Evaluation of Large Ischemic Cores to Predict Outcomes of Thrombectomy: A Proposal of a Novel Treatment Phase

Endovascular treatment of large ischemic cores is challenging. The severity of ischemic stress is assessed using the apparent diffusion coefficient (ADC). We aimed to evaluate the ADC in patients with a low Alberta Stroke Program Early CT [Computed Tomography] Score using diffusion‐weighted imaging and whether it correlates with clinical outcomes. This study included consecutive patients with acute large ischemic stroke (Alberta Stroke Program Early CT Score‐diffusion‐weighted imaging ≤5) who underwent endovascular treatment with successful recanalization between April 2014 and March 2023. The most frequent ADC (peak ADC) and diffusion‐weighted imaging lesion volumes were assessed. The primary outcome was the 3‐month modified Rankin Scale (mRS) score. Good (mRS score, 0–3) and poor clinical outcomes (mRS score, 4–6) were compared to confirm whether ADC was associated with clinical outcomes. In total, 78 patients were enrolled in this study; 30 had an mRS score of 0 to 3 at 3 months. The peak ADC in these patients was significantly higher than that in patients with mRS scores of 4 to 6 ( P = 0.0002). In multivariate analysis, peak ADC was strongly associated with good clinical outcomes (odds ratio, 1.231; P = 0.0135) rather than onset‐to‐recanalization time and ischemic core volume. The optimal peak ADC threshold for discriminating between the mRS groups was 520×10 −6 mm 2 /s with a sensitivity of 75% and a specificity of 73%. Good clinical outcomes were more frequently observed in patients with peak ADC ≥520×10 −6 mm 2 /s ( P <0.0001). In large ischemic cores, diffusion‐weighted imaging lesions with peak ADCs ≥520×10 −6 mm 2 /s are associated with favorable outcomes. Evaluation of the ischemic core is necessary to confirm endovascular treatment.