Cilostazol for Preventing Delayed Cerebral Ischemia in Aneurysmal Subarachnoid Hemorrhage

The investigators propose to conduct a multicenter randomized trial to test whether cilostazol reduces the incidence of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH) and improves patients' neurological prognosis, while assessing its safety.

Inclusion Criteria: * Aged 18-80 years. * Diagnosed with subarachnoid hemorrhage (SAH) by computed tomography (CT) scan, and the responsible aneurysm is clearly identified by computed tomography angiography (CTA) or digital subtraction angiography (DSA). * Received aneurysm coil embolization or craniotomy clipping within 72 hours of symptom onset. * Hunt-Hess grade II-IV. * No rebleeding or new intracranial hemorrhage is shown on head CT within 6 hours after surgery. * Understand and follow the procedures of clinical trial, participate voluntarily and sign the informed consent (the informed consent can be signed voluntarily by the person or guardian) Exclusion Criteria: * Multiple aneurysms (\>1aneurysms confirmed by CTA/DSA) * Modified Rankin Scale (mRS) score ≥ 3 before onset * Patients with contraindications to cilostazol use: 1. Allergy to cilostazol 2. Severe heart failure（New York Heart Association (NYHA) Functional Classification Grade III or IV） 3. Coagulation disorders or systemic bleeding (e.g., hemophilia, gastrointestinal bleeding, hemoptysis, etc.) 4. Pregnant or lactating women * Patients with severe organic diseases and an expected survival time of less than 90 days * Severe liver insufficiency or renal insufficiency before randomization * Aneurysm treatment requiring the use of other antiplatelet drugs after interventional therapy * Currently receiving treatment with other investigational drugs or device trials