Troponins are proteins commonly found in cardiac tissue that are released during myocardial ischemia or necrosis. These troponins can be detected by assays that can then be used to guide clinical decision-making and disposition, especially if the suspected insult is related to acute coronary syndrome. Timing of troponin measurement can be important as elevations may not be detectible immediately after an insult. New assays have been designed to detect troponin con-centrations previously too low to be detected by conventional assays. These tests are known as high-sensitivity cardiac troponin assays. Current research is aimed at evaluating the clinical sig-nificance of troponin elevations detected by these new assays especially in management of pa-tients with suspected acute coronary syndrome. A number of risk-stratification scores exist to assist physicians with evaluating chest pain in the emergency department in the context of de-tection (or absence) of troponins in systemic circulation. Additionally, investigators are working to integrate data generated by hs-cTn measurements into existing and new risk-stratification scores.
Acute Coronary Syndrome* ; Chest Pain ; Clinical Decision-Making ; Diagnostic Tests, Routine ; Emergencies* ; Emergency Service, Hospital* ; Humans ; Myocardial Infarction ; Myocardial Ischemia ; Necrosis ; Prognosis ; Research Personnel ; Troponin*

OBJECTIVE: Contrast induced nephropathy (CIN) is a result of injury to the proximal tubules. The incidence of CIN is around 11% for imaging done in the acute care setting. We aim to analyze the metabolic patterns in the urine, before and after dosing with intravenous contrast for computed tomography (CT) imaging of the chest, to determine if metabolomic changes exist in patients who develop CIN. METHODS: A convenience sample of high risk patients undergoing a chest CT with intravenous contrast were eligible for enrollment. Urine samples were collected prior to imaging and 4 to 6 hours post imaging. Samples underwent gas chromatography/mass spectrometry profiling. Peak metabolite values were measured and data was log transformed. Significance analysis of microarrays and partial least squares was used to determine the most significant metabolites prior to CT imaging and within subject. Analysis of variance was used to rank metabolites associated with temporal change and CIN. CIN was defined as an increase in serum creatinine level of ≥ 0.5 mg/dL or ≥ 25% above baseline within 48 hours after contrast administration. RESULTS: We sampled paired urine samples from 63 subjects. The incidence of CIN was 6/63 (9.5%). Patients without CIN had elevated urinary citric acid and taurine concentrations in the pre-CT urine. Xylulose increased in the post CT sample in patients who developed CIN. CONCLUSION: Differences in metabolomics patterns in patients who do and do not develop CIN exist. Metabolites may be potential early identifiers of CIN and identify patients at high-risk for developing this condition prior to imaging.
Citric Acid ; Creatinine ; Humans ; Incidence ; Least-Squares Analysis ; Metabolomics* ; Spectrum Analysis ; Taurine ; Thorax ; Tomography, X-Ray Computed ; Xylulose

BACKGROUND: We aimed to compare the diagnostic accuracy of the Alere Triage Cardio3 Tropinin I (TnI) assay (Alere, Inc., USA) and the PathFast cTnI-II (Mitsubishi Chemical Medience Corporation, Japan) against the central laboratory assay Singulex Erenna TnI assay (Singulex, USA). METHODS: Using the Markers in the Diagnosis of Acute Coronary Syndromes (MIDAS) study population, we evaluated the ability of three different assays to identify patients with acute myocardial infarction (AMI). The MIDAS dataset, described elsewhere, is a prospective multicenter dataset of emergency department (ED) patients with suspected acute coronary syndrome (ACS) and a planned objective myocardial perfusion evaluation. Myocardial infarction (MI) was diagnosed by central adjudication. RESULTS: The C-statistic with 95% confidence intervals (CI) for diagnosing MI by using a common population (n=241) was 0.95 (0.91-0.99), 0.95 (0.91-0.99), and 0.93 (0.89-0.97) for the Triage, Singulex, and PathFast assays, respectively. Of samples with detectable troponin, the absolute values had high Pearson (R(P)) and Spearman (R(S)) correlations and were R(P)=0.94 and R(S)=0.94 for Triage vs Singulex, R(P)=0.93 and R(S)=0.85 for Triage vs PathFast, and R(P)=0.89 and R(S)=0.73 for PathFast vs Singulex. CONCLUSIONS: In a single comparative population of ED patients with suspected ACS, the Triage Cardio3 TnI, PathFast, and Singulex TnI assays provided similar diagnostic performance for MI.
Acute Coronary Syndrome/*diagnosis ; Biomarkers/analysis ; Emergency Service, Hospital ; Humans ; Laboratories/standards ; Myocardial Infarction/diagnosis ; *Point-of-Care Systems ; Prospective Studies ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; Troponin I/*analysis

Objective: To determine the utility of a highly sensitive troponin assay when utilized in the emergency department. Methods The FAST-TRAC study prospectively enrolled >1,500 emergency department patients with suspected acute coronary syndrome within 6 hours of symptom onset and 2 hours of emergency department presentation. It has several unique features that are not found in the majority of studies evaluating troponin. These include a very early presenting population in whom prospective data collection of risk score parameters and the physician’s clinical impression of the probability of acute coronary syndrome before any troponin data were available. Furthermore, two gold standard diagnostic definitions were determined by a pair of cardiologists reviewing two separate data sets; one that included all local troponin testing results and a second that excluded troponin testing so that diagnosis was based solely on clinical grounds. By this method, a statistically valid head-to-head comparison of contemporary and high sensitivity troponin testing is obtainable. Finally, because of a significant delay in sample processing, a unique ability to define the molecular stability of various troponin assays is possible.Trial registration ClinicalTrials.gov Identifier NCT00880802