Neutrophil-to-lymphocyte ratio and clinical outcomes across the acute coronary syndrome trajectory: insights from the CardioMining Study

BACKGROUND: Inflammation contributes to plaque instability and adverse outcomes in acute coronary syndromes (ACS). The neutrophil-to-lymphocyte ratio (NLR) is an inexpensive inflammatory marker, but its prognostic value for in-hospital and postdischarge outcomes remains incompletely defined. OBJECTIVE: To evaluate the association of admission NLR with postdischarge mortality, in-hospital adverse events, and length of stay (LOS) in patients with ACS. METHODS: We retrospectively analyzed adults with ACS in the CardioMining database (NCT05176769). Admission NLR was ln-transfor med and analyzed continuously and by quartiles. Associations with postdischarge all-cause mortality were assessed using multivariable Cox proportional hazards models with sequential adjustment and restricted cubic spline analyses. Secondary outcomes were evaluated using logistic and linear regression. Discrimination was assessed with the C-index, and interactions by sex, age (<75 vs. ≥75 years), and ACS type were explored. RESULTS: Among 4927 patients (mean age: 66.0 ± 13.4 years; 24.3% female), higher admission lnNLR independently predicted all-cause mortality [hazard ratio: 1.372, 95% confidence interval (CI): 1.266-1.488; P < 0.001]. Mortality increased across lnNLR quartiles [Q2 adjusted hazard ratio (aHR): 1.225, Q3 aHR: 1.551, Q4 aHR: 1.831; all P < 0.05], with lower Kaplan-Meier survival at higher quartiles. Restricted cubic splines supported a predominantly linear relationship. Adding lnNLR improved discrimination (ΔC-index: +0.0096). Higher lnNLR was associated with in-hospital adverse events (adjusted odds ratio: 1.849, 95% CI 1.530-2.236; P < 0.001) and longer LOS (adjusted β: 0.129, 95% CI: 0.107-0.151; P < 0.001). CONCLUSION: Admission NLR independently predicts mortality, in-hospital complications, and longer LOS in ACS, supporting early risk stratification.