Geometric changes of mitral annulus assessed by real-time 3-dimensional echocardiography: Becoming enlarged and less nonplanar in the anteroposterior direction during systole in proportion to global left ventricular systolic function

We sought to investigate the geometric changes of the mitral annulus during systole in relation to global left ventricular (LV) systolic function using real-time 3-dimensional (3D) echocardiography. Real-time 3D echocardiography was performed in 23 patients with global LV systolic dysfunction with ejection fraction of 37 ± 19% and 9 control subjects with ejection fraction of 62 ± 4%. Volumetric data were divided into 9 rotational apical planes (angle increment = 20 degrees) using 3D software. Nine rotational annular dimensions (ADs) were measured in all planes in early and late systole. Nonplanar angle (NPA) of the annulus between two vectors from two hinge points of the annulus in the anteroposterior plane to the center between two commissures in the commissure-commissure plane was measured during early and late systole. Fractional changes of NPA and AD were defined as changes in percentage during systole. NPA significantly increased during systole (early, 145 ± 12 degrees; late, 160 ± 9 degrees; P <. 01). Among 9 ADs, 3 anteroposteriorly directed ADs showed the most prominent fractional increases during systole in all patients. Both fractional changes of NPA (R ² = 0.87, P <. 01) and the anteroposterior dimension, AD 1 (R ² = 0.85, P <. 01) showed significant positive correlation with global LV systolic function. Real-time 3D echocardiography demonstrated that saddle shape of the mitral annulus was getting enlarged and less nonplanar mainly in the anteroposterior direction during systole. These geometric changes were proportional to the global LV systolic function.