Prediction of Right Atrial Pressure from Inferior Vena Cava Parameters Derived by Three-Dimensional Echocardiography

Background: Right atrial pressure (RAP) is crucial for pulmonary pressure estimation by echocardiography, particularly in the assessment of pulmonary hypertension. Objective: To evaluate the correlation between RAP measured by right heart catheterization and parameters derived from three-dimensional (3D) echocardiographic imaging of the inferior vena cava (IVC), and to develop an equation to predict RAP from these IVC parameters. Materials and Methods: Patients scheduled for right heart catheterization or electrophysiologic study in the cardiac catheterization laboratory of the Division of Cardiology, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand, between October 2019 and February 2020 were prospectively enrolled. RAP was measured invasively via right heart catheterization. Two- and three-dimensional echocardiography were performed to acquire IVC images. The IVC parameters of interest included the maximal and minimal diameters of the longitudinal IVC, cross-sectional dimensions obtained from multiplanar 3D image analysis, and the collapsibility index. Results: Seventy-four patients, with a mean age of 50 years, were included in the study. Preexisting cardiac conditions included valvular heart disease in 45.9%, congenital heart disease in 36.5%, arrhythmia in 60.8%, and coronary heart disease in 6.8%. All IVC parameters were significantly correlated with RAP (r-value range of 0.31 to 0.67). The minimal cross-sectional area of the 3D IVC (IVC3DminCSA) showed the strongest correlation with RAP (r=0.67, p<0.001). The validated equation for estimating RAP was RAP = 5.57 + (2.10 × IVC3DminCSA). Conclusion: Predicting RAP using the IVC3DminCSA is a novel parameter that can mitigate the translational effects of respiration and facilitate more accurate, earlier detection of pulmonary hypertension.