Résumé
Objective Patients with acute ischemic stroke harboring a large vessel occlusion who present to primary stroke centers often require inter‐hospital transfer for thrombectomy. We aimed to determine clinical and imaging factors independently associated with fast infarct growth (IG) during inter‐hospital transfer. Methods We retrospectively analyzed data from acute stroke patients with a large vessel occlusion transferred for thrombectomy from a primary stroke center to one of three French comprehensive stroke centers, with an MRI obtained at both the primary and comprehensive center before thrombectomy. Inter‐hospital IG rate was defined as the difference in infarct volumes on diffusion‐weighted imaging between the primary and comprehensive center, divided by the delay between the two MRI scans. The primary outcome was identification of fast progressors, defined as IG rate ≥5 mL/hour. The hypoperfusion intensity ratio (HIR), a surrogate marker of collateral blood flow, was automatically measured on perfusion imaging. Results A total of 233 patients were included, of whom 27% patients were fast progressors. The percentage of fast progressors was 3% among patients with HIR < 0.40 and 71% among those with HIR ≥ 0.40. In multivariable analysis, fast progression was independently associated with HIR, intracranial carotid artery occlusion, and exclusively deep infarct location at the primary center (C‐statistic = 0.95; 95% confidence interval [CI], 0.93–0.98). IG rate was independently associated with good functional outcome (adjusted OR = 0.91; 95% CI, 0.83–0.99; P = 0.037). Interpretation Our findings show that a HIR > 0.40 is a powerful indicator of fast inter‐hospital IG. These results have implication for neuroprotection trial design, as well as informing triage decisions at primary stroke centers. ANN NEUROL 2023;93:1117–1129