[First clinical experience with endothelin receptor antagonist bosentan used in patients with pulmonary hypertension: results of a one-year study].

Aim: To evaluate the efficiency and safety of long-term (12-month) treatment with the endothelin receptor antagonist bosentan (tracleer (Actelion, Switzerland)) in patients with pulmonary hypertension (PH).

Subjects And Methods: The prospective observational study enrolled 10 patients (8 with idiopathic PH and 2 with PH and systemic scleroderma). The patients' mean age was 50.0 +/- 6.9 years; mean pulmonary artery pressure (mPAP) 65 +/- 12 mm Hg; cardiac output (CO) 3.4 +/- 0.8 l/min; 6-minute walk test (6'WT) distance, 318 +/- 94 m. Before and 3, 6, and 12 months after the treatment, the patients underwent Doppler echocardiography, arterial blood gas analysis, external respiratory function test, and dyspnea evaluation using the MRC scale and 6'WT. The initial dose of bosentan was 62.5 mg b.i.d., then 125 mg b.i.d. following 4 weeks.

Results: Bosentan treatment resulted in a reduction in pulmonary artery systolic pressure and mPAP (at 12 months: 76.8 +/- 11.5 and 58.8 +/- 11.4 mm Hg, respectively; p < 0.01) and an increase in CO (at 12 months: 4.2 +/- 1.2 l/min; p = 0.002). Six patients were observed to have a lower WHO classification functional class (FC). Lung diffusing capacity tended to improve (at 12 months, the increment was more than 6% of the reference value; p = 0.059). In the patients, dyspnea was relieved as shown by MRS scores from 3.1 +/- 0.7 (at baseline) to 2.1 +/- 0.6 (at 12 months); p = 0.002. The 6'WT distance increased up to 342 +/- 67 m (at 12 months); p = 0.005. The drug was well tolerated; only one patient had a transient increase in the activity of liver enzymes.

Conclusion: The long-term bosentan treatment in patients with PH leads to improvements in pulmonary hemodynamics, WHO classification functional class, a reduction in dyspnea, and a rise in exercise tolerance.