Accuracy of transthoracic Doppler echocardiography in the estimation of pulmonary artery systolic pressures

Abstract

To investigate the qualitative accuracy of pulmonary artery systolic pressure (PASP) as estimated by transthoracic Doppler echocardiography (TDE). A retrospective study was conducted on 102 adult patients with idiopathic pulmonary arterial hypertension undergoing Doppler echocardiography within 72 hours prior to right heart catheterization. During this period, all patients were stable without any specific drug therapy. Compared with right heart catheterization, the accuracy of PASP as measured by TDE was evaluated. Among them, there were 38 males and 64 females with an average age of (31 ± 11) years old (range: 18 - 59 years old). There was a moderate correlation between the measurements of PASP by TDE and right heart catheterization (r = 0.64, P < 0.01). Through the analysis of Bland-Altman, the bias for the TDE estimates of PASP was 6.7 mm Hg with a 95% limit of agreement ranging from -47.6 to 34.3 mm Hg. There were 60 (58.8%) cases with absolute differences over 10 mm Hg between two methods. Overestimation and underestimation of PASP by TDE occurred in 15.7% (16/102) and 43.1% (44/102) respectively. The magnitude of pressure underestimation and overestimation was insignificant [(25 ± 12) vs (26 ± 16) mm Hg, P = 0.765]. The probability of underestimate was higher than that of overestimate. As to the corresponding diagnostic categories of severity that each subject would fall into for each technique, the diagnostic categories of 16 overestimated patients were in accordance. Among 44 underestimated patients, 9 (20.5%) had their pressure underestimated within one diagnostic category (minor error) while 2 (4.5%) were within two diagnostic categories (major error). Due to a frequent rate of inaccurate estimation of PASP, TDE can not replace right heart catheterization. TDE tends to underestimate PASP and results in a diagnostic misclassification of degree.