Abstract: ob＜x＞jective To investigate the association between apolipoprotein E (APOE) gene polymorphism and in-stent restenosis(ISR)in patients with coronary heart disease(CHD)after percutaneous coronary intervention(PCI).Methods A total of 172 patients with coronary heart disease who underwent drug-eluting coronary stent implantation in the affiliated Hospital of Xuzhou Medical University from January 2016 to October 2018 and were reexamined by angiography within 36 months were enrolled in this study.According to the results of coronary angiography,the patients were divided into ISR group and non-ISR group.Univariate analysis was used to compare the general data,angiographic features,medication,hematological parameters and APOE genotypes between the ISR group and the non-ISR group.The independent risk factors of ISR were studied by logistic stepwise regression analysis with the independent variable and ISR as the dependent variable in univariate analysis.Results Univariate analysis showed that the levels of LDL-C and HbAlc,the frequency of genotype E3/4,the stent length and the number of stents in ISR group were higher than those in non-ISR group,while the stent diameter was smaller than that in non-ISR group (P<0.05).The level of serum LDL-C in patients with E3/E4 genotype was sig-nificantly higher than that in controls.Logistic regression analysis showed that E3/4 genotype,HbAlc and LDL-C levels were independent risk factors for in-stent restenosis.Conclusion Polymorphism of apolipoprotein E gene is associated with in-stent restenosis,and E3/4 genotype is an independent risk factor for ISR.Further genetic studies can identify risk genotypes,which is helpful for early prediction and identification of high-risk patients with ISR.