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.

Keywords: angiography; collateral circulation; magnetic resonance imaging; stroke.

Figure 1

Box plots showing relationship of NIHSSS to collateral score. Box represents interquartile range, line within box represents median value, and bars show ranges of values.

Figure 2

Box plots showing relationship of volume of tissue with Tmax ≥ 6 seconds to collateral score. Box represents interquartile range, line within box represents median value, and bars show ranges of values.

Figure 3

Box plots showing volume of infarct growth to collateral scores for patients with poor reperfusion (TICI 0–2A) and good reperfusion (TICI 2B-3). Box represents interquartile range (IQR). Line within box represents median value, and bars show ranges of values, circles are values from 1.5–3.0 IQRs and asterisk represents values > 3.0 IQRs.