Accuracy and precision of three echocardiographic methods for estimating mean pulmonary artery pressure

Pulmonary hypertension is defined as resting mean pulmonary artery pressure (MPAP) ≥ 25 mm Hg. MPAP pressure estimation by right-sided heart catheterization (RHC) is considered the gold standard; however, its invasiveness limits repeated and frequent use. The purpose of this study was to compare the accuracy and precision of three echocardiographic methods for estimating MPAP.

We prospectively studied 117 patients with simultaneous RHC and echocardiography. MPAP was calculated by three echocardiographic methods: (1) mean gradient method (adding the right ventricular-right atrial mean systolic gradient to the right atrial pressure), (2) Chemla equation (0.61 × systolic pulmonary artery pressure + 2 mm Hg), and (3) Syyed equation (0.65 × systolic pulmonary artery pressure + 0.55 mm Hg). MPAP calculated by these three methods was compared with that obtained invasively by RHC.

The mean ± SD of the differences between invasive MPAP and the three echocardiographic methods were -1.6 ± 7.7 mm Hg for the mean gradient method, -3.7 ± 7.4 mm Hg for the Chemla formula, and -3.2 ± 7.6 mm Hg for the Syyed formula. Median absolute differences were 5.5 mm Hg (mean gradient), 5.7 mm Hg (Chemla; P = .45 vs mean gradient), and 6.0 mm Hg (Syyed; P = .23 vs mean gradient). Accuracy (calculated MPAP within 10 mm Hg of RHC-measured MPAP) was 81% (mean gradient), 77% (Chemla), and 76% (Syyed).

Echocardiographic estimation of MPAP by the mean gradient method had similar accuracy and precision compared with the Chemla and Syyed methods. The acceptable accuracy of these methods suggests that they are equally suitable for clinical use.