Baseline demographics, hemodynamic, inflammatory and disease severity parameters of the study population are given in Table 1. Clinical baseline parameters did not differ between PAH and CTEPH subgroups except gender and height. PAH and CTEPH patients had severe disease as reflected by highly elevated mean pulmonary artery pressure (mPAP), mean pulmonary vascular resistance (PVR) and a World Health Organisation function class (WHO FC) of III or IV in the majority of the patients (88% and 85%, respectively). PAH and CTEPH groups did not differ regarding hemodynamic status or functional class. Median follow-up was similar in both groups: 33 months (range 4–111) in the PAH and 34 months (range 1–108) in the CTEPH subgroup.