Purpose of review: Endovascular therapy is a promising aspect of acute ischemic stroke treatment. The ideal population of patients who benefit from treatment remains undefined, and the status of collateral circulation at presentation may be a key feature in their identification.
Recent findings: Adequate collateral flow has been recently demonstrated to be associated with improved clinical status on presentation, increased likelihood of recanalization with endovascular therapy, and better functional outcome at 3 months.
Summary: In this review, we define the collateral circulation, review methods of its measurement, and present recent clinical data on its impact in endovascular therapy for acute ischemic stroke. We outline our current understandings and discuss their relevance in future directions with clinical stroke management.