arrhythmic mitral valve prolapse: beyond valve geometry, traction forces quantification
Authors: Capdeville S , Velaso A , Gonzalez Sanchez R , Wasniewski S , Fernandez Friera L , Salguero Bodes R , Arribas Ynsaurriaga F , Solis J 
Published: January 2025

Abstract

Introduction
Arrhythmic Mitral Valve Prolapse (AMVP) constitutes a subgroup of Mitral Valve Prolapse (MVP) patients who, without necessarily having significant insufficiency, exhibit an increased risk of malignant ventricular arrhythmias (VA). Although this entity has recently gained significant attention in the scientific community, its pathophysiology and phenotypic characterization remain not completely elucidated. It has been postulated that leaflet displacement increases tension on the papillary muscles (PM), causing excessive superior traction. This may serve as the trigger for VA and, over time, lead to localized myocardial remodeling and subsequent fibrosis at the level of PM and left ventricle (LV) basal inferolateral wall, which is seen in this population. We believe we can identify and quantify this mechanism using transthoracic echocardiography (TTE). Therefore, we could define high-risk patterns for VA in this population before they occur.

Purpose
The aim of the study was to describe mitral valve (MV) geometry and quantify traction forces (TF) using TTE in patients with benign MVP and AMVP, and to compare these parameters between these two populations.

Methods
This retrospective observational study included 22 patients, 18 with benign MVP and 8 with AMVP. MV geometry and TF were measured using TTE. MVP was defined as the displacement of one or both leaflets ≥ 2 mm above the mitral annulus (MA) plane in parasternal long-axis view, and AMVP as MVP combined with frequent or complex VA. Patients with significant mitral regurgitation were excluded to eliminate its potential modifying effect on TF. Clinical variables were obtained from electronic medical records. LV parameters and MV geometry were measured by TTE, and TF were quantified as the variation in distance between the PM and MA from proto to mesosystole in apical 3 chamber view.

Results
Clinical characteristics and echocardiographic measurements are presented in the Table. The groups were comparable in terms of age, gender, LV dimension, function, and Global Longitudinal Strain (GLS). As expected, the AMVP group exhibited more symptoms, pathological ECG findings, and abnormal Holter results. In terms of MV geometry, the AMVP group had larger prolapsing area and height, with predominantly bileaflet involvement. Mitral annular disjunction (MAD) was also significantly more frequent in this group. Regarding TF quantification, the AMVP group showed greater PM-MA distance in protosystole and a higher variation in this distance between proto- and mesosystole compared to the benign MVP group.

Conclusion
These results support the hypothesis that AMVP patients exhibit significantly higher TF during systole. While larger clinical trials are needed to reach firm conclusions, this parameter could constitute a new measurable characteristic of this population, contributing to phenotypic characterization and early identification of AMVP, potentially before the occurrence of a fatal event.