• Richard Body, Christian Mueller, Evangelos Giannitsis, Michael Christ, Jorge Ordonez-Llanos, Christopher R de Filippi, Richard Nowak, Mauro Panteghini, Tomas Jernberg, Mario Plebani, Franck Verschuren, John K French, Robert Christenson, Silvia Weiser, Garnet Bendig, Peter Dilba, Bertil Lindahl, and TRAPID-AMI Investigators.
• Emergency Department, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Sciences Centre, Manchester, United Kingdom. richard.body@manchester.ac.uk.
• Acad Emerg Med. 2016 Sep 1; 23 (9): 1004-13.

BackgroundRecent single-center and retrospective studies suggest that acute myocardial infarction (AMI) could be immediately excluded without serial sampling in patients with initial high-sensitivity cardiac troponin T (hs-cTnT) levels below the limit of detection (LoD) of the assay and no electrocardiogram (ECG) ischemia.ObjectiveWe aimed to determine the external validity of those findings in a multicenter study at 12 sites in nine countries.MethodsTRAPID-AMI was a prospective diagnostic cohort study including patients with suspected cardiac chest pain within 6 hours of peak symptoms. Blood drawn on arrival was centrally tested for hs-cTnT (Roche; 99th percentile = 14 ng/L, LoD = 5 ng/L). All patients underwent serial troponin sampling over 4-14 hours. The primary outcome, prevalent AMI, was adjudicated based on sensitive troponin I (Siemens Ultra) levels. Major adverse cardiac events (MACE) including AMI, death, or rehospitalization for acute coronary syndrome with coronary revascularization were determined after 30 days.ResultsWe included 1,282 patients, of whom 213 (16.6%) had AMI and 231 (18.0%) developed MACE. Of 560 (43.7%) patients with initial hs-cTnT levels below the LoD, four (0.7%) had AMI. In total, 471 (36.7%) patients had both initial hs-cTnT levels below the LoD and no ECG ischemia. These patients had a 0.4% (n = 2) probability of AMI, giving 99.1% (95% confidence interval [CI] = 96.7% to 99.9%) sensitivity and 99.6% (95% CI = 98.5% to 100.0%) negative predictive value. The incidence of MACE in this group was 1.3% (95% CI = 0.5% to 2.8%).ConclusionsIn the absence of ECG ischemia, the detection of very low concentrations of hs-cTnT at admission seems to allow rapid, safe exclusion of AMI in one-third of patients without serial sampling. This could be used alongside careful clinical assessment to help reduce unnecessary hospital admissions.© 2016 by the Society for Academic Emergency Medicine.

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