Correlation of Acute M1 Middle Cerebral Artery Thrombus Location with Endovascular Treatment Success and Clinical Outcome

Abstract

Purpose—The location of the arterial occlusion can help with prognostication and treatment triage of
acute stroke patients. We aimed to determine the effects of M1 distance-to-thrombus on angiographic
recanalization success rate and clinical outcome following endovascular treatment of acute M1 occlusion.
Methods—All acute ischemic stroke patients with M1 segment middle cerebral artery (MCA) occlusion
on admission CT angiography (CTA) who underwent endovascular treatment were analyzed. The distance
between thrombus origin and internal carotid artery (ICA) bifurcation was measured on admission CTA.
The modified thrombolysis in cerebral infarction (mTICI) grades 2b (>50% of distal branch filling) and 3
(complete) were considered as successful recanalization. Favorable outcome was defined by 3-month follow-up modified Rankin scale (mRs) score ≤2.
Results—Successful recanalization was achieved in 24 (71%) of 34 consecutive patients included in this
study. The M1 distance-to-thrombus was shorter among patients with successful recanalization (5.4 ± 5.4
mm) versus those without (11.3 ± 7.6 mm, p = 0.015). The successful recanalization rate was higher among
patients with M1 distance-to-thrombus ≤6 mm (odds ratio: 8, 95% confidence interval: 1.37–46.81, p =
0.023) compared with those with distance-to-thrombus >6 mm. There was no significant correlation
between M1 distance-to-thrombus and 3-month mRs (rho: 0.131, p = 0.461); however, the distance-tothrombus negatively correlated with admission National Institutes of Health Stroke Scale (NIHSS) scores
(rho: −0.350, p=0.043). On the other hand, successful recanalization and admission NIHSS score were the
only independent predictors of favorable outcome.
Conclusion—Shorter distance of M1 thrombus from ICA bifurcation is associated with higher rate of
successful recanalization following endovascular treatment