Prevalence of mitral annular disjunction in patients with mitral valve prolapse and severe regurgitation

Abstract

Mitral annular disjunction (MAD) is routinely diagnosed by cardiac imaging, mostly by echocardiography, and shown to be a risk factor for ventricular arrhythmias. While MAD is associated with mitral valve (MV) prolapse (MVP), it is unknown which patients with MAD are at higher risk and which additional imaging features may help identify them. The value of cardiac computed tomography (CCT) for the diagnosis of MAD is unknown. Accordingly, we aimed to: (1) develop a standardized CCT approach to identify MAD in patients with MVP and severe mitral regurgitation (MR); (2) determine its prevalence and identify features that are associated with MAD in this population. We retrospectively studied 90 patients (age 63 ± 12 years) with MVP and severe MR, who had pre-operative CCT (256-slice scanner) of sufficient quality for analysis. The presence and degree of MAD was assessed by rotating the view plane around the MV center to visualize disjunction along the annulus. Additionally, detailed measurements of MV apparatus and left heart chambers were performed. Univariate logistic regression analysis was performed to determine which parameters were associated with MAD. MAD was identified in 18 patients (20%), and it was typically located adjacent to a prolapsed or flail mitral leaflet scallop. Of these patients, 75% had maximum MAD distance > 4.8 mm and 90% > 3.8 mm. Female gender was most strongly associated with MAD (p = 0.04). Additionally, smaller end-diastolic mitral annulus area (p = 0.045) and longer posterior leaflet (p = 0.03) were associated with greater MAD. No association was seen between MAD and left ventricular size and function, left atrial size, and papillary muscle geometry. CCT can be used to readily detect MAD, by taking advantage of the 3D nature of this modality. A significant portion of MVP patients referred for mitral valve repair have MAD. The presence of MAD is associated with female gender, smaller annulus size and greater posterior leaflet length.

Keywords: Cardiac computed tomography; Mitral annular disjunction; Mitral valve prolapse.

Fig. 1

Three-chamber views at the level of mitral valve using multiplanar reconstruction to identify prolapse or flail leaflets. Starting with the medial aspect (a, b), the A3 and P3 scallops are identified. In the central portion of the MV (c, d), the A2 and P2 scallops are identified. When scrolling to the most lateral portion of the MV near the LAA (e, f), A1 and P1 are identified. In this example, there is P2 prolapse. MAD is also noted involving all three posterior scallops

Fig. 2

Measuring the mitral annulus, papillary muscles, and leaflet length. The boundaries of the mitral annulus are outlined using arrows (a, b), then using planimetry, the MV area is measured in short axis (c). The distance and angle between the two papillary muscles is measured in the short axis (d). Anterior and posterior leaflet lengths are measured in the 3-chamber view in mid-diastole (e)

Fig. 3

Guide for the CT assessment of MAD. End-systolic phase axial images (a) are loaded and then converted into “cardiac planes” (b). One of the planes going through the mitral valve is rotated (c), while the reader assesses the other two imaging planes for the presence of MAD (d)