Accuracy of Doppler Echocardiography in the Hemodynamic Assessment of Pulmonary Hypertension

Rationale. Transthoracic Doppler echocardiography is recommended for screening for the presence of pulmonary hypertension (PH): However, some recent studies have suggested that Doppler echocardiographic pulmonary artery pressure estimates may frequently be inaccurate. Objectives: Evaluate the accuracy of Doppler echocardiography for estimating pulmonary artery pressure and cardiac output. Methods: We conducted a prospective study on patients with various forms of PH who underwent comprehensive Doppler echocardiography within 1 hour of a clinically indicated right-heart catheterization to compare noninvasive hemodynamic estimates with invasively measured values. Measurements and Main Results: A total of 65 patients completed the study protocol. Using Bland-Altman analytic methods, the bias for the echocardiographic estimates of the pulmonary artery systolic pressure was -0.6 mm Hg with 95% limits of agreement ranging from +38.8 to -40.0 mm Hg. Doppler echocardiography was inaccurate (defined as being greater than +/- 10 mm Hg of the invasive measurement) in 48% of cases. Overestimation and underestimation of pulmonary artery systolic pressure by Doppler echocardiography occurred with a similar frequency (16 vs. 15 instances, respectively). The magnitude of pressure underestimation was greater than overestimation (-30 +/- 16 vs. +19 +/- 11 mm Hg; P = 0.03); underestimates by Doppler also led more often to misclassification of the severity of the PH. For cardiac output measurement, the bias was -0.1 L/min with 95% limits of agreement ranging from +2.2 to -2.4 L/min. Conclusions: Doppler echocardiography may frequently be inaccurate in estimating pulmonary artery pressure and cardiac output in patients being evaluated for PH.