Bosentan Therapy for Inoperable Chronic Thromboembolic Pulmonary Hypertension

We performed an open-label multicenter study to evaluate the safety and efficacy of the dual endothelin receptor antagonist bosentan in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). Nineteen patients with inoperable CTEPH were enrolled. The primary end point was a change in pulmonary vascular resistance (PVR). Secondary end points included 6-min walk test, peak oxygen uptake ( V˙ o2), New York Heart Association functional class, serum levels of N-terminal-pro brain natriuretic peptide (NT-pro-BNP), and various other hemodynamic parameters. After 3 months of treatment with bosentan, PVR decreased from 914 ± 329 to 611 ± 220 dyne·s·cm−5 (p < 0.001). Functional class and peak V˙ o2 remained unchanged, but 6-min walk distance increased from 340 ± 102 to 413 ± 130 m (p = 0.009), and serum NT-pro BNP levels improved from 2,895 ± 2,620 to 2,179 ± 2,301 (p = 0.027). One patient died, presumably from influenza A infection, and another patient experienced progressive fluid retention despite reduction of PVR. Other than that, treatment was well tolerated by all patients. This open-label pilot trial suggests that bosentan may offer a therapeutic option for patients with inoperable CTEPH. Randomized controlled trials are warranted to confirm these findings.