Long axis (apico-basal axis) diameter was measured from RA roof (center of superior RA wall) to the center of tricuspid valve annulus, parallel to interatrial septum (blue arrow), whereas short axis (septal-lateral axis), plane perpendicular to RA long axis was defined that reflects the maximum diameter between the lateral border of the RA and the inter-atrial septum (yellow arrow). Circumference was drawn from lateral to septal border of the tricuspid annulus, excluding the area between tricuspid leaflets and annulus, along RA endocardium, excluding Vena cava inferior/Vena cava superior and RA appendage (yellow line)2.