Upfront combination therapy including intravenous prostaglandin I (PGI-IV) is recognized as the most appropriate treatment for patients with severe pulmonary arterial hypertension (PAH). This retrospective study aimed to determine reasons why this therapy is not used for some patients with severe PAH and describe the hemodynamic and clinical prognoses of patients receiving initial combination treatment with (PGI-IV+) or without (PGI-IV-) PGI-IV.Data for patients with severe PAH (World Health Organization Functional Class III/IV and mean pulmonary arterial pressure [mPAP] ≥ 40 mmHg) were extracted from the Japan Pulmonary Hypertension Registry. Overall, 73 patients were included (PGI-IV + n = 17; PGI-IV- n = 56). The PGI-IV+ cohort was younger than the PGI-IV- cohort (33.8 ± 10.6 versus 52.6 ± 18.2 years) and had higher mPAP (58.1 ± 12.9 versus 51.8 ± 9.0 mmHg), greater prevalence of idiopathic PAH (88% versus 32%), and less prevalence of connective tissue disease-associated PAH (0% versus 29%). Hemodynamic measures, including mPAP, showed improvement in both cohorts (post-treatment median [interquartile range] 38.5 [17.0-40.0] for the PGI-IV + cohort and 33.0 [25.0-43.0] mmHg for the PGI-IV – cohort). Deaths (8/56) and lung transplantation (1/56) occurred only in the PGI-IV – cohort.These Japanese registry data indicate that older age, lower mPAP, and non-idiopathic PAH may influence clinicians against using upfront combination therapy including PGI-IV for patients with severe PAH. Early combination therapy including PGI-IV was associated with improved hemodynamics from baseline, but interpretation is limited by the small sample size.
