Can echocardiographically estimated pulmonary arterial elastance be a non-invasive predictor of pulmonary vascular resistance?

Introduction: Measurement of pulmonary vascular resistance (PVR) is essential in evaluating a patient with pulmonary hypertension. Material and methods: Data from right heart catheterization (RHC) and echocardiograms performed within 90 days of each other on 45 non-consecutive adult patients were reviewed in this retrospective study. Patients were recruited using an assortment of strategies to ensure the presence of patients with a wide range of PVR. Results: The linear regression equation between RHC-derived PVR and echocardiographic pulmonary arterial elastance (PAE) was: PVR = (562.6 x PAE) - 38.9 (R = 0.56, p < 0.0001). An adjustment for echocardiographic PAE was made by multiplying it by hemoglobin (in g/dl) and (right atrial area)^1.5 (in cm³). As RHC-derived PVR varies with blood hemoglobin, an adjustment for PVR was made for hemoglobin of 12 g/dl. Visualization of the XY scatter plot of adjusted PVR and adjusted PAE isolated a subset of patients with PVR higher than 8.8 Wood units, where a strong linear relationship existed (adjusted PVR = (0.89 x adjusted PAE) + 137.4, R = 0.89, p = 0.008). Conclusions: The correlation coefficient of the regression equation connecting echocardiographic PAE and RHC-derived PVR was moderate. In a subset of patients with very high PVR and after appropriate adjustment, a strong linear relationship existed with an excellent correlation coefficient.