At time of initial RHC patients with PAH or CTEPH showed significantly elevated fibrinogen plasma concentrations (PAH: 4.1 ± 1.4 g/l, p = 0.0035; CTEPH: 4.3 ± 1.2 g/l, p = 0.0004) compared to non-PH control patients (3.4 ± 0.5 g/l, mean ± standard deviation).