title: Endovascular Therapy of M2 Occlusion in IMS III: Role of M2 Segment Definition and Location on Clinical and Revascularization Outcomes.
abstract: Uncertainty persists regarding the safety and efficacy of endovascular therapy of M2 occlusions following IV tPA. We reviewed the impact of revascularization on clinical outcomes in 83 patients with M2 occlusions in the Interventional Management of Stroke III trial according to specific M1-M2 segment anatomic features.
  
  
  
  Perfusion of any M2 branch distinguished M2-versus-M1 occlusion. Prespecified modified TICI and arterial occlusive lesion revascularization and clinical mRS 0-2 end points at 90 days for endovascular therapy-treated M2 occlusions were analyzed. Post hoc analyses of the relationship of outcomes to multiple baseline angiographic M2 and M1 subgroup characteristics were performed.
  
  
  
  Of 83 participants with M2 occlusion who underwent endovascular therapy, 41.0% achieved mRS 0-2 at 90 days, including 46.6% with modified TICI 2-3 reperfusion compared with 26.1% with modified TICI 0-1 reperfusion (risk difference, 20.6%; 95% CI, -1.4%-42.5%). mRS 0-2 outcome was associated with reperfusion for M2 trunk (n = 9) or M2 division (n = 42) occlusions, but not for M2 branch occlusions (n = 28). Of participants with trunk and division occlusions, 63.2% with modified TICI 2a and 42.9% with modified TICI 2b reperfusion achieved mRS 0-2 outcomes; mRS 0-2 outcomes for M2 trunk occlusions (33%) did not differ from distal (38.2%) and proximal (26.9%) M1 occlusions.
  
  
  
  mRS 0-2 at 90 days was dependent on reperfusion for M2 trunk but not for M2 branch occlusions. For M2 division occlusions, good outcome with modified TICI 2b reperfusion did not differ from that in modified TICI 2a. M2 segment definition and occlusion location may contribute to differences in revascularization and good outcome between Interventional Management of Stroke III and other endovascular therapy studies.
authors.affiliation: From the Department of Radiology (T.A.T., J.C.), University of Cincinnati Academic Health Center, University Hospital, Cincinnati, Ohio Thomas.Tomsick@UCHealth.com.
authors.forename: T A
authors.identifier: 0000-0002-8053-1551
authors.initials: TA
authors.lastname: Tomsick
authors.affiliation: From the Department of Radiology (T.A.T., J.C.), University of Cincinnati Academic Health Center, University Hospital, Cincinnati, Ohio.
authors.forename: J
authors.identifier: 0000-0001-6130-4057
authors.initials: J
authors.lastname: Carrozzella
authors.affiliation: Department of Biostatistics, Bioinformatics, and Epidemiology (L.F., Y.P., S.D.Y.), Medical University of South Carolina, Charleston, South Carolina.
authors.forename: L
authors.identifier: 0000-0001-6856-5583
authors.initials: L
authors.lastname: Foster
authors.affiliation: Calgary Stroke Program (M.D.H., A.M.D.), Department of Clinical Neurosciences, Medicine, Community Health Sciences, Hotchkiss Brain Institute, University of Calgary, Foothills Hospital, Calgary, Alberta, Canada.
authors.forename: M D
authors.identifier: 0000-0002-6269-1543
authors.initials: MD
authors.lastname: Hill
authors.affiliation: Department of Neuroradiology (R.v.K.), Dresden University Stroke Center, Universitätsklinikum Carl Gustav Carusan deTechnischen Universität Dresden, Dresden, Germany.
authors.forename: R
authors.identifier: 0000-0003-0119-4604
authors.initials: R
authors.lastname: von Kummer
authors.affiliation: Department of Radiology and Clinical Neurosciences (M.G.), University of Calgary, Calgary, Alberta, Canada.
authors.forename: M
authors.identifier: 0000-0001-9060-2109
authors.initials: M
authors.lastname: Goyal
authors.affiliation: Calgary Stroke Program (M.D.H., A.M.D.), Department of Clinical Neurosciences, Medicine, Community Health Sciences, Hotchkiss Brain Institute, University of Calgary, Foothills Hospital, Calgary, Alberta, Canada.
authors.forename: A M
authors.identifier: 0000-0002-4930-7789
authors.initials: AM
authors.lastname: Demchuk
authors.affiliation: Department of Neurology (P.K., J.P.B.), University of Cincinnati Academic Health Center, Cincinnati, Ohio.
authors.forename: P
authors.identifier: 0000-0002-7344-8266
authors.initials: P
authors.lastname: Khatri
authors.affiliation: Department of Biostatistics, Bioinformatics, and Epidemiology (L.F., Y.P., S.D.Y.), Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Y
authors.identifier: 0000-0003-3434-8550
authors.initials: Y
authors.lastname: Palesch
authors.affiliation: Department of Neurology (P.K., J.P.B.), University of Cincinnati Academic Health Center, Cincinnati, Ohio.
authors.forename: J P
authors.identifier: 0000-0002-7323-7709
authors.initials: JP
authors.lastname: Broderick
authors.affiliation: Department of Biostatistics, Bioinformatics, and Epidemiology (L.F., Y.P., S.D.Y.), Medical University of South Carolina, Charleston, South Carolina.
authors.forename: S D
authors.identifier: 0000-0001-9235-0670
authors.initials: SD
authors.lastname: Yeatts
authors.affiliation: University of California Los Angeles Stroke Center (D.S.L.), Los Angeles, California.
authors.forename: D S
authors.identifier: 0000-0002-5109-8736
authors.initials: DS
authors.lastname: Liebeskind
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000628:therapy*; D002548:Cerebral Revascularization / Q000379:methods*; D002561:Cerebrovascular Disorders / Q000628:therapy*; D057510:Endovascular Procedures / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000628:therapy*; D016896:Treatment Outcome