Background The Society of Neurointerventional Surgery revised its operational definition of emergent large vessel occlusion (ELVO) recently to include proximal M2 segment middle cerebral artery (MCA) occlusions. We sought to assess the benefit of endovascular thrombectomy (EVT) over best medical care for M2 segment MCA occlusion.
Methods Patient level data from trials in the HERMES Collaboration were included. The HERMES core laboratory identified patients with M2 segment MCA occlusions and further classified them as proximal versus distal, anterior versus posterior division, and dominant versus co-dominant versus non-dominant. Primary outcome was modified Rankin Scale (mRS) score 0–2 at 90 days. Secondary outcomes were modified Thrombolysis in Cerebral Infarction (mTICI) rates at end of procedure, 90-day mRS shift, 90-day mRS 0–1, 24 hours National Institute of Health Stroke Scale (NIHSS) score 0–2, symptomatic intracerebral hemorrhage (ICH), and death.
Results 130 patients with M2 MCA (proximal location n=116 vs distal n=14, anterior division n=72 vs posterior n=58, dominant n=73 vs co-dominant n=50 vs non-dominant n=7) were included. Successful reperfusion (mTICI 2b or 3) among those undergoing EVT was seen in 59.2% of patients. Treatment effect favored EVT (adjusted OR 2.39, 95% CI 1.08 to 5.28, p=0.03) for 90-day mRS 0–2 (58.2% EVT vs 39.7% control). Direction of benefit favored EVT for other outcomes. Treatment effect favoring EVT was maximal in patients with proximal M2 segment MCA occlusions (n=116, adjusted OR 2.68, 95% CI 1.13 to 6.37) and in dominant M2 segment MCA occlusions (n=73, adjusted OR 4.08, 95% CI 1.08 to 15.48). No sICH (0%) was observed in patients treated with EVT compared with five (7.9%) in the control arm.
Conclusion Patients with proximal M2 segment MCA occlusions eligible for EVT trial protocols benefited from EVT.
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Contributors BKM and MG had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: BKM, MDH, DWJD, JLS, TJ, AvdL, MG. Acquisition, analysis, or interpretation of data: AD, YBWEMR, BCVC, FG, AMD, KM, PM, PW, SB. Drafting of the manuscript: BKM, SB, MDH, DWJD, MG. Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: SB. Obtained funding: MG. Administrative, technical, or material support: MDH, SB. Study supervision: BKM, MG.
Funding This work was supported by an unrestricted grant provided to the University of Calgary by Medtronic Inc.
Competing interests MDH owns stock in Calgary Scientific Inc, a company that focuses on medical imaging software, is a director of the Canadian Federation of Neurological Sciences, a not-for-profit group and has received grant support from Alberta Innovates Health Solutions, CIHR, Heart & Stroke Foundation of Canada, National Institutes of Neurological Disorders and Stroke. YBWEMR reports Stock ownership of Nico-Lab, outside the submitted work. BCVC reports grants from National Health and Medical Research Council, Royal Australasian College of Physicians, Royal Melbourne Hospital Foundation, National Heart Foundation, National Stroke Foundation of Australia, Covidien (Medtronic) during the conduct of the study. KM reports grants from Medtronic and from Codman outside the submitted work. AMD reports personal fees from Medtronic during the conduct of the study. TJ has consulted for Codman Neurovascular and Neuravi; holds stock in Silk Road, Anaconda, Route 92, and Blockade; received travel expenses from Stryker as primary investigator of the DAWN trial and from Fundacio Ictus related to the REVASCAT and RACECAT trials. PM reports receiving consulting fees from Medtronic and Stryker, personal fees from Stryker and Microvention outside the submitted work. PW reports grants from National Institutes for Health Research, the Stroke Association, Medtronic (Covidien), and Codman and has consulted for Microvention Terumo and Codman. AvdL reports grants from Dutch Heart Foundation, and consulting fees from AngioCare BV, from Covidien/EV3, from MEDAC Gmbh/LAMEPRO, from Stryker, from Penumbra Inc, during the conduct of the study; grants from Stryker, grants from Penumbra Inc, grants from Medtronic outside the submitted work. JLS has acted as a scientific consultant regarding trial design and conduct for Medtronic. SB reports personal fees from University of Calgary during the conduct of the study; personal fees from Medtronic outside the submitted work. MG reports grants from Medtronic and personal fees from Stryker, Medtronic, Microvention, and Cerenovus during the conduct of the study; grants from Stryker outside the submitted work. In addition, MG has a patent Systems of Acute Stroke Diagnosis issued to GE Healthcare.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All data are available within the article. Any additional data will be made available, upon reasonable request, by the corresponding author after getting approval from the HERMES executive.
Patient consent for publication Not required.