Standard echocardiography
Echocardiographic examinations were performed using a high-quality echocardiography machine (Vivid 7, GE, USA) by two cardiologists. Our echocardiography machine was additionally calibrated for international studies by an independent organization (certificate no: B14091148). Measurements of LV and LA dimensions were made in accordance with the most up to date European Society of Echocardiography recommendations (16). LVEF was measured using the modified biplane Simpson’s rule. The ratio between peak early (E) and late (A) diastolic LV filling velocities and E wave deceleration time was determined by standard Doppler imaging. The timing of mitral and aortic valve opening and closing were defined by a pulsed-wave Doppler tracing of the mitral inflow and LV outflow. Lateral wall and septal tissue Doppler parameters (E′ and A′) were measured as well. E/E′ was calculated manually. Particular attention was given to limit myocardial tissue and extracardiac structures, providing sufficient reliable data to obtain a gray-scale image.