MEGF9 and pulmonary arterial hypertension: Fourth, we provided evidence for five potential ECM-related biomarkers (NID1, C1QTNF1, CRTAC1, MEGF9 and SPARCL1) that were altered at both RV transcriptome and plasma proteome levels, which could classify compensated and decompensated RV and predict worse clinical outcomes in PAH participants.