The severity of functional mitral regurgitation depends on the shape of the mitral apparatus: a three-dimensional echo analysis.

BACKGROUND AND AIMS OF THE STUDY: The relationship between structural abnormalities of the mitral apparatus and severity of functional mitral regurgitation (MR) was examined in patients with non-ischemic dilated cardiomyopathy. METHODS: Three-dimensional (3D) echocardiography was performed in 13 cardiomyopathy patients with mild (n = 5) or moderate to severe (n = 8) MR, and in eight normal volunteers using freehand scanning. The size, shape and function of the left ventricle, and the dimensions of the mitral annulus, chordae tendineae and papillary muscles, were measured. RESULTS: Virtually all parameters differed significantly between normal subjects and cardiomyopathy patients. Annular size, the central angle between the anterior and posterior chordae, and dilatation of the anterior and anterolateral left ventricular (LV) wall were greater in patients with moderate to severe MR than in those with trace to mild MR. Anterior wall dilatation was associated with greater outward displacement of the anterior papillary muscle, and correlated with widening of the central chordal angle, apical displacement of the mitral leaflet coaptation point, and mitral annular dilatation. CONCLUSION: In non-ischemic dilated cardiomyopathy, functional MR is related to both annular dilatation and to dilatation of the anterior and anterolateral LV wall. The latter results in displacement of the anterior papillary muscle, narrowing of the angle of the anterior chorda to the mitral annulus, and widening of the central angle between the anterior and posterior chordae.