Echocardiographic assessment
We performed a complete conventional transthoracic echocardiogram with subjects in left lateral decubitus using a Siemens Acuson SC 2000 (Mountain View, California-USA) echocardiographic equipment with a phased array transducer. The right ventricular end-diastolic diameter was measured in the apical four-chamber view, below the tricuspid valve. The RV wall thickness was measured by 2D echocardiography in the subcostal four-chamber view. Right atrial (RA) volume was obtained using a single-plane method of disks in the apical four-chamber view at ventricular end-systole, and it was indexed by body surface area. The measurements of right ventricular fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), tricuspid S-wave velocity, Tei index, E, A-wave velocities (rapid filling and atrial contribution, respectively), E/A ratio, and tricuspid E/e’ ratio were obtained according to the guidelines of the American Society of Echocardiography and the European Association of Echocardiography (5,10,11).