Background: The aim of this study was to examine the prognostic value of admission N-terminal-pro-brain natriuretic peptide (NT-proBNP) measurements for the outcome of adverse events, and to compare it with that of cardiac troponin T in the assessment of risk in patients with acute coronary syndrome (ACS) during the hospital stay and at six months following hospital discharge.
Methods: The study population consisted of 200 Asian Indian patients admitted with a diagnosis of ACS to the Coronary Care Unit at RK Khan Hospital, Durban, South Africa. A reference group comprising 100 healthy Indian individuals drawn from the same community and who did not suffer from cardiovascular disease was also analysed.
Results: The majority of patients presented with ST segment elevation myocardial infarction (STEMI) (71%), whereas 14.5% had non-ST segment elevation MI (NSTEMI), and the remaining 14.5% had unstable angina. Patients had multiple risk factors for coronary heart disease (CHD) including hypertension (59%), hypercholesterolaemia (59%), smoking (57%), diabetes mellitus (51%), obesity (46%), and a strong family history of CHD (55%). NT-proBNP levels were significantly increased in patients with STEMI (p = 0.005) and NSTEMI (p = 0.002) who developed adverse events during their hospital stay, compared with those who did not. At the six-month followup, although NT-proBNP levels were higher in patients with STEMI and NSTEMI who developed adverse events, these differences were not statistically significant. No differences in troponin T levels were detected in patients with STEMI and NSTEMI who developed adverse events, compared to those who did not, either during the hospital stay, or at six months after release. At hospital admission, 24% of patients with unstable angina who had elevated NT-proBNP levels and normal troponin T concentrations developed adverse events, compared to 38% at six months. NT-proBNP levels in the reference group were comparable with those reported in other populations.
Conclusion: This study demonstrated that elevation in admission NT-proBNP levels is an important determinant of acute and intermediate cardiac risk in patients with ACS. NT-proBNP concentrations were superior to those of troponin T as prognostic markers in both STEMI and NSTEMI. In a low-risk group of patients with unstable angina and negative troponin T concentrations, elevated NT-proBNP levels constituted a risk for the development of adverse cardiovascular events. Therefore, NT-proBNP should be included in the risk assessment of ACS to provide guidance for further therapeutic strategies.