Few data exist on cardiac magnetic resonance (CMR) prevalence of mitral annulus disjunction (MAD) in mitral valve prolapse (MVP) and its morphological characteristics.

To assess the prevalence of MAD and its consequences on left ventricle (LV) morphology in MVP patients using CMR.

89 patients with MVP (63 women; mean age 64±13) referred for CMR assessment of mitral regurgitation (MR) were evaluated. MVP etiology was either Myxomatous Mitral Valve Disease (MMVP) (n=40; 45%) or fibroelastic disease (FED) (n=49; 55%). In total, 26/89 (29%) patients underwent injected gadolinium contrast enhancement (GE). MR severity was calculated using the volumetric method with CMR. LV systolic diameter (LVSD), and mitral annulus end systolic (ES) and diastolic (ED) diameters were measured. MAD was defined as a separation between the left atrium-valve junction and the LV posterior free wall, diagnosed by CMR from long axis view in end-systole (Figure 1). Patients were classified in 2 groups according to presence (MAD+) or absence of MAD (MAD−).

MAD was found in 35% (31/89) of MVP patients, measuring 8±4mm. MAD was more frequent in MMVP (24/40; 60%) than in FED (7/49; 14%; P<0.0001). Presence of MAD was associated with ventricular arrhythmias (VA) (P=0.037), but not with MR severity (regurgitant volume in MAD+ was 47±32 vs. 56±23ml/beat, P=0.141). MAD+ showed enlarged basal LVSD (41±9 vs. 37±7mm, P=0.014) and mitral annulus, in both ES (49±6 vs. 44±5mm, P<0.0001) and ED (48±5 vs. 44±4mm, P=0.004). Among the 11/26 patients (42%) with late GE, 83% (5/6) of the patients with LV fibrosis at the level of papillary muscle (PM) had MAD. After adjustment on age and MR severity, MMVP (HR 5.04; 95% CI [1.66–15.31], P=0.004) and dilated ES mitral annulus diameter (HR 1.17; 95% CI [1.05–1.30], P=0.005) were independent predictors of MAD (Table 1).

MMVP, enlarged LVSD, enlarged mitral annular, VA and PM fibrosis were associated with MAD, independently of MR severity.