Pathoanatomy of Mitral Regurgitation

Functional Mitral Regurgitation: Patient Selection and Optimization

Functional mitral regurgitation appears commonly among all heart failure phenotypes and can affect symptom burden and degree of maladaptive remodeling. Transcatheter mitral valve edge-to-edge repair therapies recently became an important part of the routine heart failure armamentarium for carefully selected and medically optimized candidates. Patient selection is considering heart failure staging, relevant comorbidities, as well as anatomic criteria. Indications and device platforms are currently expanding.

Mitral Valve Repair of the Anterior Leaflet: Are We There Yet?

Mitral regurgitation is one of the most prevalent valvulopathies with a disease burden that incurs significant healthcare costs globally. Surgical repair of the posterior mitral valve leaflet is a standard treatment, but approaches for repairing the anterior mitral valve leaflet are not widely established. Since anterior leaflet involvement is less common and more difficult to repair, fewer studies have investigated its natural history and treatment options. In this review, we discuss surgical techniques for repairing the anterior leaflet and their outcomes, including survival, reoperation, and recurrence of regurgitation. We show that most patients with mitral regurgitation from the anterior leaflet can be repaired with good outcomes if performed at centers with expertise. Additionally, equal consideration for early repair should be given to patients with mitral regurgitation from both anterior and posterior pathology. However, more studies to better evaluate the efficacy and safety of anterior mitral valve leaflet repair are needed.

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.