OBJECTIVESWe assessed the ability of B-type natriuretic peptide signal peptide (BNPsp) to assist with the identification of patients with myocardial infarction (MI) and unstable angina pectoris (UAP).DESIGN AND METHODSWe studied 505 patients who presented to hospital within 4h of onset of chest pain suspicious of ACS. Blood samples were drawn at 0, 1, 2 and 24h from presentation and assayed for BNPsp, NT-proBNP, TnI and high sensitivity TnT. The ability of BNPsp and other markers to diagnose acute myocardial infarction (MI) and unstable angina pectoris (UAP) and predict subsequent events within one year was assessed. Statistical analysis was made using ROC AUC in SPSS, v.22.RESULTSReceiver operator area under the curve (AUC) data for the discrimination of MI was 0.69 for BNPsp and 0.97 for troponin, with BNPsp failing to add to troponin. However, in non-MI patients, BNPsp had discriminative power for UAP (p<0.05), and when combined with presentation values of NT-proBNP, white cell count and potassium into a unique parameter (UARatio), generated an AUC of 0.76 for UAP in patients with normal ECG results (p<0.001). In non-MI patients, the UARatio was significantly predictive of subsequent stroke (AUC=0.70, p<0.05) and heart failure (AUC=0.82, p<0.01) within one year.CONCLUSIONSIn patients with chest pain, BNPsp is predictive of MI but is not a useful adjunct to troponin. However, the ability of BNPsp, in conjunction with NT-proBNP and key analytes, to diagnose UAP and other ischemic syndromes merits further investigation.