Association of neutrophil-to-lymphocyte ratio (NLR) with the infarct size in acute myocardial infarction (AMI), through peak creatine kinase (CK) and peak creatine kinase-myocardial band (CK-MB): A retrospective observational study

The neutrophil-to-lymphocyte ratio (NLR) has emerged as a marker of systemic inflammation and a prognostic indicator in acute myocardial infarction (AMI). Simultaneously, infarct size (reflected by peak serum levels of creatine kinase (CK) and creatine kinase-myocardial band [CK-MB]) correlates with clinical outcomes in AMI. Given the inflammatory nature of infarction, elevated NLR at admission may contribute to larger infarct size and higher CK and CK-MB levels; however, this association has not been clearly established. We retrospectively analyzed data from 170 patients hospitalized for AMI. Univariate and multivariate linear regression analyses were conducted to examine associations between peak creatine kinase (peak CK) and CK-MB levels and clinical variables, including age, sex, body mass index, hemoglobin, creatinine, uric acid, B-type natriuretic peptide, albumin, C-reactive protein, mean blood pressure, NLR, and platelet-to-lymphocyte ratio at admission. Structural equation modeling was also employed to explore the relationship between NLR and infarct size. Multivariate analysis revealed a significant positive association between NLR at admission and both peak CK (β = 0.342, P = .002) and peak creatine kinase-myocardial band (β = 0.352, P = .001). Structural equation modeling confirmed these findings, showing significant correlations between NLR and peak CK (β = 0.342, P = .001) and CK-MB (β = 0.352, P < .001). Elevated NLR at admission is significantly associated with increased peak CK and CK-MB levels in patients with AMI, suggesting a potential link between systemic inflammation and infarct size. NLR may serve as an early, accessible predictor of infarct magnitude following AMI.