Objective To explore the correlation between CAE and the ratio of white blood cell count to mean platelet volume ratio(WMR)in elderly patients.Methods A retrospective analysis was conducted on 238 patients who underwent coronary angiography(CAG)between January 2018 and January 2023 in Department of Cardiology of Tianjin First Central Hospital.According to the results of CAG and patient's age,they were divided into in elderly CAE group(age ≥65 years,100 cases)and non-elderly CAE group(age＜65 years,138 cases).Another 127 age-matched elderly individuals with normal coronary artery(age ≥65 years)served as normal con-trol group.The WMR levels were measured in all participants.Results The elderly CAE group had significantly higher WMR than the non-elderly CAE group and the normal control group(745.50±237.46 vs 672.43±194.52 and 610.11±144.22,P=0.000).Spearman correlation analy-sis showed that WMR was positively correlated with platelet count,neutrophil count and high-sensitivity C-reactive protein level(r=0.380,P=0.000;r=0.819,P=0.000;r=0.283,P=0.000).Multiple logistic analysis indicated that readmission,male,TC and WMR were significantly associated with CAE in elderly patients.ROC curve analysis revealed that the value of WMR to distinguish the presence of CAE in elderly patients was 0.604(95％CI:0.531-0.677,P=0.006).Conclusion Elevated WMR might be a cost-effective monitor in elderly CAE patients.