| [Background]It is well known that B-type natriuretic peptide (Brian natriuretic peptide, BNP) is synthesized and released into blood directly proportional to ventricular volume expantion and pressure overload. BNP is an independent predictor of high left ventricular end-diastolic pressure and is more useful than A-type natriuretic peptide (ANP) for assessing the mortality in patients with congestive heart failure(CHF). Recently, NT-proBNP (the N-terminal fragment of the BNP prohormone) has been shown to provide same valuable prognostic information in patients with CHF and may be superior to BNP in clinical uses for that it has a longer half life period, higher blood level, less variant and higher stability in vitro than BNP. This study is designed to observe the changes of blood natriuretic peptide levels in congestive heart failure and acute myocardial infarction and its clinical significance. [Methods](1) Serum NT-proBNP levels were measured with electrochemiluminescence immunoassay in patients with uncomplicated mild hypertension or stable exertive angina who had normal heart fuel ion ( control group, n-22), and compared with that in healthy people(n=22).(2) Serum NT-proBNP levels were measured with the same method in patients with systolic heart failure(SHF, 18, 23, 25 and 23 cases for NYHA classification I to IV respectivly) and diastolic heartfailure(DHF, n=17) . Correlation coefficients between NT-proBNP and age, NYHA classification, left ventricular ejection fraction(LVEF) were calculated with linear regression analysis.(3) Among the systolic heart failure, thirty cases (NYHA II ~IH) were administered with standard therapy (standard group,n=15) or"standard therapy + carvedilol" (carvedilol group, n=15) randomly to observe its effects on left ventricular function and serum NT-proBNP.(4) We also measured NT-proBNP levels in patients with acute myocardial infarction(AMI, n=26) in serum specimen abtaind the third day (64.3 7.6h) after the attack to analysis its relationship with location, left ventricular function and creatine kinase-MB .[Results](1) Serum NT-proBNP levels increased slightly in control group than healthy people (p<0. 01) , the value were (69.5 + 51.2) pg/ml and(37.1 + 19.7) pg/ml respectivly.(2) Serum NT-proBNP levels in patients with different NYHA classification were all higher than in control group. They increased obviously from I to IV class. The value were (388.9 + 304.7) pg/ml>(772. 7?48. 4) pg/mK (1946. 4+1914. 4) pg/ml and(3743. 4 ?2592. 5) pg/ml for NYHA I ~ IV and (69. 5 ?51. 2) pg/ml for control. It also increased in patients with DHF[ (578.1+848.3) pg/ml] .(3) Serum NT-proBNP was found to be a specific (95. 5%)and sensitive test (73.7% for symptoless S1IF.93. 3% for S11F and 70.6% for DHF) for identification patients with CHF in a cutoff of 168 pg/ml (x+2S of control).(4) Serum NT-proBNP decreased after treatment with carvedilol in patients with CHF [from (2105?425) pg/ml to ( 1134 +1121) pg/ml].(5) Levels of serum NT-proBNP increased significantly in patients with AMI and were higher in subgroup with left ventricular disfunction(KillipII ~IV) than in normal function (Killip I). [Conclusions](1) Serum NT-proBNP levels is higher in patients with normal heart function than in healthy people.(2) Serum NT-proBNP levels increases in systolic heart failure and has a positive relationship with NYHA classification.(3) It also increases in patients with diastolic heart failure or AMI(with and without heart failure).(4) Serum NT-proBNP levels decreases in patients with CHF after treatment with carvedilol.These indicated that determination of blood NT-proBNP level may have an effects on the prognosis of CHF and AMI. It can be used to help the diagnosis and monitor drug therapy.
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