Implementation of high sensitivity troponin into routine clinical practice - results of the extended CARdiac MArkers guideline uptake in Europe group (CARMAGUE) survey.

BACKGROUND: Measurement of cardiac troponin (cTn) by a high sensitivity method is now the recommended strategy for the detection of myocardial injury. An international survey was undertaken to assess how this has been implemented. METHODS: A questionnaire based around 14 domains on cardiac biomarkers was distributed electronically with the aid of professional societies accessed by a web link within the invitation. Results were returned electronically then extracted into a relational database for analysis. RESULTS: Responses were obtained from 663 laboratories across 76 countries ranging from 1 to 69 largest country. The majority of responses (79.6%) came from the European area. Responses were grouped into broad geographic areas for analysis. Most responses came from hospitals providing a local and regional service of which the majority provided angioplasty. cTn measurement was the dominant biomarker. The majority of laboratories include creatine kinase (CK) in their cardiac profile and approximately 50% also offer the MB isoenzyme of CK. The majority of laboratories (91.9%) measure cTn by a high sensitivity method. Sex specific reference ranges were typically implemented for cardiac troponin I but not for cardiac troponin T. The preferred unit of measurement was nanograms/L. A structured decision-making pathway utilising high sensitivity cTn measurement was used by 83.3% of laboratories who responded. Single sample rule out is common but the majority used serial sampling strategy based on measurement on admission and three hours. CONCLUSIONS: Measurement of cTn by a high sensitivity method is now well established internationally, the use of rapid diagnostic protocols lags behind.

Surface plasmon resonance biosensors for early troponin detection.

Acute myocardial infarction (AMI) is one of the life-threatening causes that decrease blood flow to the heart, leading to increased mortality and related complications. Recently, the measure of blood concentration of cardiac biomarkers has been suggested to overcome the limitations of electrocardiography (ECG) analyses for early diagnosis of this disease. Troponins, especially cardiac troponin I and cardiac troponin T, with high sensitivity and specificity, are considered the gold standards in myocardial diagnosis. Recently, the use of new biosensors such as surface plasmon resonance (SPR) for early detection of these biomarkers has been greatly appreciated. Due to the rapid, sensitive, real-time, and label-free detection of SPR-based biosensors, they can be applied for selective and nonspecific absorption that is intended to be used as an in situ cardiac biosensor. Here, we exclusively discussed the updated developments of these valuable predictors for the possible occurrence of AMI detected by SPR.

50 Years of the steric-blocking mechanism in vertebrate skeletal muscle: a retrospective.

Fifty years have now passed since Parry and Squire proposed a detailed structural model that explained how tropomyosin, mediated by troponin, played a steric-blocking role in the regulation of vertebrate skeletal muscle. In this Special Issue dedicated to the memory of John Squire it is an opportune time to look back on this research and to appreciate John's key contributions. A review is also presented of a selection of the developments and insights into muscle regulation that have occurred in the years since this proposal was formulated.

Analytical Considerations in Deriving 99th Percentile Upper Reference Limits for High-Sensitivity Cardiac Troponin Assays: Educational Recommendations from the IFCC Committee on Clinical Application of Cardiac Bio-Markers.

The International Federation of Clinical Chemistry Committee on Clinical Application of Cardiac Bio-Markers provides evidence-based educational documents to facilitate uniform interpretation and utilization of cardiac biomarkers in clinical laboratories and practice. The committee's goals are to improve the understanding of certain key analytical and clinical aspects of cardiac biomarkers and how these may interplay in clinical practice. Measurement of high-sensitivity cardiac troponin (hs-cTn) assays is a cornerstone in the clinical evaluation of patients with symptoms and/or signs of acute cardiac ischemia. To define myocardial infarction, the Universal Definition of Myocardial Infarction requires patients who manifest with features suggestive of acute myocardial ischemia to have at least one cTn concentration above the sex-specific 99th percentile upper reference limit (URL) for hs-cTn assays and a dynamic pattern of cTn concentrations to fulfill the diagnostic criteria for MI. This special report provides an overview of how hs-cTn 99th percentile URLs should be established, including recommendations about prescreening and the number of individuals required in the reference cohort, how statistical analysis should be conducted, optimal preanalytical and analytical protocols, and analytical/biological interferences or confounds that can affect accurate determination of the 99th percentile URLs. This document also provides guidance and solutions to many of the issues posed.

Acute Myocardial Injury Assessed by High-Sensitive Cardiac Troponin Predicting Severe Outcomes and Death in Hospitalized Patients with COVID-19 Infection.

BACKGROUND: Cardiac injury has been linked to a poor prognosis during COVID-19 disease. Nevertheless, the risk factors associated are yet to be thoroughly investigated. OBJECTIVES: We sought to compare demographical characteristics and in-hospital outcomes in patients infected by the SARS-CoV-2 with and without cardiac injury, to further investigate the prevalence of acute cardiac injury as well as its impact on their outcomes in COVID-19-patients. METHODS: We included in a retrospective analysis, all COVID-19 patients admitted between October first and December first, 2020, at the University Hospital Center of Oujda (Morocco) who underwent a troponin assay which was systematically measured on admission. The study population was divided into two groups: cardiac-injured patients and those without cardiac injury. Clinical, biological data and in-hospital outcomes were compared between the two groups. RESULTS: 298 confirmed COVID-19 cases were included. Our study found that compared to non-cardiac-injured, cardiac-injured patients are older, with higher possibilities of existing comorbidities including hypertension (68 [42.2%] vs 40 [29.2%], P = 0.02), diabetes (81 [50.3%] vs 53 [38.7%] P = 0.044), the need for mechanical ventilation, ICU admission and mortality. A Cox proportional hazards regression analysis shows a significantly increased risk of death among cardiac-injured COVID-19-patients as compared to non-cardiac injured. (HR, 1.620 [CI 95%: 2.562-1.024]). CONCLUSION: Our retrospective cohort found that old age, comorbidities, a previous history of CAD, were significantly associated with acute cardiac injury. COVID-19 patients with acute cardiac injury are at a higher risk of ICU admission, and death.

Identifying low-risk chest pain in the emergency department without troponin testing: a validation study of the HE-MACS and HEAR risk scores.

INTRODUCTION: Patients presenting to EDs with chest pain of possible cardiac origin represent a substantial and challenging cohort to risk stratify. Scores such as HE-MACS (History and Electrocardiogram-only Manchester Acute Coronary Syndromes decision aid) and HEAR (History, ECG, Age, Risk factors) have been developed to stratify risk without the need for troponin testing. Validation of these scores remains limited. METHODS: We performed a post hoc analysis of the Limit of Detection and ECG discharge strategy randomised-controlled trial dataset (n=629; June 2018 to March 2019; 8 UK hospitals) to calculate HEAR and HE-MACS scores. A <4% risk of major adverse cardiac events (MACE) at 30 days using HE-MACS and a score of <2 calculated using HEAR defined 'very low risk' patients suitable for discharge. The primary outcome of MACE at 30 days was used to assess diagnostic accuracy. RESULTS: MACE within 30 days occurred in 42/629 (7%) of the cohort. HE-MACS and HEAR scores identified 85/629 and 181/629 patients as 'very low risk', with MACE occurring in 0/85 and 1/181 patients, respectively. The sensitivities of each score for ruling out MACE were 100% (95% CI: 91.6% to 100%) for HE-MACS and 97.6% (95% CI: 87.7% to 99.9%) for HEAR. Presenting symptoms within these scores were poorly predictive, with only diaphoresis reaching statistical significance (OR: 4.99 (2.33 to 10.67)). Conventional cardiovascular risk factors and clinician suspicion were related to the presence of MACE at 30 days. CONCLUSION: HEAR and HE-MACS show potential as rule out tools for acute myocardial infarction without the need for troponin testing. However, prospective studies are required to further validate these scores.

Value of Troponin in Predicting Hospital Mortality of Older Adult Patients without Suspected Acute Coronary Syndromes.

OBJECTIVES: Some authors have recommended troponin measurement to stratify patient mortality risk, but it is unclear whether troponin values add to age and routine admission laboratory tests in the prediction of in-hospital mortality of older adult patients without suspected acute coronary syndrome (ACS). The aim of our study was to determine whether troponin testing adds significantly to routine admission laboratory testing in predicting in-hospital mortality in patients without a suspected ACS. METHODS: In 2018-2019, we reviewed all acutely admitted patients aged 60 years or older to Internal Medicine wards of a regional hospital after excluding those admitted to intensive care or with chest pain. The independent variables were troponin, age, sex, and routine admission laboratory tests. The outcome measure was in-hospital mortality. We compared c-statistics and the observed 10% to 90% risk gradients using logistic regression models for age and routine laboratory testing before and after the addition of troponin. RESULTS: The mortality risk gradient for age and admission laboratory tests was 0.2% to 29.5%. Adding troponin did not increase the gradient significantly (0.2%-34.6%, P = 0.170), and the 95% confidence intervals for the c-statistics overlapped, increasing from 0.845 (0.818-0.876) to 0.866 (0.839-0.892). CONCLUSIONS: In older adult patients without suspected ACS, troponin testing did not improve the prediction of hospital mortality above that of a model including age and common admission blood tests. In the absence of suspected ACS, troponin testing is not needed to predict the hospital mortality of older adult patients.

Types of myocardial injury and mid-term outcomes in patients with COVID-19.

AIMS: To evaluate the acute and chronic patterns of myocardial injury among patients with coronavirus disease-2019 (COVID-19), and their mid-term outcomes. METHODS AND RESULTS: Patients with laboratory-confirmed COVID-19 who had a hospital encounter within the Mount Sinai Health System (New York City) between 27 February 2020 and 15 October 2020 were evaluated for inclusion. Troponin levels assessed between 72 h before and 48 h after the COVID-19 diagnosis were used to stratify the study population by the presence of acute and chronic myocardial injury, as defined by the Fourth Universal Definition of Myocardial Infarction. Among 4695 patients, those with chronic myocardial injury (n = 319, 6.8%) had more comorbidities, including chronic kidney disease and heart failure, while acute myocardial injury (n = 1168, 24.9%) was more associated with increased levels of inflammatory markers. Both types of myocardial injury were strongly associated with impaired survival at 6 months [chronic: hazard ratio (HR) 4.17, 95% confidence interval (CI) 3.44-5.06; acute: HR 4.72, 95% CI 4.14-5.36], even after excluding events occurring in the first 30 days (chronic: HR 3.97, 95% CI 2.15-7.33; acute: HR 4.13, 95% CI 2.75-6.21). The mortality risk was not significantly different in patients with acute as compared with chronic myocardial injury (HR 1.13, 95% CI 0.94-1.36), except for a worse prognostic impact of acute myocardial injury in patients <65 years of age (P-interaction = 0.043) and in those without coronary artery disease (P-interaction = 0.041). CONCLUSION: Chronic and acute myocardial injury represent two distinctive patterns of cardiac involvement among COVID-19 patients. While both types of myocardial injury are associated with impaired survival at 6 months, mortality rates peak in the early phase of the infection but remain elevated even beyond 30 days during the convalescent phase.

The effect of a chemotherapy drug cocktail on myotube morphology, myofibrillar protein abundance, and substrate availability.

Cachexia, a condition prevalent in many chronically ill patients, is characterized by weight loss, fatigue, and decreases in muscle mass and function. Cachexia is associated with tumor burden and disease-related malnutrition, but other studies implicate chemotherapy as being causative. We investigated the effects of a chemotherapy drug cocktail on myofibrillar protein abundance and synthesis, anabolic signaling mechanisms, and substrate availability. On day 4 of differentiation, L6 myotubes were treated with vehicle (1.4 µl/ml DMSO) or a chemotherapy drug cocktail (a mixture of cisplatin [20 µg/ml], leucovorin [10 µg/ml], and 5-fluorouracil [5-FLU; 50 µg/ml]) for 24-72 h. Compared to myotubes treated with vehicle, those treated with the drug cocktail showed 50%-80% reductions in the abundance of myofibrillar proteins, including myosin heavy chain-1, troponin, and tropomyosin (p < 0.05). Cells treated with only a mixture of cisplatin and 5-FLU had identical reductions in myofibrillar protein abundance. Myotubes treated with the drug cocktail also showed >50% reductions in the phosphorylation of AKTSer473 and of mTORC1 substrates ribosomal protein S6Ser235/236 , its kinase S6K1Thr389 and eukaryotic translation initiation factor 4E-binding protein 1 (all p < 0.05). Drug treatment impaired peptide chain initiation in myofibrillar protein fractions and insulin-stimulated glucose uptake (p = 0.06) but increased the expression of autophagy markers beclin-1 and microtubule-associated proteins 1A/1B light chain 3B (p < 0.05), and of apoptotic marker, cleaved caspase 3 (p < 0.05). Drug treatment reduced the expression of mitochondrial markers cytochrome oxidase and succinate dehydrogenase (p < 0.05). The observed profound negative effects of this chemotherapy drug cocktail on myotubes underlie a need for approaches that can reduce the negative effects of these drugs on muscle metabolism.

Differentiation between myopericarditis and acute myocardial infarction on presentation in the emergency department using the admission C-reactive protein to troponin ratio.

BACKGROUND: The treatment of myopericarditis is different than that of acute myocardial infarction (AMI). However, since their clinical presentation is frequently similar it may be difficult to distinguish between these entities despite a disparate underlying pathogenesis. Myopericarditis is primarily an inflammatory disease associated with high C-reactive protein (CRP) and relatively low elevated troponin concentrations, while AMI is characterized by the opposite. We hypothesized that evaluation of the CRP/troponin ratio on presentation to the emergency department could improve the differentiation between these two related clinical entities whose therapy is different. Such differentiation should facilitate triage to appropriate and expeditious therapy. METHODS: We evaluated the CRP/troponin ratio on presentation among patients consecutively included in a large single center registry that included 1898 consecutive patients comprising 1025 ST-elevation myocardial infarction (STEMI) patients, 518 Non-STEMI (NSTEMI) patients, and 355 patients diagnosed on discharge as myopericarditis. CRP and troponin were sampled on admission in all patients and their ratio was assessed against discharge diagnosis. ROC analysis of the CRP/troponin ratios evaluated the diagnostic accuracy of myopericarditis against all AMI, STEMI, and NSTEMI patients. RESULTS: Median admission CRP/troponin ratios were 84, 65, and 436 mg×ml/liter×ng in STEMI, NSTEMI and myopericarditis groups, respectively (p<0.001) demonstrating good differentiating capability. The Receiver-operator-curve of admission CRP/troponin ratio for diagnosis of myopericarditis against all AMI, STEMI, and NSTEMI patients yielded an area-under-the curve of 0.74, 0.73, and 0.765, respectively. CRP/troponin ratio>500 resulted in specificity exceeding 85%, and for a ratio>1000, specificity>92%. CONCLUSION: The CRP/troponin ratio can serve as an effective tool to differentiate between myopericarditis and AMI. In the appropriate clinical context, the CRP/troponin ratio may preclude further evaluation.

Distribution of High-Sensitivity Troponin Taken Without Conventional Clinical Indications in Critical Care Patients and Its Association With Mortality.

OBJECTIVES: To describe the distribution of high-sensitivity troponin in a consecutive cohort of patients in critical care units, regardless of clinical indication, and its association with clinical outcomes. DESIGN: Prospective observational study. SETTING: Single-center teaching hospital. PATIENTS: Consecutive patients admitted to two adult critical care units (general critical care unit and neuroscience critical care unit) over a 6-month period. INTERVENTIONS: All patients had high-sensitivity troponin tests performed at admission and tracked throughout their critical care stay, regardless of whether the supervising team felt there was a clinical indication. The results were not revealed to patients or clinicians unless clinically requested. MEASUREMENTS AND MAIN RESULTS: There were 1,033 patients in the study cohort (general critical care unit 750 and neuroscience critical care unit 283). The median high-sensitivity troponin was 21 ng/L (interquartile range, 7-86 ng/L), with 560 patients (54.2%) above the upper limit of normal as defined by the manufacturer. Admission high-sensitivity troponin concentrations above the upper limit of normal in general critical care unit and neuroscience critical care unit were associated with increasing age, comorbidity, markers of illness severity, and the need for organ support. On adjusted analysis, the high-sensitivity troponin concentration remained an independent predictor of critical care mortality in general critical care unit and neuroscience critical care unit. CONCLUSIONS: High-sensitivity troponin elevation, taken outside the context of conventional clinical indications, was common in the critically ill. Such elevations were associated with increasing age, comorbidity, illness severity, and the need for organ support. Admission high-sensitivity troponin concentration is an independent predictor of critical care mortality and as such may represent a novel prognostic biomarker at admission.

Biomarkers of Cardiac Stress and Cytokine Release Syndrome in COVID-19: A Review.

PURPOSE OF REVIEW: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulted in the coronavirus 2019 (COVID-19) global pandemic. While primarily a respiratory virus, SARS-CoV-2 can cause myocardial injury. The pattern of injury, referred to as acute COVID-19 cardiovascular syndrome (ACovCS), is defined by cardiac troponin leak in the absence of obstructive coronary artery disease. Although the etiology of the injury is unknown, many speculate that a cytokine release syndrome (CRS) may be an important factor. We aim to review recent data concerning markers of cardiac injury in ACovCS and its relation to the CRS. RECENT FINDINGS: Cardiac injury was common in patients hospitalized for COVID-19, with both cardiac troponin and B-type natriuretic peptide (BNP) being elevated in this population. Biomarkers were correlated with illness severity and increased mortality. Cytokines such as IL-6 were more often elevated in patients with ACovCS. Myocarditis evident on cardiac MR following COVID-19 may be associated with cardiac troponin levels. The impact of dexamethasone and remdesivir, two therapies shown to have clinical benefit in COVID-19, on myocardial injury is unknown. Biomarkers of cardiac stress and injury in COVID-19 may be used to stratify risk in the future. Currently, there is no evidence that inhibition of cytokine release will reduce myocardial injury in patients with COVID-19.

Myocardial injury in hospitalized patients with COVID-19 infection-Risk factors and outcomes.

Myocardial injury in hospitalized patients is associated with poor prognosis. This study aimed to evaluate risk factors for myocardial injury in hospitalized patients with coronavirus disease 2019 (COVID-19) and its prognostic value. We retrieved all consecutive patients who were hospitalized in internal medicine departments in a tertiary medical center from February 9th, 2020 to August 28th with a diagnosis of COVID-19. A total of 559 adult patients were hospitalized in the Sheba Medical Center with a diagnosis of COVID-19, 320 (57.24%) of whom were tested for troponin levels within 24-hours of admission, and 91 (28.44%) had elevated levels. Predictors for elevated troponin levels were age (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.01-1.06), female sex (OR, 3.03; 95% CI 1.54-6.25), low systolic blood pressure (OR, 5.91; 95% CI 2.42-14.44) and increased creatinine level (OR, 2.88; 95% CI 1.44-5.73). The risk for death (hazard ratio [HR] 4.32, 95% CI 2.08-8.99) and a composite outcome of invasive ventilation support and death (HR 1.96, 95% CI 1.15-3.37) was significantly higher among patients who had elevated troponin levels. In conclusion, in hospitalized patients with COVID-19, elevated troponin levels are associated with poor prognosis. Hence, troponin levels may be used as an additional tool for risk stratification and a decision guide in patients hospitalized with COVID-19.

Biomarkers in Atrial Fibrillation: Pathogenesis and Clinical Implications.

Biomarkers derived from the key components of the pathophysiology of atrial fibrillation (AF) and its complications have the potential to play an important role in earlier characterization of AF phenotype and in risk prediction of adverse clinical events, which may translate into improved management strategies. C-reactive protein, natriuretic peptides, cardiac troponins, growth differentiation factor-15, and fibroblast growth factor-23 have been shown to be the most promising biomarkers in AF. Some biomarkers have already been included in clinical risk scores to predict postoperative AF, thromboembolism, major bleeding, and death. Considerably more work is needed to bring these novel biomarkers into routine clinical management of patients with AF.

Risk for cardiovascular events following 'microsize' versus usual myocardial infarctions.

BACKGROUND: Microsize myocardial infarction (MI) is a recently described phenomenon that meets rigorous criteria for MI with very low peak troponin elevations. We aim to compare the risk for cardiovascular events and mortality following microsize versus usual MIs. METHODS AND RESULTS: Prospective cohort analysis of REasons for Geographic And Racial Differences in Stroke (REGARDS) study participants without a history of coronary heart disease (CHD) who had an incident MI between 2003 and 2015. Incident MIs were classified as microsize MI (peak troponin <0.5 ng/mL) or usual MI (peak troponin ≥0.5 ng/mL). Participants were followed for a composite of cardiovascular events that included recurrent MI, coronary revascularisation, fatal CHD and heart failure, and all-cause mortality. Overall, 1024 participants with an incident MI were included in the analysis (328 with microsize MI and 696 with usual MI). Participants with microsize MI were more likely to be older and black. The multivariable-adjusted adjustment HR for cardiovascular events among participants with microsize versus usual MI after a median follow-up of 1.7 years was 1.11 (95% CI 0.86 to 1.44). The multivariable-adjusted HR for all-cause mortality after 28 days from incident MI among participants with microsize versus usual MI after a median follow-up of 3.6 years was 1.09 (95% CI 0.81 to 1.45). CONCLUSION: Microsize MIs have a prognostic value for future cardiovascular events and mortality comparable to usual MIs. These findings should encourage clinicians to initiate secondary prevention strategies in patients with microsize MI until this emerging clinical entity is better understood.

Incidence and determinants of high-sensitivity troponin and natriuretic peptides elevation at admission in hospitalized COVID-19 pneumonia patients.

BACKGROUND: Myocardial involvement in the course of coronavirus disease 2019 (COVID-19) pneumonia has been reported, though not fully characterized yet. The aim of the present study is to undertake a joint evaluation of hs-Troponin and natriuretic peptides (NP) in patients hospitalized for COVID-19 pneumonia. METHODS: In this multicenter observational study, we analyzed data from n = 111 patients. Cardiac biomarkers subgroups were identified according to values beyond reference range. RESULTS: Increased hs-Troponin and NP were found in 38 and 56% of the cases, respectively. As compared to those with normal cardiac biomarkers, these patients were older, had higher prevalence of cardiovascular diseases (CVD) and had more severe COVID-19 pneumonia by higher CRP and D-dimer and lower PaO2/FIO2. Two-dimensional echocardiography performed in a subset of patients (n = 24) showed significantly reduced left ventricular ejection fraction in patients with elevated NP (p = 0.02), whereas right ventricular systolic function (tricuspid annular plane systolic excursion) was significantly reduced both in patients with high hs-Troponin and NP (p = 0.022 and p = 0.03, respectively). Both hs-Troponin and NP were higher in patients with in-hospital mortality (p = 0.001 and p = 0.002, respectively). On multivariable analysis, independent associations were found of hs-Troponin with age, PaO2/FIO2 and D-dimer (B = 0.419, p = 0.001; B = - 0.212, p = 0.013; and B = 0.179, p = 0.037, respectively) and of NP with age and previous CVD (B = 0.480, p < 0.001; and B = 0.253, p = 0.001, respectively). CONCLUSIONS: Myocardial involvement at admission is common in COVID-19 pneumonia. Independent associations of hs-Troponin with markers of disease severity and of NP with underlying CVD might point toward existing different mechanisms leading to their elevation in this setting.