Abstract 15499: Adjunctive Papillary Muscle Approximation With Undersizing Mitral Annuloplasty Improves Mitral Valve Mobility and Biomechanics to Repair Functional Mitral Regurgitation

Abstract

Introduction: Undersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation (FMR) has failed to achieve durable results. Though FMR recurrence rates of 60% at 2 years are often cited, even at 30 days, nearly 30% of the patients had moderate or greater FMR in the CTSN trial. We previously demonstrated experimentally that adjunctive papillary muscle approximation (PMA) can improve valve function, with or without UMA. In this modeling study, we used patient specific mitral valve geometries to investigate the effects of UMA and UMA+PMA on mitral valve biomechanics. Methods: 3D ultrasound was obtained in 3 pigs with chronic heart failure and moderate or severe FMR. Each 3D echo was segmented, and computational valve models were developed. UMA was mimicked with ring sizes of 36, 32, and 28 mm ( Fig A ). PMA was then added to each ring size, and the outcomes were reassessed ( Fig B ). In each simulation, leaflet stresses and chordal forces, coaptation area, and tenting parameters were computed. Results: Compared to pre-repair, UMA increased coaptation area by 178.3% with 36 mm, 279.1% with 32 mm, and 356.7% with 28 mm ring ( Fig C ). With 36 mm ring, leaflet stresses increased by 4.3%, while smaller rings reduced stresses by 24.3% (32 mm) and 33.8% (28 mm) ( Fig D ). Chordal forces after UMA decreased by 37.6%, 50.6%, and 55.2% ( Fig E ). Leaflet mobility was improved, as tenting area decreased by 46.1%, 57.9%, and 67.5% ( Fig F ). Adding PMA, achieved better valve closure and coaptation without the need for excessive annular downsizing: tenting area decreased by 76.5%, 85.2%, and 92%, and coaptation area increased by 190.6%, 309.8%, and 386.4%. In addition, leaflet stresses were reduced by 17.4%, 38.5%, and 44.9%, and chordal forces by 48.1%, 63.7%, and 72.9%. Conclusions: Adjunctive addition of PMA repaired FMR and restored physiological mitral valve mobility even at 36 mm annular size, reducing the need for excessive annular undersizing and potentially resulting in a durable repair.