Based on the results of recent randomized trials of endovascular stroke therapy, focused updated guidelines released by the American Heart Association in 2015 recommended stent retriever thrombectomy for patients with acute occlusion of the internal carotid artery (ICA) or the middle cerebral artery (MCA) M1 segment (class I; level of evidence A).1 The number of patients with isolated occlusion of more distal MCA branches included in those trials was small, as the trials were not designed to evaluate the safety and efficacy of thrombectomy for more distal lesions, such as MCA M2 occlusions. Furthermore, there are no randomized trials that have specifically evaluated the benefits of thrombectomy in the setting of distal MCA occlusions as a primary outcome measure. These facts are reflected in the American Heart Association guidelines, which state distal MCA thrombectomy is reasonable but of uncertain benefit when initiated within the first 6 h of symptom onset (class IIb; level of evidence C).1
Studies comparing outcomes of stent retriever thrombectomy in patients with an isolated M2 occlusion with thrombectomy in patients with M1 occlusion showed similar rates of recanalization, favorable clinical outcomes, and adverse events.2,3 Scarce data are available on the safety and outcomes of patients with distal MCA occlusion treated with the aspiration thrombectomy approach.4,5 Further studies are needed to better understand the clinical, imaging, and procedural predictors of successful recanalization and clinical outcomes in this population of patients. In this study, we reviewed multicenter experience with modern thrombectomy approaches to acute stroke from isolated MCA M2 occlusions to identify which groups of patients were more likely to benefit from endovascular revascularization.
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