Clinical Laboratory Practice Recommendations for the Use of Cardiac Troponin in Acute Coronary Syndrome: Expert Opinion from the Academy of the American Association for Clinical Chemistry and the Task Force on Clinical Applications of Cardiac Bio-Markers of the International Federation of Clinical Chemistry and Laboratory Medicine

Reference intervals for high sensitivity cardiac troponin I and N-terminal pro-B-type natriuretic peptide in children and adolescents on the Siemens Atellica

OBJECTIVES

The cardiac biomarkers high sensitivity cardiac troponin I (hs-cTnI) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are utilised in paediatric healthcare for the diagnosis and prognostic assessment of many conditions including myocarditis, congenital heart disease, multisystem inflammatory syndrome in children (MIS-C) and heart failure. However, the standardised age-related reference intervals, 99th percentile cut-offs and clinical guidelines are not available, making the interpretation of these biomarkers challenging. This study aimed to generate normative data in a paediatric cohort for the Siemens Atellica® IM 1300 analyser.

METHODS

Residual plasma samples were collected from children aged up to 17 years attending primary care and out-patient settings and with no apparent evidence of cardiac dysfunction, renal dysfunction or other confounders. Reference intervals were generated using the 2.5th-97.5th percentiles, and 99th percentile cut-offs determined according to CLSI EP28-A3c.

RESULTS

Statistical analysis revealed that partitioning was not required for gender for either biomarker. The reference interval for hs-cTnI for children aged one month to 16 years (n=292, 146 females and 146 males) was <14 ng/L with a 99th percentile cut-off of 19 ng/L. The reference interval for NT-proBNP for children aged one month up to one year was <714 ng/L (n=14) and for children aged 1-16 years (n=339) was <295 ng/L.

CONCLUSIONS

This is the first paediatric reference interval data generated on the Siemens Atellica® solution. These reference intervals and 99th percentiles will inform clinical decisions in the paediatric cardiology setting.

Diagnostic Performance of Point-of-Care High-Sensitivity Troponin in the Exclusion of Non-ST-Elevation Myocardial Infarction in the Emergency Department

BACKGROUND

This study evaluates the diagnostic performance of high-sensitivity troponin using point-of-care testing (POCT) devices compared with main laboratory measurements for ruling out non-ST-elevation myocardial infarction (NSTEMI) in emergency department (ED) patients presenting with non-traumatic chest pain.

METHODS

This multicenter, observational, prospective, non-interventional study was conducted in two Spanish hospitals from 1 June to 31 December 2023 and included adult patients presenting with non-traumatic chest pain admitted to the ED. High-sensitivity troponin levels were measured using both the Siemens Atellica® VTLi POCT device and main laboratory testing, with data collected on analytical results and measurement times.

RESULTS

Of the 201 patients who met the inclusion criteria, a significant correlation was observed between the POCT and laboratory assays. The area under the curve (AUC) of the ROC curve was consistently greater than 0.9, indicating a high diagnostic accuracy for ruling out NSTEMI. In addition, measurement times were significantly reduced using POCT compared to the core laboratory.

CONCLUSION

These results suggest that high-sensitivity troponin POCT devices offer comparable diagnostic performance to traditional laboratory methods for the diagnosis of NSTEMI in the emergency department, potentially speeding up clinical decisions and optimizing resource utilization.

A Comparison Study: Possible Bias in Troponin I Measurement Obtained with a Point of Care Testing and a Central Laboratory Analyzers Employing Different Biological Matrices and Anticoagulants

BACKGROUND

high-sensitive cardiac TroponinI (hs-cTnI) is widely used for diagnosis of acute coronary syndromes. The latest recommendation for hs-cTnI determination is the protocol 0-1 h finalized to improve the rule out accuracy of the test. A Point of Care Testing able to guarantee these performances could be very useful due to reducing the turnaround time and ruling out patients suspected of ACS, especially by using biological matrices that are not required for centrifuge. The aim of our work is to compare the results for hs-cTnI obtained using different biological matrices and anticoagulants, obtained between Atellica® VTLi hs-cTnI POCT and Access AccuTnI+3 DxI800 performances, in order to establish a possible bias derived directly from these pre-analytical conditions.

METHODS

Li-heparinized pool samples were primary employ for hs-cTnI with Atellica® VTLi as whole blood, then centrifuged and tested on Atellica® VTLi and DxI800. K3EDTA pool samples were centrifuged and measured on DxI800 too. A comparison of methods was performed according to CLSI_EP-09A2 protocol. Constant and proportional errors were investigated with Deming regression. Bias between methods was evaluated with the Bland Altman test.

RESULTS

comparing whole blood lithium heparin results obtained with Atellica versus lithium heparin and K3EDTA plasma tested on DxI 800, the Deming regression revealed a proportional error, whereas in both cases Bland Altman highlighted a minimal underestimation. A similar performance was revealed when considering plasma lithium heparin tested on Atellica versus lithium heparin and K3EDTA plasma obtained with DxI800, confirming the same underestimation. Considering values close to the cut off, no significant differences were found.

CONCLUSIONS

in the laboratory, the estimation of the bias of two different analyzers is pivotal. Once more this is crucial when different biological matrices and anticoagulants are employed for the analysis. Our study demonstrates that no significant differences among the two matrices are present when comparing Atellica and DxI800 performances.

Determination of Clinically Acceptable Analytical Variation of Cardiac Troponin at Decision Thresholds

BACKGROUND

Clinical decision-making for risk stratification for possible myocardial infarction (MI) uses high-sensitivity cardiac troponin (hs-cTn) thresholds that range from the limit of detection to several-fold higher than the upper reference limit (URL). To establish a minimum analytical variation standard, we can quantify the effect of variation on the population clinical measures of safety (sensitivity) and effectiveness [proportion below threshold, or positive predictive value (PPV)].

METHODS

From large datasets of patients investigated for possible MI with the Abbott hs-cTnI and Roche hs-cTnT assays, we synthesized datasets of 1 000 000 simulated patients. Troponin concentrations were randomly varied several times based on absolute deviations of 0.5 to 3 ng/L and relative changes of 2% to 20% around the low-risk threshold (5 ng/L) and URLs, respectively.

RESULTS

For both assays at the low-risk thresholds, there were negligible differences in sensitivity (<0.3%) with increasing analytical variation. The proportion of patients characterized as low risk reduced by 30% to 29% (Roche) and 53% to 44% (Abbott). At the URL, increasing analytical variation also did not change sensitivity; the PPV fell by less than 3%. For risk stratification, increased delta thresholds (change between serial troponin concentrations) increased sensitivity at the cost of a decreased percentage of patients below the delta threshold, with the largest changes at the greatest analytical variation.

CONCLUSIONS

At the low-risk threshold, analytical variation up to 3 ng/L minimally impacted the safety metric (sensitivity) but marginally reduced effectiveness. Similarly, at the URL even relative variation up to 25% minimally impacted safety metrics and effectiveness. Analytical variation for delta thresholds did not negatively impact sensitivity but decreased effectiveness.

Barbed arrow-like structure membrane with ultra-high rectification coefficient enables ultra-fast, highly-sensitive lateral-flow assay of cTnI

Acute myocardial infarction (AMI) has become a public health disease threatening public life safety due to its high mortality. The lateral-flow assay (LFA) of a typical cardiac biomarker, troponin I (cTnI), is essential for the timely warnings of AMI. However, it is a challenge to achieve an ultra-fast and highly-sensitive assay for cTnI (hs-cTnI) using current LFA, due to the limited performance of chromatographic membranes. Here, we propose a barbed arrow-like structure membrane (BAS Mem), which enables the unidirectional, fast flow and low-residual of liquid. The liquid is rectified through the forces generated by the sidewalls of the barbed arrow-like grooves. The rectification coefficient of liquid flow on BAS Mem is 14.5 (highest to date). Using BAS Mem to replace the conventional chromatographic membrane, we prepare batches of lateral-flow strips and achieve LFA of cTnI within 240 s, with a limit of detection of 1.97 ng mL-1. The lateral-flow strips exhibit a specificity of 100%, a sensitivity of 93.3% in detecting 25 samples of suspected AMI patients. The lateral-flow strips show great performance in providing reliable results for clinical diagnosis, with the potential to provide early warnings for AMI.

Role of Antitroponin Antibodies and Macrotroponin in the Clinical Interpretation of Cardiac Troponin

Cardiac troponin is extensively used as a biomarker in modern medicine due to its diagnostic capability for myocardial injury, as well as its predictive and prognostic value for cardiac diseases. However, heterophile antibodies, antitroponin antibodies, and macrotroponin complexes can be observed both in seemingly healthy individuals and patients with cardiac diseases, potentially leading to false positive or disproportionate elevation of cTn (cardiac troponin) assay results and introducing discrepancies in clinical interpretations with impact on medical management. In this review article, we describe the possible mechanisms of cTn release and the sources of variations in the assessment of circulating cTn levels. We also explore the pathophysiological mechanisms underlying antitroponin antibody development and discuss the influence exerted by macrotroponin complexes on the results of immunoassays. Additionally, we explore approaches to detect these complexes by presenting various clinical scenarios encountered in routine clinical practice. Finally, unsolved questions about the development, prevalence, and clinical significance of cardiac autoantibodies are discussed.

Early detection of myocardial infarction with reference to baseline levels during health: impact on biological variation of high-sensitivity cardiac troponin

A 78-year-old male was seen in the emergency department (ED) with chest pain. Fifteen months earlier, he had presented to the ED with shoulder and elbow pain. High-sensitivity cardiac troponin I (hs-cTnI) testing was conducted at that time, which produced normal results of 10 and 13 ng/L (cutoff <48 ng/L). During the current admission, his electrocardiogram was unremarkable, with a borderline prolonged PR interval noted. The patient's hs-cTnI results were 25, 47, and 254 ng/L at 0, 1, and 7 hours, respectively. He was diagnosed with demand ischemia and admitted to the hospital. The detection of acute myocardial infarction in this case was made during the first sample collection (t = 0), despite the fact that this result was well within the normal range.

Coronary angiography in patients with kidney dysfunction and myocardial injury: A retrospective cohort study on management of myocardial injury in hospitalized patients with kidney disease

BACKGROUND

Although kidney insufficiency has been shown to be associated with increased risk of myocardial injury, benefit of coronary angiography (CAG) and revascularization remains uncertain, with implications on management strategies and outcomes. We aimed to compare rates of CAG and revascularization and subsequent risk of cardiovascular and kidney outcomes in hospitalized patients with myocardial injury and kidney dysfunction.

METHODS

Retrospective cohort study encompassing hospitalized patients with myocardial injury i.e. elevated troponin I or T and an eGFR ≤60 ml/min/1.73 m2 identified between 2011 and 2021 in Danish national registers. 30-day odds for CAG were computed across granular eGFR-categories based on multiple logistic regression. Standardized one-year risks of cardiovascular and kidney outcomes including mortality were determined based on hazards obtained in multiple Cox regression.

RESULTS

A total of 52,798 patients with myocardial injury were identified. CAG was performed in 14.3 % (n = 7549). 30-day odds ratios for CAG were 0.64 [0.60-0.68], 0.38 [0.34-0.42], 0.18 [0.14-0.22], and 0.35 [0.30-0.40] in patients with eGFR 31-45 ml/min/1.73 m2, eGFR 15-30 ml/min/1.73 m2 for eGFR<15 ml/min/1.73 m2 and chronic dialysis, respectively (eGFR 46-60 ml/min/1.73 m2 as reference). Median follow-up was 4.1 years. One-year mortality risk differences associated with CAG and revascularization (no CAG as reference) were -7.8 [-7.0; -8.7] and -9.1 [-8.4; -9.9] for eGFR 46-60 ml/min/1.73 m2; -7.0 [-5.7;-8-3] and -8.0 [-6.6; -9.5] for eGFR 31-45 ml/min/1.73 m2; -5.4 [-3.0; -7.2] and -5.2 [-2.2; -8.3] for eGFR 15-30 ml/min/1.73 m2; -8.8 [-3.1; -13.7] and -5.4 [3.1; -13.4] for eGFR<15 ml/min/1.73 m2; and -4.9 [-0.1; -9.7] and -4.2 [1.5; -9.2] for chronic dialysis, respectively.

CONCLUSION

Probability of CAG following myocardial injury declined with progressive kidney dysfunction. Overall, CAG was associated with lower mortality irrespective of kidney function and subsequent revascularization.

Evaluating the Rates of Mortality and Cardiac Catheterization Using High-Sensitivity Troponin and Conventional Troponin Assays

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).

Analytical validation of the Mindray CL1200i analyzer high sensitivity cardiac troponin I assay: MERITnI study

OBJECTIVES

This study performed an analytical validation study of the Mindray high-sensitivity cardiac troponin I (hs-cTnI) assay addressing limit of blank (LoB), limit of detection (LoD), precision, linearity, analytical specificity and sex-specific 99th percentile upper reference limits.

METHODS

LoB, LoD, precision, linearity and analytical specificity were studied according to Clinical and Laboratory Standards Institute. We used one reagent lot and one CL1200i analyzer. Skeletal troponin I and T, cardiac troponin T, troponin C, actin, tropomyosin, myosin light chain, myoglobin and creatine kinase (CK-MB) were studied for cross-reactivity. Interference with biotin was examined. Lithium heparin samples (one freeze thaw cycle) from healthy males and females were measured to determine the 99th percentiles by using the non-parametric method. Analyses were performed before and after excluding subjects with clinical conditions and/or increased surrogate biomarkers.

RESULTS

The Mindray hs-cTnI assay met criteria to be considered as a hs-cTn assay. LoB and LoD was <0.1 ng/L and 0.1 ng/L, respectively. Repeatability had a coefficient of variation 1.2-3.8 %, and within-laboratory imprecision 1.7-5.0 %. The measuring interval ranged from 1.1 to 28,180 ng/L. The analytical specificity was clinically acceptable for the interferents studied. After exclusions, the 99th percentile URLs obtained were 10 ng/L overall, 5 ng/L for females and 12 ng/L for males.

CONCLUSIONS

Analytical observations of the Mindray hs-cTnI assay demonstrated excellent LoB, LoD, precision, linearity and analytical specificity, that were in alignment with the manufacturer's claims and regulatory guidelines for hs-cTnI. The assay is suitable for clinical investigation for patient-oriented studies.

DANSPOT: A Multicenter Stepped-Wedge Cluster-Randomized Trial of the Reclassification of Acute Myocardial Infarction: Rationale and Study Design

BACKGROUND

Cardiac troponins are the preferred biomarkers for the diagnosis of acute myocardial infarction. Although sex-specific 99th percentile thresholds of troponins are recommended in international guidelines, the clinical effect of their use is poorly investigated. The DANSPOT Study (The Danish Study of Sex- and Population-Specific 99th percentile upper reference limits of Troponin) aims to evaluate the clinical effect of a prospective implementation of population- and sex-specific diagnostic thresholds of troponins into clinical practice.

METHODS

This study is a nationwide, multicenter, stepped-wedge cluster-randomized trial of the implementation of population- and sex-specific thresholds of troponins in 22 of 23 clinical centers in Denmark. We established sex-specific thresholds for 5 different troponin assays based on troponin levels in a healthy Danish reference population. Centers will sequentially cross over from current uniform manufacturer-derived thresholds to the new population- and sex-specific thresholds. The primary cohort is defined as patients with symptoms suggestive of acute coronary syndrome having at least 1 troponin measurement performed within 24 hours of arrival with a peak troponin value between the current uniform threshold and the new sex-specific female and male thresholds. The study will compare the occurrence of the primary outcome, defined as a composite of nonfatal myocardial infarction, unplanned revascularization, and all-cause mortality within 1 year, separately for men and women before and after the implementation of the new sex-specific thresholds.

CONCLUSIONS

The DANSPOT Study is expected to show the clinical effects on diagnostics, treatment, and clinical outcomes in patients with myocardial infarction of implementing sex-specific diagnostic thresholds for troponin based on a national Danish reference population.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05336435.

Derivation and Validation of Thresholds Using Synthetic Data Methods for Single-Test Screening of Emergency Department Patients with Possible Acute Myocardial Infarction Using a Point-of-Care Troponin Assay

BACKGROUND

Single-sample (screening) rule-out of acute myocardial infarction (AMI) with troponin requires derivation of a single-test screening threshold. In data sets with small event numbers, the lowest one or two concentrations of myocardial infarction (MI) patients dictate the threshold. This is not optimal. We aimed to demonstrate a process incorporating both real and synthetic data for deriving such thresholds using a novel pre-production high-precision point-of-care assay.

METHODS

cTnI concentrations were measured from thawed plasma using the Troponin I Next (TnI-Nx) assay (i-STAT; Abbott) in adults on arrival to the emergency department with symptoms suggestive of AMI. The primary outcome was an AMI or cardiac death within 30 days. We used internal-external validation with synthetic data production based on clinical and demographic data, plus the measured TnI-Nx concentration, to derive and validate decision thresholds for TnI-Nx. The target low-risk threshold was a sensitivity of 99% and a high-risk threshold specificity of >95%.

RESULTS

In total, 1356 patients were included, of whom 191 (14.1%) had the primary outcome. A total of 500 synthetic data sets were constructed. The mean low-risk threshold was determined to be 5 ng/L. This categorized 38% (95% CI, 6%-68%) to low-risk with a sensitivity of 99.0% (95% CI, 98.6%-99.5%) and a negative predictive value of 99.4% (95% CI, 97.6%-99.8%). A similarly derived high-risk threshold of 25 ng/L had a specificity of 95.0% (95% CI, 94.8%-95.1%) and a positive predictive value of 74.8% (95% CI, 71.5%-78.0%).

CONCLUSIONS

With the TnI-Nx assay, we successfully demonstrated an approach using synthetic data generation to derive low-risk thresholds for safe and effective screening.

Age- and sex-specific 99th percentile upper reference limits for high-sensitivity cardiac troponin T in Chinese older people: Real-world data mining

BACKGROUND

This study aims to investigate the impact of age and sex on high-sensitivity cardiac troponin T (hs-cTnT) and establish 99th percentile upper reference limits (URLs) in older individuals utilizing large-scale real-world data.

METHODS

40,530 outpatient hs-cTnT results were obtained from the laboratory database from January 1, 2018, to December 31, 2023. Our study included 4,199 elderly outpatients (aged ≥ 60) without cardiovascular disease or other heart-related chronic conditions. Nested analysis of variance was used to explore the necessity of partitioning reference intervals (RIs) by sex and age groups. RIs were established by the refineR algorithm and assessed based on ≤ 10% test results of validation data set outside the new RIs.

RESULTS

RIs for hs-cTnT in the older population needed to be partitioned by sex and age groups ([standard deviation ratio] SDRage = 0.75; SDRsex = 0.49). URLs in older Chinese adults were 21.8 ng/L for males, 16.5 ng/L for females, and 20.7 ng/L for the overall participant group. URLs for males aged 60-69, 70-79, and ≥ 80 were 13.7, 19.4, and 31.0 ng/L, respectively. Female values were 10.1, 17.2, and 22.0 ng/L. Importantly, manufacturer-reported RIs do not suffice for Chinese individuals aged ≥ 70. Validation data showed that 2.7-5.2% of test results fell outside the new RIs, confirming the validity of the results.

CONCLUSION

This study establishes age- and sex-specific 99th percentile URLs for hs-cTnT in Chinese older individuals, thereby enhancing the accuracy of clinical assessments.

Evaluation of analytical and clinical performance of the AFIAS Tn-I plus assay - a new point-of-care

BACKGROUND

The objective of this evaluation was to determine the analytical and clinical performance of the AFIAS point-of-care (POC) Tn-I Plus assay (Boditech Med Inc).

DESIGN AND METHODS

Limit of detection (LOD), limit of quantification (LOQ), repeatability, reproducibility, inter- and intra-individual CV were evaluated using the CLSI guidelines. The study was also designed to estimate the 99th percentile upper reference limit (URL) and to assess the diagnostic sensitivity and specificity.

RESULTS

The precision repeatability CVs were 6.7-8.5% and reproducibility was 7.5-7.6%. The LOD and LOQ were consistent with the manufacturer's specified values of 0.010 ng/mL and 0.030 ng/mL, respectively. The 99th percentile URLs for males (aged 18-75 years) and females (aged 17-65 years) in serum were 0.0300 ng/mL (7.8% CV) and 0.0239 ng/mL (9.4% CV) respectively. Overall 99th percentile URL was 0.0296 ng/mL (8.2% CV). For the overall apparently healthy population, the percentage of measurable cardiac troponin I (cTn-I) values below the 99th percentile (i.e. 0.0296 ng/mL) and above the assay's LOD (= 0.010 ng/mL) was 47,68% (391/820 samples). The diagnostic sensitivity and specificity were 100% with 95% CI (97% - 100%) and 95.2% with 95% CI (93.6% - 96.5%), respectively. No significant differences were observed for the diagnosis of acute myocardial infarction (AMI) between AFIAS Tn-I plus and Abbott ARCHITECT High Sensitive Troponin-I.

CONCLUSION

The clinical performance of AFIAS Tn-I Plus assay for AMI is comparable to the established Abbott ALINITY STAT High Sensitive Troponin-I. This assay is suitable for routine use in clinical laboratories.

The current paradigm of cardiac troponin increase among athletes

Although it is known that exercise improves cardiovascular health and extends life expectancy, a significant number of people may also experience an elevation in cardiac troponin levels as a result of exercise. For many years, researchers have argued whether exercise-induced cardiac troponin rises are a consequence of a physiological or pathological reaction and whether they are clinically significant. Differences in cardiac troponin elevation and cardiac remodeling can be seen between athletes participating in different types of sports. When forecasting the exercise-induced cardiac troponin rise, there are many additional parameters to consider, as there is a large amount of interindividual heterogeneity in the degree of cardiac troponin elevation. Although it was previously believed that cardiac troponin increases in athletes represented a benign phenomenon, numerous recent studies disproved this notion by demonstrating that, in specific individuals, cardiac troponin increases may have clinical and prognostic repercussions. This review aims to examine the role of cardiac troponin in athletes and its role in various sporting contexts. This review also discusses potential prognostic and clinical implications, as well as future research methods, and provides a straightforward step-by-step algorithm to help clinicians interpret cardiac troponin rise in athletes in both ischemic and non-ischemic circumstances.

Diagnostic performance of a point of care high-sensitivity cardiac troponin I assay and single measurement evaluation to rule out and rule in acute coronary syndrome

OBJECTIVES

About 10 million individuals in USA presented annually in the emergency department (ED) with chest pain or with signs and symptoms of acute coronary syndrome (ACS). The advent of point of care (POC) devices, able to measure high sensitivity troponin, are a very interesting tool in the ED setting for its rapid turnaround time (<10 min).

METHODS

The present study evaluates the diagnostic performance of the Atellica VTLi (Siemens) in real life setting using the clinical data derived from integrated diagnoses of emergency room staff and cardiologist and in comparison with standard laboratory hs-cTnT assay (Cobas 8000, Elecsys, Roche). 966 patients admitted to the emergency department of "G. Mazzini Hospital" in Teramo, Italy, from July 27, 2022, through June 09, 2023, were enrolled.

RESULTS

The diagnostic performance of POC hs-cTnI was evaluated. An appropriate POC hs-cTnI threshold values <4 ng/L supplied a sensitivity and an NPV of 100 % (95 % CI: 99.5-100) in order to achieve rapid rule out for MI through a single measurement at patient presentation in the ED. Furthermore, a derivation POC hs-cTnI concentration >54 ng/L provided a specificity of 97.2 % (95 % CI: 95.9-98.1) and a PPV of 43.5 % (95 % CI: 40.3-46.7) for ruling in MI.

CONCLUSIONS

This platform showed comparable diagnostic performance for myocardial infarction to the central laboratory. Our data suggest the possible use of the Atellica VTLi hs-cTnI POC assay either in emergency department of urban medical centre, either in rural hospital for triage and patient management.

Performance evaluation of a novel high-sensitivity cardiac troponin T assay: analytical and clinical perspectives

OBJECTIVES

To evaluate the analytical characteristics of a novel high-sensitivity cardiac troponin T (hs-cTnT) test on the automatic light-initiated chemiluminescent assay (LiCA®) system, and validated its diagnostic performance for non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

Studies included an extensive analytical evaluation and established the 99th percentile upper reference limit (URL) from apparently healthy individuals, followed by a diagnostic performance validation for NSTEMI.

RESULTS

Sex-specific 99th percentile URLs were 16.0 ng/L (1.7 % CV: coefficient of variation) for men (21-92 years) and 13.4 ng/L (2.0 % CV) for women (23-87 years) in serum, and 30.6 ng/L (0.9 % CV) for men (18-87 years) and 20.2 ng/L (1.4 % CV) for women (18-88 years) in heparin plasma. Detection rates in healthy individuals ranged from 98.9 to 100 %. An excellent agreement was identified between LiCA® and Elecsys® assays with a correlation coefficient of 0.993 and mean bias of -0.7 % (-1.8-0.4 %) across the full measuring range, while the correlation coefficient and overall bias were 0.967 and -1.1 % (-2.5-0.3 %) for the lower levels of cTnT (10-100 ng/L), respectively. At the specific medical decision levels (14.0 and 52.0 ng/L), assay difference was estimated to be <5.0 %. No significant difference was found between these two assays in terms of area under curve (AUC), sensitivity and specificity, negative predictive value (NPV) and positive predictive value (PPV) for the diagnosis of NSTEMI.

CONCLUSIONS

LiCA® hs-cTnT is a reliable 3rd-generation (level 4) high-sensitivity assay for detecting cardiac troponin T. The assay is acceptable for practical use in the diagnosis of NSTEMI.

E, Jones J, Li J. Evaluation of Age and Sex Differences in Contemporary versus High-Sensitivity Troponin I Measurement in Hospitalized Patients

Background: With the transition from the contemporary (cTnI) to high-sensitivity troponin assay (hs-cTnI), concerns have arisen regarding the diagnostic differences between these two assays due to analytical distinctions. This study aims to evaluate the age and sex differences between these two assays, as well as the differences resulting from using two different 99th percentile values of the high-sensitivity troponin assay. Method: A retrospective observational study was conducted at an academic medical center, encompassing a total of 449 lithium heparin plasma samples included in the dataset. Both contemporary and high-sensitivity troponin were simultaneously measured using Siemens ADVIA Centaur analyzers. Two sets of sex-specific 99th percentile URLs from the Siemens study (cutoff-1) and Universal Sample Bank data (cutoff-2) were used for the data analysis. Results: The use of cutoff-1 or cutoff-2 had a negligible impact on troponin classification. Troponin elevation significantly increased in individuals > 50 years old for males and >40 years old for females, with both troponin assays. A receiver operating characteristic analysis did not find significant differences between the two assays. The Kaplan-Meier curves showed no differences in survival in cTnI according to the non-sex-specific 99th URL or hs-cTnI (cutoff-2) but showed a slight difference in survival in hs-cTnI (cutoff-1). Conclusions: Overall, there were no significant differences in age and sex in the diagnostic performance between the contemporary and high-sensitivity troponin assays. Selection criteria for the establishment of the 99th percentile URL should be standardized to avoid the misinterpretation of the troponin results.

Diagnostic and prognostic value of cardiac troponins in emergency department patients presenting after a fall: A prospective, multicenter study

BACKGROUND

Emergency department (ED) presentations after a ground-level fall (GLF) are common. Falls were suggested to be another possible presenting feature of a myocardial infarction (MI), as unrecognized MIs are common in older adults. Elevated high-sensitivity cardiac troponin (hs-cTn) concentrations could help determine the etiology of a GLF in ED. We investigated the prevalence of both MI and elevated high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI), as well as the diagnostic accuracy of hs-cTnT and hs-cTnI regarding MI, and their prognostic value in older ED patients presenting after a GLF.

METHODS

This was a prospective, international, multicenter, cohort study with a follow-up of up to 1 year. Patients aged 65 years or older presenting to the ED after a GLF were prospectively enrolled. Two outcome assessors independently reviewed all discharge records to ascertain final gold standard diagnoses. Hs-cTnT and hs-cTnI levels were determined from thawed samples for every patient.

RESULTS

In total, 558 patients were included. Median (IQR) age was 83 (77-89) years, and 67.7% were female. Elevated hs-cTnT levels were found in 384 (68.8%) patients, and elevated hs-cTnI levels in 86 (15.4%) patients. Three patients (0.5%) were ascertained the gold standard diagnosis MI. Within 30 days, 18 (3.2%) patients had died. Nonsurvivors had higher hs-cTnT and hs-cTnI levels compared with survivors (hs-cTnT 40 [23-85] ng/L in nonsurvivors and 20 [13-33] ng/L in survivors; hs-cTnI 25 [14-54] ng/L in nonsurvivors and 8 [4-16] ng/L in survivors; p < 0.001 for both).

CONCLUSIONS

A majority of patients (n = 364, 68.8%) presenting to the ED after a fall had elevated hs-cTnT levels and 86 (15.4%) elevated hs-cTnI levels. However, the incidence of MI in these patients was low (n = 3, 0.5%). Our data do not support the opinion that falls may be a common presenting feature of MI. We discourage routine troponin testing in this population. However, hs-cTnT and hs-cTnI were both found to have prognostic properties for mortality prediction up to 1 year.

Cardiovascular risk evaluation in pregnancy: focus on cardiac specific biomarkers

Despite the evidence demonstrating the clinical utility of cardiac specific biomarkers in improving cardiovascular risk evaluation in several clinical conditions, even the most recent reviews and guidelines fail to consider their measurement in order to enhance the accuracy of the evaluation of cardiovascular risk in pregnant women. The aim of this review article was to examine whether the assay of cardiac specific biomarkers can enhance cardiovascular risk evaluation in pregnant women, first by reviewing the relationships between the physiological state of pregnancy and cardiac specific biomarkers. The clinical relevance of brain natriuretic peptide (BNP)/NT-proBNP and high-sensitivity cardiac troponin I/high-sensitivity cardiac troponin T (hs-cTnI/hs-cTnT) assay in improving cardiovascular risk evaluation is examined based on the results of clinical studies on subjects with normal and those with complicated pregnancy. Finally, the analytical approaches and clinical objectives related to cardio specific biomarkers are advocated in order to allow an early and more accurate evaluation of cardiovascular risk in pregnant women.

From volume to value: a watershed moment for the clinical laboratory

The clinical laboratory is often evaluated for the volume of testing. However, it is undeniable that laboratory tests affect clinical decision-making and are included in many clinical guidelines, meaning their contribution to determining clinical outcomes. Therefore, the clinical laboratory professional has the task of enhancing laboratory tests by optimizing the request and reporting phase and addressing patient outcomes. This opinion paper, presenting practical examples of managing value-based health care in the clinical laboratory context, underlines the need to shift towards value-based management to optimize outcome-based health care.

Lower Limits for Reporting High-Sensitivity Cardiac Troponin Assays and Impact of Analytical Performance on Patient Misclassification

BACKGROUND

Cardiac troponin measurements are indispensable for the diagnosis of myocardial infarction and provide useful information for long-term risk prediction of cardiovascular disease. Accelerated diagnostic pathways prevent unnecessary hospital admission, but require reporting cardiac troponin concentrations at low concentrations that are sometimes below the limit of quantification. Whether analytical imprecision at these concentrations contributes to misclassification of patients is debated.

CONTENT

The International Federation of Clinical Chemistry Committee on Clinical Application of Cardiac Bio-Markers (IFCC C-CB) provides evidence-based educational statements on analytical and clinical aspects of cardiac biomarkers. This mini-review discusses how the reporting of low concentrations of cardiac troponins impacts on whether or not assays are classified as high-sensitivity and how analytical performance at low concentrations influences the utility of troponins in accelerated diagnostic pathways. Practical suggestions are made for laboratories regarding analytical quality assessment of cardiac troponin results at low cutoffs, with a particular focus on accelerated diagnostic pathways. The review also discusses how future use of cardiac troponins for long-term prediction or management of cardiovascular disease may require improvements in analytical quality.

SUMMARY

Clinical guidelines recommend using cardiac troponin concentrations as low as the limit of detection of the assay to guide patient care. Laboratories, manufacturers, researchers, and external quality assessment providers should extend analytical performance monitoring of cardiac troponin assays to include the concentration ranges applicable in these pathways.

Imprecision of high-sensitivity cardiac troponin assays at the female 99th-percentile

BACKGROUND

An analytical benchmark for high-sensitivity cardiac troponin (hs-cTn) assays is to achieve a coefficient of variation (CV) of ≤ 10.0 % at the 99th percentile upper reference limit (URL) used for the diagnosis of myocardial infarction. Few prospective multicenter studies have evaluated assay imprecision and none have determined precision at the female URL which is lower than the male URL for all cardiac troponin assays.

METHODS

Human serum and plasma matrix samples were constructed to yield hs-cTn concentrations near the female URLs for the Abbott, Beckman, Roche, and Siemens hs-cTn assays. These materials were sent (on dry ice) to 35 Canadian hospital laboratories (n = 64 instruments evaluated) participating in a larger clinical trial, with instructions for storage, handling, and monthly testing over one year. The mean concentration, standard deviation, and CV for each instrument type and an overall pooled CV for each manufacturer were calculated.

RESULTS

The CVs for all individual instruments and overall were ≤ 10.0 % for two manufacturers (Abbott CVpooled = 6.3 % and Beckman CVpooled = 7.0 %). One of four Siemens Atellica instruments yielded a CV > 10.0 % (CVpooled = 7.7 %), whereas 15 of 41 Roche instruments yielded CVs > 10.0 % at the female URL of 9 ng/L used worldwide (6 cobas e411, 1 cobas e601, 4 cobas e602, and 4 cobas e801) (CVpooled = 11.7 %). Four Roche instruments also yielded CVs > 10.0 % near the female URL of 14 ng/L used in the United States (CVpooled = 8.5 %).

CONCLUSIONS

The number of instruments achieving a CV ≤ 10.0 % at the female 99th-percentile URL varies by manufacturer and by instrument. Monitoring assay precision at the female URL is necessary for some assays to ensure optimal use of this threshold in clinical practice.

Clinical Interpretation of Serum Troponin in the Era of High-Sensitivity Testing

Cardiac troponin (Tn) plays a central role in the evaluation of patients with angina presenting with acute coronary syndrome. The advent of high-sensitivity assays has improved the analytic sensitivity and precision of serum Tn measurement, but this advancement has come at the cost of poorer specificity. The role of clinical judgment is of heightened importance because, more so than ever, the interpretation of serum Tn elevation hinges on the careful integration of findings from electrocardiographic, echocardiographic, physical exam, interview, and other imaging and laboratory data to formulate a weighted differential diagnosis. A thorough understanding of the epidemiology, mechanisms, and prognostic implications of Tn elevations in each cardiac and non-cardiac etiology allows the clinician to better distinguish between presentations of myocardial ischemia and myocardial injury-an important discernment to make, as the treatment of acute coronary syndrome is vastly different from the workup and management of myocardial injury and should be directed at the underlying cause.

Circulating biomarkers in the diagnosis and prognosis of immune checkpoint inhibitor-related myocarditis: time for a risk-based approach

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that block immune checkpoints and therefore activate immune cells, allowing them to recognize and attack cancer cells. ICIs have revolutionized oncology practice, but their use has been complicated by immune-related adverse events (irAEs). Of cardiovascular (CV) irAEs, ICI-related myocarditis has received significant attention due to high mortality rates, ranging from 25% to 50%, despite its overall low incidence. Establishing the early diagnosis of ICI-myocarditis is important for early initiation of steroids and consideration of hospitalization in patients who are at risk for hemodynamic compromise and need high acuity care in a tertiary setting. In this review, we summarize the diagnostic and prognostic tools for ICI-myocarditis, including electrocardiography, echocardiography, cardiac magnetic resonance imaging, with emphasis on circulating biomarkers. Cardiac troponins (cTns) are an essential component of the diagnosis of ICI-myocarditis, and we provide a summary of the recent studies that utilized different assays (cTnI vs. cTnT) and outcomes (diagnosis vs. prognosis including major adverse cardiac outcomes). With the exponential increase in ICI use across different oncology indications, there is a major need to include biomarkers in risk stratification to guide diagnosis and treatment. Our review proposes a framework for future multisite registries, including cTn evaluation at baseline and at the time of irAE suspicion, with development of central biobanking to allow head-to-head evaluation and clinical validation of different biomarker assays in ICI-myocarditis. This approach, with the inclusion of CV biomarkers into clinical and pragmatic oncology trials, holds promise to improve the early recognition and management of ICI-myocarditis and CV irAEs, thus leading to better outcomes.

Global research trends on cardiac troponin and physical activity among pediatric populations: a bibliometric analysis and science mapping study

Background

Cardiac troponin (cTn) is a reliable marker for evaluating myocardial damage. cTn is a very specific protein involved in myocardial injury, and it is a key factor in the diagnosis of coronary syndromes. Bibliometric analysis was applied in the present work, with the main goal of evaluating global research on the topic of cardiac troponin in pediatric populations.

Methods

Publications about cardiac troponin and physical activity in pediatric populations were retrieved from the Social Sciences Citation Index (SSCI) and the Science Citation Index Expanded (SCIE) of the Web of Science Core Collection, and they were then analyzed. The study was able to identify the key bibliometric indicators, such as publications, keywords, authors, countries, institutions, and journals. For the analysis, VOSviewer, R-based Bibliometrix (4.2.2), and MapChart were used.

Results

Initially, 98 documents were identified; however, once inclusion and exclusion criteria were applied, the number of documents decreased to 88. The search yielded 79 original research articles and 9 reviews, almost all of which were published in the past 2 decades. The total number of citations (Nc) of the retrieved publications was 1,468, and the average number of citations per article (Na) was 16.68. In general, 508 authors were found to have participated in research about troponin; they were associated with 256 institutions, and their work was published in 65 different journals from around the world. The authors hailed from 30 countries and/or regions. The year 2022 was the most productive year for the publication of the selected documents. The bibliometric analysis provided information regarding levels of cooperation among authors and institutions. In fact, China, the United States, and England were the most productive nations, and the journal with the greatest number of publications on the topic was Pediatric Cardiology.

Summary

The number of publications and the trend line show that research on this topic has not yet reached a stage of maturity. There are referent investigators, countries, and institutions that have laid the foundations for subsequent studies on the analyzed topic.

Hemodialysis and biomarkers of myocardial infarction - a cohort study

OBJECTIVES

End-stage renal disease is associated with a high risk of cardiovascular disease. We compared the concentration and prognostic ability of high sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI) and cardiac myosin-binding protein C (cMyC) among stable hemodialysis patients.

METHODS

Patients were sampled before and after hemodialysis. We measured hs-cTnI, hs-cTnT and cMyC and used Cox regressions to assess the association between quartiles of concentrations and all-cause mortality and a combination of cardiovascular events and all-cause mortality during follow-up.

RESULTS

A total of 307 patients were included, 204 males, mean age 66 years (SD 14). Before dialysis, 299 (99 %) had a hs-cTnT concentration above the 99th percentile, compared to 188 (66 %) for cMyC and 35 (11 %) for hs-cTnI. Hs-cTnT (23 %, p<0.001) and hs-cTnI (15 %, p=0.049) but not cMyC (4 %, p=0.256) decreased during dialysis. Follow-up was a median of 924 days (492-957 days); patients in the 3rd and 4th quartiles of hs-cTnT (3rd:HR 3.0, 95 % CI 1.5-5.8, 4th:5.2, 2.7-9.8) and the 4th quartile of hs-cTnI (HR 3.8, 2.2-6.8) had an increased risk of mortality. Both were associated with an increased risk of the combined endpoint for patients in the 3rd and 4th quartiles. cMyC concentrations were not associated with risk of mortality or cardiovascular event.

CONCLUSIONS

Hs-cTnT was above the 99th percentile in almost all patients. This was less frequent for hs-cTnI and cMyC. High cTn levels were associated with a 3-5-fold higher mortality. This association was not present for cMyC. These findings are important for management of hemodialysis patients.

Investigating outlier rates of cardiac troponin I and troponin T assays: A systematic review

Objectives

This review aimed to harmoniously summarize and compare outlier rates for various cardiac troponin (cTn) assays, including high-sensitivity-cTn (hs-cTn) assays and contemporary cTn (generation of assays prior to hs-cTn ones) assays, from the published studies.

Methods

The PRISMA guidelines were utilized to perform this systematic review. Five databases, including PubMed, Scopus, Embase, Cochrane Library, and Web of Science, were searched using specific keywords up to June 30th, 2023. Studies reporting specifically calculated outlier rates for cTn assays when conducting in-vitro diagnosis in human samples were included. Selected studies were then further assessed using the GRADE tool.

Results

Thirteen studies were included. The data from the studies were summarized statistically in this review. The results showed substantial evidence of improved analytical robustness or reduced respective mean rates of outliers, critical outliers, and analytical outliers for hs-cTn assays (0.14 %, 0.18 %, and 0.18 %) compared to contemporary cTn assays (0.63 %, 0.71 %, and 0.50 %).

Conclusion

The findings offer promisingly provide a comprehensive reference for laboratory scientists and clinical staff in choosing the most suitable cTn assay for patient care regrading outlier rates. Besides, this review reveals the advancements of hs-cTn assays with lower outlier rates than contemporary cTn assays. The emerging challenges for continuously improving analytical robustness of cTn assays are also elaborated.

Establishing optimal cutoff values for high-sensitivity cardiac troponin algorithms in risk stratification of acute myocardial infarction

Acute myocardial infarction (AMI) is a leading cause of mortality globally, highlighting the need for timely and accurate diagnostic strategies. Cardiac troponin has been the biomarker of choice for detecting myocardial injury. A dynamic change in concentrations supports the diagnosis of AMI in the setting of evidence of acute myocardial ischemia. The new generation of high-sensitivity cardiac troponin (hs-cTn) assays has significantly improved analytical sensitivity but at the expense of decreased clinical specificity. As a result, sophisticated algorithms are required to differentiate AMI from non-AMI patients. Establishing optimal hs-cTn cutoffs for these algorithms to rule out and rule in AMI has been the subject of intensive investigations. These efforts have evolved from examining the utility of the hs-cTn 99th percentile upper reference limit, comparing the percentage versus absolute delta thresholds, and evaluating the performance of an early European Society of Cardiology-recommended 3 h algorithm, to the development of accelerated 1 h and 2 h algorithms that combine the admission hs-cTn concentrations and absolute delta cutoffs to rule out and rule in AMI. Specific cutoffs for individual confounding factors such as sex, age, and renal insufficiency have also been investigated. At the same time, concerns such as whether the small delta thresholds exceed the analytical and biological variations of hs-cTn assays and whether the algorithms developed in European study populations fit all other patient cohorts have been raised. In addition, the accelerated algorithms leave a substantial number of patients in a non-diagnostic observation zone. How to properly diagnose patients falling in this zone and those presenting with elevated baseline hs-cTn concentrations due to the presence of confounding factors or comorbidities remain open questions. Here we discuss the developments described above, focusing on criteria and underlying considerations for establishing optimal cutoffs. In-depth analyses are provided on the influence of biological variation, analytical imprecision, local AMI rate, and the timing of presentation on the performance metrics of the accelerated hs-cTn algorithms. Developing diagnostic strategies for patients who remain in the observation zone and those presenting with confounding factors are also reviewed.

Optimizing the Clinical Use of High-Sensitivity Troponin Assays: A Review

Ischemic heart diseases (IHDs) remain a global health concern. Many IHD cases go undiagnosed due to challenges in the initial diagnostic process, particularly in cases of acute myocardial infarction (AMI). High-sensitivity cardiac troponin (hs-cTn) assays have revolutionized myocardial injury assessment, but variations in diagnostic cut-off values and population differences have raised challenges. This review addresses essential laboratory and clinical considerations for hs-cTn assays. Laboratory guidelines discuss the importance of establishing standardized 99th-percentile upper reference limits (URLs) considering factors such as age, sex, health status, and analytical precision. The reference population should exclude individuals with comorbidities like diabetes and renal disease, and rigorous selection is crucial. Some clinical guidelines emphasize the significance of sex-specific URL limits while others do not. They highlight the use of serial troponin assays for AMI diagnosis. In addition, timely reporting of accurate hs-cTn results is essential for effective clinical use. This review aims to provide a clearer understanding among laboratory professionals and clinicians on how to optimize the use of hs-cTn assays in clinical settings in order to ensure accurate AMI diagnosis and thus improve patient care and outcomes.

Changes in circulating ApoJ-Glyc levels in patients with suspected acute coronary syndrome: The EDICA trial

BACKGROUND

Myocardial ischemia induces intracellular accumulation of non-glycosylated apolipoprotein J that results in a reduction of circulating glycosylated ApoJ (ApoJ-Glyc). The latter has been suggested to be a marker of transient myocardial ischemia.

OBJECTIVE

This proof-of-concept clinical study aimed to assess whether changes in circulating ApoJ-Glyc could detect myocardial ischemia in patients attending the emergency department (ED) with chest pain suggestive of acute coronary syndrome (ACS).

METHODS

In suspected ACS patients, EDICA (Early Detection of Myocardial Ischemia in Suspected Acute Coronary Syndromes by ApoJ-Glyc a Novel Pathologically based Ischemia Biomarker), a multicentre, international, cohort study assessed changes in 2 glycosylated variants of ApoJ-Glyc, (ApoJ-GlycA2 and ApoJ-GlycA6), in serum samples obtained at ED admission (0 h), and 1 h and 3 h thereafter, blinded to the clinical diagnosis (i.e. STEMI, NSTEMI, unstable angina, non-ischemic).

RESULTS

404 patients were recruited; 291 were given a clinical diagnosis of "non-ischemic" chest pain and 113 were considered to have had an ischemic event. ApoJ-GlycA6 was lower on admission in ischemic compared with "non-ischemic" patients (66 [46-90] vs. 73 [56-95] μg/ml; P = 0.04). 74% of unstable angina patients (all with undetectable hs-Tn), had ischemic changes in ApoJ-Glyc at 0 h and 89% at 1 h. Initially low ApoJ-Glyc levels in 62 patients requiring coronary revascularization increased significantly after successful percutaneous intervention.

CONCLUSIONS

Circulating ApoJ-Glyc concentrations decrease early in ED patients with myocardial ischemia compared with "non-ischemic" patients, even in the absence of troponin elevations. ApoJ-Glyc may be a useful marker of myocardial ischemia in the ED setting.

Circulating Cardiovascular Biomarkers in Cancer Therapeutics-Related Cardiotoxicity: Review of Critical Challenges, Solutions, and Future Directions

Cardiotoxicity is a growing concern in the oncology population. Transthoracic echocardiography and multigated acquisition scans have been used for surveillance but are relatively insensitive and resource intensive. Innovative imaging techniques are constrained by cost and availability. More sensitive, cost-effective cardiotoxicity surveillance strategies are needed. Circulating cardiovascular biomarkers could provide a sensitive, low-cost solution. Biomarkers such as troponins, natriuretic peptides (NPs), novel upstream signals of oxidative stress, inflammation, and fibrosis as well as panomic technologies have shown substantial promise, and guidelines recommend baseline measurement of troponins and NPs in all patients receiving potential cardiotoxins. Nonetheless, supporting evidence has been hampered by several limitations. Previous reviews have provided valuable perspectives on biomarkers in cancer populations, but important analytic aspects remain to be examined in depth. This review provides comprehensive assessment of critical challenges and solutions in this field, with focus on analytical issues relating to biomarker measurement and interpretation. Examination of evidence pertaining to common and serious forms of cardiotoxicity reveals that improved study designs incorporating larger, more diverse populations, registry-based approaches, and refinement of current definitions are key. Further efforts to harmonize biomarker methodologies including centralized biobanking and analyses, novel decision limits, and head-to-head comparisons are needed. Multimarker algorithms incorporating machine learning may allow rapid, personalized risk assessment. These improvements will not only augment the predictive value of circulating biomarkers in cardiotoxicity but may elucidate both direct and indirect relationships between cardiovascular disease and cancer, allowing biomarkers a greater role in the development and success of novel anticancer therapies.

Measurement of Cardiac-Specific Biomarkers in the Emergency Department: New Insight in Risk Evaluation

The aim of this article review is to analyze some models and clinical issues related to the implementation of accelerated diagnostic protocols based on specific cardiac biomarkers in patients admitted to the emergency department (ED) with symptoms compatible with acute cardiac disorders. Four specific clinical issues will be discussed in detail: (a) pathophysiological and clinical interpretations of circulating hs-cTnI and hs-cTnT levels; (b) the clinical relevance and estimation of the biological variation of biomarkers in patients admitted to the ED with acute and severe diseases; (c) the role and advantages of the point-of-care testing (POCT) methods for cardiac-specific biomarkers in pre-hospital and hospital clinical practice; and (d) the clinical role of specific cardiac biomarkers in patients with acute heart failure (AHF). In order to balance the risk between a hasty discharge versus the potential harms caused by a cardiac assessment in patients admitted to the ED with suspected acute cardiovascular disease, the measurement of specific cardiac biomarkers is essential for the early identification of the presence of myocardial dysfunction and/or injury and to significantly reduce the length and costs of hospitalization. Moreover, specific cardiac biomarkers (especially hs-cTnI and hs-cTnT) are useful predictors of mortality and major adverse cardiovascular events (MACE) in patients admitted to the ED with suspected acute cardiovascular disease. To guide the implementation of the most rapid algorithms for the diagnosis of Non-ST-Elevation Myocardial Infarction (NSTEMI) into routine clinical practice, clinical scientific societies and laboratory medicine societies should promote collaborative studies specifically designed for the evaluation of the analytical performance and, especially, the cost/benefit ratio resulting from the use of these clinical protocols and POCT methods in the ED clinical practice.

Higher troponin T serum concentrations in hospital patients without diagnosed cardiac diseases compared to a population-based cohort

OBJECTIVES

Upper reference limits of high-sensitivity cardiac troponin T (hs-cTnT) are derived from healthy, population-based cohorts, and are frequently exceeded in hospitalized patients. In this study we aim to systematically examine the differences between in-hospital patients with no diagnosed cardiac diseases and a population-based cohort.

METHODS

Retrospective analyses were performed in two independent cohorts. We included 5,652 participants of the prospective population-based LIFE cohort as well as 9,300 patients having been treated at our hospital between 2014 and 2021. In both cohorts, subjects with diagnosed or suspected cardiac diseases were excluded. We used Spearman's rank correlation for correlation analyses of hs-cTnT serum concentrations and age. Sex- and age-adjusted 99th percentiles for hs-cTnT in subjects with preserved renal function were obtained in both cohorts.

RESULTS

In both cohorts, hs-cTnT serum concentrations positively correlated with age. Male sex was associated with higher hs-cTnT serum concentrations. Persons treated in hospital showed significantly higher hs-cTnT concentrations in females and males aged above 50. While in the population-based cohort only 99th percentile hs-cTnT results of females aged above 70 and males aged above 60 years exceeded the assay's upper reference limit, the 99th percentiles of in-hospital females over 40 years and males of all age groups exceeded this threshold.

CONCLUSIONS

Besides age and sex, hospitalization per se is correlated with higher serum concentrations of hs-cTnT in most age groups. Our results indicate, that unconditionally applying current hs-cTnT cut-offs to inpatients might overestimate myocardial infarction and potentially lead to overdiagnosis.

High-sensitivity troponin-T levels and associated health conditions in 3146 women aged 46

OBJECTIVE

The aim of the study was to investigate are there associations between common female sex-specific health conditions (oligo/amenorrhea, hyperandrogenism, menopause and polycystic ovary syndrome [PCOS]) and high-sensitivity troponin-T (hs-TnT) levels.

METHODS

Cross-sectional and longitudinal analyses of a general population-based prospective cohort study were performed. The hs-TnT levels of 3146 women aged 46 were measured using an Elecsys® Troponin T high-sensitivity assay. Median hs-TnT levels and 25 and 75 percentiles of the cases and controls were compared. Also, a logistic regression analysis using a binary outcome - undetectable hs-TnT (< 3.0 ng/L) versus detectable hs-TnT (≥ 3.0 ng/L) - was performed.

RESULTS

Women with oligo/amenorrhea at age 31 had significantly higher hs-TnT levels at age 46 than women without oligo/amenorrhea (4.06 [3.59; 4.86] vs 3.98 [3.44; 4.71] ng/L, p = .042). Menopausal women had significantly higher hs-TnT levels than premenopausal women (4.15 [3.54; 4.91] vs 3.95 [3.45; 4.68] ng/L, p = .012) at age 46. Women with PCOS or hyperandrogenism had comparable hs-TnT levels with their controls. In the adjusted logistic regression analysis, oligo/amenorrhea (odds ratio [OR] = 1.52 [0.90-2.57]), hyperandrogenism (OR = 1.20 [0.75-1.92]), PCOS (OR = 1.51 [0.81-2.84]) and menopause (OR = 1.05 [0.63-1.74]) were not significantly associated with detectable hs-TnT.

CONCLUSIONS

This study was the first to investigate how oligo/amenorrhea, hyperandrogenism, PCOS and menopause are associated with hs-TnT. Although women with oligo/amenorrhea and menopause had higher hs-TnT levels than women without these conditions, the difference was small. Larger studies are required to better understand the effects of oligo/amenorrhea on cardiovascular health.

Diagnostic and Cost Efficiency of the 0-h/1-h Rule-out and Rule-in Algorithm for Patients With Chest Pain in the Emergency Department

BACKGROUND

This study investigated the economic impact of the European Society of Cardiology (ESC) clinical practice guideline recommendation of using the 0-h/1-h rule-out and rule-in algorithm with high-sensitivity cardiac troponin assays (0/1-h algorithm) to triage patients presenting with chest pain.Methods and Results: This post hoc cost-effectiveness evaluation (DROP-ACS; UMIN000030668) used deidentified electronic medical records from health insurance claims from 2 diagnostic centers in Japan. A cost-effectiveness analysis was conducted with 472 patients with care provided following the 0/1-h algorithm (Hospital A) and 427 patients following point-of-care testing (Hospital B). The clinical outcome of interest was all-cause mortality or subsequent myocardial infarction within 30 days of the index presentation. The sensitivity and specificity for the clinical outcome were 100% (95% confidence interval [CI] 91.1-100%) and 95.0% (95% CI 94.3-95.0%), respectively, in Hospital A and 92.9% (95% CI 69.6-98.7%) and 89.8% (95% CI 89.0-90.0%), respectively, in Hospital B. If the diagnostic accuracy of the 0/1-h algorithm was implemented in Hospital B, it is expected that the number of urgent (<24-h) coronary angiograms would decrease by 50%. Incorporating this assumption, implementing the 0/1-h algorithm could potentially reduce medical costs by JPY4,033,874 (95% CI JPY3,440,346-4,627,402) in Hospital B (JPY9,447 per patient; 95% CI JPY 8,057-10,837 per patient).

CONCLUSIONS

The ESC 0/1-h algorithm was efficient for risk stratification and for reducing medical costs.

Predictive and prognostic value of different cardiac troponin assays: a nationwide register-based cohort study

AIMS

Guidelines do not differentiate between the available assays of cardiac troponin (cTn). We compared the prognostic and predictive ability of cTn assays.

METHODS AND RESULTS

This was a nationwide cohort study of patients with acute coronary syndrome (ACS) and ≥ 2 cTn measurements of one of four assays: Roche high-sensitivity cTnT (hs-cTnT), Abbott high sensitivity cTnI (hs-cTnI), Siemens Vista cTnI, and Siemens cTnI Ultra. Data were collected from Danish registries from 2009-18. Peak cTn concentration normalized to the 99th percentile was used. Outcomes were myocardial infarction (MI) during admission, one-year all-cause-, cardiovascular-, and non-cardiovascular mortality. Receiver operating characteristics and logistic regression calculating odds ratios (OR) were used. A total of 90 705 patients were included, of which 20 550 (23%) had MI. Siemens Vista cTnI was the strongest predictor of MI, Area under the curve (auc) 0.93 (95% CI 0.93-0.93). In 1 year 9012 (9.9%) of patients had died. An inverted U-shape relationship was observed between concentration of cTn and all-cause mortality. Hs-cTnT OR 21.3 (95% CI 18.4-24.8) at 2-5 times the 99th percentile and 12.1 (95% CI 10.3-14.1) for concentrations >100 times the 99th percentile. The inverted U-shape relationship was only present for non-cardiovascular mortality. The strongest predictor of cardiovascular mortality was hs-cTnT, OR 11.3 (95% CI 6.4-21.8) at 1-2 times the 99th percentile and 88.8 (95% CI 53.2-163.0) for concentrations >100 times the 99th percentile.

CONCLUSION

Siemens Vista cTnI was the strongest predictor of MI and hs-cTnT was the strongest predictor of mortality. An inverted U-shape relationship was observed between cTn concentration and non-cardiovascular mortality.

Review of cardiac safety in onasemnogene abeparvovec gene replacement therapy: translation from preclinical to clinical findings

Human gene replacement therapies such as onasemnogene abeparvovec (OA) use recombinant adeno-associated virus (rAAV) vectors to treat monogenic disorders. The heart and liver are known target organs of toxicity in animals; with cardiac and hepatic monitoring recommended in humans after OA dosing. This manuscript provides a comprehensive description of cardiac data from preclinical studies and clinical sources including clinical trials, managed access programs and the post-marketing setting following intravenous OA administration through 23 May 2022. Single dose mouse GLP-Toxicology studies revealed dose-dependent cardiac findings including thrombi, myocardial inflammation and degeneration/regeneration, which were associated with early mortality (4-7 weeks) in the high dose groups. No such findings were documented in non-human primates (NHP) after 6 weeks or 6 months post-dose. No electrocardiogram or echocardiogram abnormalities were noted in NHP or humans. After OA dosing, some patients developed isolated elevations in troponin without associated signs/symptoms; the reported cardiac adverse events in patients were considered of secondary etiology (e.g. respiratory dysfunction or sepsis leading to cardiac events). Clinical data indicate cardiac toxicity observed in mice does not translate to humans. Cardiac abnormalities have been associated with SMA. Healthcare professionals should use medical judgment when evaluating the etiology and assessment of cardiac events post OA dosing so as to consider all possibilities and manage the patient accordingly.

Diagnoses and Outcomes of Patients with Suspicion of Acute Coronary Syndrome and Raised High Sensitive Troponin I: A Single Center Study from Pakistan

Objectives  Troponins are classically raised in acute coronary syndrome (ACS) although other cardiovascular and non-cardiovascular causes are recognized. We aimed to see the association of high sensitivity (Hs) Troponin I values exceeding the sex-specific 99th percentile upper reference limit (URL) with diagnoses, emergency department (ED) outcomes, 30-day outcomes of admitted patients and predictors of ACS in both genders. Materials and Methods  A retrospective study of all patients presenting to the emergency department from January 2019 to April 2021 with suspicion of ACS and Hs-Troponin I values greater than the sex-specific 99th percentile URL. Statistical Analysis  SPSS version 24 was used, Pearson's chi-square tests, Fisher's exact test, Kruskal-Wallis test, Mann-Whitney U test, and odds ratios, including the 95% confidence intervals, for each characteristic were used for analysis. A p -value of < 0.05 was considered significant. Results  There were a total of 5,982 patients (3,031 males, 2,951 females), out of which 878 patients were admitted under the cardiology specialty. In patients who were admitted to the ward, mortality was higher in females (8.2%) with less than a 10-fold rise in Hs-Troponin I while similar in both genders (7.6%) in patients with Hs-troponin I greater than 10-fold of sex-specific 99th percentile URL. Raised low-density lipoprotein-cholesterol was a significant factor associated with 2.4 times higher odds of ACS. Conclusion  Women with Hs-Troponin values up to 10 times the URL, i.e., 15.6-160 ng/L have higher mortality than their male counterparts. LDL-cholesterol is a significant risk factor for ACS which should be controlled for its prevention.

Cardiomuscular Biomarkers in the Diagnosis and Prognostication of Immune Checkpoint Inhibitor Myocarditis

BACKGROUND

Immune checkpoint inhibitors (ICIs) are approved for multiple cancers but can result in ICI-associated myocarditis, an infrequent but life-threatening condition. Elevations in cardiac biomarkers, specifically troponin-I (cTnI), troponin-T (cTnT), and creatine kinase (CK), are used for diagnosis. However, the association between temporal elevations of these biomarkers with disease trajectory and outcomes has not been established.

METHODS

We analyzed the diagnostic accuracy and prognostic performances of cTnI, cTnT, and CK in patients with ICI myocarditis (n=60) through 1-year follow-up in 2 cardio-oncology units (APHP Sorbonne, Paris, France and Heidelberg, Germany). A total of 1751 (1 cTnT assay type), 920 (4 cTnI assay types), and 1191 CK sampling time points were available. Major adverse cardiomyotoxic events (MACE) were defined as heart failure, ventricular arrhythmia, atrioventricular or sinus block requiring pacemaker, respiratory muscle failure requiring mechanical ventilation, and sudden cardiac death. Diagnostic performance of cTnI and cTnT was also assessed in an international ICI myocarditis registry.

RESULTS

Within 72 hours of admission, cTnT, cTnI, and CK were increased compared with upper reference limits (URLs) in 56 of 57 (98%), 37 of 42 ([88%] P=0.03 versus cTnT), and 43 of 57 ([75%] P<0.001 versus cTnT), respectively. This increased rate of positivity for cTnT (93%) versus cTnI ([64%] P<0.001) on admission was confirmed in 87 independent cases from an international registry. In the Franco-German cohort, 24 of 60 (40%) patients developed ≥1 MACE (total, 52; median time to first MACE, 5 [interquartile range, 2-16] days). The highest value of cTnT:URL within the first 72 hours of admission performed best in terms of association with MACE within 90 days (area under the curve, 0.84) than CK:URL (area under the curve, 0.70). A cTnT:URL ≥32 within 72 hours of admission was the best cut-off associated with MACE within 90 days (hazard ratio, 11.1 [95% CI, 3.2-38.0]; P<0.001), after adjustment for age and sex. cTnT was increased in all patients within 72 hours of the first MACE (23 of 23 [100%]), whereas cTnI and CK values were less than the URL in 2 of 19 (11%) and 6 of 22 (27%) of patients (P<0.001), respectively.

CONCLUSIONS

cTnT is associated with MACE and is sensitive for diagnosis and surveillance in patients with ICI myocarditis. A cTnT:URL ratio <32 within 72 hours of diagnosis is associated with a subgroup at low risk for MACE. Potential differences in diagnostic and prognostic performances between cTnT and cTnI as a function of the assays used deserve further evaluation in ICI myocarditis.

Myocardial Injury Thresholds for 4 High-Sensitivity Troponin Assays in a Population-Based Sample of US Children and Adolescents

BACKGROUND

Myocardial injury is an important pediatric diagnosis. Establishing normative data from a representative pediatric sample is vital to provide accurate upper reference limits (URLs) for defining myocardial injury using high-sensitivity cardiac troponin.

METHODS

Among participants 1 to 18 years of age in the 1999-2004 National Health and Nutrition Examination Survey, we measured high-sensitivity troponin T using one assay (Roche) and high-sensitivity troponin I using 3 assays (Abbott, Siemens, and Ortho). In a strictly defined healthy subgroup, we estimated 97.5th and 99th percentile URLs for each assay using the recommended nonparametric method.

RESULTS

Of 5695 pediatric participants, 4029 met criteria for the healthy subgroup (50% males; mean age 12.6 years). Our 99th percentile URL estimates for all 4 high-sensitivity troponin assays among children and adolescents were lower than the manufacturer-reported URLs (derived from adults). The 99th percentile URLs (95% CI) were 15 ng/L (95% CI, 12-17) for high-sensitivity troponin T, 16 ng/L (95% CI, 12-19) for high-sensitivity troponin I with the Abbott assay, 38 ng/L (95% CI, 25-46) for high-sensitivity troponin I with the Siemens assay, and 7 ng/L (95% CI, 5, 12) for high-sensitivity troponin I with the Ortho assay. The 95% CIs for age-, sex-, and race and ethnicity-specific 99th percentile URLs overlapped. However, the 97.5th percentile URL for each assay was measured with superior statistical precision (ie, tighter 95% CIs) and demonstrated differences by sex. For male compared with female children and adolescents, 97.5th percentile URLs were 11 ng/L (95% CI, 10-12) versus 6 ng/L (95% CI, 6-7) for high-sensitivity troponin T, 9 ng/L (95% CI, 7-10) versus 5 ng/L (95% CI, 4-6) for high-sensitivity troponin I with the Abbott assay, 21 ng/L (95% CI, 18-25) versus 11 ng/L (95% CI, 9-13) for high-sensitivity troponin I with the Siemens assay, and 4 ng/L (95% CI, 3-5) versus 2 ng/L (95% CI, 1-3) for high-sensitivity troponin I with the Ortho assay. In contrast to the 99th percentiles, the point estimates of 97.5th percentile pediatric URLs for high-sensitivity troponin were also much more stable to differences in the analytic approaches taken to estimate URLs.

CONCLUSIONS

Because myocardial infarction is rare in children and adolescents, the use of statistically more precise and reliable sex-specific 97.5th percentile high-sensitivity troponin URLs might be considered to define pediatric myocardial injury.

Single Troponin Measurement to Rule Out Myocardial Infarction: JACC Review Topic of the Week

The term "single-sample rule-out" refers to the ability of very low concentrations of high-sensitivity cardiac troponin (hs-cTn) on presentation to exclude acute myocardial infarction with high clinical sensitivity and negative predictive value. Observational and randomized studies have confirmed this ability. Some guidelines endorse use of a concentration of hs-cTn at the assay's limit of detection, while other studies have validated the use of higher concentrations, allowing this approach to identify a greater proportion of patients at low risk. In most studies, at least 30% of patients can be triaged with this approach. The concentration of hs-cTn varies according to the assay used and sometimes how regulations permit reporting. It is clear that patients need to be at least 2 hours from the onset of symptoms being evaluated. Caution is warranted, particularly with older patients, women, and patients with underlying cardiac comorbidities.

Variability of cardiac troponin levels in normal subjects and in patients with cardiovascular diseases: analytical considerations and clinical relevance

In accordance with all the most recent international guidelines, the variation of circulating levels of cardiac troponins I and T, measured with high-sensitivity methods (hs-cTnI and hs-cTnT), should be used for the detection of acute myocardial injury. Recent experimental and clinical evidences have demonstrated that the evaluation of hs-cTnI and hs-cTnT variations is particularly relevant: a) for the differential diagnosis of Acute Coronary Syndromes (ACS) in patients admitted to the Emergency Department (ED); b) for the evaluation of cardiovascular risk in patients undergoing major cardiac or non-cardiac surgery, and in asymptomatic subjects of the general population aged >55 years and with co-morbidities; c) for the evaluation of cardiotoxicity caused by administration of some chemotherapy drugs in patients with malignant tumors. The aim of this document is to discuss the fundamental statistical and biological considerations on the intraindividual variability of hs-cTnI and hs-cTnT over time in the same individual. Firstly, it will be discussed in detail as the variations of circulating levels strictly depend not only on the analytical error of the method used but also on the intra-individual variability of the biomarker. Afterwards, the pathophysiological interpretation and the clinical relevance of the determination of the variability of the hs-cTnI and hs-cTnT values ​​ in patients with specific clinical conditions are discussed. Finally, the evaluation over time of the variation in circulating levels of hs-cTnI and hs-cTnT is proposed for a more accurate estimation of cardiovascular risk in asymptomatic subjects from the general population.

Myocardial Injury Thresholds for 4 High-Sensitivity Troponin Assays in U.S. Adults

BACKGROUND

Myocardial injury is currently defined as a cardiac troponin above the sex-specific 99th percentile of a healthy reference population (upper reference limit [URL]).

OBJECTIVES

The purpose of this study was to estimate high-sensitivity (hs) troponin URLs in a representative sample of the U.S. adult population; overall and by sex, race/ethnicity, and age group.

METHODS

Among adults participating in the 1999-2004 National Health and Nutrition Examination Survey (NHANES), we measured hs-troponin T using 1 assay (Roche) and hs-troponin I using 3 assays (Abbott, Siemens, and Ortho). In a strictly defined healthy reference subgroup, we estimated 99th percentile URLs for each assay using the recommended nonparametric method.

RESULTS

Of 12,545 participants, 2,746 met criteria for the healthy subgroup (mean age 37 years, 50% men). The NHANES 99th percentile URL for hs-troponin T (19 ng/L) matched the manufacturer-reported URL (19 ng/L). NHANES URLs were 13 ng/L (95% CI: 10-15 ng/L) for Abbott hs-troponin I (manufacturer: 28 ng/L), 5 ng/L (95% CI: 4-7 ng/L) for Ortho hs-troponin I (manufacturer: 11 ng/L), and 37 ng/L (95% CI: 27-66 ng/L) for Siemens hs-troponin I (manufacturer: 46.5 ng/L). There were significant differences in URLs by sex, but none by race/ethnicity. Furthermore, the 99th percentile URLs for all 4 hs-troponin assays were statistically significantly lower in healthy adults aged <40 years compared with healthy adults ≥60 years (all P < 0.001 by rank sum testing).

CONCLUSIONS

We found URLs for hs-troponin I assays that were substantially lower than currently listed 99th percentile URLs. There were significant differences in hs-troponin T and I URLs by sex and by age group in healthy U.S. adults but none by race/ethnicity.

Ethnicity and sex-specific 99th percentile upper reference limits of high-sensitivity cardiac troponin I among adults in Xinjiang, China

OBJECTIVES

To determine the 99th percentile upper reference limit (URL) of high-sensitivity cardiac troponin I (hs-cTnI) in a healthy population in Xinjiang, China, and investigate the impact of ethnicity, sex, and age on this limit.

DESIGN AND METHODS

From September 2018 to March 2022, 5,090 Han and Uyghur adults aged 20-79 years were recruited. After questionnaire screening, 2,970 participants with physical and/or laboratory normality were enrolled. Participants recruited between September 2018 and October 2021 (2,109/2,970) were evaluated by ARCHITECTi2000 to determine the 99th percentile URL of hs-cTnI. The results were then validated in 861/2,970 participants recruited from November 2021 to March 2022. A criterion of ≤10% of test results falling outside the original determined value was used to determine whether the newly established reference intervals were valid.

RESULTS

The hs-cTnI concentration was higher among Uyghurs than among Han participants (p<0.001). The 99th percentile URLs were 17.52 ng/L for all participants, 18.96 ng/L for Uyghur, and 16.93 ng/L for Han. Hs-cTnI concentration was also correlated with sex and age. In the Han and Uyghur groups, male participants had a higher hs-cTnI concentration than female participants (p<0.001); the 99th percentile URLs of hs-cTnI among male and female participants were 17.80 vs. 13.67 ng/L and 19.47 vs. 16.52 ng/L, respectively. Stratified by age, hs-cTnI concentrations were higher in participants aged >60 years than in those of other age categories (p<0.001), in both the Han and Uyghur groups. Finally, <2% of these test results exceeded the newly established reference, validating the results.

CONCLUSIONS

This study established the 99th percentile URLs of hs-cTnI in the Xinjiang. Ethnicity and sex influence the value and should be considered.

Implementation of High-Sensitivity Troponin with a Rapid Diagnostic Algorithm Reduces Emergency Department Length of Stay for Discharged Patients

INTRODUCTION

High sensitivity troponin (hs-cTn) and diagnostic algorithms are used to rapidly triage patients with symptoms of acute myocardial infarction in emergency departments (ED). However, few studies have evaluated the impact of simultaneously implementing hs-cTn and a rapid rule-out algorithm on length of stay (LOS).

METHODS

We assessed the impact of transitioning from contemporary cTnI to hs-cTnI in 59,232 ED encounters over three years. hs-cTnI was implemented with an orderable series that included baseline, two-, four-, and six-hour specimens collected at provider discretion and operationalized with an algorithm to calculate the change in hs-cTnI from baseline and provide interpretations of "insignificant", "significant," or "equivocal." Patient demographics, results, chief complaint, disposition, and ED LOS were captured from the electronic medical record.

RESULTS

cTnI was ordered for 31,875 encounters prior to hs-cTnI implementation and 27,357 after. The proportion of cTnI results above the 99th percentile upper reference limit decreased from 35.0% to 27.0% for men and increased from 27.8% to 34.8% for women. Among discharged patients, the median LOS decreased by 0.6 h (0.5-0.7). LOS among discharged patients with a chief complaint of chest pain decreased by 1.0 h (0.8-1.1) and further decreased by 1.2 h (1.0-1.3) if the initial hs-cTnI was below the limit of quantitation. The rate of acute coronary syndrome upon re-presentation within 30 days did not change post-implementation (0.10% versus 0.07%).

CONCLUSION

Implementation of an hs-cTnI assay with a rapid rule-out algorithm decreased ED LOS among discharged patients, particularly among those with a chief complaint of chest pain.