Initial combination therapy with ambrisentan+tadalafil on pulmonary arterial hypertensionrelated hospitalization in the AMBITION trial

BACKGROUND: In the randomized, double-blind, event-driven AMBITION study, initial combination therapy with ambrisentan and tadalafil was associated with a 50% reduction in risk of clinical failure (first occurrence of all-cause death, hospitalization for worsening pulmonary arterial hypertension [PAH], disease progression, or unsatisfactory long-term clinical response) vs pooled monotherapy. These results were primarily driven by a reduction in PAH-related hospitalization in the combination therapy group, although a significant effect was not observed in a post-hoc analysis of all-cause hospitalization. METHODS: The effect of initial combination therapy with ambrisentan and tadalafil in AMBITION was further explored to study PAH-related hospitalization, which was not reported in the primary publication. RESULTS: Initial combination therapy was associated with a 63% reduction in risk of PAH-related hospitalization when compared with pooled monotherapy (hazard ratio [HR] 0.372, 95% confidence interval [CI] 0.217 to 0.639, p=0.0002). For every 9 patients treated with combination therapy vs monotherapy, 1 PAH-related hospitalization could be prevented over a 1-year period. Serious adverse events leading to hospitalization, not necessarily PAH-related, occurred in 87 of 253 (34%) and 89 of 247 (36%) of patients on combination therapy and pooled monotherapy, respectively (post-hoc summary). CONCLUSIONS: Initial combination therapy with ambrisentan and tadalafil was found to reduce the risk of PAH-related hospitalization by 63% compared with pooled monotherapy.

• Vachiery, J. L.
• Galie, N.
• Barbera, J. A.
• Frost, A. E.
• Ghofrani, H. A.
• Hoeper, M. M.
• McLaughlin, V. V.
• Peacock, A. J.
• Simonneau, G.
• Blair, C.
• Miller, K. L.
• Langley, J.
• Rubin, L. J.
• Ambition Study Group