Echocardiography:
1- Two-dimensional and Doppler Echocardiography
All echocardiographic studies were performed using a Vivid 9 machine (GE Vingmed Ultrasound AS, Horten, Norway), equipped with a 3.5 MHz transducer. A total of 3 cardiac cycles were recorded at the end of expiration. Frame rate was set in the range 60-80 frames per second for 2-D image acquisition. Settings were adjusted manually to obtain optimal images. All data were transferred to a workstation for further offline analysis (EchoPAC PC; GE Vingmed Ultrasound AS).
Maximal wall thickness was measured from all LV segments from base to apex in parasternal short axis view. Left ventricular end-systolic diameter (ESD) and end-diastolic diameter (EDD) were measured from parasternal long axis view according to recommendations of American Society of Echocardiography (ASE) 14. Left ventricular end-systolic volume (ESV), end-diastolic volume (EDV) and EF were determined from the apical four and two-chamber views using Simpson’s modified biplane method. Atrial diameter was calculated by M-mode or 2-D echocardiography in the parasternal long axis plane. Left atrial (LA) volume was obtained using the biplane area length method from apical four and two- chamber images at end-systole and it was also indexed to body surface area (BSA) as recommended 15.