Echocardiographic evaluation

Subjects underwent comprehensive transthoracic echocardiography (2-dimensional, M-mode, and tissue Doppler echocardiography) using commercially available equipment (Vivid 7, GE Medical Systems, Milwaukee, WI, USA). Well-trained echocardiographers interpreted all echocardiograms and obtained the following measurements: left ventricle internal dimension measured at end diastole (LVIDd), left ventricle internal dimension measured at end systole (LVIDs), interventricular septal wall thickness at end diastole (IVSd), left ventricle posterior wall thickness at end diastole (LVPWd), and left ventricular mass index (LVMI), left ventricular mass divided by body surface area (BSA), height (cm)^0.725×weight (kg)^0.425×0.007184 measured with M-mode; early diastolic mitral inflow velocity/late diastolic mitral inflow velocity (E/A), early diastolic mitral inflow velocity/peak early diastolic mitral septal annular velocity (E/e') measured by flow and tissue Doppler analysis; left ventricular ejection fraction (LVEF) measured on 2-dimensional (2-D) echocardiography using biplane Simpson's method; and left atrial volume index (LAVI) measured on 2-D echocardiography calculated by the area-length method and indexed to BSA. Left ventricular diastolic dysfunction was categorized as normal, grade 1, grade 2, grade 3, or grade 4 according to the guidelines of the American Society of Echocardiography. All echocardiographic data were measured and obtained in accordance with the American Society of Echocardiography guidelines and the European Association of Echocardiography guidelines.^5),6) Unless otherwise specified in this paper, diastolic dysfunction referenced herein refers to left ventricular diastolic dysfunction.