Endovascular Revascularization for Chronic Carotid Artery Occlusion Trial

Part 1: Clinical registry study Inclusion criteria for clinical registry study * Patient age 20 years or older * Abnormal cerebral perfusion by CTP or MRI * No medical history of stroke or transient ischemic attack (TIA) ipsilateral to the carotid occlusion within 90 days of randomization * Women must not be of childbearing potential or, if of childbearing potential, have a negative pregnancy test prior to randomization. Exclusion Criteria for clinical registry study * Patient has acute stroke within 90 days, * Intolerance or allergic reaction to a study medication without a suitable management alternative. * Patient is expected to have the ADP antagonist therapy interruption within 3 months after the procedure. * GI hemorrhage within 1 month prior to enrollment that would preclude antiplatelet therapy * Bleeding diathesis * Intracranial hemorrhage within the past 12 months. * Platelet count \<100,000/μl or history of heparin-induced thrombocytopenia. * Other high-risk cardiac sources of emboli, including left ventricular aneurysm, severe cardiomyopathy, aortic or mitral mechanical heart valve, severe calcific aortic stenosis (valve area \< 1.0 cm2), endocarditis, moderate to severe mitral stenosis, left atrial thrombus, or any intracardiac mass, or known unrepaired patent foramen ovale (PFO) with prior paradoxical embolism. * Any major surgery, major trauma, revascularization procedure within the past 1 month. * Acute coronary syndrome within the past 1 month or acute coronary syndrome (ACS) that is not amenable to revascularization (patients should undergo planned coronary revascularization at least 30 days before randomization). * Inability to understand and cooperate with study procedures or provide informed consent. * Patients with \< 5 years life expectancy * Concomitant vascular conditions precluding endovascular revascularization procedure; * Previous ipsilateral carotid artery stenting * Intracranial aneurysm or arteriovenous malformation; * Educational level lower than elementary school; * Aphasia or right-sided hemiparesis * Marked depression. * Severe dementia. Part 2: Randomized control study Inclusion Criteria for randomized control study * Patient age 20 years or older * Abnormal cerebral perfusion by CTP or MRI * No medical history of stroke or TIA ipsilateral to the carotid occlusion within 90 days of randomization * Patients must have a modified Rankin Scale (mRS) ≤2 at the time of informed consent. * Women must not be of childbearing potential or, if of childbearing potential, have a negative pregnancy test prior to randomization. * Randomization will apply to only 1 carotid artery occlusion for patients with bilateral carotid occlusion. Intervention of the contralateral stenosis, should it exists, may be done in according to clinical indications at least 30 days prior to randomization. Exclusion Criteria randomized control study * Patient has acute stroke within 90 days, * Prior major ipsilateral stroke in the past with moderate disability (mRS ≥ 3) that is likely to confound study outcomes. * Current neurologic illness characterized by fleeting or fixed neurologic deficits that cannot be distinguished from TIA or stroke. * Patient has significant renal insufficiency with estimated glomerular filtration rate (eGFR) \<30 ml/min (at screening). and would not receive renal replacement therapy if contrast agent related nephropathy occurs * Intolerance or allergic reaction to a study medication without a suitable management alternative. * Patient is expected to have the ADP antagonist therapy interruption within 3 months after the procedure. * GI hemorrhage within 1 month prior to enrollment that would preclude antiplatelet therapy * Bleeding diathesis * Intracranial hemorrhage within the past 12 months. * Platelet count \<100,000/μl or history of heparin-induced thrombocytopenia. * Other high-risk cardiac sources of emboli, including left ventricular aneurysm, severe cardiomyopathy, aortic or mitral mechanical heart valve, severe calcific aortic stenosis (valve area \< 1.0 cm2), endocarditis, moderate to severe mitral stenosis, left atrial thrombus, or any intracardiac mass, or known unrepaired PFO with prior paradoxical embolism. * Major (non-carotid) surgery/procedures planned within 3 months after enrollment. * Any major surgery, major trauma, revascularization procedure within the past 1 month. * Acute coronary syndrome within the past 1 month or ACS that is not amenable to revascularization (patients should undergo planned coronary revascularization at least 30 days before randomization). * Coronary artery disease with two or more proximal or major diseased coronary arteries with ≥ 70% stenosis that have not, or cannot, be revascularized. * Inability to understand and cooperate with study procedures or provide informed consent. * Patients with \< 5 years life expectancy * Concomitant vascular conditions precluding endovascular revascularization procedure; * Previous ipsilateral carotid artery stenting * Intracranial aneurysm or arteriovenous malformation; * Educational level lower than elementary school; * Aphasia or right-sided hemiparesis * Marked depression. * Severe dementia.