Stent Retriever Versus Contact Aspiration in Irregular Occlusion Phenotype

Patients with a clinico-neuroradiological mismatch pattern shown on the magnetic resonance imaging/Computed Tomography in the acute phase of stroke are more likely to benefit from reperfusion, are suitable candidates for endovascular therapy, and have a better clinical prognosis.

The ASTER Trial showed similar results between stent-retrievers and contact aspiration concerning the recanalization grade in anterior circulation occlusions. However, we still observe late and futile recanalizations, secondary either to extended ischemic lesions at baseline, long-time procedures or intraprocedural complications. The First Pass Effect that is the complete/nearly complete recanalization after the first maneuver, independently on the technique used, has been strongly associated with better clinical outcomes . In a recent paper we proposed a novel approach to identify those cases that could be treated with a specific technique (stent-retriever) with higher chances to achieve a complete or nearly complete recanalization, with lower procedure times and lower complication rates. This approach is focused on the identification of a regular or irregular phenotype of the occlusion site in patients with an M1-Middle Cerebral Artery occlusion. The phenotype is defined as "regular" whether the profile of the occlusion is abruptly cut without any irregularity and as "irregular" if any irregularity of the profile of the occlusion is observed. One of the hypotheses that could explain these results could be related to the composition of the clot : a soft and less organized clot could be more easily flattened by the pulsatile flow and therefore determine a regular aspect of the occlusion. A more solid and organized clot would, on the contrary, maintain an irregular profile because it would not be flattened by the blood flow and the contrast medium could highlight the irregularities of the proximal face of the clot.

The latter could be a favorable target for the use of a stent-retriever since the interaction between a solid clot and the struts of the stent could increase the chance to retrieve the clot. Therefore, we propose this randomized controlled trial to assess the superiority of stent-retrievers compared to contact aspiration in the treatment of irregular phenotype occlusions of the M1-Middle Cerebral Artery.