Correlation between the venous excess ultrasound score (VExUS) and right atrial pressure

Background Fluid overload is a defining feature in acute heart failure, and accurate assessment of volume status is important in the acute management. Although right heart catheterization (RHC) is the gold standard for directly measuring right atrial pressure (RAP), it is resource-demanding and often limited in availability. The Venous Excess Ultrasound Score (VExUS) is a promising, non-invasive method to assess venous congestion. Using ultrasound, which is widely available and simple to implement in clinical practice, the VExUS score could significantly improve monitoring and management of patients with acute heart failure. However, the relationship between RAP and the VExUS score is not well established. Purpose To investigate the correlation between RAP and VExUS. Methods In a prospective, observational cohort study, patients undergoing RHC on clinical indication were included. Each patient had VExUS performed within 4 hours of RHC. VExUS is an ultrasound-based method that assesses systemic venous congestion by integrating inferior vena cava (IVC) size with Doppler flow patterns from the hepatic, portal, and renal veins, and is graded from 0-3 based on severity. An extended version (eVExUS) using the same parameters but with a more granular 0-7 scoring system was also applied (Fig. 1). Correlations between VExUS or eVExUS and RAP were assessed using Spearman’s rank correlation. Diagnostic performance of IVC diameter alone, VExUS, and eVExUS to detect RAP of >8 mmHg and RAP >12 mmHg was evaluated with receiver operating characteristics (ROC) analysis. Results Among 170 patients included, the median RAP was 6 mmHg (interquartile range (IQR): 3-10 mmHg). The VExUS score showed a significant positive correlation with RAP (Spearman’s ρ = 0.49, p <0.001). Patients with VExUS ≥2 had a significantly higher RAP (12 mmHg; IQR: 10-14 mmHg) than patients with VExUS ≤1 (5 mmHg; IQR: 3-7 mmHg; p <0.001). The extended scoring system, eVExUS, demonstrated an even stronger positive correlation with RAP (Spearman’s ρ = 0.65, p <0.001). In ROC analysis for predicting RAP >12 mmHg, the area under curve was 0.79 for IVC diameter, 0.81 for VExUS, and 0.89 for eVExUS (Fig. 2). eVExUS demonstrated significantly enhanced diagnostic performance compared with IVC diameter (p = 0.003). Furthermore, comparison of AUC between VExUS and eVExUS demonstrated a trend towards eVExUS being superior in performance (p = 0.053). Conclusion In this prospective cohort of patients undergoing RHC, both VExUS and the extended scoring system, eVExUS, correlated significantly with invasively measured right atrial pressure. eVExUS demonstrated the strongest association and the highest diagnostic accuracy for identifying elevated RAP. These findings support the use of VExUS - particularly eVExUS - as practical, non-invasive bedside tools for assessing and grading systemic venous congestion.