Thrombectomy in ischemic stroke patients with large core but minor ischemic changes on non-enhanced computed tomography

Purpose: The Alberta Stroke Program Early CT Score (ASPECTS) is regularly used to guide patient selection for mechanical thrombectomy (MT). Similarly, penumbral imaging based on computed tomography perfusion (CTP) may serve as neuroimaging tool to guide treatment. Yet, patients with a large ischemic core on CTP may show only minor ischemic changes resulting in a high ASPECTS. Aim: We hypothesized twofold: 1) the treatment effect of vessel recanalization in patients with core volume >50ml but ASPECTS≥6 is not different compared to high ASPECTS patients with core volume <50ml, and 2) recanalization is associated with core overestimation. Methods: We conducted an observational study analyzing ischemic stroke patients consecutively treated with MT after triage by multimodal-CT. Functional endpoint was the rate of functional independence at day-90 defined as modified Rankin Scale (mRS) 0-2. Imaging endpoint was core overestimation, which was considered when CTP-derived core was larger than final infarct volume assessed on follow-up imaging. Recanalization was evaluated with the eTICI (extended Thrombolysis in Cerebral Infarction) scale. Multivariable logistic regression analysis and prospensity score matching (PSM) were used to assess the association of recanalization (eTICI≥2b) with functional outcome and core overestimation. Results: Of 630 patients with ASPECTS≥6, 91 patients (14.4%) had a large ischemic core. Following 1:1 PSM, the treatment effect of recanalization was not different in patients with large core and ASPECTS≥6 (+25.8%,95%CI: 16.3-35.4,p<0.001) compared to patients with ASPECTS≥6 and core volume <50 ml (+14.9%,95%CI: 5.7-24.1,p=0.002). Recanalization (aOR: 3.87, 95%CI: 1.66-9.00, p=0.002) and higher core volume (aOR: 1.04,95%CI: 1.02-1.05,p<0.001) were significantly associated with core overestimation. Conclusions: In patients with ASPECTS≥6, core volumes did not significantly modify outcomes following recanalization. Reperfusion and higher core volume were significantly associated with core overestimation which may explain the treatment effect of MT for patients with a large ischemic core but minor ischemic changes on non-enhanced CT.