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).

Subarachnoid hemorrhage (SAH) is relatively frequent, accounting for 5% of strokes, and affects a relatively young population. It is essentially caused by cerebral aneurysm rupture. 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, delayed or not, which in turn is responsible for severe morbidity (neurological deficit, neuro psychiatric disorders...), poorer quality of life (institutionalization, inability to return to work ...) and increased mortality.

The pathophysiology of vasospasm is complex, multifactorial and far from being fully understood. Many drugs have been studied in the treatment of symptomatic vasospasm but none has really proven its efficacy. Milrinone is proposed for the treatment of cerebral vasospasm, either as intra-arterial injection (during angiography) or intravenously using continuous infusion. Indeed, among new vasospasm's treatments, Milrinone seems to have good angiographic and clinical results. There is no randomized controlled trials evaluating Milrinone for preventive and/or curative treatment of cerebral vasospasm following aneurysmal SAH. The literature is made only of clinical cases, cases series with angiographic studies or interventional studies not controlled and with no more than 10 patients.

Thus we hypothesize that the intravenous infusion of Milrinone will improve the neurological recovery of patients with vasospasm following aneurysmal SAH at 3 months.

Adult patients, hospitalized for a vasospasm complicating subarachnoid hemorrhage secondary to intracranial aneurysm rupture will be included and randomized within 6 hours of the CT-scanner confirming the vasospasm diagnosis to receive either the study drug (milrinione, a 0,1 mg/kg bolus followed by a 1 μg/kg/min perfusion) or placebo (saline, with a bolus and a continuous infusion). Study drug administration will be formalized (minimum duration 48 hours, maximum duration 14 days).The primary endpoint will be the proportion of patients with a good outcome 3 months (defined as a modified rankin score ≤2).

Inclusion Criteria:

• Adult patients hospitalized for aneurysmal SAH
• First episode of vasospasm, with a diagnosis confirmed on cerebral arterial CT-scanner
• Delay between diagnosis of vasospasm (done by CT-scanner) and inclusion ≤6 hours
• Informed consent from a legal representative, or emergency procedure

Exclusion Criteria:

• Initial Glasgow score at 3 with a bilateral mydriasis
• Moribund patient
• Contraindication to Milrinone (notably obstructive cardiomyopathy…)
• Cerebral infarction in the vasospasm area already present on the CT-scanner at the time of diagnosis (lack of expected benefit of treatment in this case according to medical judgement)
• Cardiac failure requiring inotrope administration at the time of randomisation
• Uncontrolled elevated intra-cranial pressure (i.e. ICP>25 mmHg for more than 20 minutes)
• Patient with flutter or cardiac arrhythmia (atrial fibrillation) poorly tolerated
• Major metabolic disturbance (uncorrected hypokalaemia <3 mmol/L)
• Non-affiliation to French health care coverage,
• Pregnant, breastfeeding or parturient woman
• Adult deprived of their liberty by judicial or administrative decision
• Adult under compulsory psychiatric care
• Adult patient protected under the law (guardianship or trusteeship)
• Inclusion in an interventional study using Milrinone, or evaluating a treatment of cerebral vasospasm or with the same primary endpoint (mRS at 3 months).

Data will be shared upon reasonable request. Only de-identified data will be shared. Any data collected during the study may be shared. The protocol will be shared initially. Other documents may be shared later upon request (e.g., the CRF to allow a collaborator to select the data to which they wish to have access). The recipients of the data will be researchers. The data will be available for any purpose deemed relevant by the MIVAR investigator, based on a protocol provided by the applicant, after verification of obtaining regulatory authorizations, including the favorable opinion of an ethics committee.

The data will be shared after signing a negotiated data transfer contract (data access agreement), for the duration indicated in the contract.

The data will be made available via secure transfer (sharing platform validated by Angers CHU: BlueFiles or Oodrive).