Right ventricular (RV) dysfunction is a predictor of adverse outcomes in patients with pulmonary arterial hypertension (PAH). Three-dimensional (3D) speckle-tracking echocardiography (STE) has been increasingly used to quantify RV function. However, the strain parameters evaluated by two-dimensional (2D) STE and 3D STE, which provide the most valuable clinical information, remain unknown. The purpose of our study was to investigate whether RV longitudinal strain (LS) provided a superior estimation of RV systolic performance and prognostic information compared with other strain vectors.

We prospectively studied 54 treatment-naïve patients with PAH and 35 normal controls. Pulmonary artery systolic pressure classified patients with PAH into three subgroups. Patients with PAH underwent echocardiography, cardiac magnetic resonance (CMR) imaging, 6-minute walking tests, and right-sided cardiac catheterization before and six months after vasodilator therapy. The 2D LS, 3D LS, circumferential strain (CS), and radial strain (RS) of RV free wall were calculated by 2D and 3D STE. RV ejection fraction (RVEF) was obtained from CMR. The patients were followed for a predefined endpoint of PAH-related hospitalization and death.

Our findings revealed that 2D and 3D LS showed significant reduction in mild PAH patients, whereas CS and RS were decreased in moderate and severe PAH patients. Right ventricular 3D LS had a similar correlation with CMR RVEF and hemodynamic parameters as 2D LS and the other strain vectors. The 2D and 3D LS improved 6 months after vasodilator therapy (P < .001 for both). After a median follow-up of 28 months, 20 patients had endpoint events. Receiver operating characteristic curve analysis demonstrated that RV 3D LS displayed a similar diagnostic performance for detecting adverse cardiac events as 2D LS (area under the curve: 0.84 vs 0.76, P = .11). Separate multivariable Cox analysis showed that RV 2D LS (hazard ratio [HR] = 1.19; 95% CI, 1.03～1.45; P = .01) and 3D LS (HR = 1.28; 95% CI, 1.08～1.52; P = .005) were significant predictors of adverse outcomes.

Patients with PAH show reduced RV strain. Two-dimensional and 3D LS can track clinical improvement following vasodilator therapy and provide valuable prognostic information.