Interaction of heparin with human cardiac troponin complex and its influence on the immunodetection of troponins in human blood samples

OBJECTIVES

Heparin is a highly charged polysaccharide used as an anticoagulant to prevent blood coagulation in patients with presumed myocardial infarction and to prepare heparin plasma samples for laboratory tests. There are conflicting data regarding the effects of heparin on the measurement of cardiac isoforms of troponin I (cTnI) and troponin T (cTnT), which are used for the immunodiagnosis of acute myocardial infarction. In this study, we investigated the influence of heparin on the immunodetection of human cardiac troponins.

METHODS

Gel filtration (GF) techniques and sandwich fluoroimmunoassay were performed. The regions of сTnI and cTnT that are affected by heparin were investigated with a panel of anti-cTnI and anti-cTnT monoclonal antibodies, specific to different epitopes.

RESULTS

Heparin was shown to bind to the human cardiac full-size ternary troponin complex (ITC-complex) and free cTnT, which increased their apparent molecular weights in GF studies. Heparin did not bind to the low molecular weight ITC-complex and to binary cTnI-troponin С complex. We did not detect any sites on cTnI in the ITC-complex that were specifically affected by heparin. In contrast, cTnT regions limited to approximately 69-99, 119-138 and 145-164 amino acid residues (aar) in the ITC-complex and a region that lies approximately between 236 and 255 aar of free cTnT were prone to heparin influence.

CONCLUSIONS

Heparin binds to the ITC-complex via cTnT, interacting with several sites on the N-terminal and/or central parts of the cTnT molecule, which might influence the immunodetection of analytes in human blood.

Advances in nanotechnological approaches for the detection of early markers associated with severe cardiac ailments

Mortality from cardiovascular disease (CVD) accounts for over 30% of all deaths globally, necessitating reliable diagnostic tools. Prompt identification and precise diagnosis are critical for effective personalized treatment. Nanotechnology offers promising applications in diagnostics, biosensing and drug delivery for prevalent cardiovascular diseases. Its integration into cardiovascular care enhances diagnostic accuracy, enabling early intervention and tailored treatment plans. By leveraging nanoscale innovations, healthcare professionals can address the complexities of CVD progression and customize interventions based on individual patient needs. Ongoing advancements in nanotechnology continue to shape the landscape of cardiovascular medicine, offering potential for improved patient outcomes and reduced mortality rates from these pervasive diseases.

Antibody-functionalized gold nanoclusters/gold nanoparticle platform for the fluorescence turn-on detection of cardiac troponin I

A selective fluorescence turn-on immunosensor for the specific detection of cardiac troponin I (cTnI), the potent biomarker for myocardial infarction diagnosis, was developed with a nano couple comprised of protein-stabilized gold nanocluster and gold nanoparticle. The red fluorescence of cTnI-specific antibody tagged bovine serum albumin stabilized gold nanoclusters was quenched with gold nanoparticles (AuNP) via the intensive interaction between amine and hydroxyl functionalities of BSA and AuNP. Through this, the adsorption of gold nanoclusters at the surface of AuNP, resulting in a core-satellite assembly, was assumed to quench the fluorescence emission. While in the presence of cTnI antigen, this gets disturbed due to the formation of immunocomplex between cTnI antigen and antibody, which restricts the close interaction between gold clusters and nanoparticles, thereby restoring quenched fluorescence. The enhancement in fluorescence signal is directly related to the concentration of cTnI, and this facilitates the selective detection of cTnI in the linear concentration range 0.7 to 10 ng/mL without any interference from other potentially interfering co-existing biomolecules. An appreciable limit of detection of 0.51 ng/mL and a limit of quantification of 0.917 ng/mL for cTnI is comparable to that of the previous report.

Do quantitative levels of cardiac troponin I implicate on severity of disease in children, adolescences, and young adults with acute myocarditis and myopericarditis?

OBJECTIVES

When cardiac muscle damage occurs, cardiac troponins are released to blood and their detection is used as a marker in clinical setting. The prognostic value of the quantitative levels of blood troponin I in cases of myocarditis and myopericarditis is unclear. The aim of this study was to analyse whether troponin quantitative blood levels can be correlated with the course of hospitalisation and prognosis.

METHODS

Retrospective data was collected from all consecutive patients aged ≤30 hospitalised with a diagnosis of acute myocarditis or acute myopericarditis in our health Care Campus between the years 2010-2016.

RESULTS

Ninety-three patients with myocarditis and myopericarditis were identified. Higher peak troponin levels correlated with longer hospitalisation times in the cardiac or paediatric wards (p = 0.03, Pearson correlation: r -0.23), and median troponin level at admission correlated with longer overall hospitalisation (p = 0.026, Pearson correlation: r = 0.23). Patients admitted to ICU, received oral cardiac supportive therapy or that were discharged with cardiac drugs had higher median troponin compared to patients who were not but this was not statistically significant. A small group of patients that needed intravenous cardiac support had significantly lower median peak troponin levels (n = 4, 0.375ng/ml, p = 0.048). Only two patients needed extracorporeal membrane oxygenation support, and one died. The small number of patients precludes statistical analysis.

CONCLUSION

Higher troponin levels correlated significantly with longer hospitalisation, lower troponin values correlated with intravenous cardiac support, while other variables related to the severity of disease could not be significantly related to higher troponin levels.

Electrochemical Biosensors for Whole Blood Analysis: Recent Progress, Challenges, and Future Perspectives

Whole blood, as one of the most significant biological fluids, provides critical information for health management and disease monitoring. Over the past 10 years, advances in nanotechnology, microfluidics, and biomarker research have spurred the development of powerful miniaturized diagnostic systems for whole blood testing toward the goal of disease monitoring and treatment. Among the techniques employed for whole-blood diagnostics, electrochemical biosensors, as known to be rapid, sensitive, capable of miniaturization, reagentless and washing free, become a class of emerging technology to achieve the target detection specifically and directly in complex media, e.g., whole blood or even in the living body. Here we are aiming to provide a comprehensive review to summarize advances over the past decade in the development of electrochemical sensors for whole blood analysis. Further, we address the remaining challenges and opportunities to integrate electrochemical sensing platforms.

Cardiac troponins: Mechanisms of release and role in healthy and diseased subjects

The cardiac troponins (cTns), cardiac troponin C (cTnC), cTnT, and cTnI are key elements of myocardial apparatus, fixed as protein complex on the thin filament of sarcomere and are involved in the regulation of excitation-contraction coupling of cardiomyocytes in the presence of Ca²⁺ . Circulating cTnT and cTnI (cTns) increase following cardiac tissue necrosis, and they are consolidated biomarkers of acute myocardial infarction (AMI). However, the use of high sensitivity (hs)-immunoassay tests for cTnT and cTnI has made it possible to identify a multitude of other clinical conditions associated with increased circulating levels of cTns. cTns can be measured also in the peripheral circulation of healthy subjects or athletes, suggesting that different mechanisms are involved in the release of cTns in the blood independently of cardiac cell necrosis. In this review, the molecular/cellular mechanisms involved in cTns release in blood and the exploitation of cTnI and cTnT as biomarkers of cardiac adverse events, in addition to cardiac necrosis, are discussed.

Biomarker Development in Cardiology: Reviewing the Past to Inform the Future

Cardiac biomarkers have become pivotal to the clinical practice of cardiology, but there remains much to discover that could benefit cardiology patients. We review the discovery of key protein biomarkers in the fields of acute coronary syndrome, heart failure, and atherosclerosis, giving an overview of the populations they were studied in and the statistics that were used to validate them. We review statistical approaches that are currently in use to assess new biomarkers and overview a framework for biomarker discovery and evaluation that could be incorporated into clinical trials to evaluate cardiovascular outcomes in the future.

Long-term in vivo operation of implanted cardiac nanogenerators in swine

Implantable nanogenerators (i-NG) provide power to cardiovascular implantable electronic devices (CIEDs) by harvesting biomechanical energy locally eliminating the need for batteries. However, its long-term operation and biological influences on the heart have not been tested. Here, we evaluate a soft and flexible i-NG system engineered for long-term in vivo cardiac implantation. It consisted of i-NG, leads, and receivers, and was implanted on the epicardium of swine hearts for 2 months. The i-NG system generated electric current throughout the testing period. Biocompatibility and biosafety were established based on normal blood and serum test results and no tissue reactions. Heart function was unchanged over the testing period as validated by normal electrocardiogram (ECG), transthoracic ultrasound, and invasive cardiac functional measures. This research demonstrates the safety, long term operation and therefore the feasibility of using i-NGs to power the next generation CIEDs.

Electrochemical Immunosensor for Cardiac Troponin I Detection Based on Covalent Organic Framework and Enzyme-Catalyzed Signal Amplification

Herein, a highly sensitive electrochemical immunosensor was presented for the cardiac troponin I (cTnI) determination using a multifunctional covalent organic framework-based nanocomposite (HRP-Ab2-Au-COF) as the signal amplification probe. The spherical COF with a large surface area was synthesized in a short time by a simple solution-based method at room temperature. The good biocompatibility, low toxicity, and high stability in water of the COF guarantee its application in biosensing. Besides, its high porosity makes it an excellent carrier for loading abundant horseradish peroxidase (HRP). The modified gold nanoparticles on the surface of COF not only provide a load platform for secondary antibody (Ab2) but also improve the conductivity of COF. Under the synergistic effect of the hydrogen peroxide (H₂O₂) and HRP, hydroquinone (HQ) in the solution is catalytically oxidized to benzoquinone (BQ), which is then reduced on the electrode surface to generate the electrochemical signal. The designed probes not only show the specific recognition behavior of Ab2 to cTnI but also improve the sensitivity of the biosensing system due to the signal amplification caused by the excellent enzyme catalytic performance of HRP. Based on the H₂O₂-HRP-HQ signal amplification system, the biosensor for cTnI was fabricated and exhibited a linear response as a function of logarithmic cTnI concentration ranging from 5 pg/mL to 10 ng/mL, and the detection limit was 1.7 pg/mL. Moreover, the biosensor exhibited excellent recovery and reproducibility in the actual sample testing. This work provided a simple approach to determine cTnI quantitatively in practical samples and broadened the utilization scope of the COF-based nanocomposite in the electrochemical immunosensor.

Histopathological, histochemical and biochemical postmortem changes in induced fatal hypothermia in rats

Reaching a postmortem diagnosis of hypothermia is challenging in forensic practice. Therefore, this study was conducted to detect the histopathological, histochemical and biochemical changes that occur in adult albino rats following exposure to induced fatal hypothermia. Twenty-four adult albino rats were divided into the negative control, moderate hypothermia, severe hypothermia and hypoxia groups. Rats in the control group were euthanized when those in the moderate hypothermic group died. Blood samples were collected via heart puncture, and the cerebrum, heart, suprarenal gland, kidney, liver and skeletal muscle were removed to investigate the biochemical, histochemical and histopathological changes. Postmortem assessment depicted significant changes in lipid peroxidation, represented by increased malondialdehyde levels in the studied organs of the rats in hypothermic and hypoxia groups. Histopathological examination of the rats’ organs revealed degeneration and necrosis in the hypothermia and hypoxia groups. Sections taken from the severe hypothermic rats revealed a loss of normal cardiac tissue architecture, necrotic changes in the pyramidal cells in the cerebral cortex, and massive necrosis, mainly in the tubules of the renal cortex and medulla. These findings suggest that histological changes might be used as biochemical markers for postmortem diagnosing of fatal hypothermia, particularly in severe hypothermic conditions.

Key points

Death by hypothermia is a serious public health problem worldwide.

Confirming a diagnosis and determining the cause of death in cases of hypothermia are among the most difficult practices in forensic medicine.

Death by hypothermia might be associated with structural abnormalities in various organs.

Studies using different tissue staining techniques will enable an overall illustration of the role of histopathological changes in body organs as indicators of hypothermia.

99th Percentile Upper-Reference Limit of Cardiac Troponin and the Diagnosis of Acute Myocardial Infarction

BACKGROUND

Concerns exist regarding how the 99th percentile upper reference limit (URL) of cardiac troponin (cTn) is determined and whether it should be derived from normal healthy individuals.

CONTENT

The 99th percentile URL of cTn is an important criterion to standardize the diagnosis of myocardial infarction (MI) for clinical, research, and regulatory purposes. Statistical heterogeneity in its calculation exists but recommendations have been proposed. Some negativity has resulted from the fact that with some high-sensitivity (hs) cTn assays, a greater number of increases above the 99th percentile are observed when transitioning from a contemporary assay. Increases reflect acute or chronic myocardial injury and provide valuable diagnostic and prognostic information. The etiology of increases can sometimes be difficult to determine, making a specific treatment approach challenging. For those reasons, some advocate higher cutoff concentrations. This approach can contribute to missed diagnoses. Contrary to claims, neither clinical or laboratory guidelines have shifted away from the 99th percentile. To support the diagnosis of acute MI, the 99th percentile URL remains the best-established approach given the absence of cTn assay standardization. Importantly, risk stratification algorithms using hs-cTn assays predict the possibility of MI diagnoses established using the 99th percentile.

SUMMARY

The 99th percentile of cTn remains the best-established criterion for the diagnosis of acute MI. While not perfect, it is analytically and clinically evidence-based. Until there are robust data to suggest some other approach, staying with the 99th percentile, a threshold that has served the field well for the past 20 years, appears prudent.

Heterophile antibodies, false-positive troponin, and acute coronary syndrome: a case report indicating a pitfall in clinical practice

BACKGROUND

Heterophile antibodies are one of the most common causes of false-positive troponin.

CASE SUMMARY

We report a case of a 53-year-old woman with false-positive troponin elevation and a clinical presentation understood and treated as non-ST-elevation acute coronary syndrome. Because of chronic basal elevation of troponin (at a 'plateau' level) and chest pain, the patient underwent several invasive coronary angiograms until false-positive increase of troponin due to heterophile antibodies was suspected. Borderline stenosis of a left circumflex coronary artery found on first coronary angiogram was a coincidental finding and heterophile antibodies in the patient's serum were confirmed.

DISCUSSION

This interesting case report aims to remind the clinicians about the possibility of false-positive troponin level due to laboratory analytical interference caused by heterophile antibodies. In this case, it is important to suspect false-positive troponin elevation, even when coronary artery disease is found. This rare and less mentioned and/or recognized cause of troponin elevation may lead to unnecessary invasive diagnostics and aggressive treatment of patients.

Acute Myocardial Infarction Biosensor: A Review From Bottom Up

Acute myocardial infarction (AMI) is a cardiovascular disease that is produced due to a deficiency of oxygen generating irreversible damage in the heart muscle. In diagnosis, electrocardiogram (ECG) investigation has been the main method but is insufficient, so approaches like the measurement of biomarkers levels in plasma or saliva have become one of the most commonly applied strategies for prognosis of AMI, as some of them are specifically related to a heart attack. Many tests are carrying on to determine biological markers changes, but usually, they present disadvantages related to time consumption and laborious work. To overcome the issues, researchers around the world have been developing different ways to enhance detection through the use of biosensors. These diagnostic devices have a biological sensing element associated to a physicochemical transducer that can be made from different materials and configurations giving place to different kinds of detection: Electrical/Electrochemical, Optical and Mechanical. In this review, the authors presents relevant investigations related to the most important biomarkers and biosensors used for their detection having in mind the nanotechnology participation in the process through the application of nanostructures as a good choice for device configuration.

Diagnostic Performance of Point-of-Care Troponin I and Laboratory Troponin T in Patients Presenting to the ED with Chest Pain: A Comparative Study

Background

Chest pain is a common symptom in patients visiting the emergency department (ED). Diagnosing acute coronary syndrome is a challenging task for emergency physicians. Evaluation of chest pain depends on clinical symptoms and signs, ECG, and cardiac enzymes. Here, we aimed to compare the diagnostic performance of the point-of-care troponin I assay with laboratory HsTnT assay in patients presenting to the ED with chest pain.

Methods

A prospective study was done at the ED of Alkhor Hospital, Hamad Medical Corporation, between March 2016 and December 2016. Patients more than 18 years old who presented to the ED with chest pain were enrolled. Patients with renal failure, initial ECG showing ST-elevation MI, or arrhythmias, and hemodynamically unstable patients were excluded. A blood sample was collected at 0 and 3 hours post-admission for POC TnI and laboratory HsTnT assay. The sensitivity, specificity, PPV, NPV, and AUC were determined and compared.

Results

Out of 313 patients enrolled, ten were excluded. At 0 hour, the POC TnI assay had a lower sensitivity (72.5% versus 97.5%) and had almost equal specificity (99.24% versus 93.2%) when compared to lab HsTnT assay. At 3 hours post-admission, the sensitivity increased to 95% versus 100%, and specificity was 100% versus 94.3% when compared to lab HsTnT. The POC TnI assay had a higher PPV than HsTnT, whereas both assays showed a high NPV at 0 and 3 hours.

Conclusion

Although the diagnostic performance of POC TnI was lower than that of Lab HsTnT at 0 hour, at 3 hours post-admission, the diagnostic performance was almost equal to that of HsTnT. Hence we conclude that chest pain in patients with a negative POC TnI at 3 hours post-admission is unlikely to be due to NSTEMI.

Analytical performance of cardiac troponin assays - Current status and future needs

Concurrent with the introduction of cardiac troponin measurements into the diagnostic definition of myocardial infarction (MI), clinicians and laboratory professionals signaled a clear clinical need for improved analytical quality. This was an important precipitant for developing high-sensitivity cardiac troponin (hs-cTn) assays, currently used in rapid algorithms guiding investigations of patients presenting to the emergency department with possible MI. The hs-cTn assays were also important for the detection and monitoring of low-grade chronic myocardial injury, a condition that has been linked to increased long-term risk of cardiovascular morbidity and mortality. This review summarizes the general recommendations for defining analytical performance specifications while providing relevant clinical situations related to analytical performance. Importantly, outcome studies suggest analytical quality performance for hs-cTn is sufficient for early discharge of patients investigated for possible MI. However, bias due to change in calibrators or reagents may significantly affect the percentage of patients discharged. Biological variation data is suitable for defining performance specifications when hs-cTn measurements are used for diagnosing and monitoring chronic myocardial injury. Further improvement in analytical performance for hs-cTn testing may result in even faster decision making in the emergency setting; while also identifying those with chronic injury at risk for an adverse cardiac event.

Cardiac biomarker measurement by point of care testing - Development, rationale, current state and future developments

Cardiac biomarker measurements are integral to the diagnosis and management of patients presenting with breathlessness and chest pain. Measurement of B type natriuretic peptide either directly or of the N-terminal portion of the prohormone although possible by point of care testing (POCT) has largely become a laboratory test. Measurement of the cardiac troponins cardiac troponin T (cTnT) and cardiac troponin I (cTnI) can easily and accurately be performed by POCT. The situation has been complicated by the development of high sensitivity assays for cTnT and cTnI and the subsequent development of rapid rule out algorithms allowing patient categorisation and discharge on admission and 1 to 2 h following admission. This article reviews the development of POCT for cardiac biomarkers, the evidence base comparing POCT with central laboratory testing, its strengths and limitations, and how POCT fits into the world of high sensitivity troponin assays. It also discusses what evidence there is that POCT can form part of rapid decision-making strategies and how this applies in an era of algorithms based on and is derived from measurement of high sensitivity troponin in the central laboratory.

Cardiac biomarkers by point-of-care testing – back to the future?

The measurement of the cardiac troponins (cTn), cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are integral to the management of patients with suspected acute coronary syndromes (ACS). Patients without clear electrocardiographic evidence of myocardial infarction require measurement of cTnT or cTnI. It therefore follows that a rapid turnaround time (TAT) combined with the immediacy of results return which is achieved by point-of-care testing (POCT) offers a substantial clinical benefit. Rapid results return plus immediate decision-making should translate into improved patient flow and improved therapeutic decision-making. The development of high sensitivity troponin assays offer significant clinical advantages. Diagnostic algorithms have been devised utilising very low cut-offs at first presentation and rapid sequential measurements based on admission and 3 h sampling, most recently with admission and 1 h sampling. Such troponin algorithms would be even more ideally suited to point-of-care testing as the TAT achieved by the diagnostic laboratory of typically 60 min corresponds to the sampling interval required by the clinician using the algorithm. However, the limits of detection and analytical imprecision required to utilise these algorithms is not yet met by any easy-to-use POCT systems.

Eight biomarkers on a novel strip for early diagnosis of acute myocardial infarction

Accurate detection of markers in human serum is important in the early diagnosis of acute myocardial infarction (AMI). This work presents a novel eight biomarker strip, which combines dry chemistry with a fluorescence lateral flow assay. Eight AMI markers were employed simultaneously for sensitive detection, including cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C), uric acid (UA), myoglobin (Myo), creatine kinase-MB (CK-MB), and cardiac troponin I (cTnI). The strip offers the advantages of simple fabrication, convenience, time-saving detection and accurate assessment for AMI. Moreover, the strip possesses acceptable applicability for human serum. This proposed strategy establishes a remarkable platform for the construction of a multi-target detection strip that is feasible for accurate detection for real human serum samples.

High sensitivity, contemporary and point-of-care cardiac troponin assays: educational aids developed by the IFCC Committee on Clinical Application of Cardiac Bio-Markers

The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) formed a Task Force on the Application of Cardiac Bio-markers (TF-CB) in 2008, re-designated in 2018 as a committee (C-CB), to produce educational materials on cardiac biomarkers. Established in June 2017, definitive tables covering the majority of high-sensitivity, contemporary and point-of-care (POC) cTn assays have been developed by the C-CB and are available on the IFCC website. These tables provide extensive information about assays' analytical characteristics and encompass information on diagnostic discriminants, particularly the 99th percentiles, as provided by the manufacturers.

The impact of exercise modality and menstrual cycle phase on circulating cardiac troponin T

OBJECTIVES

It is unclear whether exercise modality (moderate-intensity continuous [MCE]; high-intensity interval [HIE]) and menstrual cycle phase (follicular [FP]; luteal [LP]), individually or in combination, mediate the commonly observed exercise-induced elevation in cardiac troponin T (cTnT). This study examines cTnT responses to MCE and HIE during both the FP and LP.

DESIGN

Randomised crossover study.

METHODS

Seventeen healthy, eumenorrheic women completed four trials including MCE (60% VO_2max steady-state cycling until 300kJ) and work-equivalent HIE (repeated 4-min cycling at 90% VO_2max interspersed with 3-min rest) during both the FP and LP. The FP and LP were verified based on ovarian hormones. Serum cTnT was assessed using a high-sensitivity assay before, immediately after, and 1 (1HR), 3 (3HR) and 4 (4HR) hours after exercise. cTnT values were corrected for plasma volume changes.

RESULTS

cTnT was significantly elevated (p<0.05) post-exercise in both MCE (at 3HR and 4HR) and HIE (at 1HR, 3HR and 4HR). No statistically significant difference (p>0.05) in peak post-exercise cTnT, which mostly occurred at 3HR, was seen among the four trials (median [range], ngl^-1: 5.2 [1.7-18.1] after MCE during FP; 4.8 [1.7-24.9] after MCE during LP, 8.2 [3.9-24.8] after HIE during FP and 6.9 [1.7-23.1] after HIE during LP).

CONCLUSIONS

A single 300kJ bout of both MCE or HIE resulted in a significant post-exercise increase in cTnT, with no differences in peak cTnT response between menstrual cycle phases or between exercise modes, but the cTnT elevation occurs slightly earlier after HIE.

Acute effects of recreational soccer on inflammatory response and cardiac and skeletal muscle damage indicators

Introduction: Previous studies have indicated that acute bouts of strenuous, long duration exercise induce significant increases in the inflammatory profile and cardiovascular risk markers. Although recreational soccer (RS) is a widespread activity, there are no data on this topic. Thus, the aim of this study was to examine RS-induced changes in inflammatory, cardiac, and skeletal muscle damage indicators in young and middle-aged males.

Methods: Twelve young and 11 middle-aged males participated in the study. The participants played 6v6 1 h RS, where heart rate (HR) responses and external loads (distance covered, number of accelerations/decelerations) were determined. Blood samples were taken immediately prior to and following the matches, and 2 h, 4 h, 24 h, 48 h, and 72 h later.

Results: Absolute HR responses and the number of accelerations and decelerations were higher in young participants than the middle-aged participants (p < 0.05). RS increased high sensitivity cardiac troponin I (hs-cTnI) in almost all participants. A total of 83.3% of the young participants exceeded the upper reference limit (URL), whereas none of the middle-aged participants exceeded the URL. Hs-cTnI levels returned to baseline after 24 and 48 h in the middle-aged and young participants, respectively. High sensitivity C-reactive protein (hs-CRP) and creatine kinase (CK) increased in the middle-aged participants (p < 0.05), and in the young participants, though not significantly (p > 0.05). RS also led to significant increases in lactate dehydrogenase (LDH) in both groups (p < 0.05). Hs-CRP, CK, and LDH values returned to baseline levels within 48 to 72 h, except for the LDH values of the young participants.

Conclusion: RS induced short-term increases in cardiac and skeletal muscle damage markers and the inflammatory profile in young and middle-aged RS participants.

Cardiac troponin I autoantibody induces myocardial dysfunction by PTEN signaling activation

Background

The objective of the current study was to study the molecular mechanism(s) underlying cardiac troponin I autoantibody (cTnIAAb) binding to cardiomyocyte and resultant myocardial damage/dysfunction.

Methods

cTnIAAb was purified from serum of 10 acute myocardial infarction (AMI) patients with left ventricular remodeling. Recombinant human cTnI was used to generate three mouse-derived monoclonal anti-cTnI antibodies (cTnImAb1, cTnImAb2, and cTnImAb3). The target proteins in cardiac myocyte membrane bound to cTnImAb and effect of cTnIAAb and cTnImAb on apoptosis and myocardial function were determined.

Findings

We found that cTnIAAb/cTnImAb1 directly bound to the cardiomyocyte membraneα-Enolase (ENO1) and triggered cell apoptosis via increased expression of ENO1 and Bax, decreased expression of Bcl2, subsequently activating Caspase8, Caspase 3, phosphatase and tensin homolog (PTEN) while inhibiting Akt activity. This cTnIAAb-ENO1-PTEN-Akt signaling axis contributed to increased myocardial apoptosis, myocardial collagen deposition, and impaired systolic dysfunction.

Interpretation

Results obtained in this study indicate that cTnIAAb is involved in the process of ventricular remodeling after myocardial injury.

Fund

The National Natural Science Foundation of China (Grant#: 81260026).

Molecular markers relevant to myocardial injury following dental extraction in patients with or without coronary artery disease

Objectives

The aim of this study was to characterize biological changes following dental extractions in patients with and without coronary artery disease (CAD).

Materials and methods

Forty-five patients (36 males and 9 females) referred for dental extraction underwent treatment and provided blood samples before, immediately after, and 24 h after the procedure. A broad array of biomarkers was employed to assess myocardial injury (highly sensitive troponin T, hs-TnT), bacterial burden (LPS endotoxin activity), and systemic inflammation (CRP, fibrinogen, IFN-γ, IL-1β, IL-6, IL-8, IL-10, IL-12, and TNF-α).

Results

Dental extraction in patients with and without CAD was associated with rises in hs-TnT (p = 0.013), hs-CRP (p < 0.001), fibrinogen (p = 0.005), endotoxin activity (p < 0.001), IFN-γ (p < 0.001), IL-6 (p < 0.001), IL-8 (p = 0.011), and IL-12 (p < 0.001) at 24 h compared with immediately post procedure. Changes in systemic inflammation and endotoxin activity were more evident in those with hs-TnT rise.

Conclusions

Simple dental extractions may cause mild increase in hs-TnT, indicating minor myocardial injury in both patients with and without CAD. Acute systemic inflammation and endotoxemia could represent a possible link between invasive dental treatment and increased risk of acute cardiovascular events. These findings indicate that invasive dental treatment (as simple as a single dental extraction) may impact negatively on clinical outcomes in dental patients, especially those with CAD.

An aptasensor for troponin I based on the aggregation-induced electrochemiluminescence of nanoparticles prepared from a cyclometallated iridium(III) complex and poly(4-vinylpyridine-co-styrene) deposited on nitrogen-doped graphene

An ultrasensitive electrochemiluminescence (ECL) disposable aptamer sensor (aptasensor) is presented for detection of myocardial infarction biomarker by quantification of troponin I in blood serum. A screen-printed electrode was modified with (a) aptamer-modified gold nanoparticles, (b) cyclometallated iridium(III)-poly-4-vinylpyridine nanoparticles, and (c) nitrogen-doped graphene in order to increase the loading capacity and conductivity of the aptasensor. If the aptasensor is exposed to troponin I, it will bind to the aptamer and desorb the aptamer from gold nanoparticles and the surface of the electrode. This generates an enhancement in ECL emission depending on troponin I concentration. ECL emission is strongly improved by aggregation-induced phenomenon, which is caused by inhibition of the water and oxygen quenching effect on the iridium complex ECL in aqueous media. Under optimum conditions, the aptasensor has a wide dynamic range that extends from 0.1 pM to 10 nM, with a 20 fM detection limit (S/N = 3) and a relative standard deviation of 3.1%. The ECL aptasensor was successfully applied to 20 individual human serum for the detection of troponin I biomarker. Graphical abstract Schematic presentation of electrochemiluminescence aptamer assay fabrication for detection of Troponin I. Carbon screen printed electrode (CSPE) was modified with nitrogen doped graphene (NG), gold nanoparticles (AuNPs), cyclometallated iridium(III)-polyvinylpyridine polymer nanoparticles, ionic liquid and bovine serum albumin.

Assessment of Access hsTnI 99th percentiles upper reference limits following IFCC recommendations

BACKGROUND

The detection of an increase and/or decrease of cardiac troponin (cTnI) values, with at least one value above the 99th percentile of the upper reference limit (URL) have a central role in acute myocardial infarction (AMI) diagnosis. The employment of sex specific 99th percentile URLs and High-sensitivity (Hs) assays are recommended. We assessed sex specific 99th percentile URL for Access Hs-cTnI and AccuTnI3+ (Beckman Coulter) using European donor reference population following recent International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendations.

METHODS

300 males and 300 females plasma samples were collected. Both chemiluminescent immunoenzymatic assays were performed on UniCel DxI 800 platform (Beckman Coulter).

RESULTS

For Access hsTnI, the observed sex-specific 99th percentile URLs were 5.5 (90% CI: 4.4-7.6) for females and 13.9 ng/L (90% CI: 7.4-17.4) for males. For AccuTnI+3 we could not establish them because the assay couldn't report detectable values of troponin for most of the analyzed samples.

CONCLUSION

The sex-specific 99th percentile URLs established for Access hsTnI assay were significantly lower than those declared by the manufacturer caused by the different choice of population selection, age groups and sample types: for those reasons, we maintain the 99th URLs provided by manufacturer.

The cTnT response to acute exercise at the onset of an endurance training program: evidence of exercise preconditioning?

PURPOSE

Exercise induces a cardioprotective effect referred to as "preconditioning". Whether the preconditioning impacts upon the cardiac troponin T (cTnT) response to subsequent exercise bouts is unclear. This study investigated the effects of an initial exercise bout, a second exercise bout 48 h later, as well as subsequent exercise every 48 h for 4 days or a single identical exercise bout after 8 days of inactivity gap on cTnT response to acute exercise.

METHODS

Twenty-eight sedentary overweight young women were randomly assigned to either six bouts of exercise each separated by 48 h or three bouts of exercise with 48 h between the first two bouts and 8 days between the second and third bouts. All exercise bouts were identical (60% [Formula: see text], 200 kJ) and the total testing period (10 days) was the same for both groups. cTnT was assessed before and after the 1st, 2nd, and final exercise bouts.

RESULTS

cTnT increased (129%, P < 0.05) after the first bout of exercise in both groups (peak post-exercise cTnT, median [range], ng l^-1: 3.43[< 3.00-27.26]) with no between-group differences in the response. The second exercise bout had no significant (P > 0.05) effect on post-exercise cTnT (< 3.00[< 3.00-21.96]). The final exercise bout resulted in an increase (190%, P < 0.05) in cTnT (4.35[< 3.00-13.05]) in both groups.

CONCLUSIONS

A single bout exercise resulted in a temporary blunting of cTnT response to acute exercise 48 h later. The effect of exercise preconditioning was not preserved, regardless of whether followed by repeated exercise every 48 h or a cessation of exercise for 8 days.

The impact of high-intensity interval training on the cTnT response to acute exercise in sedentary obese young women

AIMS

This study characterized (a) the cardiac troponin T (cTnT) response to three forms of acute high-intensity interval exercise (HIE), and (b) the impact of 12 weeks of HIE training on the cTnT response to acute exercise in sedentary obese young women.

METHODS

Thirty-six sedentary women were randomized to traditional HIE training (repeated 4-minute cycling at 90% V ˙ O_2max interspersed with 3-minute rest, 200 kJ/session), work-equivalent sprint interval exercise (SIE) training (repeated 1-minute cycling at 120% V ˙ O_2max interspersed with 1.5-minute rest) or repeated-sprint exercise (RSE) training (40 × 6-second all-out sprints interspersed with 9-second rest) group. cTnT was assessed using a high-sensitivity assay before and immediately, 3 and 4 hours after the 1st (PRE), 6th (EARLY), 20th (MID), and 44th (END) training session, respectively.

RESULTS

cTnT was elevated (P < 0.05) after all forms of acute interval exercise at the PRE and EARLY assessment with cTnT response higher (P < 0.05) after HIE (307%) and SIE (318%) than RSE (142%) at the PRE assessment. All forms of acute interval exercise at MID and END had no effect on the cohort cTnT concentration post-exercise (all P > 0.05).

CONCLUSION

For sedentary obese young women, both HIE and SIE, matched for total work, induced a similar elevation in cTnT after acute exercise with a smaller rise observed after RSE. By the 44th training session, almost no post-exercise cTnT elevation was observed in all three groups. Such information is relevant for clinicians as it could improve medical decisionmaking.

Clinical use of cardiac troponin for acute cardiac care and emerging opportunities in the outpatient setting

Cardiac troponin (cTn) testing has evolved significantly in recent times. Because of increased sensitivity, its use has shifted from a marker used to help diagnose acute myocardial infarction (MI) to a marker than can be used in the outpatient setting, as well as for both detection of myocardial injury and risk-stratification. Its main role remains in the diagnosis of acute MI and the risk-stratification of patients presenting with suspected acute coronary syndrome. The analytical improvements in assays leading to precise high-sensitivity cTn assays have contributed to the development of numerous strategies to identify patients at both low- and high-risk for acute MI within a few hours. These approaches should reduce overcrowding in the emergency room and expedite triaging. The ability of measuring cTn in most patients using high-sensitivity (hs) assays has allowed for the opportunity to examine its use in the detection of cardiotoxicity in patients undergoing chemotherapy, as well as exploring the application in both primary and secondary prevention of coronary artery disease. This particular field of research has become increasingly complex, partly due to the numerous cTn assays available (I and T; point-of-care, contemporary, hs) and an array of approaches in which one can use the test. The purpose of this document is to summarize the analytical and clinical information relevant to cTn assays, in particular, hs-cTn assays, and describe present and future opportunities for use of cTn in acute cardiac care and in the outpatient setting.

The Importance of Serial Time Point Quantitative Assessment of Cardiac Troponin I in the Diagnosis of Acute Myocardial Damage

OBJECTIVE

The present study was aimed to establish a threshold value for cardiac troponin I (cTnI) for nonacute coronary syndrome (ACS) participants from the local population and also to determine the importance of serial time point estimation of cTnI in acute myocardial infarction (AMI), non-ST-elevated MI (NSTEMI), and unstable angina cases.

METHODS

The present study included 194 cases, admitted in ICCU with the complaint of anginal pain; 31 were diagnosed with AMI with typical electrocardiography (ECG) changes; whereas, 48 cases were diagnosed with NSTEMI. The latter group of cases was selected for the time point study of cTnI release at 0-4 h, 6-12 h, 72 h, and 144 h of admission. cTnI levels were assessed using the Abbott ARCHITECT i1000SR system.

RESULTS

ACS was clinically ruled out in 98 cases, and cTnI level for them was used to decide cTnI threshold for the non-ACS group. cTnI level was checked in 17 cases of unstable angina. The threshold value of cTnI for non-ACS participants was 0.1 ng/ml and can be considered as cut-off value for the regional population. The data suggested that the peak of cTnI levels in most of the AMI cases reached during 6-12 h. The cTnI levels were lower than 0.1 ng/ml, and no significant change in ECG was noticed in 17 cases of unstable angina.

CONCLUSION

The present study suggested that the repeat of cTnI assay after 4-6 h of admission is required if the initial value is <3 ng/ml.

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

This document is an essential companion to the third iteration of the National Academy of Clinical Biochemistry [NACB,8 now the American Association for Clinical Chemistry (AACC) Academy] Laboratory Medicine Practice Guidelines (LMPG) on cardiac markers. The expert consensus recommendations were drafted in collaboration with the International Federation of Clinical Chemistry and Laboratory Medicine Task Force on Clinical Applications of Bio-Markers (IFCC TF-CB). We determined that there is sufficient clinical guidance on the use of cardiac troponin (cTn) testing from clinical practice groups. Thus, in this expert consensus document, we focused on clinical laboratory practice recommendations for high-sensitivity (hs)-cTn assays. This document utilized the expert opinion class of evidence to focus on the following 10 topics: (a) quality control (QC) utilization, (b) validation of the lower reportable analytical limits, (c) units to be used in reporting measurable concentrations for patients and QC materials, (d) 99th percentile sex-specific upper reference limits to define the reference interval; (e) criteria required to define hs-cTn assays, (f) communication with clinicians and the laboratory's role in educating clinicians regarding the influence of preanalytic and analytic problems that can confound assay results, (g) studies on hs-cTn assays and how authors need to document preanalytical and analytical variables, (h) harmonizing and standardizing assay results and the role of commutable materials, (i) time to reporting of results from sample receipt and sample collection, and (j) changes in hs-cTn concentrations over time and the role of both analytical and biological variabilities in interpreting results of serial blood collections.

Cardiac injury biomarkers in paediatric age: Are we there yet?

The aim of this article is to evaluate the clinical utility of cardiac injury biomarkers in paediatric age. In December 2015, a literature search was performed (PubMed access to MEDLINE citations; http://www.ncbi.nlm.nih.gov/PubMed/ ). The search strategy included the following medical subject headings and text terms for the key words: "cardiac injury biomarkers", "creatine kinase-MB", "myoglobin", "troponin", "children", "neonate/s", "newborn/s", "infant/s" and echocardiography. In the paediatric population, troponins show a good correlation with the extent of myocardial damage following cardiac surgery and cardiotoxic medication and can be used as predictors of subsequent cardiac recovery and mortality. Elevation of cardiac injury biomarkers may also have diagnostic value in cases when cardiac contusion or pericarditis is suspected. Cardiac injury biomarkers are very sensitive markers for the detection of myocardial injury and have been studied in healthy newborns, after tocolysis, intrauterine growth restriction, respiratory distress and asphyxia. The proportion of newborns with elevated troponin was higher than that in ill infants, children, and adolescents and in healthy adults, suggesting that myocardial injury, although clinically occult, is common in this young age group. Results suggest that significant elevation of cord troponin is an excellent early predictor of severity of hypoxic-ischaemic encephalopathy and mortality in term infants. Cardiac biomarkers may also benefit centres without on-site echocardiography with evidence showing good correlation with echo-derived markers of myocardial function. Further studies are needed to better clarify the role of cardiac biomarkers in paediatric age and their correlation with echocardiographic parameters.

Prospective Validation of a Biomarker-Based Rule Out Strategy for Functionally Relevant Coronary Artery Disease

BACKGROUND

This study aimed to prospectively advance a rule-out strategy for functionally significant coronary artery disease (CAD) by use of high-sensitivity cardiac troponin I (hs-cTnI) from bench to bedside, by application of a 3-step approach: validation in serum, correlation in plasma, and application on a clinical platform.

METHODS

Patients without known CAD referred for rest/stress myocardial perfusion single-photon emission tomography/computer tomography (MPI-SPECT/CT) were assigned to 3 consecutive cohorts: validation, correlation, and application. Functionally relevant CAD was adjudicated with the use of expert interpretation of MPI-SPECT/CT and, if available, coronary angiography. In the validation cohort resting hs-cTnI was measured in serum before stress testing with the research Erenna system, in serum and plasma in the correlation cohort with the research Erenna system, and in plasma in the application cohort with the clinical Clarity system.

RESULTS

Overall, functionally relevant CAD was adjudicated in 21% (304/1478) of patients. In the validation cohort (n = 613), hs-cTnI concentrations were significantly higher in patients with functionally relevant CAD (median 2.8 ng/L vs 1.9 ng/L, P &lt; 0.001) as compared to patients without functionally relevant CAD and allowed a rule out with 95% sensitivity in 14% of patients. In the correlation cohort (n = 606), hs-cTnI concentrations in serum and plasma strongly correlated (Spearman r = 0.921) and had similar diagnostic accuracy as quantified by the area under the receiver operating characteristic curve (0.686 vs 0.678, P = 0.425). In the application cohort (n = 555), very low hs-cTnI plasma concentrations (&lt; 0.5 ng/L) ruled out functionally relevant CAD with 95% sensitivity in 10% of patients.

CONCLUSIONS

A single resting plasma hs-cTnI measurement can safely rule out functionally relevant CAD in around 10% of patients without known CAD.

Troponin-T as a biomarker in neonates with perinatal asphyxia

BACKGROUND

Troponin-T is a commonly used cardiac biomarker, which could be useful in perinatal asphyxia. We aimed to analyze troponin-T concentrations in asphyxiated neonates and to correlate the concentrations with clinical outcomes.

METHODS

Data were collected from electronic medical records of neonates diagnosed with perinatal asphyxia over a period of four years.

RESULTS

There were 63 neonates with moderate to severe encephalopathy, in whom serial troponin-T concentrations had been done on days 1, 3, and 7. 53 (84%) asphyxiated infants had troponin-T concentration >100 pg/ml at 2-4 h of life.The difference in troponin-T concentrations between moderate and severe encephalopathy was not statistically significant (173 vs. 263 pg/ml, p value 0.40). The difference in the concentrations at 72 hours between cooled and non-cooled neonates was not significant (48.5 vs. 62.5 pg/ml, p value 0.22). Troponin-T concentration was significantly higher in babies with hypotensive shock and hepatic injury, but not acute kidney injury. There was no significant correlation between troponin-T and the extent of resuscitation needed.Troponin-T concentration on day 1 of life was significantly higher in babies who died than who survived (407 vs. 168 pg/ml, p value 0.03). ROC curve for troponin-T to predict mortality had an area under the curve (AUC) of 0.803; the best cut-off value (190 pg/ml) had 82% sensitivity and 80% specificity.

CONCLUSION

There was no significant difference in troponin-T concentrations between cooled and non-cooled neonates. Troponin-T concentration had a good predictive accuracy for mortality before discharge.

Impact of high-intensity interval training and moderate-intensity continuous training on resting and postexercise cardiac troponin T concentration

NEW FINDINGS

What is the central question of this study? Does exercise training impact resting and postexercise cardiac troponin T (cTnT) concentration? What is the main finding and its importance? This randomized controlled intervention study demonstrated that 12 weeks of either high-intensity interval training or moderate-intensity continuous training largely abolished the exercise-induced elevation in cTnT when exercise was performed at the same absolute intensity. There was no impact of training on resting cTnT or postexercise appearance of cTnT when exercise was performed at the same relative intensity. These findings provide new information that might help clinicians with decision-making in relationship to basal and postexercise values of cTnT in individuals with different training status.

ABSTRACT

We evaluated the influence of 12 weeks of high-intensity interval training [HIIT; repeated 4 min cycling at 90% of maximal oxygen uptake (V̇O2max) interspersed with 3 min rest, 200-300 kJ per session, 3 or 4 days each week] and work-equivalent moderate-intensity continuous training (MICT; continuous cycling at 60% V̇O2max) on resting cardiac troponin T (cTnT) and the appearance of exercise-induced cTnT. Forty-eight sedentary obese young women were randomly assigned to HIIT, MICT or a control group. The V̇O2max and body composition were measured before and after training. At baseline, cTnT was assessed using a high-sensitivity assay at rest and immediately, 2 and 4 h after 45 min cycling at 60% V̇O2max. After a 12 week training period, cTnT was assessed before and after 45 min cycling at the same relative and absolute intensities as before training. Training led to higher V̇O2max and lower fat mass in both HIIT and MICT groups (all P < 0.05). Before training, cTnT was significantly elevated in all three groups (by 35-118%, all P < 0.05) with acute exercise. After training, both resting and postexercise cTnT concentrations (same relative intensity) were similar to pretraining values. In contrast, postexercise cTnT (same absolute intensity, which represented a smaller exercise stimulus) was not elevated from rest in both HIIT and MICT groups. In conclusion, 12 weeks of either HIIT or MICT largely abolished the postexercise elevation of cTnT concentration when exercise was performed at the same absolute intensity. There was, however, no impact of training on resting cTnT or postexercise appearance of cTnT for exercise performed at the same relative intensity.

Cardiac Biomarkers in Youth with Type 2 Diabetes Mellitus: Results from the TODAY Study

OBJECTIVES

To examine cardiac biomarkers over time in youth-onset type 2 diabetes, and relate serum concentrations to cardiovascular disease risk factors, and left ventricular structure and function.

STUDY DESIGN

TODAY (Treatment Options for type 2 Diabetes in Adolescents and Youth) was a multicenter randomized trial of 3 treatments including 521 participants with type 2 diabetes, aged 10-17 years, and with 2-6 years of follow-up. Participants were 36% male, obese, and ethnically diverse. Annual serum concentrations of brain natriuretic peptide, troponin, tumor necrosis factor (TNF)-α, receptors 1 and 2 were related to blood pressure, body mass index, hemoglobin A1c, and left ventricular ejection fraction, diastolic function, relative wall thickness, and mass.

RESULTS

Elevated concentrations of brain natriuretic peptide (≥100 pg/mL), TNF-α (≥5.6 pg/mL) and troponin (≥0.01 ng/mL), were present in 17.8%, 18.3%, and 34.2% of the cohort, respectively, at baseline, and in 15.4%, 17.1%, and 31.1% at the end of the study, with wide variability over time, without persistence in individuals or clear relationship to glycemia or cardiovascular structure/function. TNF receptors concentrations were increased at baseline and not significantly different from end-of-study concentrations. Adverse echocardiographic measures were more likely in the highest TNF receptor tertile (all P < .05): higher left ventricular mass (39.3 ± 9.0 g/m^2.7), left atrial internal dimension (3.7 ± 0.4 cm) and E/Em ratio, a measure of diastolic dysfunction (6.2 ± 1.9). After adjustment for body mass index, these relationships were no longer significant.

CONCLUSIONS

Elevated serum concentrations of cardiac biomarkers were common in youth with type 2 diabetes, but their clinical significance is unclear and will require further long-term study.

TRIAL REGISTRATION

ClinicalTrials.govNCT00081328.

Cardiac troponins: from myocardial infarction to chronic disease

Elucidation of the physiologically distinct subunits of troponin in 1973 greatly facilitated our understanding of cardiac contraction. Although troponins are expressed in both skeletal and cardiac muscle, there are isoforms of troponin I/T expressed selectively in the heart. By exploiting cardiac-restricted epitopes within these proteins, one of the most successful diagnostic tests to date has been developed: cardiac troponin (cTn) assays. For the past decade, cTn has been regarded as the gold-standard marker for acute myocardial necrosis: the pathological hallmark of acute myocardial infarction (AMI). Whilst cTn is the cornerstone for ruling-out AMI in patients presenting with a suspected acute coronary syndrome (ACS), elevated cTn is frequently observed in those without clinical signs indicative of AMI, often reflecting myocardial injury of 'unknown origin'. cTn is commonly elevated in acute non-ACS conditions, as well as in chronic diseases. It is unclear why these elevations occur; yet they cannot be ignored as cTn levels in chronically unwell patients are directly correlated to prognosis. Paradoxically, improvements in assay sensitivity have meant more differential diagnoses have to be considered due to decreased specificity, since cTn is now more easily detected in these non-ACS conditions. It is important to be aware cTn is highly specific for myocardial injury, which could be attributable to a myriad of underlying causes, emphasizing the notion that cTn is an organ-specific, not disease-specific biomarker. Furthermore, the ability to detect increased cTn using high-sensitivity assays following extreme exercise is disconcerting. It has been suggested troponin release can occur without cardiomyocyte necrosis, contradicting conventional dogma, emphasizing a need to understand the mechanisms of such release. This review discusses basic troponin biology, the physiology behind its detection in serum, its use in the diagnosis of AMI, and some key concepts and experimental evidence as to why cTn can be elevated in chronic diseases.

Point-of-care testing (POCT) and evidence-based laboratory medicine (EBLM) - does it leverage any advantage in clinical decision making?

Point-of-care testing (POCT) is the analysis of patient specimens outside the clinical laboratory, near or at the site of patient care, usually performed by clinical staff without laboratory training, although it also encompasses patient self-monitoring. It is able to provide a rapid result near the patient and which can be acted upon immediately. The key driver is the concept that clinical decision making may be delayed when samples are sent to the clinical laboratory. Balanced against this are considerations of increased costs for purchase and maintenance of equipment, staff training, connectivity to the laboratory information system (LIS), quality control (QC) and external quality assurance (EQA) procedures, all required for accreditation under ISO 22870. The justification for POCT depends upon being able to demonstrate that a more timely result (shorter turnaround times (TATs)) is able to leverage a clinically important advantage in decision making compared with the central laboratory (CL). In the four decades since POCT was adapted for the self-monitoring of blood glucose levels by subjects with diabetes, numerous new POCT methodologies have become available, enabling the clinician to receive results and initiate treatment more rapidly. However, these instruments are often operated by staff not trained in laboratory medicine and hence are prone to errors in the analytical phase (as opposed to laboratory testing where the analytical phase has the least errors). In some environments, particularly remote rural settings, the CL may be at a considerable distance and timely availability of cardiac troponins and other analytes can triage referrals to the main centers, thus avoiding expensive unnecessary patient transportation costs. However, in the Emergency Department, availability of more rapid results with POCT does not always translate into shorter stays due to other barriers to implementation of care. In this review, we apply the principles of evidence-based laboratory medicine (EBLM) looking for high quality systematic reviews and meta-analyses, ideally underpinned by randomized controlled trials (RCTs), looking for evidence of whether POCT confers any advantage in clinical decision making in different scenarios.

The continuing evolution of cardiac troponin I biomarker analysis: from protein to proteoform

INTRODUCTION

The troponin complex consists of three proteins that fundamentally couple excitation with contraction. Circulating cardiac-specific Troponin I (cTnI) serves as diagnostic biomarker tools for risk stratification of acute coronary syndromes and acute myocardial infarction (MI). Within the heart, cTnI oscillates between inactive and active conformations to either block or disinhibit actinomyosin formation. This molecular mechanism is fine-tuned through extensive protein modifications whose profiles are maladaptively altered with co-morbidities including hypertrophic cardiomyopathy, diabetes, and heart failure. Technological advances in analytical platforms over the last decade enable routine baseline cTnI analysis in patients without cardiovascular complications, and hold potential to expand cTnI readouts that include modified cTnI proteoforms. Areas covered: This review covers the current state, advances, and prospects of analytical platforms that now enable routine baseline cTnI analysis in patients. In parallel, improved mass spectrometry instrumentation and workflows already reveal an array of modified cTnI proteoforms with promising diagnostic implications. Expert commentary: New analytical capabilities provide clinicians and researchers with an opportunity to address important questions surrounding circulating cTnI in the improved diagnosis of specific patient cohorts. These techniques also hold considerable promise for new predictive and prescriptive applications for individualized profiling and improve patient care.

Laboratory Medicine is Faced with the Evolution of Medical Practice

Laboratory medicine and clinical medicine are co-dependent components of medicine. Laboratory medicine functions most effectively when focused through a clinical lens. Me dical practice as a whole undergoes change. New drugs, treatments and changes in management strategies are introduced. New techniques, new technologies and new tests are developed. These changes may be either clinically or laboratory initiated, and so their introduction requires dialogue and interaction between clinical and laboratory medicine specialists. Treatment monitoring is integral to laboratory medicine, varying from direct drug measurement to monitoring cholesterol levels in response to treatment. The current trend to »personalised medicine« is an extension of this process with the development of companion diagnostics. Technological innovation forms part of modern laboratory practice. Introduction of new technology both facilitates standard laboratory approaches and permits introduction of new tests and testing strategies previously confined to the research laboratory only. The revolution in cardiac biomarker testing has been largely a laboratory led change. Flexibility in service provision in response to changing clinical practice or evolving technology provides a significant laboratory management challenge in the light of increasing expectations, shifts in population demographics and constraint in resource availability. Laboratory medicine practitioners are adept at meeting these challenges. One thing remains constant, that there will be a constant need laboratory medicine to meet the challenges of novel clinical challenges from infectious diseases to medical conditions developing from lifestyle and longevity.

Cardiac metastasis of tongue squamous cell carcinoma complicated by pulmonary embolism: A case report

RATIONALE

Cardiac metastasis is known as a rare complication of head and neck malignancy.

PATIENT CONCERNS

We present a 58-year-old woman patient with a history of tongue carcinoma who was admitted in emergency department for sudden chest pain. Imaging work-up by computed tomography (CT) and positron emission tomography-computed tomography (PET-CT) diagnosed a cardiac metastasis complicated by intraventricular thrombus and pulmonary embolism.

DIAGNOSIS

Cardiac metastasis from tongue carcinoma complicated by pulmonary embolism.

INTERVENTIONS

After undergoing 2 cycles of palliative chemotherapy, the patient declined any further treatment.

OUTCOMES

Patient died 3 months after the diagnosis of cardiac metastasis.

LESSONS

Cardiac metastasis should be considered as a differential diagnosis in patients with a history of head and neck malignancy who present non-specific cardiac symptoms.

Ratio of high-sensitivity troponin to creatine kinase-MB in takotsubo syndrome

BACKGROUND

Takotsubo syndrome (TT) and myocardial infarction (MI) share numerous similarities in clinical presentation, ECG modifications and biomarker elevation. We sought to determine whether the ratio of high-sensitivity cardiac troponin T (hs-TnT) to the myocardial fraction of creatine kinase (CKMB) could be a potent discriminator between TT and MI patients.

METHODS

We separately present analysis of data from retrospective files and prospectively recruited patients presenting with TT (35 retrospective and 42 prospective), NSTEMI (48 retrospective and 75 prospective) and STEMI (20 retrospective and 39 prospective). We compared ratios of hs-TnT to CKMB on admission to the hospital between TT, NSTEMI and STEMI patients. Receiver operating characteristic (ROC) curves were analysed to determine optimal cut-off values.

RESULTS

On admission, hs-TnT/CKMB ratio was significantly higher in TT patients than in NSTEMI and STEMI patients in both the retrospective phase (median and interquartile range, TT 0.024 [0.018-0.047] vs NSTEMI 0.009 [0.006-0.022], p<0.0001; TT vs STEMI 0.011 [0.006-0.016], p=0.0002) and the prospective cohort (median and interquartile range, TT 0.032 [0.018-0.040] vs NSTEMI 0.009 [0.006-0.015], p<0.0001; TT vs STEMI 0.009 [0.005-0.017], p<0.0001). A cut-off hs-TnT/CKMB ratio of 0.015 distinguished TT from MI with a sensitivity of 85.7% and a specificity of 67.6% (AUC 0.796; 95%CI: 0.71-0.89) in the retrospective phase. In the prospective phase, a ratio of 0.017 distinguished TT from MI with a sensitivity of 83.3% and a specificity of 78.1% (AUC 0.88; 95%CI: 0.83-0.94).

CONCLUSION

hs-TnT/CKMB ratio is a novel, readily available parameter that could be used alongside clinical risk scores, other biomarkers and ECG findings to discriminate between TT and MI.

Discrimination of stress (Takotsubo) cardiomyopathy from acute coronary syndrome with clinical risk factors and coronary evaluation in real-world clinical practice

BACKGROUND

Diagnosing stress cardiomyopathy (SCMP) apart from acute coronary syndrome (ACS) is challenging since coronary evaluation is not always feasible in real-world clinical practice. We explored the current practice pattern of coronary evaluation in patients suspected to have SCMP and divulged the distinguishable features of SCMP from ACS.

METHODS AND RESULTS

From 2010 to 2015, only 219 out of 691 (32%) hospitalized patients suspected to have SCMP have received coronary evaluation in two tertiary hospitals. After the evaluation, 66 patients (30%) turned out to have ACS. Coronary evaluation was performed based on coronary risk factors, clinical presentations, and test results including electrocardiograms (ECG), cardiac biomarkers, and echocardiography. Whereas initial presentations, ECG changes, cardiac biomarkers, and regional wall motion abnormality patterns were not significantly different, multivariate logistic regression analysis showed that age (≥70years), diabetes, a history of percutaneous coronary intervention (PCI), and the absence of evident triggers were significant factors discriminating ACS from SCMP. A decision tree based on classification and regression analysis also revealed the consistent results.

CONCLUSIONS

Although it is hard to differentiate SCMP from ACS merely based on clinical features, a substantial proportion of patients suspected to have SCMP did not undergo coronary evaluation to exclude ACS in real-world clinical practice. Coronary evaluation should be more actively performed in patients with old age, prior PCI history, diabetes, and less evident trigger.