Stent retriever size and outcomes after anterior circulation occlusion thrombectomy

Background The impact of stent retriever size on mechanical thrombectomy (MT) outcomes remains uncertain. We aim to clarify the influence of stent retriever size on MT outcomes by analyzing data from two national prospective registries.Methods A retrospective analysis was performed on data from the French and German MT registries including consecutive patients with anterior circulation large vessel occlusion who underwent Solitaire stent retriever MT with or without additional aspiration. Efficacy outcomes were successful reperfusion and complete reperfusion. Safety outcomes included any intracerebral hemorrhage (ICH) and symptomatic intracerebral hemorrhage (sICH).Results Complete reperfusion was lower in the 4x20 mm stent retriever group than in the 4x40 mm stent retriever group (47% vs 53%; OR 0.61, P=0.0039). Successful reperfusion did not differ between the 4x20 mm and 4x40 mm stent retriever groups (89% vs 93%; OR 0.69, P=0.25). There was no difference between the 6x30/6x40 mm and 4x20 mm stents, and there was no difference in functional outcomes between the groups. In terms of safety, any ICH was lower in the 4x20 mm group than in the 4x40 mm group (20% vs 36%; OR 0.60, P=0.0095). Symptomatic ICH was lower in the 4x20 mm group than in the 4x40 mm group (5% vs 10%; OR 0.58, P=0.086), but the difference did not reach statistical significance. Mortality was lower in the 4x20 mm than in the 6x40 mm group (26% vs 33%; OR 0.70, P=0.044). When compared according to occlusion location, the results were overall similar.Conclusion This study suggests that longer and larger stent retrievers lead to a higher reperfusion rate but also a higher rate of hemorrhagic complications. Overall, the size of the stent did not affect functional outcomes.