How temporal evolution of intracranial collaterals in acute stroke affects clinical outcomes

Abstract

Objective: We compared intracranial collaterals on pretreatment and day 2 brain CT angiograms (CTA) to assess their evolution and relationship with functional outcomes in acute ischemic stroke (AIS) patients treated with IV tissue plasminogen activator (tPA).Methods: Consecutive AIS patients who underwent pretreatment and day 2 CTA and received IV tPA during 2010-2013 were included. Collaterals were evaluated by 2 independent neuroradiologists using 3 predefined criteria: the Miteff system, the Maas system, and 20-point collateral scale by the Alberta Stroke Program Early CT Score methodology. We stratified our cohort by baseline pre-tPA state of their collaterals and by recanalization status of the primary vessel for analysis. Good outcomes at 3 months were defined by a modified Rankin Scale score of 0-1.Results: This study included 209 patients. Delayed collateral recruitment by any grading system was not associated with good outcomes. All 3 scoring systems showed that collateral recruitment on the follow-up CTA from a baseline poor collateral state was significantly associated with poor outcome and increased bleeding risk. When the primary vessel remained persistently occluded, collateral recruitment was significantly associated with worse outcomes. Interestingly, collateral recruitment was significantly associated with increased mortality in 2 of the 3 grading systems.Conclusions: Not all collateral recruitment is beneficial; delayed collateral recruitment may be different from early recruitment and can result in worse outcomes and higher mortality. Prethrombolysis collateral status and recanalization are determinants of how intracranial collateral evolution affects functional outcomes. Neurology ® 2016;86:434-441 GLOSSARY AF 5 atrial fibrillation; AIS 5 acute ischemic stroke; ASPECTS 5 Alberta Stroke Program Early CT Score; CI 5 confidence interval; CTA 5 CT angiography; IRB 5 institutional review board; mRS 5 modified Rankin Scale; NIHSS 5 NIH Stroke Scale; OR 5 odds ratio; ROC 5 receiver operating characteristic; SICH 5 symptomatic intracranial hemorrhage; tPA 5 tissue plasminogen activator.Ischemic stroke is the largest contributor to disability in most developed countries. In clinical practice, infarct growth does not always progress to involve the full extent of the vascular territory, even if the affected intracranial artery fails to recanalize. The presence and recruitment of various collateral channels are believed to be responsible for this phenomenon in acute ischemic stroke (AIS).1 These collaterals may also play an important role in influencing the safety and efficacy of acute revascularization approaches. 2Although blood supply from the leptomeningeal collaterals may temporarily maintain the ischemic penumbra, the persistence and effectiveness of this alternative circulatory supply is erratic and unpredictable. Some collaterals may disappear over time (collateral failure); this is one of the mechanisms responsible for clinical deterioration following initial improvement. Conversely, dra...

Factors influencing infarct growth including collateral status assessed using computed tomography in acute stroke patients with large artery occlusion

“…This is in agreement with previous studies showing that a better collateral score was associated with smaller infarcts and slower IGR. [14][15][16][17][18][19][20] In patients with no collaterals, the IGR could reach 31.56 ml/log(min).…”

The Association Between Recanalization, Collateral Flow, and Reperfusion in Acute Stroke Patients: A Dynamic Susceptibility Contrast MRI Study

“…Firstly, collateral flow is dynamic and changes over time. Yeo et al (35) found that an improvement in collateral grade over time assessed using CTA in patients without recanalization was associated with worse outcome and mortality. Such slower recruitment of collaterals is mediated by metabolic factors and angiogenesis, as compared to the rapid response due to drop in perfusion pressure and relaxation of smooth muscles with a resulting pressure gradient (36).…”

Acute reperfusion without recanalization: Serial assessment of collaterals within 6 h of using perfusion-weighted magnetic resonance imaging

“…However, causality was uncertain given the delayed follow-up assessment (day 3-5), when extensive infarction and edema can severely impede retrograde (or anterograde) flow. Interestingly, using CT-angiography, Yeo et al 17 recently reported that in patients without recanalization or with poor collaterals at baseline, late (i.e. 24 h) recruitment of cortical collaterals was associated with worse clinical outcome and higher mortality.…”

“…14 In our previous work, lower hypoperfusion intensity ratio (proportion of voxels with T max !7 s within the T max !2 s lesion), an indirect marker of good collaterals, was observed at baseline in patients showing subsequent reperfusion without recanalization. 3 Still, only limited data so far have related the evolution of collateral flow to infarct growth 13 or clinical outcome, 17 and these studies explored late follow-up time points only (i.e. !24 h).…”

“…Still, only limited data so far have related the evolution of collateral flow to infarct growth 13 or clinical outcome, 17 and these studies explored late follow-up time points only (i.e. ≥24 h).…”