Background: Bosentan, an oral endothelin (ET)-A/ET-B receptor antagonist, is effective in the treatment of pulmonary arterial hypertension.
Objective: To investigate the safety and efficacy of bosentan therapy in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).
Design: Case series.
Setting: Pulmonary Hypertension Unit of the Medical University of Vienna, Austria.
Patients: Sixteen patients (9 women and 7 men; mean age ± SD, 70 ± 13 years).
Intervention: Off-label bosentan treatment over 6 months.
Measurements: Changes from baseline in liver enzymes, New York Heart Association (NYHA) functional class, 6-min walking distance (6-MWD), and serum amino-terminal pro-brain natriuretic peptide (proBNP).
Results: After 6 months, NYHA functional class improved by one class in 11 patients. Mean 6-MWDs increased from 299 ± 131 m at baseline to 391 ± 110 m at 6 months (p = 0.01). In parallel, proBNP decreased from 3,365 ± 2,923 to 1,755 ± 1,812 pg/mL (p = 0.01). Neither aspartate aminotransferase (25 ± 2 U/L vs 25 ± 2 U/L, p = 0.25) nor alanine aminotransferase (23 ± 12 U/L vs 24 ± 9 U/L, p = 0.57) changed significantly. Limitations of the study were uncontrolled design and small sample size.
Conclusions: Our study suggests a beneficial effect of the oral dual ET receptor antagonist bosentan in patients with inoperable CTEPH, urging the need for a randomized, placebo-controlled trial.