Prognosis of Ischemic Stroke Patients Undergoing Endovascular Thrombectomy is Influenced by Systemic Inflammatory Index Through Malignant Brain Edema

Purpose: The systemic immune inflammatory index (SII), as a new marker, is widely used to predict the disease prognosis. We investigated the predictive value of SII for malignant cerebral edema (MCE) and whether postoperative MCE mediates the relationship between SII and functional prognosis in patients undergoing endovascular thrombectomy (EVT). Patients and Methods: A total of 829 patients with anterior circulation large-vessel occlusive stroke (LVOS) were registered, and 675 (81.4%) met the inclusion criteria. We collected baseline data upon admission, including SII. Postoperative computed tomography was performed to assess the presence and grading of cerebral edema (CED), and MCE was defined as a CED score of 3. A good prognosis was defined as a modified Rankin Scale (mRS) score of 0-2 at the 90-day follow-up. Results: A total of 132 patients developed MCE after EVT. The patients were divided into MCE and non-MCE groups, and univariate and multifactorial analyses were performed. Among these risk factors, an elevated SII was independently correlated with the occurrence of MCE. In addition, the receiver operating characteristic (ROC) curve was used to assess the predictive capability of SII levels for prognosis. The area under the ROC was 0.69, and the optimal critical value was 2.14. In addition, postoperative MCE may partially account for the poorer functional prognosis of patients with elevated SII (regression coefficient changed by 40.3%). Conclusion: The SII is an independent predictor of malignant brain edema after EVT. Postoperative MCE is partly the reason for the poorer prognosis in patients with elevated SII.