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Non-ST segment elevation myocardial infarction (NSTEMI) is an acute coronary syndrome event where myocardial ischemia is present, with an increase of cardiac troponins without an elevation of the ST segment. One of the fundamental measures used to diagnose or rule out acute coronary syndrome (ACS) is troponin levels in the blood. Troponin is a broad term used for the category of muscle contraction regulatory proteins and is commonly measured during ACS evaluation. Troponin I is only released by cardiac tissue, while some assay measurements will also pick up troponin released by skeletal muscle injury. This retrospective observational study was performed investigating troponin assays and how they relate to patient's outcomes. The troponin assays used in this Miami hospital where the database of patients was collected between 2018 and 2023 were troponin I (cTnI), the conventional troponin assay, and the newer high-sensitivity troponin I assay (hs-cTn). In this observational study patients who received an admitting diagnosis of NSTEMI corroborated by an independent cardiologist had their respective troponin assay levels included. Patients found to have ECG changes significant for non-ischemic pathologies, or echocardiogram findings suggestive of myocardial dysfunction not clinically correlated to an ACS were excluded from the study. A total of 75 patients were included in this study and the mean age was 75.97 ±14.72 years, with a presentation of chest pain, dyspnea and general weakness recorded in 59% (n = 45) of patients. The median time between troponin samples was 6.63 hours across both assays and hs-cTn showed a 4.99% increase in variation between samples while cTnI had a decrease of 2.53%. The study objective is to support whether there is a difference in rates of cardiac catheterization or mortality based on the type of troponin testing. There was no significant association found between, the type of troponin assay used during hospital admission, and the outcomes of catheterization and death (p > 0.009).

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BACKGROUND: Cardiac biomarkers, such as high-sensitivity cardiac troponin (hs-cTn) and brain natriuretic peptide (BNP) or N­terminal prohormone of brain natriuretic peptide (NT-proBNP) are measured perioperatively to improve the prognosis and risk prediction. The European Society of Cardiology (ESC), European Society of Anesthesiology and Intensive Care (ESAIC) and the German Society of Anesthesiology and Intensive Care Medicine (DGAI) have recently published guidelines on the use of cardiac biomarkers prior to surgery. OBJECTIVE/RESEARCH QUESTION: This article provides an overview of the available evidence on perioperative troponin and BNP/NT-proBNP measurements. Current guideline recommendations are presented and discussed. MATERIAL AND METHODS: MEDLINE, Cochrane and google.scholar were searched for relevant keywords. Titles and abstracts of identified papers were checked for relevance and published results were summarized. Guideline recommendations from the ESC, ESAIC and DGAI are presented, compared and evaluated based on the available literature. In addition, the significance of new perioperative cardiac biomarkers is discussed based on the existing evidence. RESULTS: The definitions, diagnosis and management of cardiovascular events in the perioperative context differ from those in the nonsurgical setting. The evidence for the measurement of hs-cTn and BNP/NT-proBNP is evaluated differently in the guidelines and the resulting recommendations are partly contradictory. In particular, recommendations for changes in perioperative management based on biomarker measurements diverge. The ESC guidelines propose an algorithm that uses preoperative biomarkers as the basis for additional cardiac investigations. In particular, invasive coronary angiography is recommended for patients with stable chronic coronary syndrome who have no preoperative cardiac symptoms but elevated biomarkers. In contrast, the ESAIC guidelines emphasize that the available evidence is not sufficient to use perioperative biomarker measurements as a basis for a change in perioperative management. DISCUSSION: Treating physicians should coordinate interdisciplinary (surgery, anesthesiology, cardiology) recommendations for clinical practice based on the aforementioned guidelines. If cardiac biomarkers are routinely determined in high-risk patients, this should be done in accordance with the ESC algorithm.

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More than 300 million surgeries are performed annually worldwide. Patients are progressively aging and often have multiple comorbidities that put them at increased cardiovascular risk in the perioperative period. The United States published latest guidelines regarding preoperative cardiac evaluation and risk stratification for patients undergoing non-cardiac surgery in 2014. There are multiple risk stratification tools available that can help guide management. Furthermore, newer laboratory tests, such as preoperative NT-proBNP and high-sensitivity troponin assays, may aid in preventing and diagnosing perioperative myocardial injury.

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BACKGROUND: Non-ST-segment elevation myocardial infarction (NSTEMI) is a common form of acute myocardial infarction and rapid and accurate diagnosis is crucial for timely treatment. Current guidelines recommend using high-sensitivity cardiac troponin (hs-cTn) assays to determine circulating cTnI or cTnT levels. While the accuracy of the 0 h/1 h algorithm for diagnosing NSTEMI in different regions and patient populations remains controversial. Additionally, point-of-care testing (POCT) cTn assays have the potential to provide troponin readings to physicians within 15 min, but their accuracy in diagnosing NSTEMI in the emergency department (ED) requires further investigation. METHODS: A single-center prospective observational cohort study was conducted at Shaanxi Provincial People's Hospital to assess the analytical and diagnostic performance of the laboratory-based Roche Modular E170 hs-cTnT using the 0 h/1 h algorithm with Radiometer AQT90-flex POCT cTnT assay in undifferentiated chest pain patients presenting to the ED. Whole-blood samples were collected and hs-cTnT and POCT cTnI were measured simultaneously at baseline and after 1 h. RESULTS: The study results showed that the POCT cTnT assay using the 0 h/1 h algorithm had comparable diagnostic accuracy to the laboratory-based Roche Modular E170 hs-cTnT assay in diagnosing NSTEMI in patients with chest pain. CONCLUSION: The laboratory-based Roche Modular E170 hs-cTnT using the 0 h/1 h algorithm is reliable and accurate method for diagnosing NSTEMI in undifferentiated chest pain patients presenting to the ED. POCT cTnT assay has comparable diagnostic accuracy to the hs-cTnT assay and its rapid turnaround time makes it a valuable tool in expediting the diagnostic workup of chest pain patients.

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INTRODUCTION: This study examined the analytical performance of a whole blood (WB) point of care (POC) hs-cTnI assay compared to a plasma central laboratory hs-cTnI assay in patients presenting with ischemic symptoms to a US emergency department. METHODS: Fresh WB specimens collected at 0 and 2 h from 1089 consecutive patients (2152 total from 1076 matched specimens) were analyzed for hs-cTnI using WB on POC Siemens Atellica VTLi assay and plasma on central laboratory Siemens Atellica IM assay. Concordances were determined based on concentrations ranging from < limit of detection (LoD), LoD to overall and sex specific 99th percentiles from both the IFCC manufacturer package inserts and Universal Sample Bank (USB) data, and > 99th percentiles. Method comparisons were calculated using Passing Bablok regression and Bland Altmann plots, and linear regression determined by Pearson correlation coefficient. RESULTS: Baseline concentration comparisons showed: POC VTLi < LoD 4-5 %, ≥ LoD 95 %; Atellica IM < LoD 5-7 %, and ≥ LoD 94-95 %. From the 2152 paired 0 and 2-hour samples, based on 99th percentiles, overall concordance was 91-92 % (kappa 0.72-0.77) and discordance 8 %. Passing Bablok regression analysis using 1924 specimens between LoD to 500 ng/L showed: slopes 0.469-0.490; y-intercepts 1.753-2.028; r values 0.631-0.817. Pearson correlation coefficient showed moderate to strong correlation strength, even with up to 53 % cTnI concentrations variance (Passing Bablok slopes) vs 27.0-40.1 % (Bland-Altmann plots). CONCLUSIONS: Up to 95 % of measured samples were > LoD for both the POC (Atellica VTLi) and central laboratory (Atellica IM) hs-cTnI assays. Moderate to strong concordance and correlation were observed between assays, despite up to 53 % variances in cTnI concentration.

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Background: The outcomes of real-world unstable angina (UA) in the high-sensitivity troponin era are unclear. We aimed to investigate the outcomes of UA referred to coronary angiography compared to stable angina (SA), non-ST-segment elevation myocardial infarction (NSTEMI), STEMI and a general population. Methods: We included the 9,694 patients with no prior coronary artery disease (CAD) referred to invasive or CT coronary angiography from 2013 to 2018 in Northern Norway (51% SA, 12% UA, 23% NSTEMI and 14% STEMI), and 11,959 asymptomatic individuals recruited from the Tromsø Study. We used Cox models to estimate the hazard ratios (HR) for all-cause mortality and major adverse cardiovascular events (MACE), defined as cardiovascular death, MI or obstructive CAD. Results: The median follow-up time was 2.8 years. The incidence rate of death was 8.5 per 1000 person-years (95 % confidence interval [CI] 8.0-9.0) in the general population, 9.7 (95 % CI 8.3-11.5) in SA, 14.9 (95 % CI 11.4-19.6) in UA, 29.7 (95 % CI 25.6-34.3) in NSTEMI and 36.5 (95 % CI 30.9-43.2) in STEMI. In multivariable adjusted analyses, compared with UA, SA had a 38 % lower risk of death and a non-significant lower risk of MACE (HR 0.62, 95 % CI 0.44-0.89; HR 0.86, 95 % CI 0.66-1.11). NSTEMI had a 2.4-fold higher risk of death (HR 2.39, 95 % CI 1.38-4.14) and a 1.6-fold higher risk of MACE (HR 1.62, 95 % CI 1.11-2.38) compared tox UA during the first year after coronary angiography, but a similar risk thereafter. There was no difference in the risk of death for UA with non-obstructive CAD and obstructive CAD (HR 0.78, 95 % CI 0.39-1.57). Conclusion: UA had a higher risk of death but a similar risk of MACE compared to SA and a lower 1-year risk of death and MACE compared to NSTEMI.

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Ischemic heart disease (IHD) is one of the leading causes of death globally. Rapid diagnosis of myocardial infarction (MI) will enable earlier initiation of the treatment and improve patient outcomes. Practice guidelines for non-ST-elevation acute coronary syndromes by the American College of Cardiology (ACC)/American Heart Association (AHA) had listed the diagnostic performance of absolute versus relative changes in evidence gaps. We aimed to address this evidence gap by examining the diagnostic accuracy of absolute versus relative changes in cardiac troponins at various time intervals in diagnosing MI. Grey literature, conference abstracts, animal studies, and reports published before 2009 and in languages other than English were excluded. We included reports that investigated absolute or relative changes in highly sensitive cardiac troponin T (hs-cTnT) or sensitive/highly sensitive cardiac troponin I (s/hs-cTnI) assays after specific time intervals (1, 2, or 3 h) in patients presenting with symptoms suggestive of the acute coronary syndrome. After screening, we arranged the reports in 12 separate groups based on the variables for which the data was reported. Quality assessment of the diagnostic accuracy studies-2 (QUADAS-2) was used to assess the risk of bias in the included studies. The weighted summary area under the curve (AUC) was calculated for each pool. We then performed two-sided (or two-tailed) tests to compare independent receiver operating characteristic (ROC) curves. MedCalc version 20.106 (MedCalc Software Ltd., Ostend, Belgium) was used for all statistical analysis. We included eight reports with 23,450 patients in the meta-analysis. Weighted summary estimates and their respective 95% confidence intervals (CI) under random-effects model for ROC-AUC are as follows: absolute hs-cTnI at 1 h - 0.94 (95% CI: 0.922 to 0.959, p < 0.001); absolute hs-cTnT at 1 h - 0.921 (95% CI: 0.902 to 0.941, p < 0.001); absolute s/hs-cTnI at 2 h - 0.953 (95% CI: 0.926 to 0.980, p < 0.001); absolute hs-cTnT at 2 h 0.951 (95% CI: 0.940 to 0.962, p < 0.001); relative hs-cTnT at 2 h - 0.818 (95% CI: 0.733 to 0.903, p < 0.001); relative s/hs-cTnI at 2 h - 0.762 (95% CI: 0.726 to 0.798, p < 0.001); absolute hs-cTnI at 3 h - 0.967 (95% CI: 0.95 to 0.984, p < 0.001); absolute hs-cTnT at 3 h - 0.959 (95% CI: 0.950 to 0.968, p < 0.001); and relative hs-cTnT at 3 h - 0.926 (95% CI: 0.907 to 0.945, p < 0.001). P-values of comparison of absolute and relative changes are as follows: hs-cTnT at 1 h: <0.0001; hs-cTnI at 1 h: <0.0001; hs-cTnT at 2 h: 0.0024; s/hs-cTnI at 2 h: <0.0001; hs-cTnT at 3 h: 0.0022; and hs-cTnI at 3 h: 0.0005. Our analysis found absolute changes to be superior to relative changes in both hs-cTnT and s/hs-cTnI at 1, 2, and 3 h in the diagnosis of MI. There was no statistically significant difference in comparing s/hs-cTnI vs. hs-cTnT using absolute or relative changes at any time interval. Our findings suggest that future research investigating a potential 0 h/30 min algorithm should use absolute Δ over relative Δ. A suboptimal number of reports in the groups limited our ability to establish the robustness of the results. We did not receive any funding for this review.

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BACKGROUND: N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (hs-cTnT) are associated with disease severity and outcomes among patients with heart failure (HF) with preserved ejection fraction. OBJECTIVES: The authors evaluated associations between both biomarkers and clinical outcomes in the EMPEROR-Preserved (Empagliflozin Outcome Trial in Patients with Chronic Heart Failure with Preserved Ejection Fraction) trial. METHODS: Of 5,988 study participants, 5,986 (99.9%) and 5,825 (97.3%) had available baseline NT-proBNP and hs-cTnT; postbaseline NT-proBNP was also available. Baseline characteristics were expressed by biomarker quartiles. The effect of empagliflozin on cardiovascular death/ HF hospitalization, the individual components, total HF hospitalizations, slope of decline of estimated glomerular filtration rate (eGFR), and a composite renal endpoint were examined across biomarker quartiles. Change in NT-proBNP across study visits as a function of treatment assignment was also assessed. RESULTS: Higher baseline NT-proBNP and hs-cTnT concentrations were associated with more comorbidities and worse HF severity. Incidence rates for cardiac and renal outcomes were 2- to 5-fold higher among those in the highest vs lowest NT-proBNP or hs-cTnT quartiles. Empagliflozin consistently reduced the risk for cardiovascular events and reduced slope of eGFR decline across NT-proBNP or hs-cTnT quartiles. Empagliflozin treatment modestly lowered NT-proBNP; by 100 weeks, the adjusted mean difference in NT-proBNP from placebo was 7%. Increase in NT-proBNP from baseline to 12 weeks was strongly associated with risk of cardiovascular death/HF hospitalization. CONCLUSIONS: The benefit of empagliflozin on cardiac outcomes and decline of eGFR is preserved across the wide range of baseline NT-proBNP and hs-cTnT evaluated. Empagliflozin modestly reduces NT-proBNP in HF with preserved ejection fraction. (EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Preserved Ejection Fraction [EMPEROR-Preserved]; NCT03057951).

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BACKGROUND: Cardiac troponin (cTn) values above the 99th percentile upper reference limit (URL) indicate myocardial injury. We established 99th percentile URLs for three high-sensitivity cTn (hs-cTn) assays (Beckman Coulter Access hs-cTnI, Abbott STAT hs-cTnI, and Roche Elecsys hs-cTnT) using a healthy population in Korea. METHODS: Each cTn value was measured by three assays and analyzed by dividing by gender and age. RESULTS: The frequency histograms of log-transformed cTn values for Beckman and Abbott assays exhibited a bell-shaped distribution. The 99th percentile URLs were 9.8, 17.4, and 17.3 ng/L in the total population; 10.9/9.0, 18.9/17.0, and 18.9/17.7 ng/L in the male/female population (p < 0.001 for all three assays); and 11.2/7.2, 19.9/14.5, and 22.7/9.3 ng/L in the older/younger population (p < 0.001 for all three assays) for Beckman, Abbott, and Roche assays, respectively. CONCLUSION: Among the three assays, bell-shaped distributions were observed in a frequency histogram of log-transformed cTn values for healthy population in Beckman and Abbott assays. Also, our findings show that the 99th percentile URLs for cTn levels vary not only by gender but age.

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BACKGROUND: High-sensitivity cardiac troponin T (hs-cTnT) and the ESC 0/1h-hs-cTnT-algorithm have worse performance in the early diagnosis of myocardial infarction (MI) in patients with prior coronary artery bypass grafting (CABG). It is unknown, whether this concern applies also to hs-cTnI, the most widely used analyte worldwide. METHODS: In an international multicenter diagnostic study, two cardiologists centrally adjudicated the final diagnosis in patients presenting to the emergency department with symptoms suggestive of MI according to the Third Universal Definition of MI. The objective was to compare the diagnostic accuracy of hs-cTnI assays and their performance within the ESC hs-cTnI 0/1h-algorithms in patients with versus without prior CABG. Findings were externally validated in an U.S. multicenter diagnostic study. RESULTS: A total of 392/5'200 patients (8%) had prior coronary artery bypass grafting (CABG). Diagnostic accuracy of hs-cTnI as quantified by the area under the receiver-operating characteristics-curve (AUC) in these patients was high, but lower versus patients without prior CABG (e.g. hs-cTnI-Architect 0.91 versus 0.95; p = 0.016). Sensitivity/specificity of rule-out/in by the European Society of Cardiology (ESC) 0/1h-hs-cTnI-algorithms remained very high [e.g. hs-cTnI-Architect 100% and 93.5%], but efficacy was lower (52% versus 74%, p < 0.01). External validation (n = 2113) confirmed these findings in 192 patients with prior CABG using hs-cTnI-Atellica, with 52% versus 36% (p < 0.001) remaining in the observe zone. CONCLUSIONS: Diagnostic accuracy of hs-cTnI and efficacy of the ESC 0/1h-hs-cTnI-algorithms are lower in patients with prior CABG, but sensitivity/specificity remain very high. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT00470587, number NCT00470587.

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In the first case, we describe a 45-year-old man who presented to the emergency department for evaluation of chest pain. He reported having chest discomfort 5 days prior that lasted a few minutes after an altercation with his coworker. In the second case, we describe a 54-year-old woman with history of well-controlled diabetes mellitus, hypertension, and dyslipidemia who presented to the ED with a 10-day history of intermittent sharp and burning chest pain in the substernal region, 5/10 intensity, lasting 15-20 minutes, associated with exertion. (Level of Difficulty: Intermediate.).

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BACKGROUND: Many reports noted a disagreement between High sensitivity cardiac Troponin (hs-cTn) assays on the diagnosis of Acute Coronary Syndrome (ACS). METHODS: We conducted a retrospective study aiming to assess the agreement between hs-cTn T (Roche) and hs-cTn I (Abbott) in patients presenting with a suspected ACS to the emergency department at Hotel-Dieu hospital between September 2017 and October 2019 using overall, sex-specific, and age-adjusted sex-specific cut-off values. This was measured using Cohen's Kappa. We explored whether renal function, circadian rhythm, age and sex influenced the discordance. And we analyzed the trend of agreement between baseline and repeated measurements. RESULTS: 4856 patients who had simultaneous hs-cTn I and T values were retained for the analysis. 53.5% had a hs-cTn T above the overall 99th percentile, compared to 19.9% for hs-cTn I. The numbers were significantly reduced when applying age-adjusted sex-specific 99th percentile. A disagreement was seen in 34% of cases using overall 99th percentile. Using sex-specific cut off values did not impact this discordance; however, age-adjusted sex-specific cut-off values reduced the percentage of discrepancies to 15.8%. The decreased renal function had a negative effect on the agreement while the circadian rhythm had minimal effect. This initial discordance was carried forward into repeated measurements. CONCLUSION: The disagreement between hs-cTn T and I assays could be imputed to the choice of cut-off values. The use of age-adjusted sex specific 99th percentile reduced majorly these discordances. Further studies are needed in order to evaluate their clinical utility in patients presenting with ACS.

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BACKGROUND: High-sensitivity cardiac troponin I (hs-cTnI) assays have been developed that quantify lower cTnI concentrations with better precision versus earlier generation assays. hs-cTnI assays allow improved clinical utility for diagnosis and risk stratification in patients presenting to the emergency department with suspected acute myocardial infarction. We describe the High-Sensitivity Cardiac Troponin I Assays in the United States (HIGH-US) study design used to conduct studies for characterizing the analytical and clinical performance of hs-cTnI assays, as required by the US Food and Drug Administration for a 510(k) clearance application. This study was non-interventional and therefore it was not registered at clinicaltrials.gov. METHODS: We conducted analytic studies utilizing Clinical and Laboratory Standards Institute guidance that included limit of blank, limit of detection, limit of quantitation, linearity, within-run and between run imprecision and reproducibility as well as potential interferences and high dose hook effect. A sample set collected from healthy females and males was used to determine the overall and sex-specific cTnI 99th percentile upper reference limits (URL). The total coefficient of variation at the female 99th percentile URL and a universally available American Association for Clinical Chemistry sample set (AACC Universal Sample Bank) from healthy females and males was used to examine high-sensitivity (hs) performance of the cTnI assays. Clinical diagnosis of enrolled subjects was adjudicated by expert cardiologists and emergency medicine physicians. Assessment of temporal diagnostic accuracy including sensitivity, specificity, positive predictive value, and negative predictive value were determined at presentation and collection times thereafter. The prognostic performance at one-year after presentation to the emergency department was also performed. This design is appropriate to describe analytical characterization and clinical performance, and allows for acute myocardial infarction diagnosis and risk assessment.

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BACKGROUND: Suspicion of acute myocardial infarction (AMI) is among the most common reasons for admission to hospital in Denmark. Owing to this suspicion, an estimated 50,000 patients are admitted every year. Only 15-20% are finally diagnosed with AMI, whereas 40% are discharged after rule-out of AMI and without initiation of any treatment or need for further admission. In patients discharged after rule-out, the current diagnostic protocol, using consecutive troponin measurements, results in an average length of stay (LOS) of 8-12 h. This leads to overcrowding in both the emergency departments and coronary care units. Measuring copeptin and high-sensitivity cardiac troponin (hs-cTn) upon hospital arrival has shown potential for early rule-out of AMI. However, the diagnostic performance may be improved by accelerating the copeptin measurement of blood sampled already in the pre-hospital phase. Additional evidence on LOS reduction and safety of the rule-out strategy in a large cohort of all-comers is needed. METHODS/DESIGN: The rule-out potential is being evaluated in a randomized controlled trial including 4800 patients admitted to hospital for suspicion of AMI. Patients are randomized to either standard rule-out (consecutive troponin measurements) or accelerated rule-out (copeptin measured in a blood sample acquired before hospital admission, combined with troponin measured in the first blood sample upon admission). DISCUSSION: Sampling blood for copeptin analysis already in the pre-hospital phase and combining this with a later hs-cTn measurement may be the optimal timing for achieving the best diagnostic performance in an AMI rule-out protocol/strategy. Moreover, we are directly comparing pre-hospital and in-hospital blood sample results to address this issue of timing, and we also are comparing single-marker strategies with dual-marker strategies. If the combination of copeptin and hs-cTn is confirmed to rule out AMI safely, implementation of this fast rule-out protocol could optimize patient flow, reduce health care expenses and enable allocation of resources to patients with confirmed illness. In future, when point-of-care analyses of copeptin and hs-cTn are available, hospitalization of the large proportion of patients with symptoms raising suspicion of AMI could potentially be avoided. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02666326 . Registered on January 24, 2016.

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Chest pain accounts for approximately 6% of Emergency Department (ED) attendances and is the most common reason for emergency hospital admission. For many years, our approach to diagnosis has required patients to stay in hospital for at least 6-12 h to undergo serial biomarker testing. As less than one fifth of the patients undergoing investigation actually has an acute coronary syndrome (ACS), there is tremendous potential to reduce unnecessary hospital admissions. Recent advances in diagnostic technology have improved the efficiency of care pathways. Decision aids such as the Thrombolysis in Myocardial Infarction (TIMI) risk score and the History, Electrocardiogram, Age, Risk factors and Troponin (HEART) score enable rapid 'rule out' of ACS within hours of patients arriving in the ED. With high sensitivity cardiac troponin (hs-cTn) assays, approximately one third of patients can have ACS 'ruled out' with a single blood test, and up to two thirds could have an acute myocardial infarction 'ruled out' with a second sample taken after as little as 1 h. Building on those recent advances, this paper presents an overview of the principles behind the development of the Troponin-only Manchester Acute Coronary Syndromes (T-MACS) decision aid. This clinical prediction model could be used to 'rule out' and 'rule in' ACS following a single blood test and to calculate the probability of ACS for every patient. The future potential of this approach is then addressed, including practical applications of artificial intelligence, shared decision making, near-patient testing and personalized medicine.

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The European Society of Cardiology (ESC) guidelines recommend the use of high-sensitivity cardiac troponin (hs-cTn) 0-hour/1-hour algorithms in patients presenting with suspected non ST elevation myocardial infarction (NSTEMI) as Class I, Level B. This algorithm stratified patients into three group including, rule-out, observe, and rule-in. The introduction of a time axis consisting of a relatively short time, 0-hour/1-hour, is worth mentioning in this algorithm. The specificity and negative predictive value to rule-out of myocardial infarction (MI) was more than 95%, respectively. In prospective Asian study consist of around 400 patients with suspected NSTEMI, "elective" catheter intervention was performed on 13 patients in both rule-out and observe group. None of them had MI, or needed an urgent coronary angiography (CAG) within 30 days. Although there was two patients on whom CAG and percutaneous coronary intervention (PCI) were performed less than 7 hours after presenting to the emergency department (ED), they were classified as moderate risk according to the Framingham Risk Score. The diagnostic performance for patients with suspected NSTEMI to combine the novel risk score with the algorithm would be much improved. The development of excellent assays was also key to establish the algorithm. The hs-cTn assay has limits of detection (LoD) approximately 10-fold lower than those of conventional assays, and their 99th percentiles are analytically very precise. After the emergence of the hs-cTn assays, rises in the cases of NSTEMI were accompanied by a reciprocal reduction in the percentage of patients diagnosed with unstable angina (UA). This excellent algorithm has a possibility to reduce ED crowding and unnecessary CAG.

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OBJECTIVES: High sensitivity cardiac troponin T and I (hs-cTnT and hs-cTnI) assays show analytical, diagnostic and prognostic improvement over contemporary sensitive cTn assays. However, given the importance of troponin in the diagnosis of myocardial infarction, implementing this test requires rigorous analytical and clinical verification across the total testing pathway. This was the aim of this study. DESIGN AND METHODS: Analytical verification included assessment of critical outlier frequency, for hs-cTnI and cTnI assays. Concordance for paired cTnI and hs-cTnI measurements (n=1096) was verified using 99th percentiles for both genders (cTnI: 30 ng/L, hs-cTnI: 25 ng/L) and for men and women separately (hs-cTnI: M: 34;F: 16 ng/L). Discordant data was correlated with clinical and laboratory information. Diagnosis of Acute Coronary Syndrome (ACS) or Non-ACS was adjudicated by two cardiologists independently. RESULTS: The hs-cTnI assay showed a lower (10-fold) critical outlier rate (0.091%) and more detectable results above the limit of detection (LOD) (23.4%) and 99th percentile (2.4%), compared to cTnI. Analytical concordance between the two assays was high (94.5%) but decreased (91.7%) when gender-specific hs-cTnI cut-offs were used. The hs-cTnI assay gave fewer false negatives (up to 1.0%) but disproportionately more false positives (up to 6.7%) overall, which improved (3.9%) for serial measurements. CONCLUSIONS: Laboratories should analytically and clinically verify hs-cTn assays before use, with attention to performance and the clinical and diagnostic algorithms that support appropriate testing and result interpretation. Work in the pre- and post-analytical phases is necessary to augment the analytical improvement in the new era of troponin testing.

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OBJECTIVE: We aimed to prospectively derive and validate a novel 1h-algorithm using high-sensitivity cardiac troponin I (hs-cTnI) for early rule-out and rule-in of acute myocardial infarction. METHODS: We performed a prospective multicenter diagnostic study enrolling 1811 patients with suspected acute myocardial infarction. The final diagnosis was centrally adjudicated by 2 independent cardiologists using all available information, including coronary angiography, echocardiography, follow-up data, and serial measurements of hs-cTnT (but not hs-cTnI). The hs-cTnI 1h-algorithm, incorporating measurements performed at baseline and absolute changes within 1 hour, was derived in a randomly selected sample of 906 patients (derivation cohort), and then validated in the remaining 905 patients (validation cohort). RESULTS: Acute myocardial infarction was the final diagnosis in 18% of patients. After applying the hs-cTnI 1h-algorithm developed in the derivation cohort to the validation cohort, 50.5% of patients could be classified as "rule-out," 19% as "rule-in," 30.5% as "observe." In the validation cohort, the negative predictive value for acute myocardial infarction in the "rule-out" zone was 99.6% (95% confidence interval, 98.4%-100%), and the positive predictive value for acute myocardial infarction in the "rule-in" zone was 73.9% (95% confidence interval, 66.7%-80.2%). Negative predictive value of the 1h-algorithm was higher compared with the classical dichotomous interpretation of hs-cTnI and to the standard of care combining hs-cTnI with the electrocardiogram (both P < .001). Positive predictive value also was higher compared with the standard of care (P < .001). CONCLUSION: Using a simple algorithm incorporating baseline hs-cTnI values and the absolute change within the first hour allows safe rule-out as well as accurate rule-in of acute myocardial infarction in 70% of patients presenting with suspected acute myocardial infarction.

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Regulators and healthcare payers are increasingly demanding evidence that biomarkers deliver patient benefits to justify their use in clinical practice. Laboratory professionals need to be familiar with these evidence requirements to better engage in biomarker research and decisions about their appropriate use. This paper by a multidisciplinary group of the European Federation of Clinical Chemistry and Laboratory Medicine describes the pathway of a laboratory assay measuring a biomarker to becoming a medically useful test. We define the key terms, principles and components of the test evaluation process. Unlike previously described linearly staged models, we illustrate how the essential components of analytical and clinical performances, clinical and cost-effectiveness and the broader impact of testing assemble in a dynamic cycle. We highlight the importance of defining clinical goals and how the intended application of the biomarker in the clinical pathway should drive each component of test evaluation. This approach emphasizes the interaction of the different components, and that clinical effectiveness data should be fed back to refine analytical and clinical performances to achieve improved outcomes. The framework aims to support the understanding of key stakeholders. The laboratory profession needs to strengthen collaboration with industry and experts in evidence-based medicine, regulatory bodies and policy makers for better decisions about the use of new and existing medical tests.

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