Treatment of degenerative mitral regurgitation in elderly patients

Benefits of mitral valve repair over replacement in the elderly: a systematic review and meta-analysis

OBJECTIVES

Mitral valve (MV) repair has demonstrated excellent short- and long-term outcomes, however, its merit in the elderly population is still debated. We conducted a meta-analysis of studies that have compared the MV repair to replacement in the elderly population.

METHODS

A systematic literature search was conducted for any study published on MV surgery on elderly patients (≥75 years old). A pooled risk-ratio meta-analysis was done to evaluate short-term mortality, postoperative complications, surgical timings, and long-term survival rates.

RESULTS

A total of nine retrospective observational studies were included in the quantitative meta-analysis. Pooled meta-analysis showed a reduced risk of short-term mortality for the MV repair group (risk ratio [RR] = 0.41 [0.24-0.71], p-value = .005). Postoperative neurological complications were in favor of repair, although not significantly (RR = 0.49 [0.21-1.11], p-value = .07). Operative timings (cardiopulmonary bypass and crossclamp time) were not different between the groups although no data were available on the complexity of the repairs. Long-term survival rates were in favor of the repairs (pooled treatment effect of -0.47 [-0.64; -0.29], p = .005).

CONCLUSIONS

MV surgery is a safe and effective procedure for the elderly. MV repair demonstrated better short-term outcomes compared to replacement. Long-term survival rates are significantly better after repair.

Transcatheter mitral valve implantation using a novel system: preclinical results

BACKGROUND

This preclinical study in sheep sought to demonstrate the initial safety and feasibility of a novel transcatheter mitral valve system (Mi-thos valve) composed of a self-expanding frame and a bovine pericardial tissue bioprosthesis.

METHODS

The valve was implanted in 26 sheep using a transapical approach for short- and long-term evaluation. The technical feasibility, safety, durability, and valve function were evaluated during and 6 months after the procedure using intracardiac and transthoracic echocardiography, multisliced computed tomography, histological analysis, and electron microscopy.

RESULTS

The success rate of valve implantation was 100%, and the immediate survival rate after surgery was 84%. Five animals died within 90 min after the development of the prosthetic valve due to an acute left ventricular outflow tract obstruction (n = 2) and sudden intraoperative ventricular fibrillation (n = 3). Twelve animals died within 1 month due to acute left heart dysfunction. Mild (n = 5) and moderate (n = 2) paravalvular leakage occurred in seven animals, and two moderate PVL animals died of chronic heart failure within three months. Multimodality imaging studies of the remaining seven animals showed excellent function and alignment of the valves, with no coronary artery obstruction, no left ventricular outflow tract obstruction, no severe transvalvular gradients and no paravalvular leakage. Macroscopic evaluation demonstrated stable, secure positioning of the valve, with full endothelialization of the valve leaflets without injury to the ventricular or atrial walls. Histological and electron microscopic examinations at six months showed no obvious macro- or microcalcification in the leaflets.

CONCLUSIONS

Preclinical studies indicate that transcatheter implantation of the Mi-thos valve is technically safe and feasible. The durability, functionality, and lack of leaflet calcification were all verified in animal experiments. The information from these preclinical studies will be applied to patient selection criteria and the first-in-human studies.

Novel Direct Annuloplasty Fastener System for Minimally Invasive Mitral Valve Repair

The development of less invasive approaches for mitral valve repair remains an important objective, particularly in patients with multiple comorbidities. We describe a novel method to affix a mitral valve annuloplasty ring in a minimally invasive manner. A delivery apparatus for an annuloplasty fastener system was designed. Two channels were created, one for advancing the annuloplasty ring, and another to accommodate the fastener applicator. Custom designed fasteners, either with a helical-shaped screw or a strap-shaped tack structure, were tested. Fasteners were primed within an application device and automatic alignment of fasteners was achieved to allow accurate firing of the fixators securing the ring. The delivery apparatus was constructed to be deployed within a 10 mm trocar through a left atrial approach. Using a cadaveric swine heart model, access to the mitral valve from the left atrium was obtained with insertion of a trocar. The delivery apparatus was accurately directed to the mitral annulus under echocardiographic guidance. Fasteners were placed along the annular plane to secure the annuloplasty ring. Both fastener designs achieved considerable fixation force; the helical-shaped screw was found to have significantly greater fixation force compared to the strap-shaped tack design. The annuloplasty ring remained intact and did not experience any structural deformity during the fixation process. The use of a novel fastener system was successful in deploying and securing a mitral valve annuloplasty ring. These promising results may have further application for minimally invasive mitral valve repairs. Additional evaluation of this procedure with pre-clinical in vivo animal studies is necessary.

Mitral Regurgitation After Transcatheter Aortic Valve Replacement: Prognosis, Imaging Predictors, and Potential Management

OBJECTIVES

This study sought to analyze the clinical impact of the degree and improvement of mitral regurgitation in TAVR recipients, validate the main imaging determinants of this improvement, and assess the potential candidates for double valve repair with percutaneous techniques.

BACKGROUND

Many patients with severe aortic stenosis present with concomitant mitral regurgitation (MR). Cardiac imaging plays a key role in identifying prognostic factors of MR persistence after transcatheter aortic valve replacement (TAVR) and for planning its treatment.

METHODS

A total of 1,110 patients with severe aortic stenosis from 6 centers who underwent TAVR were included. In-hospital to 6-month follow-up clinical outcomes according to the degree of baseline MR were evaluated. Off-line analysis of echocardiographic and multidetector computed tomography images was performed to determine predictors of improvement, clinical outcomes, and potential percutaneous alternatives to treat persistent MR.

RESULTS

Compared with patients without significant pre-TAVR MR, 177 patients (16%) presented with significant pre-TAVR MR, experiencing a 3-fold increase in 6-month mortality (35.0% vs. 10.2%; p < 0.001). After TAVR, the degree of MR improved in 60% of them. A mitral annular diameter of >35.5 mm (odds ratio: 9.0; 95% confidence interval: 3.2 to 25.3; p < 0.001) and calcification of the mitral apparatus by multidetector computed tomography (odds ratio: 11.2; 95% confidence interval: 4.03 to 31.3; p < 0.001) were independent predictors of persistent MR. At least 14 patients (1.3% of the entire cohort, 13.1% of patients with persistent MR) met criteria for percutaneous mitral repair with either MitraClip (9.3%) or a balloon-expandable valve (3.8%).

CONCLUSIONS

Significant MR is not uncommon in TAVR recipients and associates with greater mortality. In more than one-half of patients, the degree of MR improves after TAVR, which can be predicted by characterizing the mitral apparatus with multidetector computed tomography. According to standardized imaging criteria, at least 1 in 10 patients whose MR persists after TAVR could benefit from percutaneous mitral procedures, and even more could be treated with MitraClip after dedicated pre-imaging evaluation.

Current challenges in interventional mitral valve treatment

Transcatheter mitral valve therapies have emerged as an alternative option in high surgical risk or inoperable patients with severe and symptomatic mitral regurgitation (MR). As multiple technologies and different approaches will become available in the field of mitral valve interventions, different challenges are emerging, both patient- (clinical challenges) and procedure-related (technical challenges). This review will briefly explore the current open challenges in the evolving fields of interventional mitral valve treatment.