The Plasma NT-proBNP Level And Its Clinical Significance In Patients With Unstable Angina Pectoris

Objective To investigate the change and clinical significance of plasma N-terminalpro-brain natriuretic peptide(NT-proBNP) concentrations and to evaluate the influence ofpercutaneous coronary intervention (PCI) on the NT-proBNP level in patients withunstable angina pectoris. Methods 88 patients with coronary heart disease confirmedby coronary angiography (CAG) were composed of 67 patients with unstable anginapectoris (UAP) and 21 patients with stable angina pectoris(SAP). Plasma NT-proBNPconcentrations of the subjects on admission were measured. All subjects underwent acommon laboratory examination. Troponin-Ⅰand CK-MB levels were measuredquantitatively in all patients. All patients underwent echocardiography to evaluate the leftventricular function within 24 hours from admission and CAG to evaluate the severity ofcoronary artery stenosis within 5 days from admission. Gensini score and the number ofvessels with stenosis≥50％were computed in patients. Especially of all 42 cases weredynamically observed (including 22 cases in the PCI group,20 cases in the CAG group).Serial samples were taken on admission, before and at 0, 24h,72h after PCI or CAG.CTnI,CK-MB were measured at 24h after the operation in the PCI group. The normalcontrol group comprised 21 healthy subjects. Results 1. Plasma NT-proBNPconcentrations were increased in patients with UAP compared with those of SAP andcontrol subjects,p＜0.01, respectively. However, there was no significant differencebetween the patients with SAP and control subjects,p＞0.05. 2. Plasma NT-proBNPconcentrations correlated with LVEF in patients with UAP, r=-0.710, P＜0.05,andincreased significantly in patients with LVEF(LVEF＜50％) compared with patients withnormal LVEF(LVEF≥50％),P＜0.01. There was no significant correlation between theplasma NT-proBNP concentration and LVEF in patients with SAP, r=-0.271, P=0.310. 3.Even though the LVEF was normal in patients with UAP, the plasma NT-proBNP levelwas still higher than that in patients with SAP, p＜0.01. 4. There was significantlypositive correlation between the plasma NT-proBNP level and and Gensini score inpatients with UAP, r=0.917, P＜0.01. There was no significant correlation between theplasma NT-proBNP level and Gensini score in patients with SAP, r=0.257,p=0.261. 5.With the increasing of the number of involved vessels with more than 50％diameter stenosis, the level of NT-proBNP in patients with UAP increased gradually, There wassignificantly difference in different groups, P＜0.01. 6. The sensitivity was 96.08％,specificity 93.75％, positive predictive accuracy value 98.00％, and negative predictiveaccuracy value 88.24％for a plasma NT-proBNP cut-off level of 920 fmol/ml toestimate≥70％coronary artery stenosis in patients with UAP. 7. In the PCI group therewere not significant diference in the plasma NT-proBNP concentrations on admission,before and at 0 after PCI therapy, the plasma NT-proBNP concentrations at 24h after PCIhad partly elevated, there were significant difference compared with those of admission,before and at 0 After PCI therapy(P＜0.05).Then the plasma NT-proBNP concentrations at72h after PCI apparently dropped but there were also significant diference compared withthe control group(P＜0.05). In the CAG group there were not significant diference in theplasma NT-proBNP concentrations on admission, before and at 0,24h after CAG(P＞0.05).Then the plasma NT-proBNP concentrations at 72h after CAG apparentlydropped but there were also significant difference compared with the controlgroup(P＜0.05). There were no significant difference in plasma NT-proBNP concentrationson admission, before and at 0 after the operation between the PCI and CAG group.Statistical differeces were observed at 24h and 72h after the operation between the PCIgroup and CAG group. Plasma NT-proBNP level was higher in the PCI group than in theCAG group at 24h after the operation,but it was lower in the PCI group than in the CAGgroup at 72h after the operation. Conclusion 1. The plasma NT-proBNP level in patientswith UAP obviously elevates compared with stable angina patients and normal controls.2. The plasma NT-proBNP level negatively correlates with LVEF in patients with UAP.3. The plasma NT-proBNP concentration is closely related to the severity of coronaryartery stenosis in unstable angina patients: with the upgrading of the severity of thedisease, the concentration of NT-proBNP increases gradually. 4.The sensitivity andspecificity are high for the plasma NT-proBNP concentration to estimate≥70％coronaryartery stenosis in patients with UAP. 5.The plasma NT-proBNP level elevates at 24hafter PCI, but it apparently drops at 72h after PCI in the PCI group compared with thecontrol group.