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The cut-off value of N-terminal portion of pro-brain natriuretic peptid in heart failure at different ages

Objective To investigate the cut-off value of N-terminal portion of pro-brain nairiuretic peptid (NT-proBNP)for detecting various degrees of heart failure(HF)at different ages.Method Totally 48 patients with cardiac dysfunction(NYHA Ⅰ-Ⅳ)were from Department of Emergency Nedicine of Zhongshan Hospital Fudan University.The inclusion criteria inclued:organic heart disease,cardiac dysfunction(NYHA Ⅰ-Ⅳ).The exclusion criteria included:acute coronary syndrome,continuous atrial fibrillation,pulmonary emphysema,lung embolism,chronic renal insufficiency,anaemia,abnormal function of glandula thyreoidea,and tumor.The NT- proBNP was studied in order to find out the relevance of NT-proBNP to the classification of HF among patients aged over75 years old(age≥75 years)and patients aged below 75 years old(age＜75 years).Moreover,the NT- proBNP values were used to differentiate acute cardiogenic dyspnea.The data were expressed as(x±s)and ana- lyzed using analysis of variance and Student's t test with SPSS 11.0.A P value less than 0.05 indicated statistical significance.Results The analysis of NT-proBNP levels showed the leveis of it were associated with the grades of cardiac function and left ventricular ejection fraction(LVEF).NT-proBNP levels in patients aged over 75 years were higher than those in patients aged below 75 years.When patients wele of NYI-IA Ⅱ grade and NYHA Ⅳ grade,the levels of NT-proBNP showed signitieant differences between two sorts of patients(407±277 vs.1358± 967 P＜0.05;3727±1342 vs.9031±2363,P＜0.01).The cut-off value of NT-proBNP determined in 48 patients was at 525 pg/ml(AUC=0.958,sensitivity 100%,specificity 76%),at 1911 pg/ml(sensitivity 73%, specificity 96%)in patients with NYHA Ⅱgrade,which were used to identify severe symptomatic heart failure.The cut-off value of NT-proBNP determined in patients aged over 75 yeats was 849pg/ml(AUC=0.922,sensitivity 100%,s pecificity 57%),at 2990 pg/ml(semitivity 81%,specificity 100%)in patients with NYHA Ⅳ grade.Cobckysions NT-proBNP levels are associated with grades of cardiac functions limit of 75 years.It suggests that higher NT-proBNP value in patients aged over 75 years should be considered to evaluate caidiac function and identify acute cardiac dyspnea. 
 
Key words: 
Cardiac functional grading; Acute cardiac dyspnea; Eld; NT-proBNP