Combination therapy with bosentan and sildenafil in Eisenmenger syndrome: a randomized, placebo-controlled, double-blinded trial

To evaluate the efficacy of combining the dual endothelin receptor antagonist, bosentan, and the phosfodiesterase-5-inhibitor, sildenafil, in patients with Eisenmenger syndrome. The study was a randomized, placebo-controlled, double-blinded, cross-over design. Patients with Eisenmenger syndrome (n = 21) were treated open label with bosentan for 9 months. After 3 months, sildenafil/placebo was added for 3 months, and a cross-over was performed for the last 3 months. At baseline and after 3, 6, and 9 months, patients were examined with 6 min walk test, oxygen saturations, N-terminal pro-brain natriuretic peptide, New York Heart Association (NYHA) classification, cardiac catheterization, and magnetic resonance imaging. The primary endpoint was changed in 6 min walk distance (MWD). Bosentan improved the 6 MWD (377 vs. 414 m, P = 0.001), pulmonary vascular resistance (PVR) (28 vs. 22 wood, P = 0.01), and pulmonary blood flow (2.6 vs. 3.5 L/min, P = 0.01). Adding sildenafil to bosentan did not improve the 6 MWD significantly (21 vs. 8 m, P = 0.48), but increased saturation at rest (2.9 vs. -1.8%, P < 0.01). In Eisenmenger syndrome, treatment with bosentan significantly improved walking distance, pulmonary blood flow, and PVR. Adding sildenafil to bosentan did not significantly improve walking distance but did increase saturation at rest.