| Background and objective:In China, with the improvement of people's life, coronary heart disease had become the major cardiovascular disease which harmed to the aged people. Compared with the other types of coronary heart disease ,acute coronary syndrome had its own characteristics such as bad prognosis and higher mortality rate. The problems which must to be solved were how to evaluate the ACS, how to predict the prognosis, how to judge the risk of individual patient and provide the patients with appropriate treatment. B–type natriuretic peptide (BNP) was a kind of neurohormone mainly secreted by cardiac ventricles. It could be synthesized and secreted when the volume expansion and pressure overload happened in patients with heart failure. Early studies had shown that BNP could be used for diagnoses,evaluating the prognosis and guiding the therapies in patients with congestive heart failure. Current studies suggested that BNP in plasma of patients with ACS also changed. But the mechanism and effect to evaluate prognosis were not clear. So we chose 120 patients with ACS, 20 cases of non-coronary heart disease, used case-control study to research the change of the BNP in ACS patients and the relationships among levels of BNP, coronary artery lesions and levels of troponin.Study Methods :We chose 140 patient which had chest pain and examed with coronary angiography and / or had been stented from January to October in our hospital. And the diagnostic criteria of CHD was that the stenosis of coronary artery was more than 50% than normal ones. According to theclinical symptoms and laboratory tests, 120 cases were diagnosed as acute coronary syndrome. Among the total,66 cases had acute myocardial infarction and 54 cases had unstable angina. These two groups were divided into three sub-groups on the basis of coronary lesions. And the others were as a normal control group. All patients had ECG, blood, urine and other routine checks. Except these, hypertension, diabetes and other risk factors were analyzed. BNP levels were measured by ELISA, and measurement data were processed via standard deviation ( x±S), Intra-team comparison were conducted via t test(P<=0.05). And the relationships between BNP and troponin I in patients with AMI were processed via related analysis.Methods :1 AMI groups : From18 to 24 hours after symptom onset, the blood were collected, then added into EDTA tubes. After centrifugation, they were stored at -70°C in refrigerator. UA group : from 20 minutes to 1 hour after angina onset , the manipulations were the same to the AMI group. BNP were measured by ELISA. Patients of AMI, from12 to 24 hours after onset of symptoms, were collected blood samples to exam the troponin I. 2 : In addition to some patients which were given emergency PCI or intravenous thrombolytic therapy within12 hours from onset of AMI,others were collected bloodsamples before coronary angiography or PCI. Results :In the AMI group, the UA group and the control group, various indicators which could affect secretion of BNP such as age, sex ratio, hypertension, etal had no significant statistical difference(P> 0.05).Meanwhile liverdisease, kidney disease, cardiac dysfunction and other factors which could affect the level of BNP were eliminated.1. The mean levels of BNP in AMI Group, UA group and control group were respectively 57.4±16.6, 18.8±9.3 and 7.9±5.94 fmol/ml. And the levels decreased gradually. There were significant differences(P <0.05).2. According to the results of the coronary angiography, the AMI group was divided into three groups which were single-vessel group, two-vessel group and three-vessel group. The mean levels of BNP in three groups were respectively 51.15±15.47, 56.68±17.26 and 61.7±16.5 fmol/ml. Only the result of single-vessel group and that of three-vessel group were compared with significant differences.(P <0.05).3. The UA group was also divided into single-vessel group, two-vessel group and three-vessel group. The mean levels of BNP in three groups were 15.08±8.33, 18.93±8.4 and 22.38±9.97fmol/ml. And there were significant differences between the result of single-vessel group and that of three-vessel group(P <0.05).4. The patients which were given emergency PCI or intravenous thrombolytic therapy within 12 hours from onset of AMI were divided into two groups according to therapies which were effective or not. They were early reperfusion group and control group. The mean levels of BNP in two groups were 55.33±15.43 and 58.91±17.46 fmol/ml. But there were no significant differences (P> 0.05).5. AMI patients were admitted for routine measurement of troponin I. BNP and troponin I were positively correlated via related analysis. (r =0.759 , P < 0.01 )Conclusion:1.Patients with ACS had significantly higher levels of BNP than those of normal control group. It showed that acute ischemia, chronic ischemia and hypoxia could increase secretion of BNP.2.According to the results of coronary angiography, the levels of BNP increased with the numbers of coronary artery lesions increased, but there was no direct correlation.3. The levels of BNP in patients with AMI who accept early PCI or thrombolytic therapy have no difference with control group within 24 hours.4. The cardiac troponin I and BNP were positively correlated. It indirectly showed that BNP and the areas of myocardial infarct were positively correlated. So BNP could be used to forecast the area of myocardial infarct and judged the prognosis indirectly.When myocardial ischemia, hypoxia, or myocardial cells necrosis happened, the ventricular wall motion was abnormal, wall tension changed, ventricular compliance decreased and left ventricular had dysfunction. Meanwhile activation of the neuroendocrine system and heart resulted in synthesis of BNP increasing.
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