Mechanical thrombectomy (MT) is the standard of care for the treatment of proximal anterior circulation large vessel occlusions. However, little is known about its efficacy and safety in the treatment of distal intracranial occlusions.
This is a multicenter retrospective study of patients treated with MT at 15 comprehensive centers between January 2015 – December 2018. The study cohort was divided into two groups based on the location of occlusion (proximal versus distal). Distal occlusion was defined as occlusion of M3 segment of the middle cerebral artery, any segment of the anterior cerebral artery or any segment of the posterior cerebral artery. Only isolated distal occlusion was included. Good outcome was defined as 90-day modified Rankin scale 0-2.
A total of 4710 patients were included in this study, of whom 189 (4%) had MT for distal occlusions. Compared to the proximal occlusion group, distal occlusion group had a higher rate of good outcome (45% vs. 36%; p=0.03) and a lower rate of successful reperfusion (78% vs. 84%; p=0.04). However, the differences did not retain significance in adjusted models. Otherwise there was no difference in the rate of hemorrhagic complications, mortality or procedure-related complications between the two groups. Successful reperfusion, age and admission stroke severity emerged as predictors of good functional outcome in the distal occlusion group.
Thrombectomies of distal vessels achieve high rate of successful reperfusion with similar safety profile to those in more proximal locations.

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