Study objectives: 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).
Patients: Nineteen patients with inoperable CTEPH were enrolled.
Measurements: 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.
Results: 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.
Conclusions: 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.