BACKGROUND: Pulmonary hypertension (PH) medical therapies are commonly used as a bridge to balloon pulmonary angioplasty (BPA) in patients with chronic thromboembolic PH (CTEPH) but their effectiveness remains unclear. We investigated the impact of different bridging therapies in patients undergoing BPA. METHODS: This secondary analysis of the prospective CTEPD UK Registry to Assess Treatments and OutcomEs registry evaluated the impact of different PH medical therapies on haemodynamic and physiological parameters in the UK's national CTEPH cohort. Consecutive patients undergoing first BPA at Royal Papworth Hospital between October 2015 and October 2024 were included. Baseline parameters were assessed at CTEPH diagnosis and after initiating bridging PH medical therapy prior to BPA. Periprocedural complications at first BPA were compared between groups. RESULTS: Haemodynamic and functional parameters of 158 patients were analysed. Patients managed with phosphodiesterase-5 inhibitor (PDE5i) and endothelin receptor antagonist (ERA) dual therapy had higher baseline mean pulmonary artery pressure (mPAP, p=0.019), right atrial pressure (RAP, p=0.038) and pulmonary vascular resistance (PVR, p=0.004) and lower cardiac output (CO, p=0.017) and cardiac index (CI, p=0.029) versus PDE5i or riociguat monotherapy. Dual therapy was associated with a greater percentage increase in CI (40% vs 13% vs 16%, p<0.001) and CO (34% vs 8% vs 14%, p<0.001) and a greater percentage decrease in PVR (-39% vs -30% vs -25%, p=0.008) and N-terminal pro-B-type natriuretic peptide (-67% vs -21% vs -32%, p=0.004) compared with PDE5i monotherapy and riociguat monotherapy. These differences persisted after multivariable adjustment for baseline haemodynamic severity. Lung injury occurred more frequently in patients with higher PVR (>540 dynes·s·cm⁻⁵, p=0.049) and mPAP (>40 mm Hg, p=0.001) at first BPA. Periprocedural complication rates at first BPA were similar between bridging strategies. CONCLUSIONS: Bridging with PH medical therapies to first BPA was associated with improved haemodynamic parameters in this real-world observational study. PDE5i and ERA dual therapy was associated with greater haemodynamic improvement than monotherapy with PDE5i or riociguat, without differences in complication rates.