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There is a considerable amount of clinical interest and research to identify markers of myocardial ischemia that could be monitored during the early, reversible stage of acute coronary syndromes.The purpose of this paper is to present a general overview of the clinical and analytical issues pertaining to the albumin cobalt binding (ACB) test which measures ischemia modified albumin (IMA). [ABSTRACT FROM AUTHOR]

Cardiac biomarkers, eg, cardiac troponin, have become the standard test in combination with clinical and electrocardiographic findings for physicians to conduct prompt and effective triage of patients presenting with chest pain. Cardiac biomarkers are protein components of cell structures that are released into circulation when myocardial injury occurs. The purpose of this article is multifold. First, to identify specific cardiac biomarkers and review current guidelines based on study findings on the diagnostic utility of cardiac biomarkers in detecting myocardial infarction. Recent guidelines of the European Society of Cardiology, the American College of Cardiology, the American Heart Association, and the National Academy of Clinical Biochemistry were examined, as well as relevant studies relating to the development of these guidelines. Second, to analyze the clinical significance of cardiac biomarker measurements and the challenges with existing cardiac biomarker assays. Third, to discuss our findings regarding our evaluation of the analytical performance of a chemiluminescent microparticle immunoassay for the quantitative determination of cardiac troponin I in human serum and plasma on an automated immunoassay instrument system (ARCHITECT) to aid in the diagnosis of myocardial infarction. [ABSTRACT FROM AUTHOR]

Background: Point-of-care (POC) high-sensitivity cardiac troponin (hs-cTn) assays have been shown to provide similar analytical precision despite substantially shorter turnaround times compared with laboratory-based hs-cTn assays. We applied the previously developed machine learning based personalised Artificial Intelligence in Suspected Myocardial Infarction Study (ARTEMIS) algorithm, which can predict the individual probability of myocardial infarction, with a single POC hs-cTn measurement, and compared its diagnostic performance with standard-of-care pathways for rapid rule-out of myocardial infarction., Methods: We retrospectively analysed pooled data from consecutive patients of two prospective observational cohorts in geographically distinct regions (the Safe Emergency Department Discharge Rate cohort from the USA and the Suspected Acute Myocardial Infarction in Emergency cohort from Australia) who presented to the emergency department with suspected myocardial infarction. Patients with ST-segment elevation myocardial infarction were excluded. Safety and efficacy of direct rule-out of myocardial infarction by the ARTEMIS algorithm (at a pre-specified probability threshold of <0·5%) were compared with the European Society of Cardiology (ESC)-recommended and the American College of Cardiology (ACC)-recommended 0 h pathways using a single POC high-sensitivity cardiac troponin I (hs-cTnI) measurement (Siemens Atellica VTLi as investigational assay). The primary diagnostic outcome was an adjudicated index diagnosis of type 1 or type 2 myocardial infarction according to the Fourth Universal Definition of Myocardial Infarction. The safety outcome was a composite of incident myocardial infarction and cardiovascular death (follow-up events) at 30 days. Additional analyses were performed for type I myocardial infarction only (secondary diagnostic outcome), and for each cohort separately. Subgroup analyses were performed for age (<65 years vs ≥65 years), sex, symptom onset (≤3 h vs >3 h), estimated glomerular filtration rate (<60 mL/min per 1·73 m 2 vs ≥60 mL/min per 1·73 m 2 ), and absence or presence of arterial hypertension, diabetes, a history of coronary artery disease, myocardial infarction, or heart failure, smoking, and ischaemic electrocardiogram signs., Findings: Among 2560 patients (1075 [42%] women, median age 58 years [IQR 48·0-69·0]), prevalence of myocardial infarction was 6·5% (166/2560). The ARTEMIS-POC algorithm classified 899 patients (35·1%) as suitable for rapid rule-out with a negative predictive value of 99·96% (95% CI 99·64-99·96) and a sensitivity of 99·68% (97·21-99·70). For type I myocardial infarction only, negative predictive value and sensitivity were both 100%. Proportions of missed index myocardial infarction (0·05% [0·04-0·42]) and follow-up events at 30 days (0·07% [95% CI 0·06-0·59]) were low. While maintaining high safety, the ARTEMIS-POC algorithm identified more than twice as many patients as eligible for direct rule-out compared with guideline-recommended ESC 0 h (15·2%) and ACC 0 h (13·8%) pathways. Superior efficacy persisted across all clinically relevant subgroups., Interpretation: The patient-tailored, medical decision support ARTEMIS-POC algorithm applied with a single POC hs-cTnI measurement allows for very rapid, safe, and more efficient direct rule-out of myocardial infarction than guideline-recommended pathways. It has the potential to expedite the safe discharge of low-risk patients from the emergency department including early presenters with symptom onset less than 3 h at the time of admission and might open new opportunities for the triage of patients with suspected myocardial infarction even in ambulatory, preclinical, or geographically isolated care settings., Funding: The German Center for Cardiovascular Research (DZHK)., Competing Interests: Declaration of interests BT is supported by a grant from the German Foundation of Heart Research and Werner Otto Stiftung; is the co-recipient of a grant from the Ernst und Berta Grimmke-Stiftung (unrelated to this project); and has received travel grants from the German Center for Cardiovascular Research (DZHK). BT is the local representative of the partner sites Hamburg/Kiel/Luebeck in the Use and Access Committee of the DZHK Heart Bank. JHG reports fellowship funding from Advance Queensland and payment by the Emergency Medicine Foundation to her institution. WAP reports that his institution receives consulting fees from Siemens Healthineers. WAP reports acitivities at the Board (executive and horonary treasurer) of the Cardiac Society of Australia and New Zealand. LC reports non-salaried grant support and provision of assays through her institution from Abbott Diagnostics, Abbott Point-of-Care (POC), Radiometer Pacific, Roche Diagnostics, Siemens Healthineers, and Beckman Coulter. LC also reports consulting fees from Siemens Healthineers, Beckman Coulter, Quidel/Ortho, and payment or honoraria from Abbott Diagnostics, Roche Diagnostics, and Glycardial. Both WAP and LC report research funding and provision of assays by Siemens Healthineers. FSA reports doing advisory board or consultant activities for Mindray, Wefen, and Abbott Vascular, and non-salaried grant support through the Hennepin Healthcare Research Institute from Abbott Diagnostics, Abbott POC, Roche Diagnostics, Siemens Healthineers, Beckman Coulter, Quidel/Ortho, Becton Dickinson, and Sysmex, and fees for serving as Associate Editor for Clinical Chemistry. AZ is a Board member of the Basel Biometric Society. AZ and SB are listed as co-inventors of an international patent on the use of a computing device to estimate the probability of myocardial infarction (International Publication Number WO2022043229A1). AZ is scientific director and CEO of Cardio-CARE, SB is scientific advisor of Cardio-CARE, HS was a biostatistician at Cardio-CARE, and EDC is a biostatistician at Cardio-CARE, a 100% non-profit daughter company of the Kühne Foundation. Cardio-CARE is a shareholder of ART-EMIS Hamburg. SB receives consulting fees from Thermo Fisher, and payment or honoraria from Abbott Diagnostics, Amarin, AMGEN, AstraZeneca, Bayer, Bristol Meyers Squibb, Boehringer Ingelheim, Daiichi Sankyo, GSK, LumiraDx, Novartis, Roche Diagnostics, and Thermo Fisher. SB is a member of the advisory board of Thermo Fisher. SB and AZ were co-founders of ARTEMIS in 2022. Both sold their shares in 2023 and have no personal financial or legal relationship to ARTEMIS. KS declares no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background and Aims: Strategies to assess patients with suspected acute myocardial infarction (AMI) using a point-of-care (POC) high-sensitivity cardiac troponin I (hs-cTnI) assay may expedite emergency care. A 2-h POC hs-cTnI strategy for emergency patients with suspected AMI was derived and validated., Methods: In two international, multi-centre, prospective, observational studies of adult emergency patients (1486 derivation cohort and 1796 validation cohort) with suspected AMI, hs-cTnI (Siemens Atellica® VTLi) was measured at admission and 2 h later. Adjudicated final diagnoses utilized the hs-cTn assay in clinical use. A risk stratification algorithm was derived and validated. The primary diagnostic outcome was index AMI (Types 1 and 2). The primary safety outcome was 30-day major adverse cardiac events incorporating AMI and cardiac death., Results: Overall, 81 (5.5%) and 88 (4.9%) patients in the derivation and validation cohorts, respectively, had AMI. The 2-h algorithm defined 66.1% as low risk with a sensitivity of 98.8% [95% confidence interval (CI) 89.3%-99.9%] and a negative predictive value of 99.9 (95% CI 99.2%-100%) for index AMI in the derivation cohort. In the validation cohort, 53.3% were low risk with a sensitivity of 98.9% (95% CI 92.4%-99.8%) and a negative predictive value of 99.9% (95% CI 99.3%-100%) for index AMI. The high-risk metrics identified 5.4% of patients with a specificity of 98.5% (95% CI 96.6%-99.4%) and a positive predictive value of 74.5% (95% CI 62.7%-83.6%) for index AMI., Conclusions: A 2-h algorithm using a POC hs-cTnI concentration enables safe and efficient risk assessment of patients with suspected AMI. The short turnaround time of POC testing may support significant efficiencies in the management of the large proportion of emergency patients with suspected AMI., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Introduction: Clinical assessment in emergency departments (EDs) for possible acute myocardial infarction (AMI) requires at least one cardiac troponin (cTn) blood test. The turn-around time from blood draw to posting results in the clinical portal for central laboratory analysers is ~1-2 hours. New generation, high-sensitivity, point-of-care cardiac troponin I (POC-cTnI) assays use whole blood on a bedside (or near bedside) analyser that provides a rapid (8 min) result. This may expedite clinical decision-making and reduce length of stay. Our purpose is to determine if utilisation of a POC-cTnI testing reduces ED length of stay. We also aim to establish an optimised implementation process for the amended clinical pathway., Methods and Analysis: This quality improvement initiative has a pragmatic multihospital stepped-wedge cross-sectional cluster randomised design. Consecutive patients presenting to the ED with symptoms suggestive of possible AMI and having a cTn test will be included. Clusters (comprising one or two hospitals each) will change from their usual-care pathway to an amended pathway using POC-cTnI-the 'intervention'. The dates of change will be randomised. Changes occur at 1 month intervals, with a minimum 2 month 'run-in' period. The intervention pathway will use a POC-cTnI measurement as an alternate to the laboratory-based cTn measurement. Clinical decision-making steps and logic will otherwise remain unchanged. The POC-cTnI is the Siemens (Erlangen Germany) Atellica VTLi high-sensitivity cTnI assay. The primary outcome is ED length of stay. The safety outcome is cardiac death or AMI within 30 days for patients discharged directly from the ED., Ethics and Dissemination: Ethics approval has been granted by the New Zealand Southern Health and Disability Ethics Committee, reference 21/STH/9. Results will be published in a peer-reviewed journal. Lay and academic presentations will be made. Māori-specific results will be disseminated to Māori stakeholders., Trial Registration Number: ACTRN12619001189112., Competing Interests: Competing interests: Siemens Healthcare had no part in the writing of the protocol, and will play no part in the data analysis, interpretation or writing of manuscripts. JWP reports consultancy with Upstream, Luminoma, Siemens Healthineers, Quidel Corporation and Radiometer Health. NM has received honoraria from Abbott Diagnostics, Roche Diagnostics, Siemens Healthineers and LumiraDx and the University of Edinburgh have received research grants from Siemens Healthineers and Abbott Diagnostics unrelated to this work. LC has received honoraria/speakers’ fees from Abbott Diagnostics, Beckman Coulter and Siemens Healthineers, and institutional research grants from Siemens Healthineers, Beckman Coulter and Abbott Diagnostics unrelated to this work. ASJ reports work with all major diagnostic companies. FP reports research grants with Brainbox, Quidel; Consultancies with Abbott, Brainbox, Instrument Labs, Janssen, Osler, Roche, Siemens, Spinchip, Vifor; Stock/Ownership Interests with AseptiScope, Brainbox, Braincheck, Coagulo, Comprehensive Research Associates LLC, Comprehensive Research Management, Emergencies in Medicine LLC, Fast, Forrest Devices, Ischemia DX LLC, Lucia, Prevencio, RCE Technologies, ROMTech, ScPharma, Trivirum, Upstream. MT has received honoraria and research funding from Abbott, Alere, Beckman, QuidelOrtho, Radiometer, Roche and Siemens., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

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., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

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., (© Association for Diagnostics & Laboratory Medicine 2024. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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., (© Association for Diagnostics & Laboratory Medicine 2023.)

In 2021, the Association for Diagnostics & Laboratory Medicine (ADLM) (formerly the American Association for Clinical Chemistry [AACC]) developed a scientific study that aimed to contribute to the understanding of SARS-CoV-2 immunity during the evolving course of the pandemic. This study was led by a group of expert member volunteers and resulted in survey data from 975 individuals and blood collection from 698 of those participants. This paper describes the formulation and execution of this large-scale scientific study, encompassing best practices and insights gained throughout the endeavor., (© Association for Diagnostics & Laboratory Medicine 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

This study aimed to evaluate and compare the performance of three anti-S and one anti-N assays that were available to the project in detecting antibody levels after three commonly used SARS-CoV-2 vaccines (Pfizer, Moderna, and Johnson & Johnson). It also aimed to assess the association of age, sex, race, ethnicity, vaccine timing, and vaccine side effects on antibody levels in a cohort of 827 individuals. In September 2021, 698 vaccinated individuals donated blood samples as part of the Association for Diagnostics & Laboratory Medicine (ADLM) COVID-19 Immunity Study. These individuals also participated in a comprehensive survey covering demographic information, vaccination status, and associated side effects. Additionally, 305 age- and gender-matched samples were obtained from the ADLM 2015 sample bank as pre-COVID-19-negative samples. All these samples underwent antibody level analysis using three anti-S assays, namely Beckman Access SARS-CoV-2 IgG (Beckman assay), Ortho Clinical Diagnostics VITROS Anti-SARS-CoV-2 IgG (Ortho assay), Siemens ADVIA Centaur SARS-CoV-2 IgG (Siemens assay), and one anti-N antibody assay: Bio-Rad Platelia SARS-CoV-2 Total Ab assay (BioRad assay). A total of 827 samples (580 COVID-19 samples and 247 pre-COVID-19 samples) received results for all four assays and underwent further analysis. Beckman, Ortho, and Siemens anti-S assays showed an overall sensitivity of 99.5%, 97.6%, and 96.9%, and specificity of 90%, 100%, and 99.6%, respectively. All three assays indicated 100% sensitivity for individuals who received the Moderna vaccine and boosters, and over 99% sensitivity for the Pfizer vaccine. Sensitivities varied from 70.4% (Siemens), 81.5% (Ortho), and 96.3% (Beckman) for individuals who received the Johnson & Johnson vaccine. BioRad anti-N assays demonstrated 46.2% sensitivity and 99.25% specificity based on results from individuals with self-reported infection. The highest median anti-S antibody levels were measured in individuals who received the Moderna vaccine, followed by Pfizer and then Johnson & Johnson vaccines. Higher anti-S antibody levels were significantly associated with younger age and closer proximity to the last vaccine dose but were not associated with gender, race, or ethnicity. Participants with higher anti-S levels experienced significantly more side effects as well as more severe side effects (e.g., muscle pain, chills, fever, and moderate limitations) ( p < 0.05). Anti-N antibody levels only indicated a significant correlation with headache. This study indicated performance variations among different anti-S assays, both among themselves and when analyzing individuals with different SARS-CoV-2 vaccines. Caution should be exercised when conducting large-scale studies to ensure that the same platform and/or assays are used for the most effective interpretation of the data.

Competing Interests: Disclosures Dr Ashburn receives funding from the National Heart, Lung, and Blood Institute (T32HL076132). Dr McCord receives research funding and support from Beckman Coulter, Roche Diagnostics, Abbott Laboratories, and Siemens. He is a consultant for Beckman Coulter, Roche Diagnostics, and Siemens. Dr Snavely receives funding from Abbott and Health Resources and Services Administration (1H2ARH399760100). Dr Christenson is a consultant for and receives funding and support from Roche Diagnostics, Siemens Healthineers, Beckman Coulter Diagnostics, Becton Dickinson and Co, Quidel Corp, and Sphingotec GMBH. Dr Apple reports consulting fees from HyTest Ltd., advisory fees from Werfen and Qorvo Biotechnology, nonsalaried grant support through the Hennepin Healthcare Research Institute from Abbott Diagnostics, Abbott POC, Roche Diagnostics, Siemens Healthcare, Quidel, Ortho-Clinical Diagnostics, Becton Dickinson; and fees for serving as Associate Editor for Clinical Chemistry. Dr Peacock received research grants from Brainbox, RCE, and Salix, served as a consultant for Abbott, Brainbox, Instrument Labs, Janssen, Osler, Roche, Siemens, and Vifor, and has stock/ownership interests in AseptiScope Inc, Brainbox Inc, Braincheck Inc, Coagulo Inc, Comprehensive Research Associates LLC, Comprehensive Research Management Inc, Emergencies in Medicine LLC, Fast Inc, Forrest Devices, Ischemia DX LLC, Lucia Inc, Prevencio Inc, RCE Technologies, ROMTech, ScPharma, Trivirum Inc, Upstream Inc. Dr. deFilippi consults for Abbott Diagnostics, Fujirebio, Ortho Diagnostics, Quidell, Roche Diagnostics and Siemens Healthineers. Dr Mahler receives funding and support from Roche Diagnostics, Abbott Laboratories, Ortho Clinical Diagnostics, Siemens, Grifols, Pathfast, OrthoQuidel, Beckman Coulter, Genetesis, Cytovale, Health Resources and Services Administration (1H2ARH399760100) and AHRQ (R01HS029017). He is a consultant for Roche, Quidel, Abbott, Genetesis, Inflammatix, Radiometer, and Amgen and is the Chief Medical Officer for Impathiq Inc.

Background: In suspected myocardial infarction (MI), guidelines recommend using high-sensitivity cardiac troponin (hs-cTn)-based approaches. These require fixed assay-specific thresholds and timepoints, without directly integrating clinical information. Using machine-learning techniques including hs-cTn and clinical routine variables, we aimed to build a digital tool to directly estimate the individual probability of MI, allowing for numerous hs-cTn assays., Methods: In 2,575 patients presenting to the emergency department with suspected MI, two ensembles of machine-learning models using single or serial concentrations of six different hs-cTn assays were derived to estimate the individual MI probability (ARTEMIS model). Discriminative performance of the models was assessed using area under the receiver operating characteristic curve (AUC) and logLoss. Model performance was validated in an external cohort with 1688 patients and tested for global generalizability in 13 international cohorts with 23,411 patients., Results: Eleven routinely available variables including age, sex, cardiovascular risk factors, electrocardiography, and hs-cTn were included in the ARTEMIS models. In the validation and generalization cohorts, excellent discriminative performance was confirmed, superior to hs-cTn only. For the serial hs-cTn measurement model, AUC ranged from 0.92 to 0.98. Good calibration was observed. Using a single hs-cTn measurement, the ARTEMIS model allowed direct rule-out of MI with very high and similar safety but up to tripled efficiency compared to the guideline-recommended strategy., Conclusion: We developed and validated diagnostic models to accurately estimate the individual probability of MI, which allow for variable hs-cTn use and flexible timing of resampling. Their digital application may provide rapid, safe and efficient personalized patient care., Trial Registration Numbers: Data of following cohorts were used for this project: BACC ( www., Clinicaltrials: gov ; NCT02355457), stenoCardia ( www., Clinicaltrials: gov ; NCT03227159), ADAPT-BSN ( www.australianclinicaltrials.gov.au ; ACTRN12611001069943), IMPACT ( www.australianclinicaltrials.gov.au , ACTRN12611000206921), ADAPT-RCT ( www.anzctr.org.au ; ANZCTR12610000766011), EDACS-RCT ( www.anzctr.org.au ; ANZCTR12613000745741); DROP-ACS ( https://www.umin.ac.jp , UMIN000030668); High-STEACS ( www., Clinicaltrials: gov ; NCT01852123), LUND ( www., Clinicaltrials: gov ; NCT05484544), RAPID-CPU ( www., Clinicaltrials: gov ; NCT03111862), ROMI ( www., Clinicaltrials: gov ; NCT01994577), SAMIE ( https://anzctr.org.au ; ACTRN12621000053820), SEIGE and SAFETY ( www., Clinicaltrials: gov ; NCT04772157), STOP-CP ( www., Clinicaltrials: gov ; NCT02984436), UTROPIA ( www., Clinicaltrials: gov ; NCT02060760)., (© 2023. The Author(s).)

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., Competing Interests: Funding Support and Author Disclosures Dr Mills is supported by the British Heart Foundation through a Chair Award (CH/F/21/90010), a Programme Grant (RG/20/10/34966), and a Research Excellent Award (RE/18/5/34216). Dr Jaffe has consulted for Abbott, Beckman Coulter, Siemens, Roche, Ortho Diagnostics, ET Healthcare, SphingoTec, Radiometer, SpinChip, LumiraDX, Astellas, Amgen, Novartis, and RCE Technologies; and holds patent 20210401347 along with others. Dr Body has received consulting fees from Roche, Aptamer Group, Abbott, Psyros Diagnostics, Siemens Healthineers, Beckman Coulter, and Radiometer; and has participated on advisory boards for the FORCE Trial (funded by the National Institute for Health and Care Research), the REWIRE trial (Queen Mary University), the PRONTO trial (funded by the National Institute for Health and Care Research), and LumiraDx. Dr Mills has received research grants from Abbott Diagnostics and Siemens Healthineers; and has received personal fees for participation on advisory boards or speaking from Abbott Diagnostics, Roche Diagnostics, Siemens Healthineers, LumiraDx, and Psyros Diagnostics. Dr Aakre is an associate editor of Clinical Biochemistry; is chair of the International Federation of Clinical Chemistry and Laboratory Medicine Committee on Clinical Applications of Cardiac Bio-Markers; has served on advisory boards for Roche Diagnostics and SpinChip; has received consulting honoraria from CardiNor; has received lecture honorarium from Siemens Healthineers and Snibe Diagnostics; and has received research grants from Siemens Healthineers and Roche Diagnostics. Dr Collinson is an associate editor of the Journal of Applied Laboratory Medicine; is an advisory board member for Psyros Diagnostics; and has previously advised LumiraDX, Radiometer, and Siemens. Dr Saenger has received consulting fees from Radiometer. Dr Hammarsten has stock options with Aligned Bio. Dr Omland has received consulting fees from Roche, Bayer, and CardiNor; has received honoraria from Roche; has a patent pending with Roche; has participated on advisory boards for Bayer and Roche; has a fiduciary role with CardiNor; holds stock in CardiNor; and has received equipment and material from Novartis and Abbott. Dr Sandoval has been on advisory boards and has served as a speaker for Abbott Diagnostics and Roche Diagnostics; and holds patent 20210401347 along with others. Dr Ordonez-Llanos has received consulting fees from AWE Medical and Hemcheck. Dr Apple has received consulting fees from HyTest and AWE Medical; has received advisory fees from Werfen, Siemens Healthineers, and Qorvo Biotechnology; has received nonsalaried grant support through the Hennepin Healthcare Research Institute from Abbott Diagnostics, Abbott POC, Roche Diagnostics, Siemens Healthineers, Quidel/Ortho, Becton Dickinson, and Beckman Coulter; and has received fees for serving as associate editor for Clinical Chemistry. Dr Wereski has reported that he has no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Cardiovascular disease is the leading cause of death in patients receiving hemodialysis. Currently, there is no standardized definition of myocardial infarction (MI) for patients receiving hemodialysis. Through an international consensus process MI was established as the core CVD measure for this population in clinical trials. The Standardised Outcomes in Nephrology Group-Hemodialysis (SONG-HD) initiative convened a multidisciplinary, international working group to address the definition of MI in this population. On the basis of current evidence, the working group recommends using the Fourth Universal Definition of Myocardial Infarction with specific caveats with regard to the interpretation of "ischemic symptoms" and performing a baseline 12-lead electrocardiogram to facilitate interpretation of acute changes on subsequent tracings. The working group does not recommend obtaining baseline cardiac troponin values, though does recommend obtaining serial cardiac biomarkers in settings where ischemia is suspected. The application of an evidence-based uniform definition should increase the reliability and accuracy of trial results., (Copyright © 2023 International Society of Nephrology. All rights reserved.)

Background: Our study addressed the diagnostic performance of the Atellica® IM High-Sensitivity Troponin I (hs-cTnI) assay for the rapid rule-out of myocardial infarction (MI) using a single hs-cTnI measurement at presentation in patients presenting to a US emergency department (ED)., Methods: This was a prospective, observational, cohort study of consecutive ED patients with suspected acute coronary syndrome, using 12-lead electrocardiogram and serial hs-cTnI measurements ordered on clinical indication (SAFETY, NCT04280926). ST-segment elevation MI patients were excluded. The optimal threshold required a sensitivity ≥99% and a negative predictive value (NPV) ≥99.5% for MI during index hospitalization as primary outcome. Type 1 MI (T1MI), myocardial injury, and 30-day adverse events were considered secondary outcomes. Event adjudications were established using the hs-cTnI assay used in clinical care., Results: In 1171 patients, MI occurred in 97 patients (8.3%), 78.3% of which were type 2 MI. The optimal rule out hs-cTnI threshold was <10 ng/L, which identified 519 (44.3%) patients as low risk at presentation, with sensitivity of 99.0% (95% CI, 94.4-100) and NPV of 99.8% (95% CI, 98.9-100). For T1MI, sensitivity was 100% (95% CI, 83.9-100) and NPV 100% (95% CI, 99.3-100). Regarding myocardial injury, the sensitivity and NPV were 99.5% (95% CI, 97.9-100) and 99.8% (95% CI, 98.9-100), respectively. For 30-day adverse events, sensitivity was 96.8% (95% CI, 94.3-98.4) and NPV 97.9% (95% CI, 96.2-98.9)., Conclusions: A single hs-cTnI measurement strategy enabled the rapid identification of patients at low risk of MI and 30-day adverse events, allowing potential discharge early after ED presentation., Clinicaltrials.gov Registration Number: NCT04280926., (© American Association for Clinical Chemistry 2023. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Although guidelines recommend fixed cardiac troponin thresholds for the diagnosis of myocardial infarction, troponin concentrations are influenced by age, sex, comorbidities and time from symptom onset. To improve diagnosis, we developed machine learning models that integrate cardiac troponin concentrations at presentation or on serial testing with clinical features and compute the Collaboration for the Diagnosis and Evaluation of Acute Coronary Syndrome (CoDE-ACS) score (0-100) that corresponds to an individual's probability of myocardial infarction. The models were trained on data from 10,038 patients (48% women), and their performance was externally validated using data from 10,286 patients (35% women) from seven cohorts. CoDE-ACS had excellent discrimination for myocardial infarction (area under curve, 0.953; 95% confidence interval, 0.947-0.958), performed well across subgroups and identified more patients at presentation as low probability of having myocardial infarction than fixed cardiac troponin thresholds (61 versus 27%) with a similar negative predictive value and fewer as high probability of having myocardial infarction (10 versus 16%) with a greater positive predictive value. Patients identified as having a low probability of myocardial infarction had a lower rate of cardiac death than those with intermediate or high probability 30 days (0.1 versus 0.5 and 1.8%) and 1 year (0.3 versus 2.8 and 4.2%; P < 0.001 for both) from patient presentation. CoDE-ACS used as a clinical decision support system has the potential to reduce hospital admissions and have major benefits for patients and health care providers., (© 2023. The Author(s).)

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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.)

The International Federation of Clinical Chemistry Committee on Clinical Applications of Cardiac Biomarkers (IFCC C-CB) provides educational documents to facilitate the interpretation and use of cardiac biomarkers in clinical laboratories and practice. Our aim is to improve the understanding of certain key analytical and clinical aspects of cardiac biomarkers and how these may interplay. Measurements of cardiac troponin (cTn) have a prominent place in the clinical work-up of patients with suspected acute coronary syndrome. It is therefore important that clinical laboratories know how to recognize and assess analytical issues. Two emerging analytical issues resulting in falsely high cTn concentrations, often several fold higher than the upper reference limit (URL), are antibody-mediated assay interference due to long-lived cTn-antibody complexes, called macrotroponin, and crosslinking antibodies that are frequently referred to as heterophilic antibodies. We provide an overview of antibody-mediated cTn assay interference and provide recommendations on how to confirm the interference and interpret the results., (© 2023 the author(s), published by De Gruyter, Berlin/Boston.)

Objectives: The objective of this prospective study was to investigate the role of adaptive immunity in response to SARS-CoV-2 vaccines., Design and Methods: A cohort of 677 vaccinated individuals participated in a comprehensive survey of their vaccination status and associated side effects, and donated blood to evaluate their adaptive immune responses by neutralizing antibody (NAb) and T cell responses. The cohort then completed a follow-up survey to investigate the occurrence of breakthrough infections., Results: NAb levels were the highest in participants vaccinated with Moderna, followed by Pfizer and Johnson & Johnson. NAb levels decreased with time after vaccination with Pfizer and Johnson & Johnson. T cell responses showed no significant difference among the different vaccines and remained stable up to 10 months after the study period for all vaccine types. In multivariate analyses, NAb responses (<95 U/mL) predicted breakthrough infection, whereas previous infection, the type of vaccine, and T cell responses did not. T cell responses to viral epitopes (<0.120 IU/mL) showed a significant association with the self-reported severity of COVID-19 disease., Conclusion: This study provides evidence that NAb responses to SARS-CoV-2 vaccination correlate with protection against infection, whereas the T cell memory responses may contribute to protection against severe disease but not against infection.

Background: Few data exist regarding the implementation of high-sensitivity cardiac troponin (hs-cTn) assays in the United States since their approval., Objectives: This study sought to explore trends in hs-cTn assay implementation over time and assess the association of their use with in-hospital cardiac testing and outcomes., Methods: The study examined trends in implementation of hs-cTn assays among participating hospitals in the National Cardiovascular Data Registry Chest Pain-MI [Myocardial Infarction] Registry from January 1, 2019 through September 30, 2021. Associations among hs-cTn use, use of in-hospital diagnostic imaging, and patient outcomes were assessed using generalized estimating equation models with logistic or gamma distributions., Results: Among 550 participating hospitals (N = 251,000), implementation of hs-cTn assays increased from 3.3% in the first quarter of 2019 to 32.6% in the third quarter of 2021 (P trend  < 0.001). Use of hs-cTn was associated with more echocardiography among persons with non-ST-segment elevation acute coronary syndrome (NSTE-ACS; 82.4% vs 75.0%; adjusted odds ratio: 1.43; 95% CI: 1.19-1.73) but not among low-risk chest pain individuals. Use of hs-cTn was associated with less invasive coronary angiography among low-risk patients (3.7% vs 4.5%; adjusted odds ratio: 0.73; 95% CI: 0.58-0.92) but similar use for patients with NSTE-ACS. There was no association between hs-cTn use and noninvasive stress testing or coronary computed tomography angiography testing. Among individuals with NSTE-ACS, hs-cTn use was not associated with revascularization or in-hospital mortality. Use of hs-cTn was associated with a shorter length of stay (median 47.6 hours vs 48.0 hours; ratio: 0.94; 95% CI: 0.90-0.98)., Conclusions: Implementation of hs-cTn among U.S. hospitals is increasing, but most U.S. hospitals continue to use less sensitive assays. The use of hs-cTn was associated with modestly shorter length of stay, greater use of echocardiography for NSTE-ACS, and less use of invasive angiography among low-risk patients., Competing Interests: Funding Support and Author Disclosures This research was supported by the American College of Cardiology’s National Cardiovascular Data Registry (NCDR). The views expressed in this manuscript represent those of the author(s) and do not necessarily represent the official views of the NCDR or its associated professional societies identified at CVQuality.ACC.org/NCDR. Dr McCarthy has received support from the National Heart, Lung, and Blood Institute (NHLBI) T32 postdoctoral training grant (5T32HL094301-12); and has received consulting income from Abbott Laboratories. Dr Wang has received research grants to the Duke Clinical Research Institute from Abbott, AstraZeneca, Bristol Myers Squibb, Boston Scientific, Cryolife, Chiesi, Merck, Portola, and Regeneron; and has received consulting honoraria from AstraZeneca, Bristol Myers Squibb, Cryolife, and Novartis. Dr Sandoval has served on advisory boards for Roche Diagnostics and Abbott Diagnostics without personal financial compensation; and has also been a speaker without personal financial compensation for Abbott Diagnostics. Dr Smilowitz has received partial support from a Career Development Award from NHLBI (K23HL150315); and has received consulting honoraria from Abbott Vascular. Dr Wasfy has received support from the American Heart Association (18 CDA 34110215). Dr de Lemos has received grant support from Abbott Diagnostics and Roche Diagnostics; and has received consulting income from Ortho Clinical Diagnostics, Quidel, Beckman Coulter, and Siemens’s Health Care Diagnostics. Dr Kontos has served as chair of the Chest Pain-MI Steering committee. Dr Apple has served as an Associate Editor of Clinical Chemistry; has participated in the advisory boards of Werfen, Siemens Healthineers, and Qorvo Biotechnology; has received consulting income from AWE Medical and Hytest; and has received cardiac biomarker grant support (nonsalaried) through his institutional research institute from Abbott Diagnostics, Abbott POC, Siemens Healthcare, Ortho-Clinical Diagnostics, Roche Diagnostics, Beckman Coulter, BD, and Quidel. Dr Daniels has received consulting income from Quidel, Roche, and Siemens; and has participated in clinical endpoint committees or data safety monitoring boards for Abbott, Applied Therapeutics, and Quidel. Dr Newby has received research grant support from Roche Diagnostics and BioKier; and has received consulting honoraria from Beckman-Coulter, CSL, and Medtronic. Dr Jaffe has served as a consultant for Abbott, Beckman-Coulter, Siemens, Roche, Ortho Diagnostics, Radiometer, ET Healthcare, Sphingotec, Astellas, RCE Technologies, Amgen, and Novartis. Dr Januzzi has served as a Trustee of the American College of Cardiology; has received grant support from Abbott, Applied Therapeutics, HeartFlow Inc, Innolife, and Roche Diagnostics; has received consulting income from Abbott, Janssen, Novartis, Merck, and Roche Diagnostics; and has participated in clinical endpoint committees or data safety monitoring boards for Abbott, AbbVie, Bayer, CVRx, Pfizer, and Takeda. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2023 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The International Federation of Clinical Chemistry and Laboarator Medicine (IFCC) Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) has provided evidence-based educational resources to aid and improve the understanding of important analytical and clinical aspects of cardiac biomarkers. The present IFCC C-CB educational report focuses on recommendations for appropriate use, analytical performance, and gaps in clinical studies related to the use of cardiac troponin (cTn) by point of care (POC) measurement, often referred to as a point of care testing (POCT). The use of high-sensitivity (hs)-cTn POC devices in accelerated diagnostic protocols used in emergency departments or outpatient clinics investigating acute coronary syndrome has the potential for improved efficacy, reduction of length of stay and reduced costs in the health care system. POCT workflow integration includes location of the instrument, assignment of collection and testing responsibility to (non-lab) staff, instrument maintenance, in-service and recurrent training, quality control, proficiency assessments, discrepant result trapping, and troubleshooting and inventory management., (© 2022 Walter de Gruyter GmbH, Berlin/Boston.)