1048 Evaluation of mitral annular disjunction in mitral valve prolapse: is echo imaging enough?
Authors: Mantegazza V , Fusini L , Gripari P , Volpato V , Italiano G , Muratori M , Tamborini G , Guglielmo M , Pontone G , Pepi M 
Published: January 2020

Abstract

Funding Acknowledgements
None

Background
The separation between the atrial wall-mitral valve (MV) junction and the left ventricular (LV) attachment (mitral annulus disjunction, MAD) is a recently discovered feature linked to MV prolapse (MVP). It is associated to higher complexity of MV lesions and is possibly responsible for mechanically induced fibrosis of the LV inferobasal wall and consequently for malignant ventricular events. MAD has been described in different studies evaluating the MV either by transthoracic (TTE) or transoesophageal (TOE) echocardiography or by cardiac magnetic resonance (CMR).

Purpose
The aim of the present study was to assess MAD and compare the ability of identifying and localizing MAD with different imaging techniques in a cohort of patients with MVP and severe mitral regurgitation eligible for surgery.

Methods
A total of 108 patients with MVP requiring surgery and undergoing CMR and TTE were enrolled in the study. Ninety of them underwent also intraoperative TOE. MAD was defined as any distance observed between the atrial wall-MV junction and the LV wall at end-systole. It was retrospectively assessed in the long axis views (4-, 3-, 2-chamber) and compared between the 3 imaging techniques.

Results
MAD was identified in 18 out of 108 patients at TTE (16.7%), in 15 among 90 patients undergoing TOE (16.7%) and in 42 patients at CMR (38.9%). Comparing data per patient regardless of MAD localization, a good correlation in identifying MAD was obtained between TTE and TOE (Kendall’s τ coefficient 0.83, p &lt; 0.001); a lower but still significant correlation was observed between TTE and CMR (τ coefficient 0.46, p &lt; 0.001) and between TOE and CMR (τ coefficient 0.39, p &lt; 0.001). Higher Kendall rank correlation coefficients were obtained comparing data per view (TTE vs. TOE: τ coefficient 0.86, p &lt; 0.001; TTE vs. CMR: τ coefficient 0.48, p &lt; 0.001; TOE vs. CMR: τ coefficient 0.42, p &lt; 0.001). Considering only patients with MAD (Figure 1), the agreement rate between TTE and TOE (14 patients) in identifying MAD in the same view was 95%, whereas a lower agreement was observed between TTE and CMR (79% in 16 patients) and between TOE and CMR (67% in 13 patients). MAD measured 7.5 ± 1.9 mm at TTE, 6.3 ± 1.7 mm at TOE and 6.9 ± 3.4 mm at CMR.

Conclusion
In surgical MVP patients, MAD showed a higher prevalence at CMR and a lower detection rate by echo imaging. Therefore, an integrated imaging approach could be necessary in the evaluation of MVP. This relatively mild separation of the atrial wall-MV junction and LV myocardium may probably be better recognized by CMR due to a higher spatial resolution. Echo is fundamental for the anatomic and haemodynamic characterization of the valvulopathy by itself, while CMR may better define MAD and myocardial fibrosis helping the physician in identifying PVM patients with higher arrhythmic risk independent of mitral regurgitation grade.
Abstract 1048 Figure 1