Mitral loop cerclage as a variant form of mitral cerclage annuloplasty that adds a device (CSTV) for preventing potential complications: a preclinical proof of concept and feasibility study.

Aims: Although mitral cerclage annuloplasty can reduce mitral regurgitation, the potential risks for erosion of the surrounding tissue or conduction blockage are barriers to human translation. This preclinical study aimed to provide a proof of concept for a novel approach, mitral loop cerclage (MLC), designed to address these shortcomings.

Methods And Results: MLC consists of: (1) a novel appliance termed a coronary sinus and tricuspid valve protective device (CSTV) that includes a tension locker, and (2) a nylon-coated, braided stainless steel rope (0.6 mm thick) with a coronary artery protective device in a single unit (cerclage rope). Nine healthy farm swine underwent MLC in short-term (two weeks, n=4) and midterm (six weeks, n=5) survival experiments under X-ray fluoroscopic guidance imaging. The procedural success rate was 100%. MLC resulted in a significant reduction of the septal lateral dimension of the mitral annulus (24.58±2.16 vs. 21.26±1.43 mm, p=0.04) and left ventricular (LV) volume in diastole (75.9±3.9 vs. 70.6±5.0 ml, p=0.04) in the midterm group. No conduction abnormalities or serious complications were noted beyond trivial tricuspid regurgitation in all cases (n=9). Necropsy showed no evidence of tissue erosion and an excellent biocompatibility of the implanted devices.

Conclusions: MLC, as a novel approach for catheter-based mitral valve repair, appeared feasible in this short-term preclinical model. Further studies with longer follow-up in a cardiomyopathic animal model are needed to verify the clinical feasibility and safety of MLC.