Posterior Papillary Muscle Suspension for Treating Systolic Anterior Motion in Hypertrophic Obstructive Cardiomyopathy

Systolic anterior motion of the anterior mitral leaflet can persist after ventricular septal myectomy for obstructive hypertrophic cardiomyopathy, resulting in residual pressure gradients and mitral regurgitation. However, additional procedures for systolic anterior motion involving mitral valve leaflet suturing and resection may lead to future valve disease. Therefore, we adopted posterior papillary muscle suspension, a subvalvular procedure for functional mitral regurgitation, to treat systolic anterior motion without directly intervening in the mitral valve leaflets. Papillary muscle suspension toward the posterior mitral annulus moved the papillary muscles away from the interventricular septum and successfully eliminated the systolic anterior motion and midventricular pressure gradient. In terms of avoiding direct mitral interventions, this procedure is a viable option for systolic anterior motion, especially in cases of very mild mitral regurgitation.

Surgical repair of ischemic mitral regurgitation: one ring does not fit all

PURPOSE OF REVIEW

The review summarizes the key parameters that can aid in determining the optimal treatment of ischemic mitral regurgitation (IMR).

RECENT FINDINGS

Left ventricular (LV) and mitral valve (MV) parameters are important for surgical planning and risk stratification in IMR. Although LV dimensions is one of the main parameters used in the guidelines, volumes more accurately depict LV remodelling. Furthermore, wall motion abnormalities and wall motion score index can also be useful for surgical planning in treatment of IMR. Viability is best measured with cardiac magnetic resonance, but it is not feasible in certain centres. In contrast, measurement of strain with echocardiography is an emerging and feasible tool for estimating viability. MV leaflet tethering and pattern measured with echocardiography are also useful for MV surgery. Anterior leaflet excursion angle can identify patients in whom undersized ring annuloplasty is potentially unsuitable.

SUMMARY

Treatment of IMR relies on accurate parameters that can determine the optimal surgical approach. In some patients, lack of viable myocardium suggests inadequacy of revascularization and thus, an adjunctive left ventricular reconstruction may be necessary. Degree and pattern of MV leaflet tethering can indicate whether ring annuloplasty, which is the most common repair technique, is sufficient or an adjunctive sub-valvular intervention is beneficial.

Meta-analysis of results of subvalvular repair for severe ischemic mitral regurgitation

BACKGROUND AND AIM OF THE STUDY

The aim of this meta-analysis was to compare short- and long-term outcomes of patients undergoing mitral annuloplasty (MA) with or without papillary muscle surgery (PMS) for the treatment of ischemic mitral regurgitation (IMR).

METHODS

A systematic review and meta-analysis in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement were performed.

RESULTS

Nine studies met the inclusion criteria. This meta-analysis identified 478 patients: 228 patients underwent MA alone and 250 patients underwent concomitant PMS. Early mortality was similar between two groups (odds ratio [OR] 1.14, 95% confidence interval [CI], 0.51-2.53; P = .75). PMS was associated at follow-up with a higher freedom from cardiac-related events (P = .050); moreover, although both surgical techniques had a positive impact on ventricular remodeling, the PMS group showed a significant higher reduction of left ventricle end-diastolic diameter (OR, 4.89, 95% CI, 2.77-7.01; P < .001) and left ventricle end-systolic diameter values (OR, 4.11, 95% CI, 1.98-6.24; P < .001). Finally, PMS compared with MA alone was associated with a significant reduction of recurrent mitral regurgitation at follow-up (OR, 3.25, 95% CI, 1.60-6.59; P = .001).

CONCLUSIONS

This meta-analysis demonstrated superiority in terms of ventricular remodeling of a combined approach encompassing PMS and MA over MA alone in IMR. Moreover, the association of subvalvular surgery with restrictive MA decreases the incidence of mitral regurgitation recurrence and cardiac-related events at follow-up.

Echocardiographic assessment of mitral regurgitation

Mitral regurgitation (MR) is one of the most frequent indications for valve surgery in developed countries, and echocardiographic assessment is an essential tool to evaluate its etiologies, severity, and therapeutic indications. The mitral valve apparatus is a complex structure composed of several parts: apart from the mitral valve leaflets and annulus, it also includes the chordae tendineae, papillary muscles, and left ventricular (LV) wall. MR can be caused not only by organic changes of the mitral valve leaflets or chordae (primary MR) but also by extreme mitral annular enlargement or mitral leaflet tethering due to displacement and malfunction of papillary muscles and LV wall (secondary MR). In secondary MR with LV dysfunction, a milder degree of MR can be associated with adverse outcomes compared with primary MR. Grading the severity is the first step in evaluation of indication for surgical/transcatheter interventions. As such, there are several techniques to assess the severity of MR using echocardiography. However, none of the techniques is reliable enough by itself, and it is always recommended to integrate multiple methods. In cases where echocardiographic assessment of MR severity is inconclusive, magnetic resonance may be helpful. In addition to the severity, anatomical information, such as localization in primary MR due to mitral valve prolapse and LV size in secondary MR due to LV dilatation/dysfunction, is an important concern in presurgical echocardiography. Transesophageal echocardiography and three-dimensional echocardiography are key techniques for anatomical evaluation including mitral valve and LV volumes. In transcatheter intervention for MR, echocardiography plays a pivotal role as a guide for procedures and endpoints. In this review article, the authors provide a comprehensive summary of current standards of echocardiographic assessment of MR.

Pathological Remodeling of Mitral Valve Leaflets from Unphysiologic Leaflet Mechanics after Undersized Mitral Annuloplasty to Repair Ischemic Mitral Regurgitation

Background Undersized ring annuloplasty is a commonly used surgical repair for ischemic mitral regurgitation, in which annular downsizing corrects regurgitation, but alters valve geometry and elevates tissue stresses. In this study, we investigated if unphysiological leaflet kinematics after annuloplasty might cause pathogenic biological remodeling of the mitral valve leaflets, and if preserving physiologic leaflet kinematics with a better technique can moderate such adverse remodeling. Methods and Results Twenty-nine swine were induced with ischemic mitral regurgitation, and survivors were assigned to groups: 7 underwent annuloplasty, 12 underwent annuloplasty with papillary-muscle approximation, 6 underwent papillary-muscle approximation, and 3 were sham controls. Pre-and post-surgery leaflet kinematics were measured, and valve tissue was explanted after 3 months to assess biological changes. Anterior leaflet excursion was unchanged across groups, but persistent tethering was observed with annuloplasty. Posterior leaflet was vertically immobile after annuloplasty, better mobile with the combined approach, and substantially ( P=0.0028) mobile after papillary-muscle approximation. Procollagen-1 was higher in leaflets from annuloplasty compared with the other groups. Heat shock protein-47 and lysyl oxidase were higher in groups receiving annuloplasty compared with sham. α- SMA was elevated in leaflets from animals receiving an annuloplasty, indicating activation of quiescent valve interstitial cells, paralleled by elevated transforming growth factor-β expression. Conclusions This is the first study to demonstrate that surgical valve repairs that impose unphysiological leaflet mechanics have a deleterious, pathological impact on valve biology. Surgeons may need to consider restoring physiologic leaflet stresses as well as valve competence, while also exploring pharmacological methods to inhibit the abnormal signaling cascades.

Feasibility and limitations of mitral valve repair, with or without left ventricular reconstruction in non-ischemic dilated cardiomyopathy

BACKGROUND

Although non-transplant surgical interventions for non-ischemic dilated cardiomyopathy (NIDCM) are relatively effective, their feasibility and limitations have not been fully elucidated. The aim of this study was to define the feasibility and limitations of mitral valve repair, with or without surgical ventricular reconstruction for patients with NIDCM in terms of postoperative low cardiac output syndrome (LOS).

METHODS

Twenty non-transplant candidates (aged 57±13 years) with NIDCM and significant mitral regurgitation had undergone mitral valve repair combined with submitral procedures. Using a 72-mL plastic ellipsoidal sizer, left ventricular reconstruction was performed concomitantly in 14/20 (70%) patients with extremely large ventricles. Total stroke volume, deceleration time of early trans-mitral flow wave, and the slope (Mw) in the preload recruitable stroke-work relationship were assessed using transthoracic echocardiography. LOS was defined as in-hospital death due to heart failure or a cardiac index less than 2.2L/min/m² before discharge.

RESULTS

There were three in-hospital deaths and four patients with postoperative cardiac index less than 2.2L/min/m² [n=7 (35%), LOS group]. Preoperative total stroke volume, deceleration time, and the Mw were significantly lower in the LOS group compared to those in the non-LOS group; the predicted cut-off values for LOS were 84mL/beat (p=0.008), 133ms (p=0.015), and 45ergcm^-3×10³ (p=0.036), respectively. Preoperative left ventricular ejection fraction and ventricular size could not predict postoperative LOS. The one-year survival rate was 0% in the LOS group and 84% in the non-LOS group (p<0.001).

CONCLUSIONS

Mitral valve repair, with or without left ventricular reconstruction, could be contraindicated for NIDCM patients with low total stroke volume, deceleration time, and Mw in terms of high postoperative incidence of LOS. For high-risk patients, other therapeutic strategies might be necessary.

The role of papillary muscle approximation in mitral valve repair for the treatment of secondary mitral regurgitation

Secondary mitral regurgitation (MR) is present in up to half of patients with dilated cardiomyopathy, and is associated with a poor prognosis. It primarily results from progressive left ventricular remodelling, papillary muscle displacement and tethering of the mitral valve leaflets. Mitral valve repair with an undersized ring annuloplasty is the reparative procedure of choice in the treatment of secondary MR. However, this technique is associated with a 30-60% incidence of recurrent moderate or greater MR at mid-term follow-up, which results in progressive deterioration of left ventricular function and increased morbidity. Combined mitral valve repair and papillary muscle approximation has been applied in order to address both the annular and subvalvular dysfunction that coexist in secondary MR, which include graft and suture-based techniques. Herein, we provide a systematic review of the published literature regarding the technical aspects, clinical application, and outcomes of mitral valve repair with combined ring annuloplasty and papillary muscle approximation for the treatment of secondary MR.

Benefits of submitral procedures for ischemic mitral regurgitation

The surgical strategy for ischemic mitral regurgitation (MR) remains controversial. Ischemic MR is a secondary valve disease caused by left ventricular (LV) remodeling and subsequent papillary muscle displacement, usually without structural valve lesions. Reduction annuloplasty is the standard surgical procedure for this condition, though it cannot clearly provide a survival benefit for those with LV dysfunction and is associated with a high prevalence of late recurrence of MR. The valvular procedure alone could be insufficient to treat ischemic MR in terms of long-term survival and the prevention of recurrence because ischemic MR is primarily a ventricular disorder. Thus, recent studies have focused on alternative procedures that target the primary cause of ischemic MR, the papillary muscles and left ventricle. We believe that the appropriate selection of surgical procedures among valvular, subvalvular, and even ventricular ones, considering the severity of LV remodeling for each patient would be more beneficial. Here we review recent studies featuring various surgical approaches to ischemic MR, especially with submitral procedures.

Impact of left ventricular remodelling on outcomes after left ventriculoplasty for ischaemic cardiomyopathy: Japanese surgical ventricular reconstruction group experience

OBJECTIVES

Surgical ventricular reconstruction (SVR) for patients with severe left ventricular (LV) remodelling due to ischaemic cardiomyopathy is still controversial, because the Surgical Treatment for Ischaemic Heart Failure (STICH) trial demonstrated that SVR not only has no beneficial effect on survival compared with coronary artery bypass grafting (CABG) alone, but also is worse for those with a larger LV. Therefore, we assessed the impact of LV remodelling on the outcomes after SVR for ischaemic cardiomyopathy in Japan, using Di Donato's LV shape classification.

METHODS

From 2000 to 2010, 627 patients underwent SVR for ischaemic heart failure in 11 Japanese hospitals. To assess the patients with an LV ejection fraction (LVEF) of ≤ 35% like the STICH trial, considering the severity of LV remodelling, the patients with a preoperative LVEF of >35%, no preoperative LV volume assessment and no preoperative LV shape classification were excluded. Finally, 323 patients were selected as the study subjects. The LV shape was divided into three types according to Di Donato's classification. Types 1 and 3 indicate the aneurysmal and globally akinetic LV, respectively. Type 2 is the intermediate shape.

RESULTS

Type 1, 2 and 3 LV shapes were observed in 85 (26%), 104 (32%) and 134 (42%) of the patients, respectively. The preoperative LV volume and diameter increased if the LV became more akinetic (Type 3 > 2 > 1, P < 0.001). LVEF was lower in those with more akinetic LV (P = 0.002). The preoperative LV end-diastolic volume index and LVEF in Type 3 patients were 133 ± 47 ml/m(2) and 22 ± 7%, respectively. Mitral valve repair was more frequently performed for patients with the Type 3 LV shape (65%) than for the others (P < 0.001). The hospital mortality rates were 2.4, 2.9 and 7.4% for Type 1, 2 and 3 patients, respectively (P = 0.16). Kaplan-Meier analysis demonstrated no significant difference in mortality among the three groups (log-rank P = 0.37). The 5-year survival rates were 81, 70 and 73% for Type 1, 2 and 3 patients, respectively.

CONCLUSIONS

The severity of LV remodelling did not affect survival after SVR plus CABG. The results of SVR were acceptable even for those with globally akinetic LV due to ischaemic cardiomyopathy.

Restrictive mitral annuloplasty for functional mitral regurgitation: acute hemodynamics and serial echocardiography

BACKGROUND

Long-term effects of restrictive mitral annuloplasty (RMA), especially on hemodynamics and left ventricular (LV) function in patients with functional mitral regurgitation (MR), have not been fully investigated.

METHODS AND RESULTS

From 1999 to 2008, 44 patients with refractory heart failure and functional MR underwent RMA with stringent downsizing of the mitral annulus. Serial echocardiography was performed to evaluate LV function (reverse remodeling), estimated systolic pulmonary artery pressure (PAP) and mitral valve geometry at baseline and at discharge, and annually thereafter. Cardiac catheterization was performed at baseline, and at discharge to evaluate acute hemodynamic change. There were 3 early deaths, and the 5-year survival rate was 78 ± 8%. In 41 survivors the clinical symptoms, stratified according to New York Heart Association class, significantly improved after surgery. Postoperative cardiac catheterization showed significant unloading for left ventricle, as well as improvement in LV systolic function. Serial echocardiography showed that improvements in LV function and systolic PAP were sustained in the majority of patients. Multivariate Cox regression analysis identified preoperative pulmonary hypertension (systolic PAP>60 mm Hg) as the significant predictor for postoperative adverse cardiac events.

CONCLUSIONS

RMA for functional MR resulted in sustained improvement of hemodynamics and LV function over time. Additional studies are needed to define the negative impact of preoperative pulmonary hypertension in patients with this condition.