Mechanical thrombectomy with second-generation devices for acute cerebral middle artery M2 segment occlusion: A meta-analysis

The benefit of mechanical thrombectomy for an acute ischemic stroke involving M2 segment occlusion is not clear, especially when performed with second-generation thrombectomy devices.

We reviewed the literature to investigate clinical outcomes and the rates of recanalization, symptomatic intracerebral hematoma, and mortality in mechanical thrombectomy performed using second-generation thrombectomy devices. We compared the outcomes between patients treated for M2 and M1 occlusions.

Seven studies involving 805 patients with M2 thrombectomy were included in this meta-analysis. The functional independence rate 90 days after thrombectomy (modified Rankin Scale 0–2) was 59.3% (OR 1.81, 95% CI 1.74–1.88). The recanalization rate (thrombolysis in cerebral infarction 0–2) was 84.16% (OR 2.32, 95% CI 2.08–2.29). The symptomatic intracerebral hematoma rate was 4.9% (OR 1.05, 95% CI 1.03–1.09). The mortality was 7.7% (OR 1.08, 95% CI 1.03–1.13). The outcomes were better in patients with M2 occlusion than in those with M1 occlusion. In a subgroup analysis, we found that among patients with hypertension, mechanical thrombectomy achieved better functional outcomes and recanalization in M2 occlusion than M1 occlusion.

Mechanical thrombectomy performed with second-generation thrombectomy devices for M2 occlusion can provide a good functional outcome as well as satisfying recanalization. Moreover, there was no significant difference in the symptomatic intracerebral hematoma and mortality rates, suggesting this procedure is as safe in M2 occlusion as in M1 occlusion.