Mitral Annulus Disjunction and Arrhythmic Mitral Valve Prolapse: Emerging Role of Cardiac Magnetic Resonance Imaging in the Workup

Abstract

Mitral valve prolapse is a commonly described entity with a highly variable and benign course. However, it is associated with ventricular arrhythmias and sudden cardiac death in a small subset of patients. Recent studies have yielded insight into myocardial mechanics and the causation of ventricular arrhythmias in these groups of patients. Mitral annular disjunction (MAD) characterized by detachment of mitral annulus from left ventricular myocardium is associated with morphological and functional remodeling of the left ventricular myocardium. Resultant fibrosis acts as a substrate of ventricular arrhythmia and sudden cardiac death. We present two such cases of arrhythmic mitral valve prolapse associated with MAD. Cardiac magnetic resonance imaging provides excellent morphological information and also helps in the assessment of fibrosis.

Keywords: cardiac MRI; mitral annulus disjunction; mitral regurgitation; mitral valve prolapse.

Fig. 1

Diagrammatic representation of pathophysiology of arrhythmic mitral valve prolapse. LA, left atrium; LV, left ventricle.

Fig. 2

Case1 echocardiography ( A ) Parasternal long-axis view showing mitral regurgitation with prolapse and annular disjunction. ( B ) Doppler tissue imaging showing spiked systolic lateral mitral annular velocities: Pickelhaube sign ( C ); a spiked helmet worn in the 19th and 20th centuries by Prussian and German military. (©Engelberger/Wikimedia Commons/CC-BY-SA-3.0/GFDL).

Fig. 3

Case 1 CMR ( A ) 3D Long axis view showing bileaflet prolapse. The prolapsed distance is measured as superior displacement of leaflet beyond mitral annulus ( orange arrows ) ( B ) Long-axis view, Longitudinal mitral annulus disjunction (MAD; green line ) length is measured from the junction of left atrial (LA) wall–posterior MV leaflet to the top of the left ventricular (LV) inferobasal wall during end systole ( C ). Same image as in ( B ) showing measurement of curling distance by tracing a line between the LA wall–posterior MV leaflet junction and top of LV inferobasal wall, and from this line, a perpendicular line to the lower limit of the mitral annulus during end-systole. ( D ) LV basal hypertrophy. The LV thickness of basal and mid segments of the inferolateral wall is measured at diastole on long axis view. Base-to-mid ratio: 2.7. 3D, three-dimensional; CMR, cardiac magnetic resonance imaging; MV, mitral valve.

Fig. 4

Case 2 echocardiography. ( A ) Apical four-chamber view showing mitral regurgitation with prolapse and annular disjunction. ( B ) Jet in interatrial septum suggestive of ostium secundum atrial septal defect.

Fig. 5

Case 2 CMR. ( A ) Two-chamber view demonstrating bileaflet mitral valve prolapse with prolapse distance measurements ( orange arrows ). ( B ) Note regurgitant jet from mitral regurgitation ( green arrow ) ( C ) Note the separation of LV myocardium from mitral annulus ( green line : MAD distance). ( D ) Curling of LV myocardium seen in two-chamber view with quantitative measurement of curling distance ( yellow arrow ). ( E ) LV basal hypertrophy Base: Mid LV thickness ratio of 2:1. ( F ) Focal LGE involving the posterobasal wall of LV myocardium. ( G ) Color coded feature tracking map in long axis views with global longitudinal strain curve depicting reduction in GLS. CMR, cardiac magnetic resonance imaging; GLS, global longitudinal strain; LV, left ventricle; MAD, mitral annulus disjunction.

Fig. 6

CMR planning for assessment of mitral valve. ( A ) CMR short axis view at the level of mitral valve showing anatomy of mitral valve. A1, A2, and A3 scallops in the anterior leaflet. P1, P2, and P3 scallops in the posterior leaflet. ( B ) Modified left ventricular outflow tract view. Contiguous stack of cine images perpendicular to the mitral commissures transecting the principal line of coaptation to visualize and assess all the mitral scallops A1–P1, A2–P2, and A3–P3. ( C ) Additional/alternative slices perpendicular to the coaptation plane of the valve leaflets ( yellow and/or purple lines ) ( D ) For circumferential assessment of annular plane, six left ventricular long-axis cine slices are acquired at every 30degrees. The first projection was aligned through the superior right ventricular free wall insertion into the septum, and was defined as 0° in the annular plane, followed by clockwise labeling of the long-axis slices. CMR, cardiac magnetic resonance imaging.