Introduction. Pre-capillary pulmonary hypertension (PH), including pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH), is a severe condition leading to right heart failure and death. In these patients timely diagnosis, risk stratification and treatment are of extreme importance. The aim of the study was to investigate the changes of the electrocardiogram-derived ventricular gradient (VG) and spatial QRS-T angle in different forms of pre-capillary PH. Methods. We examined 3 groups of female PH patients: 21 with idiopathic PAH (IPH, mean age 50±6 years); 18 with PAH associated with systemic sclerosis (SS, 58±10 years); 21 with CTEPH (54±8 years). 30 healthy females (55±9 years) comprised the control group. Spatial QRS-T angle and VG were calculated using digital derived vectorcardiogram. Systolic pulmonary artery pressure (SPAP), right ventricular anterior-posterior dimension (RV APD) and right atrial area (RAA) were estimated using transthoracic echocardiography. Results. As compared with normal group in PH patients QRS-T angle was significantly increased, VG significantly decreased. These changes were the most pronounced in patients with SS: QRS-T angle, degrees: 49±20 in normal group; 90±41 in IPH; 89±40 in CTEPH; 122±31 in SS; VG, mV*ms: 77±13 in normal group; 48±26 in CTEPH; 34±14 in IPH; 30±17 in SS. Groups of PH patients had no statistically significant differences in SPAP and RV APD. RAA was greater in SS (27±7 cm2) as compared with IPH (23±6 cm2) and CTEPH (22±7 cm2). QRS-T angle correlated with RAA (r=0.4, p<0.01). VG correlated with RAA (r= –0.4, p<0.01), SPAP (r= –0.3, p<0.05), RV APD (r= –0.3, p<0.05) and heart rate (r= –0.4, p<0.01). Conclusions. Patients with PAH associated with SS were characterized with the most pronounced changes in spatial QRS-T angle and VG as compared with IPH and CTEPH. In patients with pre-capillary PH spatial QRS-T angle and VG had statistically significant correlations with RAA — important echocardiographic predictor of poor prognosis.