In the VECTOR trial, the aim is to analyze, in case of SVS+ occlusions, a first line Embotrap II added to CA combined strategy compare to CA alone strategy.

Many practitioners are convinced that a first line strategy with CA alone is easy, safe, rapid and efficient. Maybe, after two, three, four ... passes and with the secondary help of a combined strategy, a high rate of eTICI 2b/3 could be reached with a CA first line strategy. But this could go with a higher number of passes, a waste of time and a suboptimal angiographic results (eTICI 2b) due to distal emboli, especially in case of friable, non-well organized, red blood cell rich (RBC) i.e. SVS + thrombi (25-28). This could, be related to worst clinical outcome at 3 months. VECTOR asks a relevant question: Do the invetigators have to add the use of an Embotrap II or III to the CA, from the first passes, in case of SVS+ clots?

Sudden occlusion of an intracranial artery by a thrombus represents the initial and pivotal event of large vessel occlusion acute ischemic stroke (AIS). The primary goal of AIS treatment is to re-open this artery with intravenous tissue-type plasminogen activator infusion (IV t-PA) and/or endovascular therapy (EVT). Thrombus characterization could be useful to predict AIS etiology, IV t-PA response and to adapt the device or technique for EVT. Especially, approaching the red blood cell (RBC) content of the thrombus would be helpful to plan a treatment strategy or identify specific EVT approaches in order to maximize the rate of early successful reperfusion .

The susceptibility vessel sign (SVS) on T2*-MRI sequence is defined as a hypo-intense signal exceeding the diameter of the contralateral artery located at the site of the thrombus. Several studies have demonstrated SVS to be a negative predictor of early reperfusion after IV t-PA and an incentive to EVT . Two studies identified a correlation between the SVS and the thrombus composition (specifically the RBC composition). In the ASTER trial, the presence of SVS impacted the success rate of the EVT strategy. In the SVS (+) sub-population of this study, compared to contact aspiration (CA), patients treated with stent retrievers achieved higher rates of complete reperfusion within fewer passes, which translated into a better functional outcome. In the absence of SVS, no differences were observed between the two techniques. Furthermore; based on the ASTER and THRACE trial populations treated with stent retriever as a first line strategy, a higher rate of favorable clinical outcome at 3 months in SVS (+) patients was recently found . Hence, that differences in terms of reperfusion results are thought to be related to different clot compositions between SVS + and SVS - occlusions.

In the VECTOR trial, the aim is to analyze, in case of SVS+ occlusions, a first line Embotrap II added to CA combined strategy compare to CA alone strategy.

Many practitioners are convinced that a first line strategy with CA alone is easy, safe, rapid and efficient. Maybe, after two, three, four passes and with the secondary help of a combined strategy, a high rate of eTICI 2b/3 could be reached with a CA first line strategy. But this could go with a higher number of passes, a waste of time and a suboptimal angiographic results (eTICI 2b) due to distal emboli, especially in case of friable, non-well organized, red blood cell rich (RBC) i.e. SVS + thrombi. This could, be related to worst clinical outcome at 3 months.

VECTOR asks a relevant question: Do the investigators have to add the use of an Embotrap II or III to the CA, from the first passes, in case of SVS+ clots? The hypothesis in the VECTOR trial is that the Embotrap II or III, thanks to its dedicated design will help to the stabilization of friable clots and allow better retrieving of SVS + thrombi in a lower number of passes.

Inclusion Criteria:

• Age 18 and older (i.e., candidates must have had their 18th birthday)
• Puncture carried out within 24 hours of first symptoms
• Suitable 1.5T MRI T2 * Gradient echo that shows a clear susceptibility vessel sign facing the occlusion
• Neuroimaging demonstrates large vessel proximal occlusion (distal ICA through MCA bifurcation, M1 or proximal M2)
• Patient or trustworthy person informed about the study and having orally consented to participation in the study. If the patient is unable to receive information and no trustworthy person can be contacted during screening for the study, trial inclusion will be completed as an emergency procedure by the investigator, in compliance with the French laws
• With or without intravenous thrombolysis

Exclusion Criteria:

• Absence of large vessel occlusion on non-invasive imaging
• Known or suspected pre-existing (chronic) large vessel occlusion in the symptomatic territory
• Suspected pregnancy; if, in a woman is of child-bearing potential, a urine or serum beta HCG test is positive
• Severe contrast medium allergy or absolute contraindication to use of iodinated products
• Clinical history, past imaging or clinical judgment suggests that the intracranial occlusion is chronic
• Patient has severe or fatal comorbidities that will likely prevent improvement or follow-up or that will render the procedure unlikely to benefit the patient
• Acute ischemic stroke involving posterior circulation (vertebro-basilar occlusion)
• Angiographic evidence of carotid dissection or tandem cervical occlusion or stenosis requiring treatment
• Pregnant or breast-feeding women
• Patient benefiting from a legal protection
• Non-membership of a national insurance scheme
• Opposition of the patient or (in case of inclusion as a matter of urgency) of the trustworthy person
• Patient with modified Rankin score > 3 before qualifying stroke

Open-label study with blinded evaluation (PROBE)