Comparison of pulmonary hypertension (PH) associated to chronic lung disease to other PH groups

Introduction: Group 3 pulmonary hypertension (PH) is a common complication of advanced chronic lung disease, with no demonstrated benefit of specific therapy. Objectives: Our hypothesis was that group 3 PH is associated with a more severe baseline presentation and a worse prognosis compared to group 1 pulmonary arterial hypertension (PAH), chronic thromboembolic PH (group 4) and group 5 PH. Methods: We retrospectively analysed consecutive incident patients with PH, from a single center between January 2006 and November 2014. Data were acquired from a prospective database. Clinical, functional and haemodynamic characteristics as well as survival were compared between the 4 precapillary PH groups. Results: 363 patients were included, with a median age of 69 years. 164 patients (45.2%) belonged to group 1 PAH, 109 (30%) to group 3 PH, 65 (17.9%) to group 4 and 25 (6.9%) to group 5 PH. Group 3 patients had more frequently NYHA class III or IV. Patients with groups 3 and 4 PH were older, had significantly lower 6 minute walk distance, higher mean pulmonary arterial pressure, higher pulmonary vascular resistance and lower cardiac index. Group 3 patients had significantly lower values of total lung capacity, forced vital capacity and carbon monoxyde transfer coefficient (KCO). PH specific therapy was used in 90.9% of group 3 patients. Compared to PAH, group 3 patients had significantly higher mortality. In multivariate analysis, age > 65 years and group 3 PH were significantly associated with mortality. Conclusions: Patients with group 3 PH are older, have more severe clinical, functional and haemodynamic characteristics, and worse survival, than PAH patients, despite specific therapy.