摘要Background The neutrophil-to-lymphocyte ratio(NLR)stands as a valuable marker for assessing inflamma-tion and predicting adverse outcomes post-cardiac surgery.This study aimed to ascertain the prognostic relevance of preoperative NLR concerning prolonged ICU stay among infants undergoing congenital heart surgery employing cardiopulmonary bypass.Methods A retrospective review was conducted involving 187 consecutive infants(≤1 year)who underwent congenital heart disease surgery between January and April 2019,stratified into two groups based on NLR(NLR＜0.484,NLR ≥0.484).The primary outcome was prolonged intensive care unit(ICU)length of stay,defined patients with ICU stays duration higher than the third quartile.Correlations between preoperative NLR and clinical outcomes were assessed.Receiver operating characteristic curve analysis,multivariable Logistic regression,and restricted cube plots were utilized to gauge the association of preoperative NLR with prolonged ICU stay.Results The area under the receiver operating characteristic curve of NLRpredictive capability for prolonged ICU length of staywas 0.691.Subgroup analyses revealed poorer prognoses among patients with high NLR(≥0.484).Multivariable Logistic regression analysis indicated that heightened preoperative NLR(OR:2.63,95％CI:1.18-5.83,P=0.018)independently was correlated with prolonged ICU length of stay in infants'post-cardiac surgery.Conclusions In summary,the NLR emerges as a significant predictive factor for prolonged ICU stay in infants undergoing cardiac surgery.Nevertheless,further research is warranted to comprehensively grasp the relationship between the NLR and prolonged ICU stay.