Comparison of Two Different Antiplatelet Preparations for an Unruptured Intracranial Aneurysm

Inclusion Criteria: * patients with clopidogrel resistance (greater than 220 P2Y12 reaction units using VerifyNow) * patients with unruptured intracranial aneurysms * patients over 20 years old * patients who can communicate with each other * patients who agreed to this study (with informed consent) Exclusion Criteria: * patients with recurrent aneurysms after coiling or clipping * patients with allergic reaction to antiplatelets * patients with high risks of hemorrhage * patients with coagulopathy * patients with thrombocytopenia (\<100,000/mm3) * patients with liver disease (\> 100 of aspartate aminotransferase or alanine aminotransferase) * patients with renal disease (\> 2mg/dL of serum creatinine) * patients with uncontrolled heart failure or angina * patients with malignant tumor * pregnant patients * patients with past history that may associated with headache, including subarachnoid hemorrhage, head trauma, intracerebral hemorrhage, trigeminal neuralgia, arteriovenous malformation, brain tumor) * Patients who are determined to be disqualified by researchers