Hidden Core: Unveiling the Clinical Impact of CTP-Invisible Ischemic Lesions in Large Vessel Occlusion Stroke Treated with Thrombectomy
Abstract Body: Background and Purpose: Acute ischemic stroke (AIS) may present with an estimated core of 0 ml on CT perfusion imaging without a visible decrease in cerebral blood flow (CBF) maps. When the ischemic core is not visible, assessing the full extent of stroke severity can be challenging. We assessed the clinical outcomes of patients with and without a CBF core at stroke onset, who underwent mechanical thrombectomy. Methods: Data from the National Cerebral and Cardiovascular Center Endovascular Thrombectomy database (January 2018 to April 2024) were analyzed. Anterior circulation AIS patients with large vessel occlusion were grouped based on the presence of a CBF core, defined as either 0 mL or greater than 0 mL, with a relative CBF less than 30% of normally perfused tissue on CT perfusion imaging. The primary outcome was a modified Rankin Scale (mRS) score of 0-2 at 90 days. Secondary outcomes included mRS 0-1 at 90 days, symptomatic intracranial hemorrhage (sICH), and death. Results: A total of 704 patients (mean age 75±13 years, 52% women) were included in the study, with 214 having no CBF core (0 mL) and 490 having a CBF core. Median CBF core volume in the CBF core group was 26 mL (IQR 12-64). The median baseline NIHSS score was significantly lower in the no CBF core group (13; IQR 7-18) compared to the CBF core group (19; IQR 14-25, p < 0.01). Additionally, the no CBF core group had higher hemoglobin levels (p <0.01) and a lower percentage of M1distal (M1d) occlusion (15% vs. 23%, p=0.02). The rate of intravenous thrombolysis (45% vs. 39%, p=0.13) and the median time from onset to imaging (143 minutes vs. 162 minutes, p=0.43) were similar between groups. Favorable outcomes (mRS 0-2 at 90 days) were significantly more frequent in the no CBF core group (44% vs. 34%, p=0.01), as were excellent outcomes (32% vs. 20%, p <0.01). There was no significant difference in rates of sICH (4% vs. 3% p=0.81) and death (5% vs. 8%, p=0.26) between the groups. Logistic regression analysis, adjusted for age, sex, NIHSS, hemoglobin, blood glucose, M1d occlusion, and intravenous thrombolysis, showed a significant association between the absence of a CBF core and favorable outcomes, with an adjusted OR of 1.51 (95% CI 1.00-2.25, p=0.04). Conclusions: Stroke patients without a CBF core at baseline have better clinical outcomes. The higher incidence of M1d occlusions in the CBF core group suggests that these patients have poorer collateral flow, leading to more evident decreases in CBF.
