Evaluating Oral Peri-operative Acetylsalicylic Acid in Subjects Undergoing Endovascular Coiling-only of Unruptured Brain Aneurysms

Inclusion Criteria: * Unruptured intracranial aneurysm suitable for coiling-only (primary coiling or balloon-assisted) as a primary treatment. * Functionally independent at baseline (modified Rankin scale \<3). * Informed consent and availability of the subject for the entire study period. Exclusion Criteria: 1. Planned complex aneurysm treatment including use of any device that requires post-operative antiplatelet therapy (stent-assisted coiling or flow-diverter device), or endovascular vessel sacrifice. 2. Dissecting or mycotic brain aneurysm. 3. Any ongoing ischemic symptoms such as transient ischemic attacks, minor strokes, or stroke-in-evolution within 2 weeks before randomization. 4. Allergy or contraindication to ASA. 5. Unable to take study drug orally for any reason. 6. Subjects already taking single or dual antiplatelet, warfarin, or any of the non-Vitamin K antagonist oral anticoagulants. 7. Subjects unable to undergo MRI imaging for any reason (e.g., severe claustrophobia or presence of metals). 8. Any other medical condition that the site investigator deems would put the subject at excessive risk by participation in the study (e.g. active bleeding, symptomatic peptic ulcer disease, liver or kidney failure, thrombocytopenia or coagulopathy) or an expected life expectancy less than one year, or that would result in an inability to collect radiological outcomes and clinical outcomes at 90 days. 9. Pregnancy or breastfeeding. 10. Prior enrollment in EVOLVE trial for another aneurysm. 11. Participation in another clinical trial of an investigational drug, device or procedure if the subject received the trial drug, device or procedure in the preceding 30 days from the anticipated coiling date.