Predictors of Futile Inter-Hospital Transfer for Endovascular Thrombectomy in Anterior Circulation Acute Ischemic Stroke Due to Large Vessel Occlusion

Background: Endovascular therapy (EVT) is a standard treatment for acute ischemic stroke (AIS) with large vessel occlusion (LVO), but inter-hospital transfers from primary stroke centers (PSCs) to comprehensive stroke centers (CSCs) can result in delayed treatment and worse outcomes. Up to 30-40% of patients transferred may not receive EVT. This study investigates the causes of futile transfers to a CSC in Canada, aiming to identify its predictors. Methods: We conducted a retrospective analysis of consecutive patients transferred for EVT between 1 April 2017 and 31 December 2020, from PSCs and community hospitals (CH) to a CSC in an urban area of Canada. Data on demographics, clinical characteristics, and treatment outcomes were collected. Descriptive and comparative analyses were performed to identify factors contributing to non-receipt of EVT. Results: Of the transferred 326 patients, 241 (73.9%) underwent EVT, and 85 (26%) did not. The main reasons for not performing EVT were recanalization of the target vessel (44.7%), infarct growth (29.4%), clinical improvement or low NIHSS (17.6%), and hemorrhagic transformation (8.2%). Predictors of futility were lower NIHSS at presentation, intravenous thrombolysis (IVT) at the PSC, and greater ASPECTS decay during transport. Conclusions: Our study concluded that 26% of inter-hospital transfers for EVT were futile, primarily due to infarct growth, recanalization of the target vessel, and low NIHSS. These findings suggest that closer monitoring of clinical status, consideration of direct transfers to CSCs, and enhanced triage strategies may help reduce futile transfers and improve patient outcomes.