Exploring biomarkers in CTEPH: prognostic significance and post-PEA dynamics analysis

<bold>Background:</bold> CTEPH is a progressive pulmonary vascular (PV) disease defined by elevated pulmonary arterial pressure resulting from PV obstruction and microvasculopathy. Tools to quantify microvasculopathy extension and residual PH post-PEA are lacking. This study aims to assess if circulating biomarkers can predict responsiveness to PEA (defined as mPAP<25mmHg at least 3months post-PEA) in operable CTEPH patients and to determine if their levels vary post-PEA. <bold>Methods:</bold> Data were collected at CTEPH diagnosis and at least 3 months after PEA. CRP, FSTL3 and activin A were measured using standard ELISA, BMP9, ET1, CXCL9, TRAIL, βNGF using SimplePlex ELLA on plasma samples obtained shortly before and 6 months after PEA. <bold>Results:</bold> 71 CTEPH and 43 controls were enrolled. ET1, CXCL9, activin A, FSTL3, CRP and βNGF were higher in CTEPH vs controls (all p<0.001), while TRAIL and BMP9 were similar. In univariate analysis, higher levels of CRP, FSTL3 and activin A before surgery were predictors of unresponsiveness to PEA. Higher levels of activin A were predictors of unresponsiveness even after adjustment for mPAP, age and CRP (Table1). After PEA, plasma levels of ET1, CXCL9 and βNGF reduced, while TRAIL increased (Table2). <bold>Conclusions:</bold> Higher concentrations of activin A, FSTL-3 and CRP before PEA are predictive of residual PH. Activin A might be a marker of microvasculopathy in CTEPH considering that its level does not vary after PEA. <fig><object-id>erj;64/suppl_68/OA1875/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>