All studies are performed by experienced sonographers and reviewed by staff cardiologists with advanced training in echocardiography. Left ventricular function is assessed by Simpson's method. Mitral regurgitation is graded with color flow imaging. Mitral inflow is assessed with pulsed wave Doppler echocardiography form the apical 4-chamber view. The Doppler bean is aligned parallel to the direction of flow, and a 1- to 2-mm sample volume is placed between the tips of mitral leaflets during diastole. From the mitral inflow profile, the E- and A-wave velocity, E-deceleration time, and E/A velocity ration are measured. Pulmonary venous flow is recorded with pulsed-wave Doppler with a sample volume placed 1 cm into the right upper pulmonary vein. The flow velocities are recorded, and the ratio of systolic to diastolic forward flow (S/D ratio) is calculated. Doppler tissue imaging of mitral annulus over septal, lateral and inferior borders is also obtained from apical views. Diastolic filling is categorized as normal (grade 0), impaired relaxation (grade 1), pseudonormalization (grade 2), and restrictive (grade 3) by a combination of transmitral and pulmonary flow patterns as validated previously.