Tadalafil for Severe Pulmonary Hypertension Due to Chronic Obstructive Pulmonary Disease

Inclusion Criteria: * Patients ≥ 18 and \<85 years at inclusion, * Dyspnea WHO functional class II to IV, * Severe precapillary pulmonary hypertension defined by : * a mean pulmonary artery pressure (mPAP) \>20 * associated with normal pulmonary artery wedge pressure (PawP ≤15 mmHg) * and pulmonary vascular resistance (PVR) \>5 WU * COPD diagnosed according to current international recommendation with persistent airflow limitation defined by post-bronchodilatator Forced expiratory volume in 1 second (FEV1) / forced vital capacity (FVC): FEV1/FVC \< 0.70, * Naive patients from PDE5i (sildenafil, tadalafil) PH treatments and who did not receive other specific PH treatment in the last 3 months (bosentan, ambrisentan, macitentan, riociguat, epoprostenol, treprostinil, iloprost), * Treatments for COPD need to be stable for at least 1 month before screening visit, * Patients who fulfill criteria for a supplemental long-term oxygen therapy need to be supplied sufficiently before study entry. The amount of supplemental oxygen and the delivery method need to be stable for at least 1 month before screening visit, * Patients who are able to understand and follow instructions and who are able to participate in the study for the entire period, * Patients must have given their written informed consent to participate in the study after having received adequate previous information and prior to any study-specific procedures, * Affiliation to a social security regime, Exclusion Crite…