Long-term effect of bosentan in adults versus children with pulmonary arterial hypertension associated with systemic-to-pulmonary shunt: does the beneficial effect persist?

BACKGROUND: Data on long-term response to bosentan in adults and especially children with pulmonary arterial hypertension (PAH) associated with systemic-to-pulmonary shunt are scarce.
METHODS: We studied bosentan efficacy in 30 patients (20 adults, 10 children) with the disease at short- (4 months), and long-term follow-up (through 2.7 years). World Health Organization functional class (WHO class), transcutaneous oxygen saturation, and 6-minute walk distance were assessed at baseline, 4 months, 1 year, 1.5 years, and at latest follow-up (median 2.7 years).
RESULTS: At baseline, children tended to have more severe disease compared with adults with regard to WHO class and congenital heart defects. At 4 months' follow-up, WHO class and 6-minute walk distance significantly improved in both adults and children. During long-term follow-up, this improvement persisted through 1 year but declined thereafter in the total group. In the children, a progressive decline in exercise capacity was observed from 1-year follow-up, whereas in the adults, improvement lasted longer. No change from baseline was seen in transcutaneous oxygen saturation. Three (10%) patients died, 2 (7%) discontinued bosentan, and 5 (17%) required additional PAH therapy (of whom 1 eventually died). One- and 2-year persistence of beneficial bosentan effect was 68% and 43% (total group), 78% and 57% (adults), and 50% and 20% (children), respectively.
CONCLUSIONS: Our experience with bosentan suggests short-term improvement in both adults and children with PAH associated with systemic-to-pulmonary shunt. At long-term follow-up, a progressive decline in beneficial bosentan effect was observed. The decline appeared most pronounced in the pediatric patients, who, in this study, tended to have more severe disease at baseline.