Evaluation of reproducibility of the cTnT immunoassay using quality control samples

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

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

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

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

Evaluation of the cardiovascular risk in patients undergoing major non-cardiac surgery: role of cardiac-specific biomarkers

Major adverse cardiovascular events are frequently observed in patients undergoing major non-cardiac surgery during the peri-operative period. At this time, the possibility to predict cardiovascular events remains limited, despite the introduction of several algorithms to calculate the risk of adverse events, mainly death and major adverse cardiovascular events (MACE) based on the clinical history, risk factors (sex, age, lipid profile, serum creatinine) and non-invasive cardiac exams (electrocardiogram, echocardiogram, stress tests). The cardiac-specific biomarkers natriuretic peptides (NPs) and cardiac troponins (cTn) have been proposed as additional tools for risk prediction in the peri-operative period, particularly for the identification of myocardial injury in patients undergoing major non-cardiac surgery. The prognostic information from the measurement of BNP/NT-proBNP and hs-cTn is independent and complementary to other important indicators of risk, also including ECG and imaging techniques. Elevated levels of cardiac-specific biomarkers before surgery are associated with a markedly higher risk of MACE during the peri-operative period. BNP/NT-proBNP and hs-cTn should be measured in all patients during the clinical evaluation before surgery, particularly during intermediate- or high-risk surgery, in patients aged >65 years and/or with comorbidities. Several questions remain to be assessed in dedicated clinical studies, such as how to optimize the management of patients with raised cardiac specific biomarkers before surgery, and whether a strategy based on biomarker measurement improves patient outcomes and is cost-effective.

Natriuretic Peptides and Troponins to Predict Cardiovascular Events in Patients Undergoing Major Non-Cardiac Surgery

Patients undergoing major surgery have a substantial risk of cardiovascular events during the perioperative period. Despite the introduction of several risk scores based on medical history, classical risk factors and non-invasive cardiac tests, the possibility of predicting cardiovascular events in patients undergoing non-cardiac surgery remains limited. The cardiac-specific biomarkers, natriuretic peptides (NPs) and cardiac troponins (cTn) have been proposed as additional tools for risk prediction in the perioperative period. This review paper aims to discuss the value of preoperative levels and perioperative changes in cardiac-specific biomarkers to predict adverse outcomes in patients undergoing major non-cardiac surgery. Based on several prospective observational studies and six meta-analyses, some guidelines recommended the measurement of NPs to refine perioperative cardiac risk estimation in patients undergoing non-cardiac surgery. More recently, several studies reported a higher mortality in surgical patients presenting an elevation in high-sensitivity cardiac troponin T and I, especially in elderly patients or those with comorbidities. This evidence should be considered in future international guidelines on the evaluation of perioperative risk in patients undergoing major non-cardiac surgery.

High-sensitivity troponins for outcome prediction in the general population: a systematic review and meta-analysis

BACKGROUND

High-sensitivity (hs) assays allow to measure cardiac troponin T and I (cTnT/I) even in healthy individuals. The higher hs-cTn values, the higher the ongoing cardiomyocyte damage, and then reasonably the risk of developing symptomatic cardiac disease.

METHODS

We retrieved all studies evaluating the prognostic value of hs-cTnT or I in the general population. We calculated pooled hazard ratio (HR) values for all-cause and cardiovascular death, cardiovascular events and heart failure (HF) hospitalization.

RESULTS

We included 24 studies for a total of 203,202 subjects; 11 studies assessed hs-cTnT and 14 hs-cTnI. One standard deviation (SD) increase in baseline hs-cTn was associated with a 23% higher risk of all-cause death (HR 1.226, 95% CI 1.083-1.388, p<0.001, I²=88.5%); all these studies measured hs-cTnI. In an exploratory analysis on 3 studies with 25,760 subjects, hs-cTn predicted cardiovascular death (HR 1.822, 95% CI 1.241-2.674, p=0.002, I²=87.2%). After synthesizing 9 studies with 58,565 subjects, hs-cTn predicted cardiovascular events (HR 1.328, 95% CI 1.167-1.513, p<0.001, I²=93.8%). Both hs-cTnT (HR 1.627, 95% CI 1.145-2.311, p<0.001) and hs-cTnI (HR 1.260, 95% CI 1.115-1.423, p<0.001; p for interaction <0.001). Furthermore, in 10 studies with 61,467 subjects, hs-cTn predicted HF hospitalization (HR 1.493, 95% CI 1.368-1.630, p<0.001, I²=76.6%). Both hs-cTnT (HR 1.566, 95% CI 1.303-1.883, p<0.001) and hs-cTnI (HR 1.467, 95% CI 1.321-1.628, p<0.001) were associated with HF hospitalization (p for interaction <0.001).

CONCLUSIONS

hs-cTn values hold strong prognostic value in subjects from the general population, predicting the risk of all-cause and cardiovascular mortality, cardiovascular events, and HF hospitalization.

High-sensitivity cardiac troponins in pediatric population

Apparently healthy children often complain of chest pain, especially after physical exercise. Cardiac biomarker levels are often measured, but the clinical relevance of these assays in children is still debated, even when a cardiac disease is present. Coronary artery disease is exceedingly rare in children, but elevated circulating levels of cardiac troponin I (cTnI) and T (cTnT) in an acute setting may help detect heart failure due to an unknown cardiac disorder, or worsening heart failure, particularly in combination with other biomarkers such as B-type natriuretic peptides. However, the interpretation of biomarkers is often challenging, especially when institutions transition from conventional cTn assays to high-sensitivity (hs-cTn) methods, as well demonstrated in the emergency setting for adult patients. From a clinical perspective, the lack of established reference values in the pediatric age is the main problem limiting the use of hs-cTn methods for the diagnosis and managements of cardiac diseases in infants, children and adolescents. This review aims to discuss the possibility to use hs-cTnI and hs-cTnT to detect cardiac disease and to explore age-related differences in biomarker levels in the pediatric age. We start from some analytical and pathophysiological considerations related to hs-cTn assays. Then, after a systematic literature search, we discuss the current evidence and possible limitations of hs-cTn assay as indicators of cardiac disease in the most frequently cardiac disease in pediatric setting.

Use of high-sensitivity cardiac troponins in the emergency department for the early rule-in and rule-out of acute myocardial infarction without persistent ST-segment elevation (NSTEMI) in Italy

Serial measurements of cardiac troponin are recommended by international guidelines to diagnose myocardial infarction (MI) since 2000. However, some relevant differences exist between the three different international guidelines published between 2020 and 2021 for the management of patients with chest pain and no ST-segment elevation. In particular, there is no agreement on the cut-offs or absolute change values to diagnose non-ST-segment elevation MI (NSTEMI). Other controversial issues concern the diagnostic accuracy and cost-effectiveness of cut-off values for the most rapid algorithms (0 h/1 h or 0 h/2 h) to rule-in and rule-out NSTEMI. Finally, another important point is the possible differences between demographic and clinical characteristics of patients enrolled in multicenter trials compared to those routinely admitted to the Emergency Department in Italy. The Study Group of Cardiac Biomarkers, supported by the Italian Scientific Societies Società Italiana di Biochimica Clinica, Italian Society of the European Ligand Assay Society, and Società Italiana di Patolgia Clinica e Medicina di Laboratorio decided to revise the document previously published in 2013 about the management of patients with suspected NSTEMI, and to provide some suggestions for the use of these biomarkers in clinical practice, with a particular focus on the Italian setting.

Laboratory-related issues in the measurement of cardiac troponins with highly sensitive assays

A number of assay-related issues can affect the performance of cardiac troponin (cTn) measurement in everyday practice. In this respect, it is vital that all information on cTn assays is known and that the performance characteristics of assays are objectively assessed and adequately described. The advent of the latest generation of more sensitive cTn assays has heralded a new wave of information about low concentrations of cTn in blood. These recent generation assays have improved analytical sensitivity and corresponding performance at low cTn concentrations when compared to their predecessors, providing a convincing goal for laboratory medicine in helping clinicians in the diagnosis of acute myocardial infarction. Crucial to the clinical utility of highly sensitive cTn assays is the laboratorians' role in closely scrutinizing proposed assays and defining their value in relation to available evidence. Analytical, as well as pre-analytical and post-analytical, aspects must be documented. In this review, we describe what laboratory professionals should know about their cTn assay performance characteristics and the pre-analytical prerequisites for robustness to ensure optimal post-analytical reporting.

Evaluation and Comparison with Other High-Sensitivity Methods of Analytical Performance and Measured Values of a New Laboratory Test for Cardiac Troponin I Assay

Bakground

The aim of this study was to evaluate both analytical characteristics and clinical results of a new chemiluminescent method for the measurement of cardiac troponin I (cTnI), named VITROS ® High Sensitivity Troponin I Assay, using the VITROS® 3600 automated platform. The results found with this new method were compared to those observed with hs-cTnI ARCHITECT and ECLIA hs-cTnT ELECSYS methods.

Methods

For evaluation of analytical performance and comparison of clinical results, plasma samples (lithium-heparin), were collected from apparently healthy subjects and patients with cardiovascular diseases.

Results

The hs-cTnI VITROS method showed values for limit of blank (LoB 0.33 ng/L), limit of detection (LoD, 0.91 ng/L), limit of quantifications at 20% (LoQ 20% CV, 1.82 ng/L), and 10% (LoQ 10% CV, 4,74 ng/L), which are comparable to those previously reported for other hs-cTnI methods. Moreover, the clinical results of the hs-cTnI VITROS method were found to be closely correlated to those of hs-cTnI ARCHITECT (R = 0,9883, N = 198) and ECLIA hs-cTnT Elecsys (R = 0,9704, N = 293) methods.

Conclusions

The hs-cTnI VITROS method shows analytical performance comparable to other cTnI and cTnT assay. The results of this study confirm that there are significant systematic differences among hs-cTnI methods. Further multicenter studies using larger reference populations are needed in order to obtain a better estimation, especially of the 99° percentile URL values categorized for sex and age of hs-cTnI and hs-cTnT methods.

Clinical relevance of biological variation of cardiac troponins

The high-sensitivity immunoassays for cardiac troponin I (hs-cTnI) and cardiac troponin T (hs-cTnT) are recommended by all the most recent international guidelines as gold standard laboratory methods for the detection of myocardial injury and diagnosis of acute myocardial infarction (AMI). In this review article, the Authors aimed at discussing the relevant biochemical, physiological, and clinical issues related to biological variability of cTnI and cTnT. Cardiac troponins, measured with hs-cTn methods, show a better clinical profile than the other cardio-specific biomarkers (such as the natriuretic peptides, BNP and NT-proBNP). In particular, the hs-cTn methods are characterized by a low intra-individual index of variation (<0.6) and reduced analytical imprecision (about 5% CV) at the clinical cut-off value (i.e., the 99th percentile URL value). Moreover, recent studies have reported that differences between two hs-cTn measured values (RCV) >30% can be considered statistically significant. These favourable biological characteristics and analytical performance of hs-cTn methods significantly improved the accuracy in the diagnostic process of acute coronary syndromes (ACS) in patients admitted to emergence department. In addition, several studies have demonstrated the clinical usefulness of cardiovascular risk evaluation with hs-cTn methods in some groups of patients with clinical conditions at high cardiovascular risk (such as systemic hypertension, severe obesity, diabetes mellitus, renal insufficiency, and chronic obstructive pulmonary disease). However, screening programs in the general population with hs-cTn methods for cardiovascular risk stratification require further investigation to define the optimal target populations, timing of measurement, and preventive interventions.

High-sensitivity methods for cardiac troponins: The mission is not over yet

The measurement of cardiac troponin (cTn) is recommended by all guidelines as the gold standard for the differential diagnosis of Acute Coronary Syndromes. The aim of this review is to discuss in details some key issues regarding both analytical and clinical characteristics of the high-sensitivity methods for cTn (hs-cTn), which are still considered controversial or unresolved. In particular, the major clinical concern regarding hs-cTn methods is the difficulty to differentiate the pathophysiological mechanism responsible for biomarker release from cardiomyocytes after reversible or irreversible injury, respectively. Indeed, recent experimental and clinical studies have demonstrated that different circulating forms of cTnI and cTnT can be respectively measured in plasma samples of patients with reversible or irreversible myocardial injury. Accordingly, a new generation of hs-Tn methods should be set up, based on immunometric immunoassays or chromatographic techniques, specific for circulating peptide forms more characteristics for reversible or irreversible myocardial injury. It is conceivable that this new generation of hs-cTn methods will complete the mission regarding the laboratory tests for specific cardiac biomarkers, started more than 20 years ago, which has already revolutionized the diagnosis, prognosis and management of patients with cardiac diseases.

Cardiotoxic effects and myocardial injury: the search for a more precise definition of drug cardiotoxicity

Drug-induced cardiotoxicity is a major clinical problem; cardiotoxic drugs may induce both cardiac dysfunction and myocardial injury. Several recent studies reported that cardiac troponins measured with high-sensitivity methods (hs-cTn) can enable the early detection of myocardial injury related to chemotherapy or abuse of drugs that are potentially cardiotoxic. Several authors have some concerns about the standard definition of cardiotoxicity, in particular, regarding the early evaluation of chemotherapy cardiotoxicity in cancer patients. Several recent studies using the hs-cTn assay indicate that myocardial injury may precede by some months or years the diagnosis of heart failure (HF) based on the evaluation of left ventricular ejection fraction (LVEF). Accordingly, hs-cTn assay should considered to be a reliable laboratory test for the early detection of asymptomatic or subclinical cardiotoxic damage in patients undergoing cancer chemotherapy. In accordance with the Fourth Universal Definition of Myocardial Infarction and also taking into account the recent experimental and clinical evidences, the definition of drug-cardiotoxicity should be updated considering the early evaluation of myocardial injury by means of hs-cTn assay. It is conceivable that the combined use of hs-cTn assay and cardiac imaging techniques for the evaluation of cardiotoxicity will significantly increase both diagnostic sensitivity and specificity, and also better prevent chemotherapy-related left ventricular (LV) dysfunction and other adverse cardiac events. However, large randomized clinical trials are needed to evaluate the cost/benefit ratio of standardized protocols for the early detection of cardiotoxicity using hs-cTn assay in patients receiving chemotherapy for malignant diseases.

Early evaluation of myocardial injury by means of high-sensitivity methods for cardiac troponins after strenuous and prolonged exercise

All the latest international guidelines recommend that cardiac troponin (cTn) I and T should be considered the preferred biomarkers for diagnosis of acute myocardial infarction. However, only in the last 5 years, a progressive improvement in analytical performance of immunometric assays has allowed the measurement of circulating levels of cTnI and cTnT in the large part of apparently healthy adult subjects. The routine use of these high-sensitivity methods for cardiac troponin (hs-cTn) assay has in a short time demonstrated that cardiac troponin concentrations frequently increase after strenuous prolonged exercise in healthy athletes. This acute response of hs-cTn assay following exercise was at first considered to be physiological and without long-term adverse consequences. More recent studies have suggested that exercise-induced increases in hs-cTn values may not be always a physiological response to exercise, but, conversely, it should sometimes be considered as an early cardiovascular risk marker. The aim of this review is to provide an overview of acute and chronic effects of strenuous physical exercise on hs-cTn circulating levels and also to discuss the potential pathophysiological and clinical implications of biomarker responses.

Evidence on clinical relevance of cardiovascular risk evaluation in the general population using cardio-specific biomarkers

In recent years, the formulation of some immunoassays with high-sensitivity analytical performance allowed the accurate measurement of cardiac troponin I (cTnI) and T (cTnT) levels in reference subjects. Several studies have demonstrated the association between the risk of major cardiovascular events and cardiac troponin concentrations even for biomarker values within the reference intervals. High-sensitivity cTnI and cTnT methods (hs-cTn) enable to monitor myocardial renewal and remodelling, and to promptly identify patients at highest risk ofheart failure. An early and effective treatment of individuals at higher cardiovascular risk may revert the initial myocardial remodelling and slow down heart failure progression. Specific clinical trials should be carried out to demonstrate the efficacy and efficiency of the general population screening by means of cost-benefit analysis, in order to better identify individuals at higher risk for heart failure (HF) progression with hs-cTn methods.

The effects of a 50 km ultramarathon race on high sensitivity cardiac troponin I and NT-proBNP in highly trained athletes

BACKGROUND

High sensitivity cardiac troponins I (hs-cTnI) and T (hs-cTnT) and natriuretic peptides (BNP and NT-proBNP) are universally recognized as cardiac reference biomarkers in patients with acute coronary syndromes and heart failure respectively. However, while on one hand the high sensitivity methods of cardiac biomarkers have provided answers to fundamental pathophysiological and clinical questions in patients with heart disease, less information is available on their assessment in paraphysiological conditions, such as high intensity exercise in healthy athletes. The aim of this study was to evaluate hs-cTnI and NT-proBNP in highly trained runners after a 50 km ultramarathon.

METHODS

We have enrolled 20 highly trained male athletes who have run a 50 km ultramarathon. Blood samples were collected 2 hours before the start of the race (T0) and 20 minutes after the end of the race (T1). The blood concentrations of hs-cTnI and NT-proBNP measured before the race were within reference intervals in all runners.

RESULTS

Hs-cTnI significantly increased after the end of the race (median: 19 ng/L [IQR: 12.5-25.75] versus 6 ng/L [IQR: 4.25-8.0]; P<0.001), in three cases over the upper reference limit (URL) of 34 ng/L. NT-proBNP also significantly increased (median: 78 ng/L [IQR: 68.25-87.75] versus 22 ng/L [IQR: 18.25-26.75]; P<0.001). Three other athletes reached concentration over the URL (125 ng/L).

CONCLUSIONS

Our study showed a significant increase in hs-cTnI and NT-proBNP in highly trained athletes after a 50 km ultramarathon race, and 30% of runners had the values of cardiac biomarkers above URL. More studies with a larger number of athletes will be needed to better understand the effects of intense exercise on the heart of trained athletes.

High-sensitivity cardiac troponin I and T methods for the early detection of myocardial injury in patients on chemotherapy

Important advances achieved in pharmacological cancer treatment have led progressively to a reduction in mortality from many forms of cancer, and increasing numbers of previously incurable patients can now hope to become cancer-free. Yet, to achieve these improved outcomes a high price has been paid in terms of untoward side effects associated with treatment, cardio-toxicity in particular. Several recent studies have reported that cardiac troponin assay using high-sensitivity methods (hs-cTn) can enable the early detection of myocardial injury related to chemotherapy or abuse of drugs that are potentially cardiotoxic. Several authors have recently suggested that changes in hs-cTn values enable the early diagnosis of cardiac injury from chemotherapy, thus potentially benefitting cancer patients with increased troponin values by initiating early cardioprotective therapy. However, large randomised clinical trials are needed in order to evaluate the cost/benefit ratio of standardised protocols for the early detection of cardiotoxicity using the hs-cTn assay in patients treated with chemotherapy.