Discriminatory ability of right atrial volumes with two- and three-dimensional echocardiography to detect elevated right atrial pressure in pulmonary hypertension

Aims: Pulmonary hypertension (PH) patients have high mortality due to right ventricular failure. Predictors of poor prognostic outcome are increased right atrial volume (RAV) and elevated mean right atrial pressure (mRAP). Our aim was to determine whether RAV measured with 2D echocardiography (2DE) and 3D echocardiography (3DE) can detect elevated mRAP in patients evaluated for PH. Methods: Of 85 patients prospectively evaluated for PH, 44 patients (63 ± 15 years, 57% female) had 2DE, 3DE and right heart catheterization within 48 h and were in sinus rhythm. Maximum (RAV_max) and minimum (RAV_min) volumes were measured with 3DE. 2D maximum RAV and RA area, inferior vena cava diameter and collapsibility were measured. Invasive mRAP > 8 mmHg was predefined as elevated. Results: RAV_max and RAV_min correlated with mRAP (r = 0·40 and r = 0·35, P<0·05, for both), and so did 2DE maximum RAV (r = 0·42, P = 0·005) and RA area (r = 0·40, P = 0·008). Area under the curve (AUC) from receiver-operating characteristics curves was for 3DE 0·77 for RAV_max, 0·74 for RAV_min, from 2DE, 0·76 for maximum RAV and 0·75 for RA area to discriminate elevated mRAP (P<0·01 for all). PH patients had larger 3D RAV compared with controls (P<0·01). IVC diameter correlated with mRAP (r = 0·41, P = 0·007), but collapsibility did not (P = 0·078). AUC was neither significant for IVC diameter nor for collapsibility for predicting mRAP>8 mmHg. The optimal threshold was 57 ml m^-2 for RAV_max, 31 ml m^-2 for RAV_min and 36 ml m^-2 for 2DE RAV. Conclusions: Enlarged RA measures with 2DE and 3DE have better discriminatory ability compared with IVC measures, to detect elevated mRAP in patients evaluated for PH.