Collateral status as the fifth dimension: warping the time clock for endovascular treatment in acute ischaemic stroke

Endovascular treatment (EVT) has radically transformed the treatment of acute ischaemic stroke during the last few years. A meta-analysis of individual data pooled from five randomised controlled trials (RCTs) of 1287 patients, the Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration, showed no heterogeneity across subgroups of patients with different characteristics in the benefit of EVT over standard medical treatment, with up to 7.3 hours of onset-to-puncture time.1 However, the odds of achieving a good 3-month outcome after EVT significantly declined with longer onset-to-treatment time intervals.2 Four of the five RCTs in the HERMES collaboration had to some extent taken into account the infarct core, evidence of salvageable tissue or the collateral status in patient eligibility criteria.1 2 Data from earlier studies also demonstrated that patients with good pretreatment collaterals, and …