In the present study, we demonstrated that our simple RV dysfunction score using four important RV echocardiographic parameters (TAPSE < 16 mm, S′ < 10 cm/s, RVFAC < 35%, and RV-MPI > 0.4) was useful for risk assessment in CTEPH patients in terms of symptoms (WHO functional class), hemodynamics, exercise capacity (6MWT and CPET) and plasma BNP level. Here, NPPB is linked to chronic thromboembolic pulmonary hypertension.