S100A9 and chronic thromboembolic pulmonary hypertension: The RAGE ligand S100A9 was not significantly different (S100A9 [μg/ml] 2.1±0.8 vs. 0.7±0.09; p = 0.064) whereas HMGB1 was significantly elevated in serum of patients with CTEPH (HMGB1 [pg/ml] 1141.1±173.1 vs. 464.3±66.6; p = 0.001; fig.