The Results of Long-Term Pah-Specific Monotherapy With Bosentan in Patients With Idiopathic Pulmonary Hypertension

Objective. To evaluate the dynamics of clinical and functional status, the parameters of central hemodynamics and tolerability of bosentan therapy lasting more than 12 months in patients with idiopathic pulmonary hypertension (IPAH). Materials and methods. In the study we included 20 IPAH non-responders with functional class II-III (WHO). All patients were assigned to treatment with bosentan in the initial dose of 125 mg/ day, which was increased to 250 mg/day after 4 wks. The mean FU duration was 15±3 months. Conducted 5 visits: at baseline and visit 5, all patients underwent a comprehensive examination, including right heart catheterization (RHC). Transthoracic echocardiography was performed additionally at visit 3. 6-minute walking (6MW) test was assessed every 3 months. For safety reasons hepatic transaminases were analyzed monthly. Results. Bosentan therapy resulted to significant improvement of functional class (FC (I/II/III) with 0%/45%/55% to 30%/45%/25%, p<0.05) to 15±3 month. Mean 6MW distance increases by 54 m. In 9 pts during extension period the achieved clinical and functional status remained stable to 54±6 months. We showed the significant decrease of right ventricle and atrium sizes. At 15±3 months RHC revealed a significant decrease in SPAP, PVR, increase of cardiac output / cardiac index, oxygen saturation of mixed venous and arterial blood. During follow-up period we found the maximal increase of liver enzymes of 1.5 ULN. Adverse events (headache and flushing) were reported in 1 pt. without requirement of treatment discontinuation. Conclusion. Bosentan therapy was highly effective in IPAH patients with FC II-III for 15±3 months. Stable functional and hemodynamic status of patients was maintained to 54±6 months with good tolerability of the treatment.