A total of 112 patients were included in this study - 52 (46%) patients with PAH, 49 (44%) with CTEPH and 11 (10%) control individuals with suspected pulmonary hypertension that was eventually ruled out by right heart catheterisation (RHC). PAH patients comprised idiopathic PAH (n = 39), familial PAH (n = 3) and PAH associated with portal hypertension (n = 6), connective tissue disease (n = 2) and congenital heart disease (n = 2).