Abstract
BACKGROUND: The combined prognostic impact of the systemic immune-inflammation index (SII) and low-density lipoprotein cholesterol (LDL-C) after primary percutaneous coronary intervention (PPCI) in acute myocardial infarction (AMI) remains unclear. We evaluated their joint predictive value for clinical outcomes. METHODS: We retrospectively analyzed 487 AMI patients who underwent PPCI at the Affiliated Hospital of Xuzhou Medical University between January 2019 and December 2021. SII and LDL-C were assessed at baseline and 1 month post-discharge. Using the guideline LDL-C target (<1.4 mmol/L or ≥50% reduction) and a receiver operating characteristic (ROC)-derived optimal SII cutoff (676.6 × 10(9) /L), patients were categorized as: both on-target, SII on-target only, LDL-C on-target only, or both off-target. The primary endpoint was the composite of major adverse cardiovascular events (MACEs): all-cause death, recurrent myocardial infarction, repeat revascularization, and ventricular arrhythmias. Candidate variables were selected with least absolute shrinkage and selection operator (LASSO); survival was analyzed using Cox proportional hazards models and Kaplan-Meier estimates. RESULTS: Versus the both off-target group, the both on-target group had significantly better outcomes (P < 0.001). The SII on-target only group also outperformed the LDL-C on-target only group (P < 0.001). Consistently, the both off-target group had markedly worse outcomes relative to the both on-target group (HR = 69.2; 95% CI: 16.8-285.0; P < 0.001). At 1 month, SII showed good discrimination for MACEs (AUC = 0.76). CONCLUSION: One month after PPCI, simultaneous achievement of SII and LDL-C targets was associated with a substantially lower 1-year risk of MACEs. Combined control of inflammation and lipids provided incremental benefit beyond lipid lowering alone, supporting a dual-target strategy in secondary prevention.