A study on 31 patients with PAH-CHD showed a significant positive linear correlation among mPAP and plasma ET-1, ADMA, BNP, and uric acid (UA) levels in all patients, and suggested that ET-1 may be a biomarker of PAH-CHD and can be used to pre-evaluate the effect of iloprost on PAH-CHD (15). Here, EDN1 is linked to pulmonary arterial hypertension.