Comparison Between Perfusion- and Collateral-Based Triage for Endovascular Thrombectomy in a Late Time Window

Background and Purpose- Perfusion-based triage has proven to be effective and safe for selecting patients who are likely to benefit from endovascular thrombectomy (EVT) in a late time window. We investigated collateral-based triage for EVT in patients presenting beyond 6 hours, in terms of interrater reliability and efficacy in predicting clinical outcome, in comparison to perfusion-based triage. Methods- One hundred and thirty-two patients who underwent both computed tomographic angiography and computed tomography perfusion for anterior circulation large artery occlusion 6 to 24 hours after last seen well were enrolled. Patients were classified into EVT-eligible and EVT-ineligible groups according to perfusion- and collateral-based triages. We evaluated the interrater reliability of collateral-based triage and differences in good outcome rates of patients who received EVT in the EVT-eligible groups based on perfusion- and collateral-based triages. Results- Both computed tomographic angiography and computed tomography perfusion were assessable in 93 patients. Seventy-six patients were eligible for EVT according to perfusion-based triage. Among them, EVT was performed in 58, of whom 32 (55.1%) had good outcome. Sixty-nine patients were eligible for EVT based on collateral-based triage. Among them, EVT was performed in 50 patients, of whom 31 (62.0%) had good outcome. Interrater reliability of collateral-based triage was good (generalized κ=0.73 [95% CI, 0.59-0.84]). Agreement on EVT eligibility between perfusion- and collateral-based triages was moderate (κ=0.41 [95% CI, 0.16-0.61]). There was no difference in good outcome rates of patients who underwent EVT in the EVT-eligible groups based on perfusion- and collateral-based triages (55.1% versus 62.0%; P=0.0675). Conclusions- Collateral-based triage showed good interrater reliability and comparable efficacy to that of perfusion-based triage in predicting clinical outcome after EVT in patients presenting beyond 6 hours. Collateral-based triage is a reliable approach for selecting patients for EVT in the extended therapeutic time window.