The aim of this study is to demonstrate that clazosentan, administered as a continuous intravenous infusion at 5 mg/h until Day 14 post aneurysmal subarachnoid hemorrhage (aSAH), reduces the incidence of cerebral vasospasm -related morbidity and all-cause mortality within 6 weeks post-aSAH treated by surgical clipping. The primary endpoint of the study is the occurrence of cerebral vasospasm-related morbidity, and mortality of all-causes within 6 weeks post-aSAH, defined by at least one of the following: