Objective To compare the performance of N-terminal proatrial natriuretic peptide (NT-proANP) and N-terminal probrain natriuretic peptide (NT-proBNP) in identifying left ventricular systolic dysfunction (LVSD) in patients at high risk for heart failure,and to determine their optimal ranges and cut-off values.Methods A total of 380 patients with cardiovascular disease were enrolled (case group).Based on left ventricular ejection fraction (LVEF),they were divided into LVSD group (LVEF≤40%,n=90) and non-LVSD group (LVEF>40%,n=290).Another 136 healthy people were taken as controls.LVEF was measured by echocardiography.Plasma concentrations of NT-proANP and NT-proBNP were measured by ELISA.Patients were further grouped according to LVEF,age,gender and primary cardiovascular diseases.The ability of NT-proANP and NT-proBNP to predict LVSD was examined from the area under the receiver operating characteristic (ROC) curve.And the cut-off values were determined.Results The plasma concentrations of NT-proANP and NT-proBNP were much higher in case group than in healthy controls log(NT-proANP): (3.30±0.41) vs (2.98±0.16),P<0.01;log(NT-proBNP): (2.71±0.30) vs (2.49±0.13),P<0.01.In case group,the area under ROC curve (AUC) for NT-proANP and NT-proBNP was at least 0.73(P<0.01).The AUC was larger for NT-proANP than NT-proBNP in patients with LVEF ≤ 40% (0.820 vs 0.738),and was smaller for NT-proANP than NT-proBNP in patients with LVEF ≤ 30% (0.853 vs 0.877).Using a cut-off value of 1676.92pmol/L,NT-proANP had a sensitivity of 88.9%-100.0%,specificity of 14.0%-58.7%,positive predictive value (PPV) of 9.04%-30.04%,and negative predictive value(NPV) of 96.96%-98.77%.Using a cut-off value of 417.37pmol/L,NT-proBNP had the sensitivity of 77.8%-94.4%,specificity of 10.0%-55.8%,PPV of 7.07%-48.88%,and NPV of 94.46%-98.87%.Conclusions Both NT-proANP and NT-proBNP have good performance in reflecting heart function of patients at high risk for heart failure,and both can be used to diagnose LVSD.For patients with LVEF≤40%,NT-proANP seems to have a better predictive value than NT-proBNP.