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Aims: To directly compare the diagnostic accuracy of high-sensitivity cardiac troponin (hs-cTn) T vs. hs-cTnI in the early non-invasive differentiation of Type 1 myocardial infarction (T1MI) due to plaque rupture and atherothrombosis from Type 2 myocardial infarction (T2MI) due to supply-demand mismatch., Methods and Results: In a prospective multicentre diagnostic study, two independent cardiologists centrally adjudicated the final diagnosis of T1MI vs. T2MI according to the fourth universal definition of myocardial infarction (MI), using all available clinical information including cardiac imaging in patients presenting with acute chest pain. Diagnostic accuracy was quantified by the area under the receiver operating characteristics curve (AUC). The most extensively validated hs-cTnT-Elecsys and hs-cTnI-Architect assays were measured at presentation, 1 h, and 2 h. Among 5887 patients, 1106 (19%) had a final diagnosis of MI, including 860 (78%) T1MI and 246 (22%) T2MI. The AUC of hs-cTnT-Elecsys to differentiate T1MI from T2MI was moderate and comparable to that provided by hs-cTnI-Architect: hs-cTnT-Elecsys AUC-presentation 0.67 [95% confidence interval (CI) 0.64-0.71], AUC-1 h 0.70 (95% CI 0.66-0.74), and AUC-2 h 0.71 (95% CI 0.66-0.75) vs. hs-cTnI-Architect AUC-presentation 0.71 (95% CI 0.67-0.74), AUC-1 h 0.72 (95% CI 0.68-0.76), and AUC-2 h 0.74 (95% CI 0.69-0.78), all P = not significant (NS). Similarly, the AUC of absolute changes was moderate and comparable for hs-cTnT-Elecsys and hs-cTnI-Architect (all P = NS). Cut-off concentrations achieving at least 90% specificity for the differentiation of T1MI vs. T2MI were >114 ng/L for hs-cTnT-Elecsys [odds ratio (OR) 4.2, 95% CI 2.7-6.6] and >371 ng/L for hs-cTnI-Architect (OR 4.0, 95% CI 2.6-6.2)., Conclusion: hs-cTnT-Elecsys and hs-cTnI-Architect provided comparable, albeit only moderate, diagnostic accuracy for the early differentiation of T1MI vs. T2MI., Clinical Trial Registration: ClinicalTrials.gov number, NCT00470587, https://clinicaltrials.gov/ct2/show/NCT00470587., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Introduction and Objectives: Release kinetics of high-sensitivity cardiac troponin (hs-cTn) T and I in patients with acute myocardial infarction (AMI) are incompletely understood. We aimed to assess whether hs-cTnT/I release in early AMI is near linear., Methods: In a prospective diagnostic multicenter study the acute release of hs-cTnT and hs-cTnI within 1 and 2hours from presentation to the emergency department was quantified using 3 hs-cTnT/I assays in patients with suspected AMI. The primary endpoint was correlation between hs-cTn changes from presentation to 1 hour vs changes from presentation to 2hours, among all AMI patients and different prespecified subgroups. The final diagnosis was adjudicated by 2 independent cardiologists, based on serial hs-cTnT from the serial study blood samples and additional locally measured hs-cTn values., Results: Among 2437 patients with complete hs-cTnT data, AMI was the adjudicated diagnosis in 376 patients (15%). For hs-cTnT, the correlation coefficient between 0- to 1-hour change and 0- to 2 hour change was 0.931 (95%CI, 0.916-0.944), P <.001. Similar findings were obtained with hs-cTnI (Architect) with correlation coefficients between 0- to 1-hour change and 0- to 2 hour change of 0.969 and hs-cTnI (Centaur) of 0.934 (P <.001 for both). Findings were consistent among type 1 and type 2 AMI and in the subgroup of patients presenting very early after chest pain onset., Conclusions: Patients presenting with early AMI showed a near linear release of hs-cTnT and hs-cTnI. This near linearity provides the pathophysiological basis for rapid diagnostic algorithms using 0- to 1-hour changes as surrogates for 0- to 2 hour or 0- to 3 hour changes. Registered at ClinicalTrials.gov (Identifier: NCT00470587)., (Copyright © 2020 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Acute heart failure (AHF) patients with high troponin levels have a worse prognosis. High-sensitive troponin T (hs-TnT) has been used as a tool to stratify prognosis in many scales but always as a qualitative and not as a quantitative variable., Objectives: The main objective of this study was to determine the best hs-TnT cut-off for prediction of 30-day all-cause mortality., Methods: The EAHFE registry, a prospective follow-up cohort of patients with AHF, was analysed. We performed a propensity score analysis of the optimal hs-TnT cut-off point previously determined by receiver operating characteristic (ROC) curve analysis., Results: Of the 13 791 patients in the EAHFE cohort, we analysed 3190 patients in whom hs-TnT determination was available. The area under the ROC curve for 30-day all-cause mortality was 0.70 (CI95% 0.68 to 0.71; P < .001), establishing an optimal cut-off of hs-TnT of 35 ng/L. The sensitivity and specificity of this cut-off were 76.2 and 55.5%, respectively, with a negative predictive value (NPV) of 95.3%. A propensity score was made with 34 variables showing differences based on the cut-off of 35 ng/L for hs-TnT. In the analysis of the population obtained with the propensity score, patients with hs-TnT > 35 ng/L showed a greater 30-day all-cause mortality, with a HR of 2.95 (CI95% 1.83-4.75; P < .001). External validation reported similar results., Conclusions: An hs-TnT value of 35 ng/L is an adequate cut-off to evaluate the prediction of 30-day all-cause mortality with a NPV of 95.3%., (© 2020 Stichting European Society for Clinical Investigation Journal Foundation.)

Background: The clinical availability of high-sensitivity cardiac troponin (hs-cTn) has enabled the development of several innovative strategies for the rapid rule-out of acute myocardial infarction (AMI). Due to the lack of direct comparisons, selection of the best strategy for clinical practice is challenging., Methods: In a prospective international multicenter diagnostic study enrolling 3696 patients presenting with suspected AMI to the emergency department, we compared the safety and efficacy of 14 different hs-cTn-based strategies: hs-cTn concentrations below the limit of detection (LoD), dual-marker combining hs-cTn with copeptin, ESC 0 h/1 h-algorithm, 0 h/2 h-algorithm, 2 h-ADP-algorithm, NICE-algorithm, and ESC 0 h/3 h-algorithm, each using either hs-cTnT or hs-cTnI. The final diagnosis of AMI was adjudicated by two independent cardiologists using all available clinical information including cardiac imaging and serial hs-cTn concentrations., Results: AMI was the final diagnosis in 16% of patients. Using hs-cTnT, safety quantified by the negative predictive value (NPV) and sensitivity was very high (99.8-100% and 99.5-100%) and comparable for all strategies, except the dual-marker approach (NPV 98.7%, sensitivity 96.7%). Similarly, using hs-cTnI, safety quantified by the NPV and sensitivity was very high (99.7-100% and 98.9-100%) and comparable for all strategies, except the dual-marker approach (NPV 96.9%, sensitivity 90.4%) and the NICE-algorithm (NPV 99.1%, sensitivity 94.7%). Efficacy, quantified by the percentage of patients eligible for rule-out, differed markedly, and was lowest for LoD-algorithm (15.7-26.8%)., Conclusion: All rapid rule-out algorithms, except the dual-marker strategy and the NICE-algorithm using hs-cTnI, favorably combine safety and efficacy, and can be considered for routine clinical practice., Clinical Trial Registration: NCT00470587, http://clinicaltrials.gov/show/NCT00470587., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: We desired to determine cardiac troponin (cTn) concentrations necessary to achieve a positive predictive value (PPV) of ≥75% for acute myocardial infarction (AMI) to justify immediate admission of patients to a monitored unit and, in general, early coronary angiography., Methods: In a prospective multicenter diagnostic study enrolling patients presenting to the emergency department with symptoms suggestive of AMI, final diagnoses were adjudicated by 2 independent cardiologists based on clinical information including cardiac imaging. cTn concentrations were measured using 5 different sensitive and high-sensitivity cTn (hs-cTn) assays in a blinded fashion at presentation and serially thereafter. The diagnostic end point was PPV for rule-in of AMI of initial cTn concentrations alone and in combination with early changes., Results: Among 3828 patients, 616 (16%) had an AMI. At presentation, 7% to 14% of patients had cTnT/I concentrations associated with a PPV of ≥75%. Adding absolute or relative changes did not significantly further increase the PPV. PPVs increased from 46.5% (95% CI, 43.6-49.4) for hs-cTnT at presentation >14 ng/L to 78.9% (95% CI, 74.7-82.5) for >52 ng/L ( P < 0.001), whereas PPVs in higher hs-cTnT strata remained largely unchanged [e.g., 82.4% (95% CI, 77.5-86.7) for >80 ng/L vs 83.9% (95% CI, 76.0-90.1) for >200 ng/L ( P = 0.72)]. The addition of early changes in hs-cTnT further increased the PPV up to 60 ng/L, but not for higher concentrations., Conclusions: Serial sampling does not seem necessary for predicting AMI and concurrent decision-making in about 10% of patients, as it only marginally increases the PPV for AMI and not in a statistically or clinically significant way., Clinicaltrialsgov Identifier: NCT00470587., (© 2018 American Association for Clinical Chemistry.)

En: Diagnosing or ruling out acute myocardial infarction (AMI) is a challenge faced daily in emergency departments. AMI evaluation usually requires the measurement of the cardiac troponin (cTn) concentration. The use of this biomarker improves AMI diagnosis provided the concentrations are properly interpreted in the context of the patient's condition and according to standard recommendations. This consensus statement was drafted by specialists in emergency medicine, cardiology and laboratory medicine. The authors recommend measuring the cTn concentration if AMI is suspected in emergency patients, whether the newest high-sensitivity cTn assays or the so-called contemporary ones are used. Diagnostic algorithms based on up-to-date evidence are also presented. The consensus statement aims to serve as a clinical practice guideline for using cTn assays to enhance the efficient differential diagnosis of acute coronary syndromes in the emergency department.

Background: Combining 2 signals of cardiomyocyte injury, cardiac troponin I (cTnI) and T (cTnT), might overcome some individual pathophysiological and analytical limitations and thereby increase diagnostic accuracy for acute myocardial infarction with a single blood draw. We aimed to evaluate the diagnostic performance of combinations of high-sensitivity (hs) cTnI and hs-cTnT for the early diagnosis of acute myocardial infarction., Methods: The diagnostic performance of combining hs-cTnI (Architect, Abbott) and hs-cTnT (Elecsys, Roche) concentrations (sum, product, ratio, and a combination algorithm) obtained at the time of presentation was evaluated in a large multicenter diagnostic study of patients with suspected acute myocardial infarction. The optimal rule-out and rule-in thresholds were externally validated in a second large multicenter diagnostic study. The proportion of patients eligible for early rule-out was compared with the European Society of Cardiology 0/1 and 0/3 hour algorithms., Results: Combining hs-cTnI and hs-cTnT concentrations did not consistently increase overall diagnostic accuracy as compared with the individual isoforms. However, the combination improved the proportion of patients meeting criteria for very early rule-out. With the European Society of Cardiology 2015 guideline recommended algorithms and cut-offs, the proportion meeting rule-out criteria after the baseline blood sampling was limited (6% to 24%) and assay dependent. Application of optimized cut-off values using the sum (9 ng/L) and product (18 ng 2 /L 2 ) of hs-cTnI and hs-cTnT concentrations led to an increase in the proportion ruled-out after a single blood draw to 34% to 41% in the original (sum: negative predictive value [NPV] 100% [95% confidence interval (CI), 99.5% to 100%]; product: NPV 100% [95% CI, 99.5% to 100%]) and in the validation cohort (sum: NPV 99.6% [95% CI, 99.0-99.9%]; product: NPV 99.4% [95% CI, 98.8-99.8%]). The use of a combination algorithm (hs-cTnI <4 ng/L and hs-cTnT <9 ng/L) showed comparable results for rule-out (40% to 43% ruled out; NPV original cohort 99.9% [95% CI, 99.2-100%]; NPV validation cohort 99.5% [95% CI, 98.9-99.8%]) and rule-in (positive predictive value [PPV] original cohort 74.4% [95% Cl, 69.6-78.8%]; PPV validation cohort 84.0% [95% Cl, 79.7-87.6%])., Conclusions: New strategies combining hs-cTnI and hs-cTnT concentrations may significantly increase the number of patients eligible for very early and safe rule-out, but do not seem helpful for the rule-in of acute myocardial infarction., Clinical Trial Registration: URL (APACE): https://www.clinicaltrial.gov . Unique identifier: NCT00470587. URL (ADAPT): www.anzctr.org.au . Unique identifier: ACTRN12611001069943.

Background: There is concern that high-sensitivity cardiac troponin (hs-cTn) may have low diagnostic accuracy in patients with low acute coronary syndrome (ACS) probability., Methods: We prospectively stratified patients presenting with acute chest discomfort to the emergency department (ED) into 3 groups according to their probability for ACS as assessed by the treating ED physician using a visual analog scale: ≤10%, 11% to 79%, and ≥80%, reviewing all information available at 90 min. hs-cTnT and hs-cTnI concentrations were determined in a blinded fashion. Two independent cardiologists adjudicated the final diagnosis., Results: Among 3828 patients eligible for analysis, 1189 patients had low (≤10%) probability for ACS. The incidence of non-ST-segment elevation myocardial infarction (NSTEMI) increased from 1.3% to 12.2% and 54.8% in patients with low, intermediate, and high ACS probability, respectively. The positive predictive value of hs-cTnT and hs-cTnI was low in patients with low ACS probability and increased with the incidence of NSTEMI, whereas the diagnostic accuracy of hs-cTnT and hs-cTnI for NSTEMI as quantified by the area under the curve (AUC) was very high and comparable among all 3 strata, e.g., AUC hs-cTnI, 0.96 (95% CI, 0.94-0.97); 0.87 (95% CI, 0.85-0.89); and 0.89 (95% CI, 0.87-0.92), respectively. Findings were validated using bootstrap analysis as an alternative methodology to define ACS probability. Similarly, higher hs-cTnT/I concentrations independently predicted all-cause mortality within 2 years (e.g., hs-cTnT hazard ratio, 1.39; 95% CI, 1.27-1.52), irrespective of ACS probability., Conclusions: Diagnostic and prognostic accuracy and utility of hs-cTnT and hs-cTnI remain high in patients with acute chest discomfort and low ACS probability.ClinicalTrials.gov Identifier: NCT00470587., (© 2017 American Association for Clinical Chemistry.)

Background: Cardiac myosin-binding protein C (cMyC) is a cardiac-restricted protein that is more abundant than cardiac troponins (cTn) and is released more rapidly after acute myocardial infarction (AMI). We evaluated cMyC as an adjunct or alternative to cTn in the early diagnosis of AMI., Methods: Unselected patients (N=1954) presenting to the emergency department with symptoms suggestive of AMI, concentrations of cMyC, and high-sensitivity (hs) and standard-sensitivity cTn were measured at presentation. The final diagnosis of AMI was independently adjudicated using all available clinical and biochemical information without knowledge of cMyC. The prognostic end point was long-term mortality., Results: Final diagnosis was AMI in 340 patients (17%). Concentrations of cMyC at presentation were significantly higher in those with versus without AMI (median, 237 ng/L versus 13 ng/L, P <0.001). Discriminatory power for AMI, as quantified by the area under the receiver-operating characteristic curve (AUC), was comparable for cMyC (AUC, 0.924), hs-cTnT (AUC, 0.927), and hs-cTnI (AUC, 0.922) and superior to cTnI measured by a contemporary sensitivity assay (AUC, 0.909). The combination of cMyC with hs-cTnT or standard-sensitivity cTnI (but not hs-cTnI) led to an increase in AUC to 0.931 ( P <0.0001) and 0.926 ( P =0.003), respectively. Use of cMyC more accurately classified patients with a single blood test into rule-out or rule-in categories: Net Reclassification Improvement +0.149 versus hs-cTnT, +0.235 versus hs-cTnI ( P <0.001). In early presenters (chest pain <3 h), the improvement in rule-in/rule-out classification with cMyC was larger compared with hs-cTnT (Net Reclassification Improvement +0.256) and hs-cTnI (Net Reclassification Improvement +0.308; both P <0.001). Comparing the C statistics, cMyC was superior to hs-cTnI and standard sensitivity cTnI ( P <0.05 for both) and similar to hs-cTnT at predicting death at 3 years., Conclusions: cMyC at presentation provides discriminatory power comparable to hs-cTnT and hs-cTnI in the diagnosis of AMI and may perform favorably in patients presenting early after symptom onset., Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00470587., (© 2017 The Authors.)

Background: The early diagnosis of acute myocardial infarction (AMI) in patients with mild elevations of high-sensitivity cardiac troponin (hs-cTn) is a challenge. It is unclear whether copeptin, a marker of endogenous stress, or 1h-hs-cTn changes are better suited to address this important unmet clinical need., Methods: We prospectively enrolled patients presenting with symptoms suggestive of AMI to the emergency department (ED). Two independent cardiologists adjudicated the final diagnosis. Mild hs-cTn elevations were defined as 26.2 ng/L (99th percentile) to 75 ng/L for hs-cTnI, and 14 ng/L (99th percentile) to 50 ng/L (biological-equivalent to 75 ng/L for hs-cTnI) for hs-cTnT., Results: Among 1356 patients, 80 (6%) had mild hs-cTnI elevations at presentation. Within this group, AMI was the final diagnosis in 39 patients (49%). The diagnostic accuracy for the diagnosis of AMI as quantified by the area under the receiver operating characteristic curve (AUC) was 0.51 (95% CI 0.39-0.64) for hs-cTnI at presentation, 0.58 (95% CI 0.45-0.71) for copeptin at presentation, and 0.78 (95% CI 0.68-0.88) for 1h-hs-cTnI changes, which was significantly higher as compared to copeptin (p = 0.02) or hs-cTnI alone (p < 0.001). The additional use of 1h-hs-cTnI changes, but not of copeptin, improved diagnostic accuracy of hs-cTnI at presentation (AUC 0.80, 95% CI 0.70-0.90; p = 0.002 for comparison). Similar findings regarding copeptin and 1h-hs-cTnT/I changes were obtained for mild hs-cTnT elevations., Conclusions: About 6-22% of patients presenting with suggestive AMI to the ED have mild hs-cTnT/I elevations at presentation. In contrast to copeptin, the addition of 1h-hs-cTn changes substantially improves the early diagnosis of AMI.

Importance: It is currently unknown whether the uniform (universal clinical practice for more than 2 decades) or 2 sex-specific cutoff levels are preferable when using high-sensitivity cardiac troponin T (hs-cTnT) levels in the diagnosis of acute myocardial infarction (AMI)., Objective: To improve the management of suspected AMI in women by exploring sex-specific vs uniform cutoff levels for hs-cTnT., Design, Setting, and Participants: In an ongoing prospective, diagnostic, multicenter study conducted at 9 emergency departments, the present study evaluated patients enrolled from April 21, 2006, through June 5, 2013. The participants included 2734 adults presenting with suspected AMI. Duration of follow-up was 2 years, and data analysis occurred from June 5 to December 21, 2015., Interventions: The final diagnosis was centrally adjudicated by 2 independent cardiologists using all available information, including measurements of serial hs-cTnT blood concentrations twice: once using the uniform 99th percentile cutoff value level of 14 ng/L and once using sex-specific 99th percentile levels of hs-cTnT (women, 9 ng/L; men, 15.5 ng/L)., Main Outcomes and Measures: Diagnostic reclassification in women and men using sex-specific vs the uniform cutoff level in the diagnosis of AMI., Results: Of the 2734 participants, 876 women (32%) and 1858 men (68%) were included. Median (interquartile range) age was 68 (55-77) and 59 (48-71) years, respectively. With the use of the uniform cutoff value, 127 women (14.5%) and 345 men (18.6%) received a final diagnosis of AMI. Among these, at emergency department presentation, levels of hs-cTnT were already above the uniform cutoff value in 427 patients (sensitivity, 91.3% [95% CI, 85%-95.6%] in women vs 90.7% [95% CI, 87.1%-93.5% in men]; specificity, 79.2% [95% CI, 76.1%-82.1%] in women vs 78.5% [95% CI, 76.4%-80.6%] in men). After readjudication using sex-specific 99th percentile levels, diagnostic reclassification regarding AMI occurred in only 3 patients: 0.11% (95% CI, 0.02-0.32) of all patients and 0.6% (95% CI, 0.13-1.85) of patients with AMI. The diagnosis in 2 women was upgraded from unstable angina to AMI, and the diagnosis in 1 man was downgraded from AMI to unstable angina. These diagnostic results were confirmed when using 2 alternative pairs of uniform and sex-specific cutoff values., Conclusions and Relevance: The uniform 99th percentile should remain the standard of care when using hs-cTnT levels for the diagnosis of AMI.

Objective: The novel high-sensitivity cardiac troponin (hs-cTn) 0h/1h-algorithm substantially improves the early triage of patient's assigned "rule-out" or "rule-in" of acute myocardial infarction (AMI), while diagnostic uncertainty remains in that 25-30% of patients assigned to "observe". We aimed to better characterize these patients., Methods: In a prospective multicenter diagnostic study, we applied the hs-cTnT 0h/1h-algorithm in 2213 unselected patients presenting with symptoms suggestive of AMI to the emergency department. The final diagnosis was adjudicated by two independent cardiologists using all available information. Survival at 720-days was the prognostic endpoint. Findings were validated using a hs-cTnI 0h/1h-algorithm., Results: Twenty-four percent (n=523) of patients were assigned to "observe" by the hs-cTnT 0h/1h-algorithm. These patients differed significantly in multiple characteristics from "rule-out" and "rule-in" patients: they were older, in 75% male, and very often (57%) had pre-existing coronary artery disease (CAD). Diagnostic uncertainty for the presence of an AMI/UA was high. Only 39% of patients were suitable for coronary computed tomography angiography (CCTA). The most common final adjudicated diagnoses were non-cardiac disease (38%), non-coronary cardiac disease (24%), unstable angina (UA, 21%), and AMI (15%). Absolute hs-cTnT-changes within 3h had the highest diagnostic accuracy for AMI (AUC 0.86). Cumulative 720-day survival rate was 86%, which was significantly lower as compared to "rule-out" (p<0.001) and comparable to "rule-in" (p=ns). Findings were similar for the hs-cTnI "observe" zone., Conclusion: "Observe" patients are typically elderly men with pre-existing CAD and high long-term mortality. Absolute hs-cTn-changes within 3h, functional stress imaging and coronary angiography are the key diagnostic modalities., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: We aimed to prospectively validate a novel 1-hour algorithm using high-sensitivity cardiac troponin T measurement for early rule-out and rule-in of acute myocardial infarction (MI)., Methods: In a multicentre study, we enrolled 1320 patients presenting to the emergency department with suspected acute MI. The high-sensitivity cardiac troponin T 1-hour algorithm, incorporating baseline values as well as absolute changes within the first hour, was validated against the final diagnosis. The final diagnosis was then adjudicated by 2 independent cardiologists using all available information, including coronary angiography, echocardiography, follow-up data and serial measurements of high-sensitivity cardiac troponin T levels., Results: Acute MI was the final diagnosis in 17.3% of patients. With application of the high-sensitivity cardiac troponin T 1-hour algorithm, 786 (59.5%) patients were classified as "rule-out," 216 (16.4%) were classified as "rule-in" and 318 (24.1%) were classified to the "observational zone." The sensitivity and the negative predictive value for acute MI in the rule-out zone were 99.6% (95% confidence interval [CI] 97.6%-99.9%) and 99.9% (95% CI 99.3%-100%), respectively. The specificity and the positive predictive value for acute MI in the rule-in zone were 95.7% (95% CI 94.3%-96.8%) and 78.2% (95% CI 72.1%-83.6%), respectively. The 1-hour algorithm provided higher negative and positive predictive values than the standard interpretation of highsensitivity cardiac troponin T using a single cut-off level (both p < 0.05). Cumulative 30-day mortality was 0.0%, 1.6% and 1.9% in patients classified in the rule-out, observational and rule-in groups, respectively (p = 0.001)., Interpretation: This rapid strategy incorporating high-sensitivity cardiac troponin T baseline values and absolute changes within the first hour substantially accelerated the management of suspected acute MI by allowing safe rule-out as well as accurate rule-in of acute MI in 3 out of 4 patients., Trial Registration: ClinicalTrials.gov, NCT00470587., (© 2015 Canadian Medical Association or its licensors.)