Mitral Valve and Subvalvular Repair for Secondary Mitral Regurgitation: Rationale and Clinical Outcomes of the Papillary Muscle Sling

Update on surgical repair in functional mitral regurgitation

BACKGROUND

Functional mitral regurgitation (FMR) is common in patients with myocardial infarction or dilated cardiomyopathy, and portends a poor prognosis despite guideline-directed medical therapy (GDMT). Surgical or transcatheter mitral repair for FMR from recent randomized clinical trials showed disappointing or conflicting results.

AIMS

To provide an update on the role of surgical repair in the management of FMR.

MATERIALS AND METHODS

A literature search was conducted utilizing PubMed, Ovid, Web of Science, Embase, and Cochrane Library. The search terms included secondary/FMR, ischemic mitral regurgitation, mitral repair, mitral replacement, mitral annuloplasty, transcatheter mitral repair, and percutaneous mitral repair. Randomized clinical trials over the past decade were the particular focus of the current review.

RESULTS

Recent data underlined the complexity and poor prognosis of FMR. GDMT and cardiac resynchronization, when indicated, should always be applied. Accurate assessment of the interplay between ventricular geometry and mitral valve function is essential to differentiate proportionate FMR from the disproportionate subgroup, which could be helpful in selecting appropriate transcatheter intervention strategies. Surgical repair, most commonly performed with an undersized ring annuloplasty, remains controversial. Adjunctive valvular or subvalvular repair techniques are evolving and may produce improved results in selected FMR patients.

CONCLUSION

FMR resulted from complex valve-ventricular interaction and remodeling. Distinguishing proportionate FMR from disproportionate FMR is important in exploring their underlying mechanisms and to guide medical treatment with surgical or transcatheter interventions. Further studies are warranted to confirm the clinical benefit of appropriate surgical repair in selected FMR patients.

Exploring the Operative Strategy for Secondary Mitral Regurgitation: A Systematic Review

Background

Mitral valve disease surgery is an evolving field with multiple possible interventions. There is an increasing body of evidence regarding the optimal strategy in secondary mitral regurgitation where the pathology lies within the ventricle. We conducted a systematic review to identify the benefits and limitations of each surgical option.

Methods

A systematic review of the literature was performed to identify pertinent randomized controlled trials (RCTs), propensity-matched observational series, and meta-analyses which were considered initially and followed by unmatched observational series using the MEDLINE, Ovid EMBASE, and Cochrane Library.

Results

We identified 6 different strategies for treating secondary mitral valve regurgitation: mitral valve replacement, restrictive mitral annuloplasty, surgical revascularization (with and without mitral annuloplasty), subvalvular procedures (papillary muscle approximation, papillary muscle relocation, ring and string procedure), and procedures directly targeting the mitral valve (edge-to-edge repair and anterior leaflet enlargement) alongside transcatheter heart valve therapy. We also highlighted the role of left ventricular assist devices in the management of this condition. The benefits and limitations of each intervention are highlighted.

Conclusion

There is currently no unanimous and shared strategy for the optimal treatment of patients with secondary IMR. The management of patients with secondary mitral regurgitation must be entrusted to a multidisciplinary Heart Team to ensure ideal intervention and patient matching for the best outcomes.

Left Ventricular remodeling after Mitral Valve repair and Papillary Muscle Approximation

BACKGROUND

Mitral valve repair with papillary muscle approximation (MVr-PMA) for severe secondary mitral regurgitation (MR) decreases MR recurrence compared with MVr alone. This study assessed the effects of MVr-PMA on left ventricular (LV) remodeling and shape, systolic function and strain mechanics.

METHODS

Forty-eight patients who underwent MVr-PMA for severe secondary MR and had follow-up echocardiograms available for review were identified. Student's t-test, linear regression modeling, and receiver-operating characteristic curves were used in the statistical analyses.

RESULTS

Median follow-up time was 14.9 months. MVr-PMA was associated with significant LV reverse remodeling with a smaller LV end-diastolic diameter, systolic sphericity index, and interpapillary muscle distance at follow-up. Nine patients (18.8%) experienced ≥ moderate recurrent MR. When compared recurrent MR patients at follow-up, those with durable MVr-PMA had a greater LV ejection fraction (32.8 vs 22.0%, p=0.03), a smaller end-diastolic diameter (59.6 vs 67.3 mm, p=0.03), systolic sphericity index (0.35 vs 0.47, p=0.03), and endsystolic interpapillary muscle distance (16.3 vs 21.1 mm, p=0.03). A durable MVr-PMA also resulted in stable global longitudinal strain when compared with pre-operative values, while the recurrent MR group experienced a further decline (no recurrent MR: -8.4 vs -7.5%; recurrent MR: -8.2 vs -5.4%; p<0.05). A pre-operative LV end-diastolic diameter ≥ 64 mm was a discriminative predictor of MR recurrence (sensitivity = 100%, specificity = 51%, AUC = 0.756, p = 0.02).

CONCLUSIONS

A durable MVr-PMA confers improved LV geometry and function, and stable LV mechanics. The extent of baseline LV remodeling identifies patients at risk for recurrent MR.

Left ventricle and mitral valve reverse remodeling in response to cardiac resynchronization therapy in nonischemic cardiomyopathy

BACKGROUND

Cardiac resynchronization therapy (CRT) improves left heart geometry and function in nonischemic cardiomyopathy (NICMP). We aimed to detail the effects of CRT on left ventricular (LV) and mitral valve (MV) remodeling using 2-dimensional transthoracic echocardiography.

METHODS

Forty-five consecutive patients with NICMP who underwent CRT implantation between 2009 and 2012, and had pre-CRT and follow-up echocardiograms available, were included. Paired t test, linear and logistic regression, and Kaplan-Meier survival analyses were used for statistical assessment.

RESULTS

The mean age and QRS duration were 60 years and 157 ms, respectively, and 13 (28.9%) were female. At a mean follow-up of 3 years, there were 22 (48.9%) "CRT responders" (≥15% reduction in LV end-systolic volume index [LVESVi]). Significant improvements were observed in LV ejection fraction (26.3% vs 34.3%) and LVESVi (87.7 vs 71.1 mL/m² ), as well as mitral regurgitation vena contracta width, MV tenting height and area, and end-systolic interpapillary muscle distance. Five-year actuarial survival was 87.5%. Multivariate regression analyses revealed the pre-CRT LVESVi (β = 0.52), and MV coaptation length (β = -0.34) and septolateral annular diameter (β = 0.25) as good correlates of follow-up LVESVi. Variables associated with CRT response were pre-CRT MV coaptation length (OR 1.75, 95% CI 1.0-3.1) and posterior leaflet tethering angle (OR 1.07, 95% CI 1.0-1.14), irrespective of baseline QRS morphology and duration (all P < .05).

CONCLUSIONS

Cardiac resynchronization therapy improves LV and MV geometry and function in half of patients with NICMP, which is paralleled by decreased mitral regurgitation severity. The extent of pre-CRT LV remodeling and MV tethering are associated with CRT response.

Risk of Ischemic Mitral Regurgitation Recurrence After Combined Valvular and Subvalvular Repair

BACKGROUND

Mitral valve repair (MVr) combined with papillary muscle approximation (PMA) may improve repair durability in severe ischemic mitral regurgitation (MR), when compared with MVr alone. We sought to identify preoperative transthoracic echocardiographic markers associated with MR recurrence after MVr with PMA.

METHODS

A post-hoc analysis was performed on patients with severe ischemic MR who underwent coronary artery bypass graft surgery with MVr with PMA in the papillary muscle approximation randomized trial. The PMA was performed utilizing a 4-mm polytetrafluoroethylene graft placed around the papillary muscles. Linear regression analyses and receiver-operating characteristic curves were used to identify echocardiographic variables and diagnostic models associated with recurrent MR.

RESULTS

There were 48 patients with a mean age of 63 ± 7 years, a left ventricular ejection fraction of 35% ± 5%, and a left ventricular end-diastolic diameter of 63 ± 3 mm. Of these, 37 patients had baseline and 5-year follow-up echocardiograms, with moderate-to-severe MR recurring in 27%. Linear regression analyses revealed associations between preoperative pulmonary artery systolic pressure (standardized beta coefficient, β = 0.49/mm Hg, p = 0.002), MV tenting area (β = 0.47/cm², p = 0.004), a symmetric MV tethering pattern (β = 0.44, p = 0.007), and left ventricular end-diastolic diameter (β = 0.37/mm, p = 0.02) with follow-up MR grade. The presence of both MV tenting area 3.1 cm² or greater (area under the curve 0.822) and left ventricular end-diastolic diameter of 64 mm or greater (area under the curve 0.801) was the most robust discriminative model for moderate-to-severe MR recurrence (specificity 92%, sensitivity 69%, area under the curve 0.804, p = 0.003).

CONCLUSIONS

In patients undergoing coronary artery bypass graft surgery with MVr plus PMA, the extent of baseline MV apparatus and left ventricle geometric remodeling identifies patients at increased risk for MR recurrence.