Methods
Consecutive patients undergoing right heart catheterization for suspected PH were included in this study (patients with mPAP ≥ 25 mm Hg were classed as having PH; those with mPAP < 25 mm Hg served as non-PH controls). In total, 160 patients with PH (idiopathic pulmonary arterial hypertension, pulmonary arterial hypertension associated with connective tissue disease, chronic thromboembolic PH, and pulmonary venous hypertension) and 44 non-PH controls were included. Plasma from the time of PH diagnosis was analyzed for levels of MMP2, MMP9, TIMP1, and TIMP4 using enzyme immunoassays. Correlation analyses were performed with Pearson's or Spearman's coefficient, as appropriate. Mortality hazard ratios were derived using Cox regression analyses.