Mechanical Thrombectomy for Stroke How Distal Can We Go?

The publication of 5 randomized trials in 2015 unequivocally established that mechanical thrombectomy is the new standard of care for patients with acute ischemic stroke and an occlusion of the proximal anterior circulation.1 Although those trials mark a huge advancement in the field of stroke, important questions regarding the implementation of mechanical thrombectomy in routine clinical care remain. One of the more important of these questions is what constitutes the definition of a proximal occlusion. In those trials, most of the patients had an occlusion of the distal internal carotid artery or of the first segment (M1) of the middle cerebral artery (MCA). Only 8% of patients had occlusion of the second segment (M2) of the MCA. Because of the limited amount of data, mechanical thrombectomy is currently not considered the standard of care for patients with an M2 occlusion.2 Given its more distal location and smaller diameter, mechanical thrombectomy of M2 branches is technically more challenging and may convey a higher risk for complications. Distal occlusions also tend to respond better than proximal occlusions to intravenous thrombolysis.3