The Combined Prognostic Value of the Systemic Immune-Inflammation Index and LDL-C in Patients with AMI Undergoing...

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.

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 × 10⁹ /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.

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).

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.