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 2 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. The 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 the TTE parasternal long-axis view. Accuracy (against CMR) and intra-/interrater 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 < .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 < .05]; 6 ± 2 mm for mild MR; 8 ± 2 mm for moderate MR; 10 ± 2 mm for severe MR [P < .05]), while True-MAD prevalence was consistent across MR grades. Pseudo-MAD was linked to systolic curling and Pickelhaube. Transthoracic echocardiography showed an overall accuracy of 0.89 (Cohen k 0.80), a substantial interrater agreement of 0.87 (k = 0.76), and an almost perfect intrarater agreement of 0.93 (k = 0.85).

Conclusions: 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. Transthoracic echocardiography is an accurate and reliable first-line method to assess mitral annulus morphology in MVP.