Atorvastatin Pretreatment in Cerebrovascular Events (APICES) After Flow Diverter Implantation

Inclusion criteria: 1. Aged 18 to 75 years old, male or non-pregnant female; 2. UIA diagnosed by CTA, MRA, or DSA; 3. Maximal aneurysmal diameter between 3 and 25mm; 4. Understands the nature of the procedure and provision of written informed consent; 5. Indications for FD implantation with or without adjunctive coiling; 6. Is willing to return to the investigational site for follow-up according to our protocol. Exclusion criteria: Patients will be excluded if they meet any of the following criteria: 1. Contraindications to atorvastatin treatment or known allergy to atorvastatin; 2. Pregnancy or lactation; 3. Presence of other vascular lesions (coronary artery disease, abdominal aortic aneurysm, intracranial atherosclerotic stenosis, arteriovenous malformation, dural arteriovenous fistula, Moyamoya disease, etc.); 4. Prolonged statin therapy (≥30 days) or prior indications for atorvastatin therapy according to the Chinese guidelines for lipid management (2023) 21; 5. Ruptured aneurysms or target aneurysm received previous operative or endovascular treatment; 6. Patient currently using drugs that interact with atorvastatin metabolism (including transporter inhibitors, cyclosporine, protease inhibitors, other lipid-lowering medications (such as fibrates, ezetimibe, pcsk9 inhibitor, etc.), antacids, erythromycin, cytochrome P450 enzyme, colchicine, etc.); 7. Patients diagnosed with multiple intracranial aneurysms who require treatment for two or more intracranial aneurysms within a one-year period; 8. The target aneurysm is non-saccular (dissecting, fusiform, pseudo, infectious, etc.) 9. Other situations that the researcher deems unsuitable for inclusion in the study (inability to receive anti-platelet or anticoagulant medication; allergy or contraindication for the use of FD alloy, history of life-threatening allergy to contrast dye, ect). 10. Patient was determined that intravenous general anesthesia or general anesthesia with tracheal intubation could not be tolerated. 11. Unwilling to be followed up or likely to have poor treatment compliance at initial screening; 12. Life expectancy less than 3 years; 13. Severe neurological deficit that renders the patient unable to live independently (modified Rankin score ≥4); 14. Enrollment in another trial. Withdrawal criteria In this trial, participants who have provided written informed consent but are unable to complete the entire study for any reason will be withdrawn. These circumstances include the following: 1. The participants voluntarily quit the trial for various reasons; 2. Occurrence of serious adverse events (SAEs). The study may be terminated by the participants, principal investigators, ethics committee, sponsor, or regulatory authorities based on ethical considerations; 3. Early termination of the process based on the investigator's judgment in order to prevent development of severe complications; 4. Significant deviation in implementation, or the subject failed to comply with the scheduled protocol; 5. Miss the follow-up due to changes in working/living places, or fortuitous accident (traffic accident, bone fracture, accidental death, ect.). Thus, close follow-up should be conducted to determine their relationship with the usage of FD and experimental drug; 6. Flawed or absence of informed consents.