A novel approach to ischemic mitral regurgitation (IMR)

Ex Vivo Model of Ischemic Mitral Regurgitation and Analysis of Adjunctive Papillary Muscle Repair

Ischemic mitral regurgitation (IMR) is particularly challenging to repair with lasting durability due to the complex valvular and subvalvular pathologies resulting from left ventricular dysfunction. Ex vivo simulation is uniquely suited to quantitatively analyze the repair biomechanics, but advancements are needed to model the nuanced IMR disease state. Here we present a novel IMR model featuring a dilation device with precise dilatation control that preserves annular elasticity to enable accurate ex vivo analysis of surgical repair. Coupled with augmented papillary muscle head positioning, the enhanced heart simulator system successfully modeled IMR pre- and post-surgical intervention and enabled the analysis of adjunctive subvalvular papillary muscle repair to alleviate regurgitation recurrence. The model resulted in an increase in regurgitant fraction: 11.6 ± 1.7% to 36.1 ± 4.4% (p < 0.001). Adjunctive papillary muscle head fusion was analyzed relative to a simple restrictive ring annuloplasty repair and, while both repairs successfully eliminated regurgitation initially, the addition of the adjunctive subvalvular repair reduced regurgitation recurrence: 30.4 ± 5.7% vs. 12.5 ± 2.6% (p = 0.002). Ultimately, this system demonstrates the success of adjunctive papillary muscle head fusion in repairing IMR as well as provides a platform to optimize surgical techniques for increased repair durability.

Moderate ischemic mitral incompetence: does it worth more ischemic time?

OBJECTIVES

Ischemic mitral regurgitation (IMR) is a common finding following myocardial infarction or ischemia. Management of moderate IMR is still a hot topic. Adding mitral valve repair (MVr) to coronary artery bypass grafting (CABG) is questionable. The goal of this study was to assess and compare short-term clinical and echocardiographic results of moderate IMR treated by CABG alone versus another group of patients treated by CABG plus MVr.

METHODS

Eighty consecutive patients with ischemic heart disease (IHD) and moderate IMR were divided randomly into two equal groups: group I (40) had only CABG and group II (40) had CABG plus MVr. Patients were evaluated at 1-week, 3-months and 1-year intervals postoperatively.

RESULTS

After 1-year follow-up, our study revealed statistically significant improvement in the grade of mitral regurgitation (MR) in group II than group I. The mean value for effective regurgitant orifice area (EROA) was 0.22 ± 0.13 for group I versus 0.03 ± 0.03 for group II (P = 0.001) and for vena contracta (VC), it was 3.8 ± 2.24 for group I versus 0.4 ± 0.49 for group II (P = 0.000). There was also a significant reduction in the New York Heart Association (NYHA) functional class in both groups.

CONCLUSIONS

MVr can be performed safely and concomitantly with CABG in patients having moderate IMR, and its addition to CABG have significant short-term impact on clinical or echocardiographic outcome of patients.

Mitral valve repair versus replacement in patients with ischemic mitral regurgitation

Background

The optimal management of ischemic mitral regurgitation (IMR) is controversial. The aim of this study was to examine our eight years' experience of surgical treatment in patients with IMR, and to compare outcomes of mitral valve repair versus replacement with concomitant coronary artery bypass grafting (CABG).

Methods

A retrospective, observational, cohort study was undertaken to collect data on consecutive patients with IMR and coronary artery disease who received CABG and mitral valve surgery in our hospital between January 2008 and December 2015. Basic patient characteristics, operative data, and postoperative clinical outcomes were examined.

Results

The series included 22 consecutive patients (21 male; 1 female). The mean age was 62.1±11.4 years old. The mean preoperative left ventricular ejection fraction (LVEF) was 33.4%±15.4%. The mean cardiopulmonary bypass (CPB) time was 165.4±38.4 minutes, and the mean aortic cross clamp time was 113.8±33.6 minutes. Eighteen patients underwent CABG plus mitral valve repair, and four patients underwent CABG plus mitral valve replacement (MVR). There were three early in-hospital mortalities: two in the mitral valve repair group, and one in the replacement group. The follow-up was complete in all patients, with a mean follow-up duration of 3.1±2.3 years. The mean last LVEF was 35.3%±17.7%. There were 2 late mortalities. Both were from the repair group. The overall late survival rate was 81.6%, with 83.0% in the repair group and 75.0% in the replacement group. In patients with echocardiography follow-up of more than or equal to 1 year duration, the residual or recurrent mitral regurgitation rates were 0.0% in the replacement group and 57.1% in the repair group. One patient in the repair group later underwent MVR due to severe regurgitation postoperatively.

Conclusions

Our preliminary findings showed that the surgical outcome of mitral valve repair might be comparable to that of MVR in terms of early mortality and long-term survival. However, mitral valve repair was associated with a higher residual or recurrent mitral regurgitation rate. According to the latest literature, the role of MVR can justifiably be indicated for severe IMR. As for moderate IMR, CABG alone without mitral valve intervention may provide similar clinical outcomes.

Papillary muscle approximation in mitral valve repair for secondary MR

Ischemic mitral regurgitation (IMR) is a complex disorder occurring after a myocardial infarction and affecting both the mitral valvular and subvalvular apparati. Several abnormalities can be detected in IMR as annular dilatation, leaflet tethering with impaired coaptation and papillary muscle (PM) displacement along a posterior, apical or lateral vectors. Treatments available include, beside myocardial revascularization, mitral-valve repair or chordal-sparing replacement. Repair is normally achieved downsizing the mitral valve annulus with a rigid or semirigid ring. However, considering the involvement of the subvalvular apparatus, techniques addressing the PM have been developed. The rationale at the basis of this strategy relies in the possibility to reduce the interpapillary muscle distance restoring the geometry of the left ventricle (LV) and ultimately resolving the leaflet tethering at the basis of IMR. Subvalvular apparatus surgical approaches include the papillary muscle approximation (PMA), surgical relocation and PM sling. Improved outcomes in terms of postoperative positive left ventricular remodeling and recurrence of mitral regurgitation have been reported, but more investigations are required to confirm the efficacy of subvalvular apparatus surgery. Application of finite element analysis to improve preoperative and intraoperative planning and achieve a correct and durable repair by means of subvalvular surgery is an exciting new avenue in IMR research.