BACKGROUND: The optimal acute management of patients with acute ischemic stroke and a tandem lesion, defined as intracranial large vessel occlusion (LVO) with concomitant carotid artery stenosis or occlusion, remains unclear. Our aim is to assess the efficacy and safety of immediate carotid artery stenting (CAS) compared to delayed management in patients undergoing endovascular treatment (EVT) for acute ischemic stroke due to tandem lesions. STUDY DESIGN: CASES is a phase 3 multicenter prospective randomized open-label blinded endpoint (PROBE) non-inferiority clinical trial. Patients with a computed tomography angiography proven intracranial LVO in the anterior circulation and ipsilateral proximal carotid artery stenosis (⩾50%) or occlusion of presumed atherosclerotic origin will be randomized to either immediate CAS during EVT or to EVT followed by a deferred strategy, which may include carotid endarterectomy (CEA), CAS, or medical management. CASES will be conducted in 27 EVT centers in Belgium and the Netherlands. A total of 600 patients will be included. STUDY OUTCOMES: The primary outcome is the score on the modified Rankin Scale (mRS) at 90 days. Secondary outcomes include excellent (mRS 0-1) and good (mRS 0-2) functional outcome at 90 days, stroke severity measured with the National Institutes of Health Stroke Scale (NIHSS) at 24 h and 5-7 days, recanalization, infarct volume at 24 h, ischemic stroke recurrence, carotid artery re-occlusion, symptomatic intracranial hemorrhage, and mortality. SUMMARY: This study will provide high-quality randomized data on the efficacy and safety of immediate CAS in patients undergoing EVT for acute ischemic stroke due to a tandem lesion. TRIAL REGISTRATION: ClinicalTrials.gov NCT06511089
ISRCTN 14956654.