Endovascular Therapy of M2 Occlusion in IMS III: Role of M2 Segment Definition and Location on Clinical and Revascularization Outcomes.

T.A Tomsick,P Khatri,L Foster,J Carrozzella,D.S Liebeskind,R Von Kummer,Y Palesch,M.D Hill,J.P Broderick,M Goyal,A.M Demchuk,S.D Yeatts

doi:10.3174/ajnr.a4979

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.

Highlights

BACKGROUND AND PURPOSEUncertainty persists regarding the safety and efficacy of endovascular therapy of M2 occlusions following IV tPA
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. mRS 0 –2 outcome was associated with reperfusion for M2 trunk (n ϭ 9) or M2 division (n ϭ 42) occlusions, but not for M2 branch occlusions (n ϭ 28)
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

Summary

MATERIALS AND METHODS

IMS III eligibility and exclusion criteria, randomization and statistical methods, and results have been previously reported.[13,14,15] CT angiography, CT perfusion, and MR angiography and/or perfusion were allowed in centers where they were established as a local standard of evaluation and care. The single vessel continuation of M1 beyond the isolated patent posterior temporal or holotemporal branches is termed the “M2 trunk,” which simulates the distal M1 trunk (Fig 3). Individual, classic M2 branches arising from the distal M1 (eg, orbitofrontal, operculofrontal, central or Rolondic, angular, parietal, or posterior temporal branches) was mRS 0 –2 and 0 –1 outcomes was determined. Including review of revascularization and clinical outcome, were performed, including analysis of the following: 1) occluded segment description (trunk, division, division-branch, branch); 2) estimated percentage MCA distribution of the region at risk according to the occluded segment anatomy; 3) M2 occlusion location (proximal, mid, or distal) and number (single or multiple) on revascularization and outcome; and 4) the presence of isolated holotemporal and posterior temporal lobe branch supply and M2 trunk occlusion on day-2 CTP core infarct and penumbra volumes. Differences in reperfusion and mRS 0 –2 outcomes between M2 occlusion subgroups were analyzed with the ␹2 test, and differences in percentage MCA distribution at risk between subgroups, via the t test

RESULTS

DISCUSSION

CONCLUSIONS