Subarachnoid hemorrhage (SAH) is a frequent and severe disease. Mortality can reach 40%. The most frequent complication of SAH is arterial vasospasm, with estimated incidence as high as 70%. Vasospasm is responsible for cerebral ischemia leading to severe morbidity, poorer quality of life and increased mortality. Intravenous Milrinone, because of vasodilatory properties could be a therapeutic option. We hypothesize that intravenous infusion of Milrinone will improve the neurological recovery of patients with vasospasm following aneurysmal SAH at 3 months. This is a Phase III, multi-center, randomized, double-blinded, placebo-controlled study. The primary outcome will be the proportion of patients with a good outcome 3 months (defined as a modified rankin score ≤2).