Inclusion criteria


Inclusion criteria

  • Patient with an intradural, saccular unruptured aneurysm in whom it is decided not to intervene with preventive endovascular or neurosurgical aneurysm repair and who are monitored on a regular basis for aneurysm growth
  • 18 years or older
  • Last aneurysm imaging with either CTA or MRA within the last 3 months
  • Ability of subject to understand character and individual consequences of clinical trial
  • Not legally incapacitated
  • Written informed consent (must be available before enrolment in the trial
  • For women with childbearing potential adequate contraception

Exclusion criteria

  • All non-saccular UIAs or aneurysm related to arteriovenous malformations
  • Daily ASA already prescribed for another indication
  • Use of a vitamin K antagonist or direct oral anticoagulant (DOAC) at baseline
  • History of hypersensitivity to ASA or to any other drug with similar chemical structure or to any excipient present in the pharmaceutical form of ASA
  • History of asthma induced by ASA or other anti-inflammatory drugs
  • Other contra-indications for low-dose ASA (81 mg - 100 mg per day) not yet mentioned, (e.g. bleeding disorders, gastric ulcers and/or intestinal ulcers, acute liver failure or kidney failure, severe heart failure, treatment with methotrexate in a dosage 15 mg/week or above)
  • Use of another platelet aggregation inhibitor, which in combination with ASA would give an unacceptable risk of side effects/complications
  • Chronic kidney disease stage IV and V (GFR < 30 mL/min/1.73 m2)
  • Pregnancy and lactation
  • Participation in another clinical trial or observation period of competing trials
  • Life-expectancy <3 years