Mechanical thrombectomy of M1 and M2 middle cerebral artery occlusions.

ABSTRACT

BACKGROUND: Over half of patients who receive intravenous tissue plasminogen activator for middle cerebral artery division (MCA-M2) occlusion do not recanalize, leaving a large percentage of patients who may need mechanical thrombectomy (MT). However, the outcomes of MT for M2 occlusion have not been well characterized. OBJECTIVE: To determine if MT of M2 occlusion is as safe and efficacious as current standard-of-care MT for M1 occlusions. METHODS: With institutional review board approval, we retrospectively reviewed records of 212 patients undergoing MT for isolated MCA M1 or M2 occlusions during a 36-month period (Sept 2013 to Sept 2016) at two centres. Treatment variables, clinical outcomes, and complications in each group were recorded. RESULTS: There were 153 M1 MCA occlusions and 59 M2 MCA occlusions. No statistically significant difference was found in the rate of mortality (20% in M1 vs 13.6% in M2, p=0.32), excellent (34.5% vs 37.3%, p=0.75) or good (51% vs 55.9%, p=0.54) clinical outcomes between the two groups. Infarct volumes (48.4 mL vs 46.2 mL, p=0.62) were comparable between the two groups, as were the rates of hemorrhagic (3.3% vs 3.4%, p=1.0) and procedural complications (3.3% vs 5.1%, p=0.69). CONCLUSION: Our data on MT targeting M2 occlusions demonstrates reasonable safety and functional outcomes. Further randomized clinical trials are needed to clarify which patients may benefit from MT for M2 occlusions.