To develop a predictive model for acute ischemic stroke patient triage decisions that typically require perfusion neuroimaging. 

Endovascular thrombectomy (EVT) and tissue plasminogen activator (tPA) are effective ischemic stroke treatments. In the extended treatment window, patients often require perfusion neuroimaging to determine eligibility. Many hospitals do not have access to advanced imaging tools or EVT. To assist transfer decisions, we developed  risk indices that could identify patients likely to be eligible for extended window EVT or tPA.

We retrospectively identified stroke patients who had concurrent CT angiogram and perfusion. The first outcome was large vessel occlusion (LVO) and target mismatch (TM) in patients 5 to 23 hours from last known normal (LKN). The second outcome was TM in patients 5 to 15 hour from LKN with known LVO. These two outcomes are relevant to the neuroimaging inclusion criteria for the DEFUSE 3 and DAWN trials of EVT. The third outcome was TM in patients 4.5 to 12 hour from LKN, which is relevant to the EXTEND trial tPA neuroimaging inclusion criteria. We created multivariable models using backward stepping with ∝-error criterion of 0.05 and assessed them using C statistics.

These risk indices are hypothesis-generating, but warrant additional prospective study to determine if they can be used to identify stroke patients that warrant expedient transfer to a center with perfusion and EVT capability.