Parenteral prostanoids for severe Group 3 pulmonary hypertension with right ventricular dysfunction

Background: Group 3 pulmonary hypertension (PH) is a common complication in patients with lung diseases but there are currently no FDA-approved therapies. The data is conflicting, but a few small studies suggest potential benefits in using Group 1 PH therapies in these patients, particularly in severe PH with right ventricular (RV) dysfunction. Methods: A retrospective cohort study of patients with severe Group 3 PH with RV dysfunction who received parenteral prostanoids from 2007-2018 at our institution was undertaken. Severe PH was defined as mean pulmonary arterial pressure (mPAP) =35 mmHg or mPAP 25-34 with cardiac index (CI) <2.4 L/min/m². Routine prognostic studies including N-terminal prohormone of brain natriuretic peptide (NT-proBNP), 6-minute walk distance (6MWD), WHO Functional Class assessment, oxygen requirement, arterial oxygen saturation, right ventricular systolic pressure (RVSP) and right heart catheterization (RHC) pressures, were obtained before initiation of parenteral therapy and at first clinical follow-up. Results: Nine patients were included. Five were female (55.6%) with a median [interquartile range (IQR)] of 69 [54-71] years. Median CI was 1.8 (1.6-2.4) L/min/m²and median pulmonary vascular resistance (PVR) was 14.7 (10.7-17.1) Wood units (WU). We found no statistically significant improvement in NTproBNP levels, exercise capacity, or functional class. Resting oxygen requirement worsened from 4 to 6 L/min (P=0.04) and exertional oxygen saturation nadir worsened from 90% to 83% (P=0.01) despite the increase in FiO2 with exertion. Overall results were heterogenous: several patients demonstrated clinical stabilization, with two undergoing lung transplantation and one showing long-term stability with medical therapy. Symptoms remained severe for most: three patients discontinued prostanoid therapy, choosing to pursue hospice care. Conclusions: We found no statistically significant improvement in NT-proBNP levels, exercise capacity, or functional class, while oxygen requirement at rest and oxygen saturation during exertion significantly worsened. Our results suggest that parenteral prostanoids should not generally be considered in the treatment of Group 3 PH patients.