Inaccuracy of Right Atrial Pressure Estimates Through Inferior Vena Cava Indices

The precision of echocardiography in estimating pulmonary pressures has been debated. A value of right atrial pressure (RAP) is needed for pulmonary pressure estimation, and it could be partly responsible for the estimation error. Several schemes based on the inferior vena cava (IVC) are commonly used in clinical practice and in experimental studies for RAP estimation. However, the majority lack proper validation, and thus far, no study has compared them all. In this prospective, blinded study, a comprehensive transthoracic echocardiography was performed on 200 patients referred for right heart catheterization. The IVC was measured in different views and RAP was estimated according to 6 different schemes. One hundred ninety patients were suitable for analysis. IVC measurements were significantly but poorly associated with invasive RAP. All RAP schemes showed poor accuracy compared with invasive RAP (average accuracy 34%). None of the schemes showed a clear superiority over the others. No echocardiographic or clinical variables showed a relevant impact on the estimation error. In conclusion, RAP estimation based on the IVC is highly inaccurate irrespective of the method used and should be avoided whenever possible. Whether adding estimated RAP values affects the estimation of pulmonary pressures is yet to be determined.