adaptatiVe Endovascular Strategy to the CloT MRI in Large Intracranial Vessel Occlusion (VECTOR)

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.