Effect of Collateral Blood Flow on Patients Undergoing Endovascular Therapy for Acute Ischemic Stroke

Abstract

Background and Purpose— Our aim was to determine the relationships between angiographic collaterals and diffusion/perfusion findings, subsequent infarct growth, and clinical outcome in patients undergoing endovascular therapy for ischemic stroke. Methods— Sixty patients with a thrombolysis in cerebral infarction (TICI) score of 0 or 1 and internal carotid artery/M1 occlusion at baseline were evaluated. A blinded reader assigned a collateral score using a previous 5-point scale, from 0 (no collateral flow) to 4 (complete/rapid collaterals to the entire ischemic territory). The analysis was dichotomized to poor flow (0–2) versus good flow (3–4). Collateral score was correlated with baseline National Institutes of Health Stroke Scale, diffusion-weighted imaging volume, perfusion-weighted imaging volume (Tmax ≥6 seconds), TICI reperfusion, infarct growth, and modified Rankin Scale score at day 90. Results— Collateral score correlated with baseline National Institutes of Health Stroke Scale ( P =0.002) and median volume of tissue at Tmax ≥6 seconds ( P =0.009). Twenty-nine percent of patients with poor collateral flow had TICI 2B–3 reperfusion versus 65.5% with good flow ( P =0.009). Patients with poor collaterals who reperfused (TICI 2B–3) were more likely to have a good functional outcome (modified Rankin Scale score 0–2 at 90 days) compared with patients who did not reperfuse (odds ratio, 12; 95% confidence interval, 1.6–98). There was no difference in the rate of good functional outcome after reperfusion in patients with poor collaterals versus good collaterals ( P =1.0). Patients with poor reperfusion (TICI 0–2a) showed a trend toward greater infarct growth if they had poor collaterals versus good collaterals ( P =0.06). Conclusions— Collaterals correlate with baseline National Institutes of Health Stroke Scale, perfusion-weighted imaging volume, and good reperfusion. However, target mismatch patients who reperfuse seem to have favorable outcomes at a similar rate, irrespective of the collateral score. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01349946.