Quantitation of the Mitral Tetrahedron in Patients With Ischemic Heart Disease Using Real-Time Three-Dimensional Echocardiography to Evaluate the Geometric Determinants of Ischemic Mitral Regurgitation

摘要

BackgroundIschemic mitral regurgitation (IMR) is common in ischemic heart disease and results in poor prognosis. However, the exact mechanism of IMR has not been fully elucidated.HypothesisQuantitation of the mitral tetrahedron using three-dimentianl (3D) echocardiography is capable of evaluating the geometric determinants and mechanisms of IMR.MethodsForty patients with a history of ST-elevation myocardial infarction at least 6 months earlier were studied. Parameters of mitral deformation and global left ventricular (LV) function and shape were evaluated by 2-dimensional echocardiography. The effective regurgitant orifice (ERO) of IMR was obtained by the quantitative continuous-wave Doppler technique. Three-dimensional (3D) echocardiography was applied to assess the mitral tetrahedron.ResultsMitral valvular tenting area (P??0.001), mitral annular area (P?=?0.032), dilation of the LV in diastole, impairment of the LV ejection fraction, and volume of the spherically shaped LV in systole were greater in patients with an ERO ≥20 mm² than in those with an ERO 20 mm². In the mitral tetrahedron, only the interpapillary muscle roots distance showed a significant difference (P?=?0.004). Multivariate analysis with the logistic regression model showed the systolic mitral tenting area (odds ratio [OR]: 280.49, 95% confidence interval [CI]: 4.59-1.72?×?10⁴, P?=?0.007) and interpapillary muscle distance (OR: 1.50, 95% CI: 1.03-2.19, P?=?0.036) to be independent factors in predicting significant IMR (ERO ≥20 mm²).Conclusions3D echocardiography can be effectively applied in measuring the mitral tetrahedron and evaluating the mechanism of IMR. Mitral valvular tenting and interpapillary muscle distance are 2 independent factors of significant IMR.