Evaluation Of B-Type Natriuretic Peptide For Coronary Disease Extension And Risk Assessment In Patients With Non-ST Elevation Coronary Syndromes

Objective:Acute coronary syndromes (ACS) are a heterogeneous disorder ranging from unstable angina pectoris with no biochemical evidence of myocardial necrosis to ST-elevation acute myocardial infarction. In recent years, the incidence of ACS increased year by year, and is the common cause of sudden coronary death. The treatment of acute coronary syndrome have made great progress, however, heart failture and left ventricular dysfunction caused by ACS are still challenges facing the clinician.Brain (B-type) natriuretic peptide (BNP) is a peptide hormone released primarily from the cardiac ventricles in response to ventricular wall stress and tissue hypoxia. It is synthesized as an inactive prohormone that is split into the active hormone BNP and the inactive N-terminal fragment (NT-proBNP). BNP has a number of systemic effects, including vasodilation, increasing in urinary volume and sodium output, and inhibition of the sympathetic nervous system and the rennin-angiotensin-aldosterone system.First studied as a diagnostic and prognostic marker among patients with congestive heart failure (CHF), BNP was subsequently found to predict outcomes in patients with acute myocardial infarction, further more, some studies extended these findings across the spectrum of patients with acute coronary syndromes. The risk of outcomes in patients of ACS depends on the presence of myocardial ischaemic areas, irreversible myocyte injury and the extent of coronary atherosclerosis, however, the correlation between BNP and these cases is not clear; in addition, BNP levels combined with the GRACE score to predict short outcome remains unknown. Therefore, we undertook the present study to evaluate the relation between plasma BNP level and coronary disease extension in patients with NSTE-ACS, and carefully assess the utility of BNP in combination with GRACE score.Methods:We conducted an observational study of the utility of BNP in168consecutive patients with non-ST-elevation acute coronary syndromes. The clinical information of patients were all collected, including age, sex, smoking, drinking, hypertension, diabetes mellitus, ECG, blood lipids, etc. Admission plasma BNP level was measured.The study was divided into two parts. In the first part, we selected144patients with normal cardiac function, all of whom underwent coronary artery angiography at our department. The patients were subdivided according to the number of vessel disease and plasma BNP levels, respectively. Correlation between plasma BNP level and Gensini score was calculated. The diagnostic value of BNP for severe coronary artery disease (Gensini score>20) was determined using the receiver operating characteristic curve (ROC curve). The logistic regression model was used to assess the prognostic contribution of BNP level for severe coronary artery disease. In the second part, all patients enrolled in the study (n=168) were followed up to30days. Death, new or worsen congestive heart failure were recorded during30days of follow-up. The patients were grouped according to end points, plasma BNP levels and GRACE score, respectively. And then, statistical analysis was done.Results:1. The patients with normal cardiac function were divided into two groups by plasma BNP levels, BNP>80ng/L and BNP<80ng/L. Patients with elevated BNP levels (>80ng/L) were older and more likely to have the ECG changes (ST depression≥1mm), they were also more likely to have a trend toward more frequent occurrence of three vessels disease, severe coronary disease and TIMI0-1flow(all P<0.05).2. BNP values progressively increased in relation to the increasing number of vessel disease (P<0.01). The analysis of the Gensini score demonstrated a strong correlation between coronary artery disease and BNP levels (r=0.632, P<0.01), and this trend was maintained in all the subgroups:UA (r=0.428, P<0.01), NSTEMI (r=0.516, P<0.01).3. The plasma BNP level has a diagnostic value for severe coronary artery disease(Gensini>20), area under curve(AUC)=0.768,(P<0.05), values of BNP>80ng/L were also shown to be able to diagnosis severe coronary artery disease compared with other cut-off points with a sensitivity of71.3%, a specificity of70.0%and a accuracy of70.8%.4. In logistic regression model, BNP level was an independent predictor of severe coronary artery disease [>80ng/L,OR=4.772,95%CI(2.188-10.406)].5. During the follow-up,31endpoints were recorded including4deaths and27new or worsen congestive heart failures. Age, heart rate and proportion of ECG changes were significantly higher while systolic blood pressure was significantly lower in endpoints group than that in the control group. The BNP level at admission (median422ng/L vs.71.3ng/L) and GRACE score (median150ng/L vs.122ng/L) were significantly higher in the endpoints group than that in the control group (all P<0.01).6. When treated dichotomously, BNP>80ng/L and GRACE>140were associated with a significantly higher risk of end points(all P<0.01), In logistic regression model, BNP level and GRACE score were independently assoctiated whith end points, BNP>80ng/L[OR=4.395,95%CI(1.353-14.276)], GRACE>140[OR=3.454,95%CI(1.380-8.645)].7. Amang patients with high GRACE score, those with BNP>80ng/L were at significantly higher risk of end points at30days(P<0.01), so do patients with low GRACE score. In Kaplan-Meier survival curve analysis, there are significant statistic sense among patients grouped according to BNP levels combined with GRACE score(P<0.01).Conclusion:1. Patients with higher BNP level are more likely to have poor coronary flow, three-vessel disease and severe coronary artery disease. BNP values progressively increase in relation to the increasing number of vessel disease.2. Circulating BNP levels are associated with the extension of coronary disease in NSTE-ACS, without cardiac dysfunction. BNP level has the diagnostic value for severe coronary artery disease.3. The value of80ng/L is an independent predictor of severe coronary artery disease, and show the good diagnostic value with the fine sensitivity, specificity and accuracy.4. Both BNP level at admission and GRACE score were independent predictors for endpoints within30days in patients with NSTE-ACS.5. The combined use of both BNP and GRACE score can enhance risk stratification in NSTE-ACS.