Imaging Strategies and Futile Transfers in the Drip-and-Ship Model Within a Densely Connected Stroke Network
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Background and Purpose
Futile interhospital transfers, where patients transferred for endovascular thrombectomy (EVT) do not ultimately receive the procedure, represent a critical systemic burden on stroke transfer network. Whether pre-transfer computed tomography angiography (CTA) at the primary stroke center (PSC) reduces futile transfers, and at what workflow cost, remains incompletely characterized.
Methods
This retrospective study enrolled 314 acute ischemic stroke patients transferred for potential EVT within the Tainan-Chiayi Stroke Network (October 2021–September 2025). Patients were stratified by CTA timing: pre-transfer (n=66) versus post-transfer (n=248). Workflow time metrics and 90-day functional outcomes were compared. Futile transfers were classified into three categories: preventable over-triage, physiological futility, and gray zone cases.
Results
The futile transfer rate was substantially lower in the pre-transfer CTA group (27.3% vs. 66.1%; P<0.001), with post-transfer CTA as the strongest independent predictor of futility (aOR 5.21; 95% CI 2.83–9.60). In the post-transfer CTA group, 40.2% of futile transfers involved conditions identifiable by pre-transfer CTA. Regardless of CTA timing, gray zone cases predominated in both groups (83.3% vs. 47.6%), driven by intracranial atherosclerotic stenosis/ chronic total occlusion, large infarct cores, and medium vessel occlusions. Pre-transfer CTA significantly prolonged PSC door-in-door-out time (140 vs. 88 min; P<0.001) and showed numerical trends toward longer onset-to-EVT time and lower rates of favorable functional outcome.
Conclusions
Adopting CTA during the pre-transfer period reduces preventable futile transfers but prolongs PSC processing time. Nevertheless, the persistent gray zone requires strategies beyond imaging alone, and the trade-off between triage precision and transfer efficiency warrants ongoing evaluation across different stroke networks settings.
