Related Experiment Video
Updated: Mar 30, 2026
The Stroke Preclinical Assessment Network Multi-laboratory Model of Thromboembolic Stroke with Thrombolysis: TE-MCAo
Published on: December 19, 2025
Mechanical Thrombectomy for Isolated M2 Occlusions: A Post Hoc Analysis of the STAR, SWIFT, and SWIFT PRIME Studies
J M Coutinho1, D S Liebeskind2, L-A Slater1
1From the Divisions of Neuroradiology (J.M.C., L.-A.S., V.M.P.).
Background And Purpose:
Mechanical thrombectomy is beneficial for patients with acute ischemic stroke and a proximal anterior occlusion, but it is unclear if these results can be extrapolated to patients with an M2 occlusion. The purpose of this study was to examine the technical aspects, safety, and outcomes of mechanical thrombectomy with a stent retriever in patients with an isolated M2 occlusion who were included in 3 large multicenter prospective studies.
Materials And Methods:
We included patients from the Solitaire Flow Restoration Thrombectomy for Acute Revascularization (STAR), Solitaire With the Intention For Thrombectomy (SWIFT), and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) studies, 3 large multicenter prospective studies on thrombectomy for ischemic stroke. We compared outcomes and technical details of patients with an M2 with those with an M1 occlusion. All patients were treated with a stent retriever. Imaging data and outcomes were scored by an independent core laboratory. Successful reperfusion was defined as modified Thrombolysis in Cerebral Infarction score of 2b/3.
Results:
We included 50 patients with an M2 and 249 patients with an M1 occlusion. Patients with an M2 occlusion were older (mean age, 71 versus 67 years; P = .04) and had a lower NIHSS score (median, 13 versus 17; P < .001) compared with those with an M1 occlusion. Procedural time was nonsignificantly shorter in patients with an M2 occlusion (median, 29 versus 35 minutes; P = .41). The average number of passes with a stent retriever was also nonsignificantly lower in patients with an M2 occlusion (mean, 1.4 versus 1.7; P = .07). There were no significant differences in successful reperfusion (85% versus 82%, P = .82), symptomatic intracerebral hemorrhages (2% versus 2%, P = 1.0), device-related serious adverse events (6% versus 4%, P = .46), or modified Rankin Scale score 0-2 at follow-up (60% versus 56%, P = .64).
Conclusions:
Endovascular reperfusion therapy appears to be feasible in selected patients with ischemic stroke and an M2 occlusion.
Insights
Mechanical thrombectomy using stent retrievers is a safe and effective treatment for acute ischemic stroke patients with M2 occlusions. Outcomes are comparable to those with M1 occlusions, demonstrating feasibility.
Area of Science:
- Neurology
- Interventional Neurology
- Stroke Medicine
Background:
- Mechanical thrombectomy is established for acute ischemic stroke with proximal anterior circulation occlusion.
- Efficacy in isolated M2 occlusions remains less understood.
- Stent retrievers are a key technology in endovascular stroke treatment.
Purpose of the Study:
- To evaluate the technical aspects, safety, and outcomes of mechanical thrombectomy with stent retrievers.
- To specifically assess treatment in patients with isolated M2 occlusions.
- To compare M2 occlusion outcomes against M1 occlusions within large prospective studies.
Main Methods:
- Analysis of patients from the STAR, SWIFT, and SWIFT PRIME prospective multicenter studies.
- Comparison of technical details and outcomes between M2 and M1 occlusion groups.
- All patients treated with stent retrievers; outcomes assessed by an independent core laboratory.
Main Results:
- 50 patients with M2 occlusions were compared to 249 with M1 occlusions.
- No significant differences in successful reperfusion rates (85% vs 82%).
- Similar rates of symptomatic intracranial hemorrhage and functional outcomes (modified Rankin Scale 0-2 at follow-up).
Conclusions:
- Mechanical thrombectomy with stent retrievers is feasible and safe for selected patients with acute ischemic stroke and M2 occlusions.
- Outcomes appear comparable to those with M1 occlusions.
- Supports the use of endovascular reperfusion therapy in this patient subgroup.
