Determination of the Best Therapeutic Strategy, Interventional With Best Medical Management (BMM) Versus BMM Alone, for Patients With Symptomatic Moderate <70% Atherosclerotic Carotid Artery Stenosis: the SIMCA Multicenter Randomized Trial

Stroke is one of the leading causes of death and the main cause of long-term disability worldwide. A frequent cause is the narrowing of the carotid artery due to atherosclerosis, known as carotid artery stenosis. When stenosis is moderate (\< 70%) and has already caused symptoms, the best strategy to prevent another stroke remains uncertain. Earlier studies compared surgery or stenting with medical therapy, but these trials were conducted before modern medical treatments were available and did not consider important plaque characteristics that may increase the risk of recurrence. As a result, current clinical practice varies widely, and existing guidelines are based on low-quality evidence. The SIMCA trial aims to address this gap by comparing two treatment strategies in patients with symptomatic moderate carotid stenosis : best medical management (BMM) alone versus BMM combined with an intervention (endarterectomy or stenting). The primary objective is To determine whether intervention (endarterectomy or stenting) plus BMM compared to BMM alone significantly reduces the incidence of ipsilateral symptomatic cerebral infarction in patients with symptomatic atherosclerotic moderate stenosis of the cervical internal carotid artery at 5 years Hypothesis : The arm of this study is therefore to determine the best therapeutic strategy between intervention with best medical management (BMM) versus BMM alone (main objective) and the best intervention (endarterectomy or stenting) (secondary objective) to prevent cerebral infarction in patients with symptomatic atherosclerotic moderate (\< 70%) CAS.

Inclusion criteria: * Age ≥ 18 years * Modified Rankin Score 0 to 3 * Atherosclerotic stenosis of the cervical internal carotid artery with * Between 50-69% (NASCET method) confirmed by computed tomography angiography (CTA) or magnetic resonance angiography (MRA) or digital subtraction angiography (DSA) OR * Stenosis \< 50% (NASCET method) confirmed by CTA or MRA or DSA with at least one of the following markers of high-risk carotid plaque features for stroke recurrence (vulnerable plaque), possibly identified by doppler ultrasound: * intra-plaque hemorrhage * irregular plaque surface defined as an indentation, fissure, erosion, or ulceration on the luminal surface of the plaque * lipid-rich necrotic core (LRNC) occupying ≥50% plaque4. Symptomatic stenosis defined as clinical signs due to * ipsilateral ischemic stroke documented on cerebral imaging OR Ipsilateral permanent or transitory retinal embolic infarction document by ophthalmologic examination OR transient ischemic attack defined as transient motor deficit and/or aphasia. AND * obviously due to the atherosclerotic stenosis: in a concordant territory, excluding lacunar infarction, and associated cardio embolic source (atrial fibrillation excluded by ECG, and 24-hour monitoring or holter), and multiterritorial simultaneous cerebral infarctions AND * within 14 days before planned intervention * For whom both kinds of intervention (endarterectomy and stenting) are allowed. * Able and willing to give consent * Person affiliated to or beneficiary of a social security plan Exclusion criteria: * Expected survival \