Abstract: Objective:To explore the diagnostic value of midregion of pro-atrial natriuretic peptide(MR-proANP) for heart failure in dyspnea patients.Methods:The serum levels of MR-proANP in 203 dyspnea patientsincluding 96 heart failure(HF) patients and 107 non-HF patients on admission was determined by KRYPTOR platform.The diagnostic value of MR-proANP for HF was analyzed using receiver operating characteristic(ROC) curve,and which was compared with amino-terminal pro-B type natriuretic peptide(NT-proBNP).The MR-proANP and NT-proBNP were combined into an index using logistic regression model,which was used to analyze its diagnostic accuracy for HF.The relationships between cardiac function of New York Heart Association(NYHA),NT-proBNP and MR-proANP were analyzed.The reference range of MR-proANP was established by 120 healthy examinees.Results:The serum level of MR-proANP in HF patients was higher than that in non-HF patients(P<0.01).The difference of the area under ROC curve between NT-proBNP and MR-proANP was not statistically significant(P>0.05).The area under ROC curve of the joint diagnosis of heart failure with NT-proBNP and MR-proANP was higher than that in MR-proANP or NT-proBNP(P<0.05).The optimal threshold,sensitivity and specificity of MR-proANP were 100 pmol/L,0.91(0.83 to 0.96) ad 0.64(0.55 to 0.74),respectively.With the cardiac function classification of NYHA increasing,the level of MR-proANP increased(P<0.01),and the MR-proANP was positively correlated with NT-proBNP(r_s=0.64,P<0.01).Conclusions:MR-proANP is a useful diagnostic marker for HF in dyspnea patients.The combined detection of MR-proANP and NT-proBNP can improve the diagnostic accuracy of HF.