Background: N-terminal proB-type natriuretic peptide (NT-proBNP) is a marker of biomechanical strain, secreted by cardiomyocytes in response to ischemia. As necrosis occurs after prolonged ischemia, a rise in NT-proBNP concentration could precede a rise in markers of necrosis.
Methods: The aim of the study was to evaluate whether NT-proBNP is able to identify those patients with an evolving myocardial infarction (MI) with high-risk non-ST-elevation acute coronary syndromes (NSTE-ACS). Data were analyzed from a prospective cohort of 103 high-risk NSTE-ACS patients admitted within 6 h after onset of pain and treated with an early invasive strategy. NT-proBNP samples, obtained immediately upon admission, were related to the presence of an in hospital MI. The optimal cut-off value for NT-proBNP was determined using receiver-operating characteristics (ROC) curve analysis.
Results: Analyses was performed separately for creatinine kinase MB-mass (CKMB) and troponin T (TnT) based MI definitions. In both cases, a NT-proBNP concentration above 40 pmol/L (339 ng/L) at admission proved to be independently associated with the presence of MI. The diagnostic odds ratio (OR) for CKMB-MI was 4.9 (confidence interval 2.0–11.9, p<0.001). The diagnostic OR for TnT-MI was 4.9 (1.8–14.4, p=0.003). Adjusting for differences in baseline variables did not weaken the diagnostic OR. In addition, elevated NT-proBNP concentrations were related to unfavour-able demographic, physical and biochemical parameters.
Conclusions: With a dichotomous cut-off value, a single elevated NT-proBNP (>40 pmol/L) at admission provides independent information about the presence of MI in high-risk NSTE-ACS patients.