BACKGROUND: In chronic thromboembolic pulmonary hypertension (CTEPH), right heart failure determines outcome. Balloon pulmonary angioplasty (BPA) therapy allows right heart recovery, which can be monitored by cardiac magnetic resonance imaging (CMR). This study evaluates whether cardiac biomarkers (NT-proBNP, MR-proANP, sST2, PAPP-A) are associated with CMR findings prior to and after BPA therapy. METHODS: This observational cohort study enrolled 22 CTEPH patients who underwent BPA therapy and completed a 6-month follow-up including CMR. Biomarker levels were compared with findings for right heart morphology and function derived from CMR. RESULTS: Pulmonary hemodynamics improved after BPA therapy [PVR: 7.7 (6.0-9.0) vs. 4.7 (3.5-5.5) WU, p<0.001; meanPAP 41 (38-47) vs. 32 (28-37) mmHg, p<0.001]. CMR findings indicated right heart maladaptation at baseline and recovery after therapy [RVEDV 192 (141-229) ml vs. 143 (128-172) ml, p=0.002; RVESV 131 (73-157) ml vs. 77 (61-99) ml (p<0.001); RVEF 34 (28-41) % vs. 52 (41-54) %; p<0.001]. Biomarker level cut-offs [NT-proBNP 347 ng/L (AUC 0.91), MR-proANP 230 pg/L (AUC 0.78), PAPP-A 14.5 mU/L (AUC 0.81), sST2 48.0 ng/ml (AUC 0.88)] indicated a RVEF â¤35% at baseline. The dynamics of NT-proBNP (rs =-0.79; p<0.001), MR-proANP (rs =-0.80; p<0.001), and sST2 (rs =-0.49; p=0.02) correlated inversely with the improvement in RVEF after therapy. A relative decrease of NT-proBNP <53% (AUC 0.86) and MR-proANP <24% (AUC 0.82) indicated a limited RVEF response. CONCLUSIONS: In CTEPH patients, CMR findings illustrate right heart failure and recovery after BPA therapy. Cardiac biomarker levels correlate with right heart parameters at baseline and their dynamics after therapy.