Background: Recent randomized trials have consistently demonstrated a clinical benefit of endovascular therapy (ET) over best medical therapy (including intravenous (IV) thrombolysis in eligible patients) or IV thrombolysis only in selected patients with acute ischemic stroke (AIS) due to proximal occlusion in the carotid territory. Previous study demonstrates that lack of improvement (LOI) at 24 hours is an independent predictor of poor outcome and death at 3 months in patients with AIS treated with IV alteplase. However, LOI at 24 hours following ET has not been studied systematically. The purpose of this study is to identify predictors of LOI at 24 hours in patients with AIS after ET as well as the relationship between LOI and unfavorable outcome at 3 months.
Methods: A total of 98 consecutive patients with AIS treated with ET in two separate stroke centers from 2010 to 2014 were retrospectively reviewed. Data on demographics, preexisting vascular risk factors, occlusion site, pre- and post-treatment modified Treatment in Cerebral Ischemia (mTICI) classification, collaterals and National Institutes of Health Stroke Scale (NIHSS) score on admission as well as 24 hours after the endovascular procedurals were collected. LOI was defined as a reduction of 3 points or less on the NIHSS at 24 hours compared with baseline. A 3-month functional outcome was assessed using the modified Rankin scale (mRS). Unfavorable outcome was prespecified as a score of more than 2 on the mRS. The onset-to-reperfusion time (ORT) was defined as time to mTICI 2b or 3 or end of procedure. Long ORT was defined as time to reperfusion beyond 6 hours. Poor reperfusion was defined as mTICI ≦2a. The pretreatment collateral circulation extent was graded as poor (grades 0-1) or good (grades 2-4).
Results: Among the 98 patients with AIS who were treated with ET, LOI was present in 48 (49%) subjects. Multivariate analysis indicated that poor collaterals (odds ratio [OR] 3.25; 95% confidence interval [CI]: 1.29-8.19; p = 0.012) and long ORT (OR 3.97, 95% CI: 1.66-9.54; p = 0.002) were independent predictors of LOI. LOI (OR 7.18, 95% CI: 2.39-21.61; p < 0.001) was independently associated with unfavorable outcome at 3 months.
Conclusion: Among patients with AIS treated with ET, as an independent predictor of unfavorable outcome, LOI at 24 hours is associated with poor collaterals and long ORT.
Keywords: acute ischemic stroke; endovascular therapy; lack of improvement; predicting factors.