Application Value Of NT-proBNP In Risk Stratification And Prognostic Evaluation Of Acute Coronary Syndrome (ACS)

[Background]Acute Coronary Syndrome (ACS) is a clinic syndrome which includs unstable angina (UA), non-ST-segment-elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI). It has become one of the major cardiovascular diseases threatening public life and health in developing countries as well as in industrialized countries.The risk stratification and prognostic evaluation of patients with ACS will contribute to effective therapy in time, thus reducing various major adverse cardiovascular events (MACE), At present, primary accepted effective indicators of prognosis are age, markers for diagnosis of myocardial necrosis, left entricular ejection fraction (LEF), hs-CRP, range of ST segment elevation or depression, admission heart rate, renal function, etc. These indicators may be useful for early risk stratification and prognostic evaluation of patients with ACS to some extent, but they are not correct enough in some ways, thus overlooking those ACS patients with serious coronary artery abnormalities and poor prognosis. Therefore it is significant to introduce a new, cheap, effective way to find other indicators to help make the risk stratification and prognostic evaluation of patients with ACS.Recent research has found that blood concentrations of NT-pro-BNP/BNP can be used to evaluate short-term and long term bad prognosis and death of patients with NSTEMI, UA, and STEMI and their recurrent events, new-onset HF and readmission events. But there is little research in which blood concentrations of NT-pro-BNP/BNP alone are applied to evaluate prognosis of patients with NSTEMI, UA, and STEMI who have received PCI/CABG. With the increased deep understanding of the importance of coronary revascularization in the treatment of patients with ACS and with the popularization of this operation, it is very meaningful to study blood concentrations of NT-pro-BNP for the risk stratification and prognostic evaluation of patients with NSTEMI, UA, and STEMI who have received coronary revascularization.[Purpose] To evaluate the application value of admission blood concentrations of NT-proBNP in prognosis monitoring of patients with ACS and in risk stratification[Method] Study subjects are those admitted into the Cardiology Department of Zhongshan Hospital for treatment, including ACS patients with STEMI, NSTEMI, and UA, from Sept.2007 to Mar.2008. Reference was made to blood samples of peripheral veins of the patients when admitted (within an average of two hours). Blood levels of NT-proBNP and other related biochemical indicators were measured, and other accessory examinations were made, such as the medical history, check-up, cardiogram, and echocardiographic images. Follow-ups within one year by phone were done to take all-cause mortality as the end point.[Result]400 patients with ACS were investigated, the average age being 66 (varying from 29 to 93) with 310 males (77.5%) and 90 females (22.5%). Of the patients there are 221 cases with STEMI,102 with NSTEMI and 77 with UA. Of the patients with STEMI,114 (51.6%) received emergency PCI within an average of 5 hours of the presence of symptoms. The rest 107_cases with STEMI failed to take PCI in time within 12h. Among the 221 cases 87 (39.4%) received PCI or CABG within an average of 8 days (5-14 days); 20 didn't take the operation because of their old age or because of their relatives'refusal for fear of high risk. In the group of the 102 patients with NSTEMI 80 (78.4%) received PCI or CABG after the presence of symptoms within an average of 7 days (0.5-16 days).22 didn't take the operation for the same reasons mentioned above.The medium blood value of NT-prpoBNP of the patients within an average of 2 hours (0.5-12 h) of being admitted was 840 (9.3-35000) pg/ml. All the ACS cases were divided into four groups according to their different blood levels of NT-proBNP, ranging from low to high. The medium blood values of NT-prpoBNP of the four groups are 104 (9-248) pg/ml,500 (248-840) pg/ml,1409 (840-2851) pg/ml and 6136 (2851-35000) pg/ml respectively. After one year's follow-up,59 patients (14.8%) died and 341 (85.2%) survived. Compared with group 1, which had the lowest blood value of NT-proBNP, the relative risks of all-cause mortality within one year in groups 2,3 and 4 were 2.812 (95%CI,0.727-10.924),2.064 (95%CI,0.502-8.493), 23.414 (95%CI,6.413-78.962) respectively. In the regression analysis blood levels of NT-proBNP, CTNT peak values and UA levels are the independent prognostic factors leading patients with ACS to die within one year, with OR being 6.429,1.004,1.004 respectively. They are factors independent of such prognostic factors as age, heart function, myocardial markers, Scr, UA, BUN, blood sugar, blood fat, etc.If all the cases with ACS were divided into group 1 (patients with STEMI who received emergency PCI), group 2 (patients with STEMI who received delayed PCI or CABG or who took conservative treatment) group 3 (patients with NSTEMI) and group 4 (patients with UA), the order of the four groups'blood levels of NT-proBNP within an average of two hours of being admitted is as follows:group 2> group 3> group 1> group 4 (p=0.001).The order of the four groups in mortality is as follows: group 2> group 3> group 1> group 4 (p=0.001), their mortality within one year being 29%,15.7%,10.5,0% correspondingly. The order of the four groups in CTNT peak value and CK-MB peak value when admitted are as follows:group 1> group 2> group 3> group 4 (p=0.001). Age ratio and sex ratio of the patients had no statistical difference.