Introduction: After the results of the new endovascular trials that demonstrated a robust effect of endovascular treatment for acute ischemic stroke (AIS), early detection of proximal artery occlusion (PAO) has become a fundamental task during the initial assessment of acute stroke patients at the emergency department. Nevertheless, an accurate identification of PAO may be particularly challenging in smaller hospitals and in developing countries, areas with restricted assess to vascular neuroimaging modalities such as CTA and MRA.
Hypothesis: Algorithms based on NIHSS and non-contrasted CT (NCCT) findings can be accurately used to detect PAO in patients with AIS of the anterior circulation.
Method: We retrospectively evaluated 194 consecutive patients with AIS of the anterior circulation from a prospective stroke registry of patients admitted to an academic tertiary emergency unit in Brazil during 2014 that had a NCCT and a CTA at admission. NIHSS scores and attenuation of major intracranial arteries of the anterior circulation on NCCT were collected by two experienced investigators that were blind to the CT angiography findings. We used a ratio between two ROIs (rVA) that were drawn on NCCT blinded to CT angiography: (i) on the region of highest vessel attenuation ipsilateral to the involved hemisphere and (ii) mirror ROI on the corresponding vessel segment of the contralateral hemisphere. We used ROC curve analysis and C-statistics to predict CT angiography PAO.
Results: NIHSS and vessel attenuation values were highly associated with the PAO with an area under the curve (AUC) of 0.88 (p < 0,001) and 0.83 (p < 0,001), respectively. An NIHSS of 10 at admission had a sensitivity, and negative predictive value of 97% and 97%, respectively. The rVA ≥ 1.50 had a specificity and positive predictive value 96% and 85%, respectively. The POA score was then built by logistic regression from NIHSS and rVA and showed even higher accuracy for the presence of POA on CTA, with an AUC of 0.93 (p < 0,001).
Conclusion: The PAO score based on admission NIHSS and proximal vessel attenuation on NCCT can be accurately used to detect PAO in patients with AIS of the anterior circulation. Further studies are necessary to validate this score in a multicenter setting.