Introduction: Five RCTs demonstrated the superiority of endovascular therapy (EVT) over best medical management (MM) for acute ischemic strokes (AIS) with large vessel occlusion (LVO) in the anterior circulation. Patients with M2 occlusions, however, were underrepresented (95 randomized; 51 EVT treated). Evidence from RCTs of the benefit of EVT for M2 occlusions is lacking, as reflected in the recent AHA guidelines.
Methods: A retrospective cohort was pooled from 10 academic centers from 1/12 to 4/15 of AIS patients with LVO isolated to M2 presenting within 8 hours from last known normal (LKN). Patients were divided into EVT and MM groups. Primary outcome was 90 day mRS (good outcome 0-2); secondary outcome was sICH. Logistic regression compared the 2 groups. Univariate and multivariate analyses evaluated predictors of good outcome in the EVT group.
Results: Figure 1 shows participating centers, 522 patients (288 EVT and 234 MM) were identified. Table (1) shows baseline characteristics. MM treated patients were older and had higher IV tPA treatment rates, otherwise the 2 groups were balanced. 62.7 % EVT patients had mRS 0-2 at 90 days compared to 35.4 % MM (figure 2). EVT patients had 3 times the odds of good outcome as compared to MM patients (OR: 3.1, 95% CI:2.1-4.4, P <0.001) even after adjustment for age, NIHSS, ASPECTS, IV tPA and LKN to door time (OR: 3.2, 95%CI: 2-5.2, P<0.001). sICH rate was 5.6 %, which was not statistically different than the MM group (table 1, P=0.1). Age, NIHSS, good ASPECTS, LKN to reperfusion time and successful reperfusion mTICI ≥ 2b were independent predictors of good outcome in EVT patients. There was a linear relationship between good outcome and time LKN to reperfusion (Figure 3).
Conclusion: Despite inherent limitations of its retrospective design, our study suggests that EVT may be effective and safe for distal LVO (M2) relative to best MM. A trial randomizing M2 occlusions to EVT vs. MM is warranted to confirm these findings.