D-dimer (399 (218, 1673) vs. 149 (106, 202) ng/ml, P < 0.001) and PCO2 (33.96 ± 11.68 vs. 28.43 ± 5.07 mmHg, P=0.019) were significantly higher, while NT-proBNP (324 (81, 893) vs. 739 (262, 1904) pg/ml, P=0.004) was significantly lower in the POPH group rather than in IPAH group. Here, NPPB is linked to idiopathic pulmonary arterial hypertension.