Objective To analyze the expression levels of serum Perilipin5(Plin5)in patients with stable coronary artery disease(SCAD)and explore their correlation with cardiac function.Methods This was a case-control study.Patients were selected from those hospitalized in Hebei General Hospital from November 2020 to June 2021,including 57 cases in the control group and 183 cases in the SCAD group.SCAD patients were divided into two groups based on the occurrence of heart failure(HF),namely SCAD group(n=62)and SCAD+HF group(n=121).Clinical data of all patients were collected,the serum level of N-terminal pro-B-type natriuretic peptide(NT-proBNP)was detected,and ultrasonic cardiography was performed.The correlation of serum Plin5 level with cardiac function was analyzed by Pearson correlation analysis.Results The SCAD+HF group was subsequently categorized into heart failure with preserved ejection fraction(n=58),heart failure with midrange ejection fraction(HFmrEF)(n=32),and heart failure with reduced ejection fraction(HFrEF)(n=31).The serum Plin5 level in the control group was the highest,followed by those in the SCAD group and SCAD+HF group(H=28.156,P<0.001).Correlation analysis showed that serum Plin5 level was positively correlated with left ventricular ejection fraction,and negatively correlated with left atrial diameter,left ventricular end-systolic diameter,left ventricular end-diastolic diameter,and NT-proBNP level in SCAD patients(all P<0.01).Multivariate logistic regression analysis showed that Plin5 was a negative factor affecting the occurrence of HFmrEF and HFrEF(both P<0.05).Conclusions The serum level of Plin5 in SCAD patients is significantly reduced and serves as a negative influencing factor for the occurrence of HFmrEF and HFrEF.