True- and pseudo-mitral annular disjunction in patients undergoing cardiovascular magnetic resonance

Background: Mitral annular disjunction (MAD) is a controversial entity. Recently, a distinction between pseudo-MAD, present in systole and secondary to juxtaposition of the billowing posterior leaflet on the left atrial wall, and true-MAD, where the insertion of the posterior leaflet is displaced on the atrial wall both in diastole or in systole, has been proposed. We investigated the prevalence of pseudo-MAD and true-MAD.

Methods: This was a retrospective study including consecutive patients referred to cardiovascular magnetic resonance (CMR). MAD was defined as a ≥1mm displacement between the left atrial wall-mitral valve leaflet junction hinge and the top of the left ventricular wall, measured from cine-CMR images in the three long-axis views. Pseudo-MAD and true-MAD were defined as presence of MAD only in systole or both in systole and diastole, respectively.

Results: Two-hundred-ninety patients (59 [47-71] years; 181 men, 62%) were included. Mitral valve prolapse (MVP) and MAD were found in 24 (8%) and 145 (50%) patients, of which 100 (35%) with true-MAD and 45 (16%) with pseudo-MAD. In all measurements, systolic MAD extent (2.3 [1.7-3.0] mm) resulted equal or greater than diastolic MAD extent (2.0 [1.5-2.9] mm). The most frequent MAD location was the inferior wall (40%) and the inferolateral wall was the rarest (17%). In patients with MVP, the prevalence of MAD was higher (88%), mainly driven by a higher prevalence of pseudo-MAD, as the prevalence of true-MAD did not vary significantly in patients with vs. without MVP (p=0.22), except for the inferolateral wall (38% vs. 8%; p<0.001). The extent of pseudo-MAD was greater in patients with MVP (4.0 [3.0-5.6] mm) than in those without MVP (2.0 [1.5-3.0]; p<0.001), whereas the extent of true-MAD did not differ significantly (2.5 [2.0-3.2] mm and 1.9 [1.5-2.9] mm; p=0.06). At the inferolateral wall, the prevalence of pseudo-MAD was 29% vs. 5% (p<0.001) in patients with vs. without MVP.

Conclusions: True-MAD was a common imaging finding in patients undergoing CMR, irrespective of MVP. Patients with MVP showed higher prevalence and extent of pseudo-MAD in all locations and true-MAD in the inferolateral wall.