Efficacy of Bosentan in patients after Fontan procedures: a double-blind, randomized controlled trial

Fontan surgery is a widely used palliative procedure that significantly improves the survival period of patients with complex congenital heart disease (CHD). However, it does not decrease postoperative complication rate. Previous studies suggested that elevated mean pulmonary artery pressure (mPAP) and vascular resistance lead to decreased exercise tolerance and myocardial dysfunction. Therapy with endothelial receptor antagonists (Bosentan) has been demonstrated to improve the patients' prognosis. A double-blind, randomized controlled trial was performed to explore the efficacy of Bosentan in treating patients who underwent the Fontan procedure. Eligible participants were randomly divided into Bosentan group and control group. Liver function was tested at a local hospital and the results were reported to the phone inspector every month. If the results suggested abnormal liver function, treatment would be adjusted or terminated. All the participants finished the follow-up study, with no patients lost to follow-up. Unblinding after 2-year follow-up, no mortality was observed in either group. However, secondary end-points were found to be significantly different in the comparable groups. The cardiac function and 6-min walking distance in the Bosentan group were significantly superior to those in the control group (P=0.018 and P=0.027). Bosentan could improve New York Heart Association (NYHA) functional status and improve the results of the 6-min walking test (6MWT) in Fontan patients post-surgery, and no other benefits were observed. Furthermore, a primary meta-analysis study systematically reviewed all the similar clinical trails worldwide and concluded an overall NYHA class improvement in Fontan patients who received Bosentan treatments.