S100A4 and chronic thromboembolic pulmonary hypertension: Before surgery, systemic S100A4 levels of CTEPH patients (1394.4 ± 960.4 pg/mL) and iPAH (1349.3 ± 894.6 pg/mL) were significantly decreased compared to healthy controls (CTEPH-control: 2065.6 ± 648.4 pg/mL; p = 0.002; iPAH-control: 2127.5 ± 706.8 pg/mL; p = 0.007) (Figure 2A,B).