Cilostazol Stroke Prevention Study for Antiplatelet Combination

Inclusion Criteria: * Patients with a diagnosis of noncardioembolic IS that developed between 8 and 180 days before the start of the protocol treatment * Patients with a responsible lesion identified by MRI * Patients aged 20 to 85 years old when providing informed consent * Patients taking clopidogrel or aspirin alone as antiplatelet therapy when providing informed consent * Patients meeting at least one of the following criteria a-c: 1. at least 50% stenosis of a major intracranial artery (to the level of A2, M2, or P2) 2. at least 50% stenosis of an extracranial artery (the common carotid artery，internal carotid artery，vertebral artery，brachiocephalic artery，or subclavian artery) 3. Two or more of the following risk factors * Aged 65 years or more * Diabetes mellitus * Hypertension * Peripheral arterial disease * Chronic kidney disease * History of IS (excluding the index IS for this study) * History of ischemic heart disease * Smoking (only current smokers) * Patients considered to be able to visit the study site for ambulatory care throughout the observation period * Patients who provided written informed consent Exclusion Criteria: * Patients with emboligenic heart disease * Patients taking any anticoagulant agents * Patients who cannot undergo MRI examination for reasons such as claustrophobia and implanted pacemaker * Patients scheduled to undergo any surgery, such as percutaneous angioplasty, stent placement, and bypass grafting, during the study period * Patients with a drug-eluting coronary stent implanted within one year * Patients with a history of symptomatic non-traumatic intracranial hemorrhage, any other hemorrhagic disease (eg, active peptic ulcer), bleeding predisposition, or blood clotting disorders * Patients with a history of hypersensitivity to cilostazol * Patients with congestive heart failure or uncontrolled angina pectoris * Patients with thrombocytopenia (platelet count ≦ 100,000/mm3) * Patients with severe liver or renal dysfunction * Women who are pregnant, breast-feeding, or of child-bearing potential * Patients with a malignant tumor requiring treatment * Patients who are taking aspirin, and meet any of the following criteria: * History of hypersensitivity to aspirin or salicylic acid analogues * Current peptic ulcer * Aspirin-induced asthma or its history * Patients who are taking clopidogrel, and meet the following criterion: ・History of hypersensitivity to clopidogrel * Patients who are participating in any other clinical studies * Patients considered by the investigator/subinvestigator to be unsuitable for participating in this study