Mitral Annular Disjunction of Degenerative Mitral Regurgitation: 3D Evaluation and Implications for Mitral Repair.

ABSTRACT Background Mitral annular disjunction (MAD) dynamic consequences on the mitral apparatus and the left ventricle (LV) remain unclear and are crucial in the context of mitral surgery. Thus, we aimed to assess mitral valvular/annular/ventricular dynamics in mitral valve prolapse (MVP) stratified by MAD presence. Methods In 61 patients (62±11 years; 25% women) with MVP and severe mitral-regurgitation undergoing mitral-surgery between 2009 and 2016, valvular/annular dimensions/dynamics by 2D transthoracic and 3D-transesophageal-echocardiography, and LV dimensions/dynamics were analyzed stratified by MAD presence, pre and post-surgery. Results MAD (8±3mm) was diagnosed in 27 (44%) patients (with effective-regurgitant-orifice area of 0.55±0.20cm2 and similar to no-MAD), more frequently in bileaflet-prolapse (52 vs. 18% in no-MAD, P=0.004), involving consistently P2 (P=0.005). MAD displayed larger diastolic annular area (1646±410 vs. 1380±348mm2), circumference (150±19 vs. 137±16mm) and intercommissural diameter (48±7 vs. 43±6mm) vs. no-MAD (all P≤0.008). Dynamically, mid- and late-systolic excess inter-commissural diameter, annular area and circumference enlargement were associated with MAD (all P≤0.01). MAD was also associated with dynamically annular slippage, larger prolapse volume and height (P≤0.007), and larger leaflet area (2053±620 vs. 1692±488mm2, P=0.01). While MAD vs no-MAD showed similar ejection fraction (65±5 vs 62±8% respectively, P=0.1), systolic basal posterior thickness was increased in MAD (19±2 vs. 15±2mm, P Conclusions MAD in MVP involves a predominant phenotype of bileaflet-MVP, and causes profound annular dynamics alterations with considerable expansion and excess annular enlargement in systole potentially affecting leaflets’ coaptation. MAD myocardial/annular slippage simulates vigorous LV function without true benefit post-surgical annular suture. Thus, while MAD does not hinder the feasibility and quality of valve repair, it requires careful suture of ring to ventricular myocardium lest it may persist postoperatively.