Systemic Inflammatory Indices Predict Survival and Limb Outcomes after Revascularization for Chronic Limb-Threatening Ischemia

● Background: Chronic limb-threatening ischemia (CLTI) carries high morbidity and mortality, yet risk stratification tools after revascularization remain limited. The Systemic Immune-Inflammation Index (SII) and Systemic Inflammatory Response Index (SIRI) have emerged as prognostic markers. This study evaluated their predictive value in CLTI patients undergoing revascularization. ● Methods: This retrospective single-center cohort study included 122 CLTI patients undergoing endovascular angioplasty (n=81) or surgical bypass (n=41) between 2017 and 2023. Pre-procedural SII and SIRI were calculated from blood counts. Outcomes included overall survival, adverse cardiovascular and limb events (MACE/MALE), and limb amputation. Kaplan-Meier analysis, Cox regression with Firth's penalized likelihood adjustment, and C-index analyses were performed. ● Results: Surgical bypass was associated with longer median survival than angioplasty (48 vs. 27 months, P=.012). Patients in the lowest SII quartile (<492) had significantly improved 84-month survival versus higher quartiles (88.4% vs. 55.1%). Elevated SII remained independently associated with mortality on multivariable analysis. SIRI was higher among patients with adverse events (2.7 vs. 2.0, P=.024) but was not independently associated with outcomes. SII demonstrated moderate-to-high predictive performance, with C-indices up to 0.921 in the bypass subgroup. ● Conclusion: Pre-procedural SII is independently associated with survival following CLTI revascularization and may aid risk stratification.