthermore, there is a lack of long-term data reporting the potential occurrence of prosthesis stenosis due to excess tissue in patients with myxomatous degenerative MV disease. A recent retrospective study (13), based on a limited number of patients, suggested that preserving the sub-valvular apparatus has a positive impact on the heart’s longitudinal function after 3 months. However, only one randomized clinical trial (14) provides an early benefit of preserving the entire mitral valve apparatus during MVR, with a reduction in LV chamber size and systolic afterload compared with partial chordal preservation.

In this preliminary analysis, we present the findings from the first 161 single-arm patients who underwent complete chordal-sparing mitral valve replacement (CCS-MVR) and were followed for an extended period. This larger retrospective observational study is based on a novel approach to MVR that preserves the anterior mitral leaflet (AML) and the entire architecture of the left ventricle. Patients with functional, degenerative and infective endocarditis (IE) of mitral valve with severe moderate to severe mitral regurgitation (MR) ineligible for MV repair may benefit from this technique. We present this article in accordance with the STROBE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-24-1555/rc).

Methods

Study design

This analysis was conducted using a single-arm cohort study design to evaluate patients with severe mitral valve regurgitation who underwent the CCS-MVR procedure. Recipient data were identified and retrieved from the prospective Centre Cardiologique du Nord Cardiovascular Information Registry and the Mitral Valve Disease Registries, covering the pre-operative, operative and post-operative periods. Three independent authors (F.N., I.A., and A.A.) adjudicated data collection, causes of death, and adverse events. The Institutional Review Board (IRB) of the University of Montpellier (dred-saine-cer@umontpellier.fr) has formally approved the utilization of the aforementioned data for research purposes (IRB No. UM 2023-010, May 17, 2023). The principles established in the Declaration of Helsinki (as revised in 2013) were followed. In addition, written informed consent having been provided by the patients in question. Enrolment for the study began in January 2014 and was completed in November 2023. A total of 161 patients received CCS-MVR and were followed for 9 years. The study aimed to describe each patient over a mean follow-up period of 2 years. Endpoints were measured at 30 days, 6 months, and annually thereafter with an outpatient visit and transthoracic echocardiography.

Patients

From January 2014 to November 2023, 1,194, adults with mitral valve disease were treated at the Centre Cardiologique du Nord; 443 patients underwent partial chordal sparing MVR (PCS-MVR), 428 patients underwent mitral valve repair, 161 patients underwent CCS-MVR using the AML translocation and 225 patients underwent Mitraclip procedure. The indication for CCS-MVR was degenerative valve disease in 94 patients (58.4%), functional MR in 58 patients (36.0%) and IE in 9 patients (5.6%). The mean age at complete chordal-sparing MV procedure was 73.98±9.72 years in the degenerative group and 71.71±9.20 years in patients with functional MR. Fifteen-point-five percent of patients with complete chordal-sparing MV indications had mitral annular disjunction (MAD), and 36.6% presented severe mitral valve calcification. In patients with functional MR, the most common aetiology was secondary ischaemic MR (72.4%), followed by secondary non-ischemic MR due to dilated cardiomyopathy (27.6%). Nine cases (5.6%) of IE were treated with a complete chordal-sparing MV procedure in persons who had an infected posterior leaflet of MV not suitable for mitral valve repair. A study flowchart in accordance with the study protocol is provided (Figure 1, Table 1).

Figure 1 The flowchart. CCF, chronic cardiac failure; CCS-MVR, complete chordal-sparing mitral valve replacement; MV, mitral valve; PCS-MVR, partial chordal sparing mitral valve replacement.

Inclusion and exclusion criteria

CCS-MVR was offered to adults over 65 years old with severe MV disease who were symptomatic for congestive heart failure, unresponsive to medical therapy, and had complex mitral valve morphology unsuitable for repair. Patients with diffuse myxomatous degeneration and bileaflet mitral valve prolapse were excluded from mitral valve repair. This category includes Barlow disease and fibroelastic degeneration (FED), as well as those requiring additional procedures on the tricuspid valve, thoracic aorta, or coronary artery bypass grafting (CABG) during mitral valve surgery. In addition to the aforementioned criteria, the CCS-MVR exclusion criteria also included any echocardiographic evidence of structural or rheumatic mitral valve pathology with fusion of the valvular and subvalvular apparatus, which would impede the sparing of MV. Furthermore, endocarditis extending to the anterior MV leaflet is also an exclusion criterion, as the damaged leaflet cannot be utilized for translocation and subsequent repair of the posterior leaflet (Figure 1). Transthoracic echocardiography was used to evaluate the severity of MR, following the criteria set by the American Society of Echocardiography’s Guidelines and Standards Committee and the Task Force on Prosthetic Valves (15). Experienced echocardiographic cardiologists, who were blinded with regard to the treatment strategy, assessed all echocardiographic measurements. According to guidelines (16,17), severe MR was defined as an effective regurgitant orifice area (EROA) of at least 0.4 cm² or by a combination of additional echocardiographic quantification methods. In detail, the MR grade was determined based on the EROA, which is considered a more reliable method than regurgitant volume (Rvol) (14,18,19) due to its objectivity and independence from loading conditions. However, the final assessment of MR severity was conducted using an additive methodology that analysed all aspects of the colour Doppler jet, including the jet area to left atrial volume index and vena contracta. Additionally, the assessment incorporated supportive data, such as left atrial size, E-wave peak, and the presence of pulmonary vein flow reversal, in accordance with guidelines (14,16-19) (Figure 1).

Endpoints

The study’s main objective was to evaluate LV remodeling, defined as an increase in LV ejection fraction (LVEF) >10% and/or its normalization (≥50%) accompanied by indexed left ventricular diameter reduction >10% and/or its normalization (≤33 mm/m²) (20). The echocardiographic parameters that were included are LVEF, recurrent moderate-to-severe prosthetic MR, left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD), pulmonary artery systolic pressure. Left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), indexed to body surface area [left ventricular end-diastolic volume indexed (LVEDVI) and LVESV indexed (LVESVI), respectively], and LVEF were attentively measured off-line from the apical views (biplane modified Simpson’s rule). MR was quantified by at least two of three well validated methods [i.e., Proximal Isovelocity Surface Area (PISA)], quantitative Doppler, and volumetric methods) averaged to calculate Rvol and effective EROA (16,17,21-25). Secondary endpoints comprised early postoperative complication within 30 days from the index hospitalization for surgery, New York Heart Association (NYHA) functional class, hospitalization rates, survival, and major adverse cardiovascular and cerebrovascular events (MACCE) (composite endpoint including death, stroke, worsening of NYHA class and rehospitalization for heart failure at follow-up).

Statistical analysis

Frequency and percentage were used to display categorical data, which were then compared using the χ² test or Fisher’s exact test where appropriate. Mean and standard deviation (SD) were used to express continuous variables, which were compared using a two-tailed t-test or Mann-Whitney test. Echocardiographic changes were compared using a paired two-tailed t-test. Missing values were imputed if they were below 20%. Predictive mean matching was used to impute numerical features, while logistic regression was used for binary variables. Least absolute shrinkage and selection operator (LASSO) regression was used to identify factors associated with LV adverse remodeling, while minimizing collinearity of variables and avoiding over-fitting. The R package ‘glmnet’ was used for this logistic regression model, which penalizes the absolute size of coefficients using λ. As penalties increase, weaker factors tend to have less influence, leaving only the strongest predictors in the model. The covariates with the most significant predictive power were selected based on λ (λ = Lambda.1se).

The risk model was formulated by including variables identified through LASSO regression analysis in logistic regression models that used stepwise variable selection based on the Akaike information criterion (AIC). Only variables that remained consistently statistically significant were used. Collinearity among the independent variables was checked using the variance inflation factor (VIF). Discrimination was assessed using the receiver operating characteristic (ROC) curve and the area under the curve (AUC). To determine calibration, predicted mortality rates from the final model were compared to actual observed rates. Survival curves were constructed using the Kaplan-Meier method and compared using the Log rank test. Multivariable logistic and Cox regression models were used to test the impact of age, sex, etiology of MR, and presence of MAD or MV calcification on mid-term survival. The proportional hazards assumption was tested using a graphical method and Schoenfeld residual-based tests from the survival package of R Statistical software. The statistical analysis was conducted using R Statistical Software (version 4.3.1; R Foundation for Statistical Computing in Vienna, Austria) with a significance level set at alpha =0.05.

Interventions

All patients underwent sternotomy. Standard normothermic (36 ℃) cardiopulmonary bypass was used for myocardial protection. Either antegrade intermittent warm potassium-rich cardioplegia or both antegrade and retrograde warm potassium-rich cardioplegia were used. The latter was used in patients requiring associated procedures with prolonged cardiopulmonary bypass. A thorough inspection was carried out on the mitral valve and subvalvular apparatus, with special attention given to the location and extent of mitral annular calcification (MAC) in the presence or absence of a MAD. For patients with rheumatic valve disease, the preferred approach is the partial chordal-sparing technique. The procedure involved excising the anterior leaflet along with its attached chordae tendineae, while preserving the posterior leaflet and its chordal attachments. If the posterior leaflet was excessively redundant or the chordae tendineae were elongated, the leaflet was attached to the mitral annulus using valve sutures. This option is for patients with degenerative mitral valve disease who have significant calcification of the anterior part of the mitral annulus. Mobilization of the AML is difficult and extremely dangerous due to the potential damage that could be done to the fibrous trigone.

For patients who are eligible for complete chordal preservation, the entire subvalvular apparatus is preserved in an anatomical manner. This approach differs from that described by Sintek and colleagues (26). To summarise, the anterior leaflet was detached from one commissure to the other, spanning the entire anterior anulus. An ellipse-shaped portion is excised due to degenerative disease with redundant tissue, leaving a 5- to 10-mm rim of leaflet-free edge attached to the primary (first order or marginal) chordae tendineae. Once fully mobilized this strip of AML was translocated and then reattached to the posterior leaflet and annulus in the corresponding location with the valve sutures. Full mobilization and translocation of the AML is the best option as it avoids the alternative Khonsari I technique (27), which is used when the AML is excessively redundant. The Khonsari I procedure involves dividing the AML into two or four segments, which are then repositioned to their normal anatomical position using valve sutures. In cases of mitral valve diseases where excess tissue is not present, such as IE with a preserved AML from infection and Carpentier morphology types I and IIIb, our procedure involves translocating the AML without removing its free edge (Figure 2).

Figure 2 The steps to achieve complete chordal preservation in mitral valve replacement are shown in this figure. (A,B) The AML with preserved chordal apparatus (yellow arrows) is dissected across the entire anterior annulus. (C) The AML is repositioned and reattached to the posterior leaflet and annulus at the appropriate location. (D,E) The stented bioprosthesis is inserted. AML, anterior mitral leaflet.

In patients with IE, CCS-MVR can use the translocated tissue of the AML to repair abscess formation on the posterior annulus. The entire AML with chordal apparatus is used for annular reconstruction in patients requiring total repair of the posterior mitral annulus due to IE. In cases where patients have multiple infected leaflets and poor annular consistency, repair is not recommended. Instead, the preferred surgical option is concomitant MVR using a conventional stented xenograft or mechanical prosthesis. Prior to this, MV annulus reconstruction should be performed using the AML sutured with 4-0 polypropylene.

Translocating the AML can create a neoanulus that prevents decalcification of the native annulus in patients with massive posterior MAC, with or without MAD. If the leaflet tissue is of sufficient consistency, the AML can be sutured over the posterior mitral leaflet (PML) or, alternatively, sutures can be passed from the left atrium around the untracted mitral annulus directly over the AML encasing the prosthetic valve stent. This technique reduces potential traction between the calcific annulus, PML, and subvalvular apparatus, avoiding strain on fragile structures. Patients with diffuse myxomatous degeneration have been observed to exhibit abnormal systolic superior shift of papillary muscles with papillary muscle traction. Although there is likely a relationship between abnormal papillary muscle mechanical motion and MAD, further investigations are needed to determine the best surgical option to avoid deleterious complications (28). For patients who require systemic cooling, warming was achieved by maintaining a 10 ℃ temperature difference between core blood and internal temperature during surgical hemostasis. Cardiopulmonary bypass was stopped once the body temperature reached 36 ℃.

Results

Baseline characteristics of the whole patient population are shown in Table 1.

A total of 107 patients underwent concomitant procedures, including CABG (37 patients), tricuspid valve repair (64 patients), aortic valve replacement (AVR) (11 patients), and septal myectomy (2 patients).

Rvol averaged 56.88±25.30 mL and effective regurgitant orifice 38.77±17.52 mm². LVEF averaged 57.93%±11.22%, 71 patients (44%) had a LVEF <60% and 49 (30%) a LVESD ≥40 mm. Fifty-nine patients (37%) presented mitral valve calcification, and 25 (16%) had MAD. One hundred and forty-two patients (88%) received a porcine bioprosthetic valve.

LV reverse remodeling after CCS-MVR

Table 2 shows the echocardiographic data. Transthoracic echocardiograms were performed within 30 days, at 6 months, and annually up to 9 years after surgery to follow up on the echocardiographic results. The elimination of Rvol resulted in a significant decrease in LVEDVI (86.08±26.02 to 72.21±25.67 mL/m², P<0.001), while LVESVI remained comparable (36.17±19.72 to 35.19±21.58 mL/m², P=0.71). After the low-impedance pathway was suppressed by MV surgery, the LVEF decreased from 56.93%±11.21% to 50%±11% at both 30-day and late follow-up (P<0.001). At 30 days, 51 out of 161 patients had an LVEF below 50%, and this number remained the same at late follow-up.

At baseline, there was no significant difference in LVEF (56% vs. 58%, P=0.18), LVEDD (31 vs. 31 mm/m²), LVEDVI (88 vs. 85 mL/m², P=0.51) or Rvol (56 vs. 57 mL/beat, P=0.87) in patients with atrial fibrillation (AF) (n=73, 55%). Out of 140 patients, 74 (52.8%) experienced LV reverse remodeling at the 6-month follow-up. Female patients had a significantly higher rate of LV reverse remodeling (71% vs. 29%, P<0.001) than male patients. Patients with MAC and mitral annular disjunction had higher rates of LV reverse remodeling compared to patients with coronary artery disease (CAD). The LASSO regression analysis included 36 variables measured at baseline (refer to Table 1). Following LASSO regression selection (Figures S1-S3, Table S1), 10 variables were identified as significant predictors of adverse LV remodeling. These variables include female gender, hypercholesterolemia, CAD, acute myocardial infarction (AMI), previous cardiac surgery, AF, preoperative LVEDVI, preoperative right ventricular (RV) dysfunction, MV calcification and MAD.

The logistic regression model included 10 variables, of which 6 were retained. Four variables were identified as noteworthy independent predictors of adverse LV remodeling: male gender, CAD, AF, and preoperative LVEDVI (refer to Table 3). Additionally, the ROC area was 0.8351 [95% confidence interval (CI): 0.7653–0.9050]. The Hosmer-Lemeshow test yielded a P value of 0.60, and the VIF was <1.1, indicating no collinearity among the independent variables.

Early and late outcomes

The 30-day mortality rate was 8.7% (n=14). It is noteworthy that 10 of the 14 patients who died (5%) underwent reoperation following the initial procedure. In seven cases, a mitral clip procedure had been performed previously due to the presence of ischemic MR. In these instances, the transcatheter edge-to-edge repair technique proved unsuccessful for recurrent MR at the level of the implanted commissural clips, necessitating MVR. This was performed using the CCS-MVR technique. Two patients underwent reoperation with the use of a conventional stented xenograft MVR. These patients developed a paravalvular leakage following the prior procedure that was achieved by mean of CCS-MVR. The remaining case had undergone MV repair with the edge-to-edge procedure, which was unsuccessful due to recurrent MR. All patients received bioprostheses despite having irreversible LV dysfunction. Acute kidney injury occurred in 27.8% of cases and was significantly more frequent in patients with functional and endocarditis etiologies than in those with degenerative and rheumatic etiologies (see Table 4). Other postoperative complications are also listed in Table 4.

The mean follow-up was 35.64 months [interquartile range (IQR), 12.6–53.8 months; median, 30.26 months; range, 0–99.5 months]. Kaplan-Meier survival curves and patients at risk are shown in Figure 3A. Actual survival was 85.5%±2.8% at 1 year, 81.6%±3.2% at 2 years, 66.5%±4.5% at 5 years, and 59.2%±5.7% at 7 years. The median survival time after CCS-MVR was 39.5 months (95% CI: 4.3–90).

Figure 3 Actuarial survival after CCS-MVR: (A) overall; (B) stratified for MAD; (C) stratified for age. CCS-MVR, complete chordal-sparing mitral valve replacement; MAD, mitral annular disjunction.

At the follow-up, 11 patients (6.9%) exhibited a deterioration in their NYHA functional classification, and 10 (6.2%) required readmission for heart failure.

The multivariable analysis identified MAD to be associated with worse survival at follow-up and, age showed to have an almost significant association (Table 5). Kaplan-Meier curves for these variables are shown in Figure 3B,3C. Freedom from MACCE is shown in Figure 4. Actual MACCE-free survival was 80.6%±3.1% at 1 year, 76.7.6%±3.4% at 2 years, 58.3%±5.0% at 5 years, and 49.6%±5.8% at 7 years.

Figure 4 Actuarial MACCE-free survival after CCS-MVR. MACCE, major adverse cardiovascular and cerebrovascular events; CCS-MVR, complete chordal-sparing mitral valve replacement.

Discussion

The most appropriate surgical approach to preserve the subvalvular apparatus in the treatment of moderate to severe MR caused by organic and functional mitral valve disease is still controversial. In recent years, mitral valve repair has become more common than replacement (29). However, in patients with severe functional MR or in patients with bivalvular prolapse degenerative valve disease complicated by severe MAC or mitral annular disjunction (12,14), there is no conclusive evidence from randomized trials of the comparative advantages of valvular and subvalvular repair (17-19). Although many clinical studies have investigated the benefits of chordal preservation in the context of MVR (1-9), the results have been inconsistent due to the retrospective nature of the studies, limited sample sizes and heterogeneous patient populations with mixed valvular disease (1-9). In addition, controlled randomized trials that evaluate outcomes in a large cohort are lacking (12,14). LV remodelling, as assessed by LVEDVI, is a predictive factor for poor prognosis in patients with severe LV overload due to mitral insufficiency, and efforts to reverse this remodelling have been correlated with improved outcomes in both clinical and experimental studies (2,5,9,30-38).

In this study, LVEDV was evaluated as the primary endpoint following CCS-MVR for moderate and severe MR. The comprehensive study spans a nine-year period, from 2014 to 2023, and the robust dataset was meticulously gathered from a single, highly-regarded centre. The majority of patients who underwent CCS-MVR exhibited evidence of degenerative MV disease or functional MV regurgitation. CCS-MVR was employed in a limited number of cases to address an abscess of the posterior mitral valve annulus resulting from IE. Figure 4 illustrates the crude operative mortality rate, which was 8.7%. The 1-, 2- and 5-year survival rates were 85.5%, 81.6% and 66.5%, respectively.

The question of whether to preserve the anterior subvalvular apparatus, which is constituted by approximately 12 chordae tendinae that arise from the anterior leaflet in addition to the posterior leaflet, remains a topic of debate in the surgical community. This is particularly the case in patients with chronic MR at significant risk of developing irreversible LV dilatation and progressive worsening of LVEF. Nevertheless, the available laboratory evidence indicates that all chordal structures contribute to LV systolic function in the normal dog heart (30-32). Prior research has definitively established that the total preservation of the chordal structures of the mitral valve is an effective means of addressing the volume overload associated with chronic MR. The subsequent reduction in LVEDV was consistently documented following surgery (2,5,9,33-38).

In a randomized controlled trial (12,14), the authors reached a definitive conclusion that the effect of complete preservation of all MV chords was consistently at the level of both LVESVI and LVEDVI. Although the CCS-MVR cohort demonstrated a notable decline in LVEDV over the course of a year, in accordance with prior observations (2,5,9,33-38), LVESV exhibited both an early and sustained reduction in the CCS-MVR cohort. Conversely, LVESV remained relatively unaltered in the partial chordal sparing MVR group (12,14).

This disparity can be directly attributed to the interdependence of the alterations in Left Ventricular End Systolic Stress (LVESS), LVEF, and LVEDV following MVR. As evidenced by the validated mathematical model developed by Goldfine and colleagues (39), a reduced LVEF is inversely correlated with an increased LVESV. This relationship is additionally corroborated by the Laplace relation, which illustrates a direct correlation between LVESS and LVEF.

The results of our nine-year study provide definitive evidence that the use of the entire subvalvular apparatus for the replacement of a diseased valve is beneficial in both organic and functional mitral valve disorders. A substantial immediate decrease in LVEDVI and LVESVI was observed (mean change from baseline, −12.15 and −4.08 mL per square meter, respectively), with LVEDVI demonstrating improvement over time (P<0.001). As anticipated, patients who underwent C-MVR exhibited a pronounced reduction in both LVESV and LVESS. Our analysis clearly demonstrated that the CCS-MVR approach, which aims to preserve all chordal structures, results in a more favorable LV geometry and lower LV afterload, leading to greater ventricular remodelling. Furthermore, a study of 14 MVR patients by Popovic et al. (7) found that those who had complete chordal preservation had a lower index of LV mass compared to those who had both leaflets removed.

Our findings encompass individuals with degenerative mitral valve disease and functional MR, thereby substantiating the notion that diminished postoperative recovery of LVEF may be attributable to preexisting myocardial scarring resulting from myocardial infarction. These patients may have derived no benefit from CABG, as demonstrated by the progression of ventricular remodelling and LVEF deterioration. It is evident that despite the preservation of all chordal structures in patients with a functional ischemic etiology, it cannot prevent a sustained increase in LV afterload and a less optimal LV geometry, which in turn will result in adverse ventricular remodelling. Thus, it is conceivable that this cohort of patients will experience a minor reduction in LV mass after one year.

It should be noted that there are differences between the technique described in this report and the one described by Sintek (26), also known as the Khonsari procedure (27). This latter technique was used in Yun’s randomized study (14). In contrast to the Khonsari procedure, our approach does not entail dividing the mitral valve into three or four parts, thereby maintaining the integrity of the entire subvalvular apparatus. As evidenced by the findings of Yun et al. (14), the preservation of the entire architecture of the AML ensures a reduction in LVEDVI and LVESVI over time. This outcome is similarly achieved in this procedure when the translation is employed without partition. It is crucial to highlight that the tri- or quadratic partitioning of the subvalvular apparatus within the bioprosthesis more accurately reflects the natural anatomy of the subvalvular apparatus than the complete translation of the entire leaflet. This aspect is not to be overlooked, as it may result in enhanced biomechanical functionality of the LV (40).

The translation of the entire anterior leaflet and reduction of the excess tissue characteristic of Barlow’s disease effectively prevent the undersizing of the valve prosthesis and obstruction of the left ventricular outflow tract (LVOT). These conditions were not observed in the present study, and with regard to prosthesis size, the minimum implanted size was 29 mm. It is important to acknowledge that a significant number of surgeons still elect to preserve only the posterior leaflet chordae tendineae, citing a variety of concerns related to the heightened technical complexity, the prolonged operating time, the potential interference with the mechanical valve leaflet motion, the necessity to undersize the mitral prosthesis, and the potential for creating an LV outflow tract obstruction. These concerns were previously reported by Come et al. (10). A recent investigation employing biomechanical three-dimensional modelling has revealed that during the systolic phase of the cardiac cycle, the mitral valve assumes a balloon-like shape due to the increased LVEDV and the hypertrophy of the heart. In the course of our investigation, we observed that the diseased valve’s anterior leaflet was deviating from its functional position, which resulted in translation and the avoidance of the occurrence of the bulge phenomenon. This differs from the behavior observed in the healthy valve, which remained in its optimal functional position (Figure 5) (41,42).

Figure 5 Biomechanical 3D modeling to analyze the MV during systole in both healthy and pathological conditions [reproduced with permission from John Wiley and Sons (40). License Number 5930860281352 Dec 16, 2024]. Point A is employed to compare the displacement of the AML in healthy MV and in Barlow’s disease. (A) Geometry of the MV at the beginning of systole, as reconstructed using finite element analysis. (B,C) Deformed configuration of healthy MV and in Barlow’s disease at 120 mmHg. AML, anterior mitral leaflet; MV, mitral valve.

Further research is necessary to investigate the structural and mechanical characteristics of the left ventricle through the utilization of biomechanical models and finite element analysis. This is of particular importance for the maintenance of the LV architecture, which is supported by the chordae tendineae that extend to the LV apex.

CCS-MVR in presence of MAD

In patients with massive annular calcification, CCS-MVR was performed in 36.6% of cases, while in patients with mitral annular disjunction complicating Barlow’s disease, it was performed in 15.5% of cases. Our series indicates that MAD in patients with Barlow’s disease is associated with increased mortality within the first two years after surgery. These patients are typically male, with preoperative AF, elevated LVEDVI, and reduced LVFE. Although mitral surgery can be technically complex in the presence of MAC and MAD, other studies have shown similar operative and long- term mortality rates, with a similar incidence of MV reoperation (43-46).

In cases of degenerative mitral valve disease, the decision to limit surgical repair may depend on the extent of involvement of the anterior and posterior leaflets. MVR is typically performed based on echocardiographic and surgical assessments of the mitral pathology, as well as the need to correct any double or triple valvular disorders. CCS-MVR is used in cases of myxomatous or fibroelastic lesions involving the AML and PML. The decision to perform more extensive repair surgery was based on the patient’s preoperative condition, the severity of mitral valve involvement, and the surgeon’s experience. This included repairing a large portion of the valve leaflets and one or more scallops.

In recent years, advances in mitral valve subspecialty services and technology, along with refinements in surgical techniques, have led to extensive surgical repair of degenerative mitral valve disease. This includes repair of more of the posterior and AMLs, as well as hybrid, staged MVR procedures, including the conservative technique of preserving the entire mitral valve apparatus. In our study, we used the CCS-MVR technique on patients with diffuse myxomatous degeneration, which includes Barlow’s disease and fibroelastic deficiency, in the context of MAD. Diffuse myxomatous degeneration causes leaflets to thicken and excess tissue to form, often leading to bileaflet prolapse and greater annular dilation compared to fibroelastic deficiency. This is supported by evidence reported in the literature (44,45). In contrast, FED typically results in the prolapse of a single mitral valve segment due to chordal thinning and rupture, while the thickening of leaflet tissue is limited to the prolapsing segment, if present at all. This offers a greater potential for mitral valve repair. It has been confirmed that patients with diffuse myxomatous degeneration usually experience a higher incidence of mitral valve prolapse with regurgitation compared to those with fibroelastic deficiency (47-50). Therefore, for patients with an unfavorable score, the approach of MV repair is limited in favor of CCS-MVR.

Although published reports suggest that the feasibility of mitral valve surgery is not affected by the presence of mitral annular disjunction in patients (48,49), the presence of MAD cannot be underestimated in patients with risk factors such as increased LVEDVI, reduced LVEF, and AF. These factors are predictors of long-term mortality in our series. Eriksson et al. (43) described a modified technique for MV repair in patients with severe MR and MAD. This technique involves detaching the posterior leaflet from the abnormal mitral annulus, repairing the annulus by suturing through the LV endocardium, and then reattaching the posterior leaflet to the LV endocardium. This approach can effectively address both MR and MAD. Patients with advanced MV degeneration, 98% of whom had MAD, reported excellent survival and freedom from reoperation after undergoing MV repair using this technique. There was no significant difference between patients with milder mitral valve degeneration and less frequent MAD compared to those without. Erikson’s procedure is generally safe and effective. However, it may carry a risk of LV rupture in the presence of solid penetrating calcifications and MAD greater than 3 mm. Although decalcification of the annulus may be less risky in MAD with less dislocation (within 2 mm on TTE and within 1 mm on cardiovascular magnetic resonance (CMR) (51,52), it carries a high risk of complications related to LV rupture in surgical patients with an average MAD distance of 6.6±2.2 mm (48) or greater than 8±4 mm (53). Our approach solidifies the posterior annulus lesion in MAD degeneration by relocating the anterior leaflet, without causing any rupture of the left ventricle.

The previous publication noted that repairing Barlow’s-type mitral valve prolapse, which is commonly associated with mitral valve anterior leaflet prolapse, can be more challenging due to the larger valve size and redundant tissue. However, several reports suggest that surgical repair outcomes are similar for patients with Barlow’s disease and fibroelastic deficiency (50,54). There are no differences in the indications for mitral valve surgery based on the specific phenotype of degenerative mitral valve disease, regardless of mitral annular disjunction. However, a Barlow syndrome complicated with bileaflet prolapse and mitral annular dilatation is more suitable for a CCS-MVR (16,17).

Outlook in mitral IE

Only a small number of patients with MV endocarditis underwent the CCS-MVR procedure because repair was not a feasible option. The goals of mitral valve repair are to remove vegetation, restore a proper line of coaptation on both leaflets, repair any leaflet perforations, and preserve the subvalvular apparatus. Vegetectomy, which involves excising the vegetation along its cleavage plane on the leaflet, is a common procedure. To reinforce the leaflets, it is generally preferred to use a pericardial patch instead of directly suturing the lesion. This approach avoids tension on the suture line. The feasibility of valve repair depends on the extent of tissue damage. The best candidates for repair are patients with limited active infection and no valve destruction. Extensive damage to the anterior leaflet, large lesions involving the posterior leaflet or the mitral valve commissures, and annular abscesses are major obstacles to mitral repair (28). Although the guidelines recommend prioritising mitral valve repair over replacement, it is important to note that the feasibility of repair depends on preoperative conditions and intraoperative findings, as discussed in recent literature (28,55,56). If the native valve is extensively infected, involving multiple leaflets, with or without a posterior mitral annular abscess, MVR using the CCS-MVR may be the preferred approach. After fully removing the damaged tissue from the mitral valve annulus, repositioning and securing the AML can help to stabilize the infected structures of the valve. MVR can be carried out using either biological or mechanical prostheses (28,56).

Limitation

Several limitations of this study must be addressed. The study is retrospective and observational in nature, so it is essential to adjust for differences at baseline in non-randomised studies. However, even these methods cannot adjust for differences when specific risk factors are unknown or not measured. This may explain why some studies showed no differences in the rates of LVESVI improvement and better short- or long-term LVFE in patients with degenerative or functional mitral disease (9,14). Although follow-up was complete, echocardiographic data were not available for 15% of patients at the last follow-up. Therefore, the statistical power to detect differences between cohorts was slightly reduced. Nevertheless, complete chordal preservation showed significant improvements compared to partial preservation.

Conclusions

In conclusion, retaining the mitral subvalvular apparatus during MVR provides an early advantage by reducing LV chamber size and diastolic after-load compared to partial chordal preservation. Additionally, LV ejection performance improves over time due to improved remodeling. Therefore, when MVR is necessary, we recommend preserving all chordal structures by translocating the AML instead of quadripartition of the MV to optimise early postoperative and late LV systolic function. Moreover, a preoperative systolic diameter of 50 mm or greater may indicate a poor prognosis.

Acknowledgments

The authors thank Karima MOUSSOUNI and Thierry PAVAN for their contribution to the follow-up of the patients.

Footnote

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Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The Institutional Review Board (IRB) of the University of Montpellier (dred-saine-cer@umontpellier.fr) has formally approved the utilization of the aforementioned data for research purposes (IRB No. UM 2023-010, May 17, 2023). The principles established in the Declaration of Helsinki (as revised in 2013) were followed. In addition, written informed consent having been provided by the patients in question.

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