Prevalence of Diastolic and Systolic Mitral Annular Disjunction in Patients with Mitral Valve Prolapse

Backgrounds: Mitral annular disjunction (MAD) is commonly evaluated at end-systole. However, a systolic-only disjunction is merely apparent and two distinct phenotypes have been identified: True-MAD (atrial displacement of the posterior leaflet in diastole and systole) and Pseudo-MAD (apparent displacement in systole only). The prevalence of True-MAD and Pseudo-MAD in mitral valve prolapse (MVP) is not known. Aim of this study was to assess the prevalence of True-MAD and Pseudo-MAD in myxomatous MVP patients by transthoracic echocardiography (TTE) and to validate TTE compared to cardiac magnetic resonance (CMR) (reference standards).

Methods: Consecutive patients who underwent TTE for MVP were included. Mitral annular phenotype was evaluated in TTE parasternal long-axis view. Accuracy (against CMR) and intra/inter rater reliability of TTE were also assessed.

Results: Six-hundred-three consecutive patients were included. The prevalence of True-MAD and Pseudo-MAD was 7% (42) and 37% (221) (p<0.05), respectively. Accordingly, 221 of 263 (84%) patients classically classified as "MAD" would have been reclassified as Pseudo-MAD. Pseudo-MAD prevalence and systolic length increased with higher mitral regurgitation (MR) severity (23% for mild MR, 36% for moderate MR, 44% for severe MR (p<0.05); 6 ± 2 mm for mild MR; 8 ± 2 mm for moderate MR; 10 ± 2mm for severe MR (p<0.05), while True-MAD prevalence was consistent across MR grades. Pseudo-MAD was linked to systolic curling and Pickelhaube. TTE showed an overall accuracy of 0.89 (Cohen k 0.80), a substantial inter-rater agreement of 0.87 (k 0.76) and an almost perfect intra-rater agreement of 0.93 (k 0.85).

Conclusion: True-MAD, unlike Pseudo-MAD, is rare in patients with MVP. Pseudo-MAD is associated with the grade of MR and other echocardiographic features of advanced myxomatous degeneration. TTE is an accurate and reliable first line method to assess mitral annulus morphology in MVP.