750 Mitral annulus disjunction in consecutive patients undergoing cardiovascular magnetic resonance: arrhythmogenic substrate or anatomical variant?

Mitral annulus disjunction (MAD) has been associated with sudden cardiac death in selected patients with arrhythmic presentation, while its clinical significance in unselected cohorts remains unknown. Our purpose was to assess the prevalence and clinical significance of MAD in consecutive patients referred to cardiovascular-magnetic-resonance (CMR).

Our population included 103 consecutive patients undergoing CMR at our Institution, between August and September 2021. MAD was defined as a  ≥ 1 mm atrial displacement of the mitral leaflet hinge point in standard long-axis cine images during end-systole. MAD analysis was performed in 97 patients (feasibility = 94%) and resulted positive in 49 (51%). MAD—patients were more often males (75% vs. 57%; P = 0.045) and affected by ischaemic (35% vs. 12%, P = 0.01) and non-ischaemic cardiomyopathy (38% vs. 16%, P = 0.026) compared to MAD+ patients. No significant differences were found in terms of age, history of ventricular arrhythmias, bi-ventricular and bi-atrial volumes, bi-ventricular ejection fraction, native T1 and T2 mapping values, extracellular volume, and prevalence of late gadolinium enhancement (P > 0.05 for all) between MAD + vs. MAD—patients. MAD extent was higher in patients with mitral valve prolapse (MVP; n = 7), (3.5 ± 1.5 mm in MVP+ vs. 2.0 ± 1.0 mm in MVP– patients; P = 0.004). No significant differences were conversely found in MAD extent between patients with and without ventricular arrhythmias (2.5 ± 1.1 mm vs. 2.3 ± 1.1 mm; P = 0.815).

Our findings suggest a high prevalence of MAD in unselected cohorts of patients, with no clinical significance. Prospective studies are needed to further elucidate the interplay between MAD and malignant ventricular arrhythmias in unselected cohorts of patients.