The previous studies demonstrated that treatment with riociguat led to a significant increase in 6-min walk distance (6MWD) as well as a decrease in pulmonary vascular resistance (PVR) and N-terminal prohormone of brain natriuretic peptide (BNP) in CTEPH1 and PAH.2 However, the mechanisms of such improvement of clinical condition remain to be clarified. Here, NPPB is linked to pulmonary arterial hypertension.