Discontinuation Versus Continuation of Riociguat Monotherapy in Chronic Thromboembolic Pulmonary Hypertension Successfully Treated With Balloon Pulmonary Angioplasty

Inclusion Criteria: * 1\. Signed informed consent and willingness to accept either discontinuation or continuation of riociguat monotherapy * 2\. Age ≥18 years * 3\. Diagnosis of inoperable CTEPH or persistent PH after PEA, with achievement of therapeutic goals following BPA, defined as: 1. WHO FC I or II 2. Pulmonary vascular resistance (PVR) \< 3 Wood units 3. Mean pulmonary artery pressure (mPAP) \< 30 mmHg * 4\. Treatment with riociguat monotherapy for ≥6 months, with stable dose for ≥3 months prior to enrollment * 5\. Last BPA session performed ≥6 months prior to enrollment * 6\. 6-minute walk distance (6MWD) ≥ 150 meters * 7\. For women of childbearing potential: highly effective contraception Exclusion Criteria: * 1\. Background treatment with any PH-targeted therapy other than riociguat, (e.g., any endothelin receptor antagonist (ERA), phosphodiesterase-5 inhibitor (PDE-5i), parenteral prostanoids, prostacyclin receptor agonist) * 2\. Post-capillary pulmonary hypertension, defined as pulmonary artery wedge pressure (PAWP) \> 15 mmHg * 3\. Significant obstructive or restrictive lung disease, defined as: * FEV₁ \< 60% predicted, with FEV₁/FVC \< 65% * and/or total lung capacity (TLC) \< 60% predicted * or known significant chronic lung disease on imaging (e.g., interstitial lung disease, emphysema) * 4\. Severe hepatic impairment, defined as: * Child-Pugh class B or C * and/or liver aminotransferase levels \> 3× upper limit of normal (ULN) * 5\. Severe renal impairment (estimated creatinine clearance ≤ 30 mL/min/1.73 m²). * 6\. Left heart failure with left ventricular ejection fraction (LVEF) \< 40% * 7\. Ongoing or planned treatment with organic nitrates. * 8\. Concomitant treatment with strong cytochrome P450 3A4 (CYP3A4) inducers (e.g., rifabutin, rifampicin, carbamazepine, phenobarbital, phenytoin, St. John's wort) * 9\. Concomitant treatment with strong multi pathway P-glycoprotein (P-gp)/ breast cancer resistance protein (BCRP) inhibitors (e.g., lopinavir/ritonavir). * 10\. Treatment with a strong CYP3A4 inhibitor (e.g., ketoconazole, itraconazole, voriconazole, clarithromycin, telithromycin, nefazodone, ritonavir, and saquinavir) or a moderate dual CYP3A4/CYP2C9 inhibitor (e.g., fluconazole, amiodarone) or co-administration of a combination of moderate CYP3A4 and moderate CYP2C9 inhibitors. * 11\. History of life-threatening hemoptysis (\>100 mL within 24 hours) or prior bronchial artery embolization for hemoptysis * 12\. Pregnancy, breastfeeding, or intention to become pregnant during the study period * 13\. Severe comorbidities or underlying conditions with an anticipated life expectancy \< 12 months, including active malignancy with localized or metastatic disease * 14\. Lack of coverage by national health or social security systems * 15\. Alcohol abuse, as determined by the investigator * 16\. Any condition or factor likely to interfere with protocol compliance, in the opinion of the investigator * 17\. Patient under guardianship or curatorship * 18\. Participation in another interventional trial or being in the exclusion period following a previous research involving the human person