Long-term oral bosentan treatment in patients with pulmonary arterial hypertension related to congenital heart disease: a 2-year study

Objective: To evaluate the long-term clinical and exercise effect of chronic oral administration of the nonselective endothelin receptor antagonist bosentan in patients with pulmonary arterial hypertension (PAH) related to congenital heart disease (CHD). Design: Extension of a preceding prospective non-randomised open clinical study on bosentan treatment in PAH related to CHD. Setting: A tertiary referral centre for cardiology. Patients: 19 of the original 21 patients of mean (standard deviation (SD)) age 22 (3) years (13 with Eisenmenger syndrome) in World Health Organization (WHO) class II-IV and having a mean (SD) oxygen saturation of 87 (2) %. Intervention: Patients received bosentan treatment for 2.4 (0.1) years and underwent clinical and exercise evaluation at baseline, 16 weeks and 2 years of treatment, with haemodynamic assessment at baseline and 16 weeks. Results: All patients remained stable with sustained subjective clinical and WHO class improvement (p < 0.01) at 16 weeks and 2 years of treatment without significant side effects or changes in oxygen saturation. After the initial 16-week improvement (p < 0.05) in peak oxygen consumption and exercise duration at treadmill test, and walking distance and Borg dyspnoea index at 6-min walk test, all exercise parameters appeared to return to their baseline values at 2 years of follow-up. Conclusions: Long-term bosentan treatment in patients with PAH related to CHD is safe and induces clinical stability and improvement, but the objective exercise values appear to slowly return to baseline. Larger studies on long-term endothelin receptor antagonism including quality of life assessment are needed to evaluate the therapeutic role of bosentan in this population.