Assessment of atrial and ventricular mitral annular disjunction using cardiac computed tomography.

Background: Mitral annular disjunction (MAD) is a spatial displacement of the leaflet hinge line towards the left atrium (a-MAD) or the left ventricle (v-MAD).

Aims: We sought to determine morphological characteristics of MAD types along the mural mitral leaflet and commissures using cardiac computed tomography (CT) imaging.

Methods: CT images from 250 adult patients were analyzed. A three-dimensional reconstruction of the left atrial wall-mitral annulus-left ventricular wall junction was performed to detect MADs and their measurements.

Results: a-MADs were identified in 25.6% of patients (12.8% of mural leaflets and 14.0% mitral commissures), while v-MAD in 27.6% of patients (23.6% of mural leaflets and 4.8% mitral commissures). Notably, the P2 scallop was the most common site for both a-MAD (10.8%) and v-MAD (22.4%). The median disjunction height and length were larger for MADs located in leaflets than for commissures (all P <0.001). No significant sex-based disparities in the presence of both a-MADs and v-MADs were found. Patients with a-MAD were younger (P = 0.006) in comparison to the v-MAD and no-MAD groups. There were no differences in the body mass index, body surface area, and comorbidities across the study groups (all P >0.05).

Conclusions: Cardiac CT emerges as a reliable tool for the precise detection and assessment of MADs, which are relatively frequent variations in the structure of the mitral valve annulus. MADs are typically sectional and do not extend beyond one of the mural mitral leaflet scallops or commissures. Further investigations are warranted to establish the clinical implications of a-MADs and v-MADs.