Technical and Clinical Outcomes After Thrombectomy for the Various Segments of the Middle Cerebral Artery

Background: After showing the success of mechanical thrombectomy (MT) in treating large-vessel occlusion stroke, the target population has been expanded to include patients with smaller and more distal vessels including the M2 segment of the middle cerebral artery. We compared the procedural and clinical outcomes of patients undergoing MT using direct aspiration (ADAPT [A Direct Aspiration at first Pass Technique]) between superior or inferior divisions of M2 and M1. Methods: We retrospectively reviewed a database of patients undergoing MT between June 2013 and July 2018 at our center for clinical and procedural variables. Patients with isolated M1 or M2 occlusions were included. M2 occlusions were classified into superior and inferior divisions. Functional outcomes were collected at 90 days. Results: A total of 205 patients with M1, 65 with M2 superior division (middle cerebral artery M2 superior segment [M2S]), and 57 with inferior division (middle cerebral artery M2 inferior segment [M2I]) stroke were included. M1 and M2S patients had comparable National Institutes of Health Stroke Scale score at presentation, but higher than M2I (P < 0.01). Compared with M1, M2 occlusions had longer procedure times and required more aspiration attempts (P < 0.05). M2S thrombectomy had a significantly lower rate of successful recanalization (P < 0.05). Rates of good outcome (modified Rankin Scale score 0–2) were 46% in M1, 34% in M2S, and 44% in M2I, and postprocedural hemorrhage rates were comparable between groups. On multivariate analysis, M2S occlusion was associated with longer procedure times, lower odds of good outcomes, and lower TICI recanalization scores (P < 0.05) compared with M1. Conclusions: ADAPT is safe and effective in M2 stroke. The procedural success and efficacy of ADAPT in M2 stroke are influenced by the anatomic division with less favorable clinical and technical outcomes in the M2S division.