Abstract DP198: Association of Systemic Immune-Inflammation Index With Hemorrhagic Transformation Following Endovascular Therapy for Ischemic Stroke

Introduction: The Systemic Immune-Inflammation Index (SII) is an inflammation–immunity marker that has recently attracted increasing attention in vascular diseases. We investigated the association between SII and hemorrhagic transformation in patients with acute ischemic stroke who underwent endovascular therapy (EVT). As secondary analyses, we examined relationships with the stress hyperglycemia ratio (SHR), a sensitive marker of acute stress response and sympathetic activation, early neurological deterioration (END), and clinical outcomes. Methods: We screened consecutive ischemic stroke patients considered eligible for EVT between May 2014 and May 2025. Inclusion criteria were: (1) availability of admission SII, calculated as platelets × neutrophils / lymphocytes (10 3 /µL); and (2) assessment of symptomatic intracerebral hemorrhage (ICH) after EVT, defined as an NIHSS score worsening ≥4. Patients achieving spontaneous recanalization on initial angiography were excluded. SHR was defined as admission glucose [mg/dL] / (28.7 × HbA1c [%] – 46.7). END was defined as neurological worsening of NIHSS ≥2 within 72 hours after admission. Unfavorable outcome was defined as mRS score 4–6 at 3 months. Results: Of 336 screened patients, 317 (161 men; median age, 80 years) were included. Symptomatic ICH was observed in 30 patients (9%). Higher SII was significantly associated with symptomatic ICH across all multivariable models ( p <0.005, Figure 1). Higher SII was also associated with European Cooperative Acute Stroke Study (ECASS)-defined parenchymal hematoma type 2 at 24 hours after EVT, as well as with ICH ≥ECASS parenchymal hematoma type 1 ( p <0.005, Figure 1). In addition, SII positively correlated with SHR (B 1090, 95% CI 636.6~1544, p <0.001, Figure 2). Finally, SII was independently associated with END (PR 1.119, 95% CI 1.002~1.249, p =0.045, Figure 3A) and unfavorable outcome (PR 1.119, 95% CI 1.029~1.217, p =0.009, Figure 3B). Conclusions: Elevated SII reflects acute stress response and sympathetic activation in ischemic stroke patients undergoing EVT and may serve as a predictor of hemorrhagic complications and unfavorable outcomes.