Abstract TP15: A Case for the Chase? A Case Series of Mechanical Thrombectomy of M2 Occlusions

Introduction: Randomized clinical trials have demonstrated an improvement in outcomes with endovascular treatment of large vessel occlusions, however studies evaluating the effectiveness of endovascular treatment of smaller vessels of the anterior circulation are lacking. We present initial data from two tertiary care centers with a focus on outcomes of patients with isolated middle cerebral artery (MCA) M2 occlusions. Methods: With institutional review board approval, we retrospectively reviewed medical records of patients who underwent mechanical thrombectomy (MT) between September 2013 and June 2016. The following data was collected: demographics, stroke risk factors, intravenous tPA use, MT treatment times, grade of recanalization, complications, and 3 month modified Rankin Scores. A favorable clinical outcome was defined as a modified Rankin Scale (mRS) 0-2 at 90 days. Results: A total of 50 patients were included in this analysis with 19 (38%) women and 31 (62%) men, with a mean age of 70 (63-80) years. One patient had an occlusion of both superior and inferior divisions of the middle cerebral artery (MCA) artery, 20 had occlusion of the inferior M2 artery, and the remaining 29 had occlusion of the superior division of the MCA. Baseline characteristics are summarized below. Average door to groin time was 75 (46-112) minutes, mean procedure time was 30 (25-47) minutes, and mean onset of symptoms to recanalization time was 220 (156-305) minutes. Of the cohort, 22 patients had a change of mRS of 3 or more at the time of discharge, 25 (50%) patients had a favorable outcome at 3 months, and 4 (8%) patients were lost to follow up. Ten (20%) patients developed hemorrhagic infarction and five (10%) developed parenchymal hematoma. Conclusions: Our data on MT targeting M2 occlusions demonstrates reasonable safety, recanalization rates, complications, and functional outcomes. Randomized studies are needed to confirm the benefit of pursuing MCA M2 occlusions with MT.