Rapid rule out of acute myocardial infarction in the observe zone using a combination of presentation N-terminal pro-B-type natriuretic peptide and high-sensitivity cardiac troponin I

Abstract

Background and aimsThe release of N-terminal pro-B-type natriuretic peptide (NT-proBNP) is strongly triggered by myocardial ischemia. We aimed to investigate whether the addition of NT-proBNP to high-sensitivity cardiac troponin (hs-cTnI) at presentation could provide better performance in risk stratification and thus early rule-out of acute myocardial infarction (AMI) in patients of the “observe zone”. MethodsEmergency department (ED) patients presenting with symptoms suspicious for AMI were consecutively enrolled. Blood samples were obtained at presentation and tested for hs-cTnI and NT-proBNP. All available medical records pertaining to the patient from ED presentation to 30-day follow-up were used for adjudication of the primary outcome. The incremental diagnostic value added by NT-proBNP to hs-cTnI was evaluated by receiver operating characteristic (ROC) analysis, continuous net reclassification improvement (cNRI), and integrated discrimination improvement (IDI). Sensitivity, specificity, positive and negative predictive values were used to assess the diagnostic accuracy of different approaches for early rule out. ResultsOf the 165 patients we analyzed, 55 (33.3%) had index AMI. For hs-cTnI alone, area under the curve for index AMI was not significantly increased after adding NT-proBNP (0.773 vs 0.809; p = .076). Adjustment of hs-cTnI by NT-proBNP improved the predictive value of hs-cTnI, showed by cNRI (0.418, 95%CI 0.102–0.735, p = .009) and IDI (0.055, 95%CI 0.017–0.092, p = .004). Compared to hs-cTnI, the combined test identified 14% more patients as low-risk and safe for early discharge. ConclusionsCombination of presentation hs-cTnI and NT-proBNP provided better predictive performance for AMI in patients of the observe zone presenting with symptoms of chest pain as compared to hs-cTnI alone. The combined test outperformed hs-cTnI by correctly identifying nearly 14% more patients as low-risk and safe for early discharge. Future multi-center studies are needed to verify the results and to determine the best clinical use of the combination of NT-proBNP and hs-cTnI in the early diagnosis of AMI.