Bedside multimarker testing for risk stratification in chest pain units: The chest pain evaluation by creatine kinase-MB, myoglobin, and troponin I (CHECKMATE) study

Post-Myocardial Infarction Ventricular Remodeling Biomarkers-The Key Link between Pathophysiology and Clinic

Studies in recent years have shown increased interest in developing new methods of evaluation, but also in limiting post infarction ventricular remodeling, hoping to improve ventricular function and the further evolution of the patient. This is the point where biomarkers have proven effective in early detection of remodeling phenomena. There are six main processes that promote the remodeling and each of them has specific biomarkers that can be used in predicting the evolution (myocardial necrosis, neurohormonal activation, inflammatory reaction, hypertrophy and fibrosis, apoptosis, mixed processes). Some of the biomarkers such as creatine kinase-myocardial band (CK-MB), troponin, and N-terminal-pro type B natriuretic peptide (NT-proBNP) were so convincing that they immediately found their place in the post infarction patient evaluation protocol. Others that are related to more complex processes such as inflammatory biomarkers, atheroma plaque destabilization biomarkers, and microRNA are still being studied, but the results so far are promising. This article aims to review the markers used so far, but also the existing data on new markers that could be considered, taking into consideration the most important studies that have been conducted so far.

Biomarkers of acute myocardial infarction: diagnostic and prognostic value. Part 1 (literature review)

Morbidity and mortality rates from acute myocardial infarction (AMI) have been growing rapidly in recent years, causing significant socio-economic damage. Cardiac biomarkers play an important role in the diagnosis and prediction of AMI. In our review article, we will summarize information about the main existing cardiac biomarkers and focus on their diagnostic and prognostic value for patients with AMI. In the first part of the review, we consider the diagnostic and prognostic value of biomarkers of necrosis and myocardial ischemia (aspartate aminotransferase; creatine phosphokinase; cardiac troponins; myoglobin, ischemia-modified albumin, fatty acid binding protein) and neuroendocrine AMI biomarkers (natriuretic peptides, adrenomedullin, catestatin, components of the renin-angiotensin-aldosterone system). In the second part of the review, we discuss the diagnostic and prognostic value of inflammatory AMI biomarkers (C-reactive protein, interleukin-6, tumor necrosis factor, myeloperoxidase, matrix metalloproteinases, soluble CD40 ligand form (sCD40L), procalcitonin, placental growth factor (PGF), procalcitonin) and recently discovered new biomarkers (microRNA, stimulating growth factor, expressed by genome 2 (ST2), growth differentiation factor 15 (GDF-15), galectin-3).

Prediction Factors of 6-Month Poor Prognosis in Acute Myocardial Infarction Patients

Background: Acute myocardial infarction (AMI) is among the leading causes of death worldwide. Patients with AMI may have the risk of developing recurrent cardiovascular events leading to rehospitalization or even death. The present study aimed to investigate the prediction factors of poor prognosis (mortality and/or readmission) after AMI during a 6-month follow-up.

Methods: A total of 206 consecutive patients hospitalized for the first visit with AMI were enrolled. Data collection included demographic characteristics, medical history, clinical information, laboratory results, and oral medications within 24 h of admission. At 1, 3, and 6 months after discharge, AMI patients were followed up to assess the occurrence of composite endpoint events including in-hospital and out-of-hospital death and/or readmission due to recurrent myocardial infarction (MI) or exacerbated symptoms of heart failure following MI.

Results: After 6-month follow-up, a total of 197 AMI patients were available and divided in two groups according to good prognosis (n = 144) and poor prognosis (n = 53). Our data identified serum myoglobin ≥651 ng/mL, serum creatinine ≥96 μM, Killip classification 2–4, and female gender as independent predictors of 6-month mortality and/or readmission after AMI. Moreover, we demonstrated that Killip classification 2–4 combined with either myoglobin (AUC_{Killip class 2−4+myoglobin} = 0.784, sensitivity = 69.8%, specificity = 79.9%) or creatinine (AUC_{Killip class 2−4+creatinine} = 0.805, sensitivity = 75.5%, specificity = 77.1%) could further enhance the predictive capacity of poor 6-month prognosis among AMI patients.

Conclusions: Patients with AMI ranked in the higher Killip class need to be evaluated and monitored with attention. Multibiomarker approach using Killip classification 2–4 and myoglobin or creatinine may be an effective way for 6-month prognosis prediction in AMI patients.

Individualized discrimination of tumor recurrence from radiation necrosis in glioma patients using an integrated radiomics-based model

PURPOSE

To develop and validate an integrated model for discriminating tumor recurrence from radiation necrosis in glioma patients.

METHODS

Data from 160 pathologically confirmed glioma patients were analyzed. The diagnostic model was developed in a primary cohort (n = 112). Textural features were extracted from postoperative ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET), ¹¹C-methionine (¹¹C-MET) PET, and magnetic resonance images. The least absolute shrinkage and selection operator regression model was used for feature selection and radiomics signature building. Multivariable logistic regression analysis was used to develop a model for predicting tumor recurrence. The radiomics signature, quantitative PET parameters, and clinical risk factors were incorporated in the model. The clinical value of the model was then assessed in an independent validation cohort using the remaining 48 glioma patients.

RESULTS

The integrated model consisting of 15 selected features was significantly associated with postoperative tumor recurrence (p < 0.001 for both primary and validation cohorts). Predictors contained in the individualized diagnosis model included the radiomics signature, the mean of tumor-background ratio (TBR) of ¹⁸F-FDG, maximum of TBR of ¹¹C-MET PET, and patient age. The integrated model demonstrated good discrimination, with an area under the curve (AUC) of 0.988, with a 95% confidence interval (CI) of 0.975-1.000. Application in the validation cohort showed good differentiation (AUC of 0.914 and 95% CI of 0.881-0.945). Decision curve analysis showed that the integrated diagnosis model was clinically useful.

CONCLUSIONS

Our developed model could be used to assist the postoperative individualized diagnosis of tumor recurrence in patients with gliomas.

Multiple Biomarker Use for Detection of Adverse Events in Patients Presenting with Symptoms Suggestive of Acute Coronary Syndrome

Background: We investigated multiple biomarkers of various pathophysiologic pathways to determine their relationships with adverse outcomes in patients presenting with symptoms of acute coronary syndrome.

Methods: We obtained plasma specimens from 457 patients on admission and measured 7 biomarkers: myeloperoxidase (MPO), soluble CD40 ligand (CD40L), placental growth factor (PlGF), metalloproteinase-9 (MMP-9), high-sensitivity C-reactive protein (hsCRP), cardiac troponin I (cTnI), and N-terminal pro-B-type natriuretic peptide (NT-proBNP). We used the Modification of Diet in Renal Disease formula to calculate the estimated glomerular filtration rate (eGFR). Endpoints were cardiac events (myocardial infarction, percutaneous coronary intervention, coronary artery bypass graft, cardiac death) and all-cause mortality. We estimated cumulative event rates over a 4-month period with the Kaplan–Meier method and relative risk (RR) with the Cox proportional hazards model.

Results: Patients with increased PlGF, NT-proBNP, hsCRP, or cTnI or decreased eGFR had 11% to 20% higher all-cause mortality rates than patients with concentrations within reference intervals: 20.4% (eGFR), 16.0% (PlGF), 15.8% (hsCRP), 12.7% (NT-proBNP), and 11.3% (cTnI; all P ≤0.03). No differences in mortality rates were observed between those with increased vs normal concentrations of MPO, CD40L, or MMP-9. Decreased eGFR (RR 3.4, P = 0.004) and increased NT-proBNP (RR 7.9, P = 0.04) were independently predictive of mortality, and PlGF (RR 2.0, P = 0.08) approached significance. Patients with increased NT-proBNP (12.3%) or cTnI (33.8%) had higher cardiac event rates (each P &lt;0.02), with increased MPO (11.1%) showing a trend (P = 0.09). Patients in whom both cTnI and MPO were increased had a cardiac event rate of 43%.

Conclusion: Multiple biomarkers that are likely indicative of different underlying pathophysiologic mechanisms are independently predictive of increased risk for adverse events in patients with acute coronary syndrome.

Diagnostic and prognostic value of biomarkers in acute myocardial infarction

The incidence of acute myocardial infarction (AMI) has been increasing rapidly in recent years, seriously endangering human health. Cardiac biomarkers play critical roles in the diagnosis and prognosis of AMI. Troponin is a highly sensitive and specific biomarker for AMI diagnosis and can independently predict adverse cardiac events. Other biomarkers such as N-terminal B-type natriuretic peptide and C reactive protein are also valuable predictors of cardiovascular prognosis. Recently, several novel biomarkers have been identified for the diagnosis and risk assessment in patients with AMI. A multibiomarker approach can potentially enhance the diagnostic accuracy and provide more information for the early risk stratification of AMI. In this review, we will summarise the biomarkers discovered in recent years and focus on their diagnostic and prognostic value for patients with AMI.

Understanding cardiac extracellular matrix remodeling to develop biomarkers of myocardial infarction outcomes

Cardiovascular Disease (CVD) is the most common cause of death in industrialized countries, and myocardial infarction (MI) is a major CVD with significant morbidity and mortality. Following MI, the left ventricle (LV) undergoes a wound healing response to ischemia that results in extracellular matrix (ECM) scar formation to replace necrotic myocytes. While ECM accumulation following MI is termed cardiac fibrosis, this is a generic term that does not differentiate between ECM accumulation that occurs in the infarct region to form a scar that is structurally necessary to preserve left ventricle (LV) wall integrity and ECM accumulation that increases LV wall stiffness to exacerbate dilation and stimulate the progression to heart failure. This review focuses on post-MI LV ECM remodeling, targeting the discussion on ECM biomarkers that could be useful for predicting MI outcomes.

The Diagnostic Value and Cost-Effectiveness of Creatine Kinase-MB, Myoglobin and Cardiac Troponin-T for Patients with Chest Pain in Emergency Department Observation Ward

Aim

To evaluate the diagnostic value and cost-effectiveness of creatine kinase-MB isomer, myoglobin and cardiac troponin-T for patients with chest pain in emergency department observation ward.

Method

A prospective study was carried out to include all patients presenting with chest pain of suspected cardiac origin and admitted to the observation ward. Electrocardiogram and blood tests for the three cardiac markers were performed at the time of consultation and six to eight hours after admission to the observation ward. Progress of the patients was followed up for 30-day survival or the condition reviewed up to six months and the final diagnoses were documented.

Result

A total of 480 patients were recruited. The incidence of acute myocardial infarction was 1.5%. No one died of cardiac cause within 30 days. Troponin was more accurate than creatine kinase for diagnosing acute myocardial infarction and it was cost-effective. Myoglobin was of no value.

Conclusion

Troponin is recommended as a diagnostic tool for evaluating patients with chest pain in observation ward.

Novel Risk Stratification Assays for Acute Coronary Syndrome

PURPOSE OF REVIEW

Since identification of aspartate aminotransferase as the first cardiac biomarker in the 1950s, there have been a number of new markers used for myocardial damage detection over the decades. There have also been several generations of troponin assays, each with progressively increasing sensitivity for troponin detection. Accordingly, the "standard of care" for myocardial damage detection continues to change. The purpose of this paper is to review the clinical utility, biological mechanisms, and predictive value of these various biomarkers in contemporary clinical studies.

RECENT FINDINGS

As of this writing, a fifth "next" generation troponin assay has now been cleared by the US Food and Drug Administration for clinical use in the USA for subjects presenting with suspected acute coronary syndromes. Use of these high-sensitivity assays has allowed for earlier detection of myocardial damage as well as greater negative predictive value for infarction after only one or two serial measurements. Recent algorithms utilizing these assays have allowed for more rapid rule-out of myocardial infarction in emergency department settings. In this review, we discuss novel assays available for the risk assessment of subjects presenting with chest pain, including both the "next generation" cardiac troponin assays as well as other novel biomarkers. We review the biological mechanisms for these markers, and explore the positive and negative predictive value of the assays in clinical studies, where reported. We also discuss the potential use of these new markers within the context of future clinical care in the modern era of higher sensitivity troponin testing. Finally, we discuss advances in new platforms (e.g., mass spectrometry) that historically have not been considered for rapid in vitro diagnostic capabilities, but that are taking a larger role in clinical diagnostics, and whose prognostic value and power promise to usher in new markers with potential for future clinical utility in acute coronary syndrome.

Outcome at 30 days for low-risk chest pain patients assessed using an accelerated diagnostic pathway in the emergency department

OBJECTIVES

Primary: to determine incidence of 30 day major adverse cardiac events (MACE) in patients discharged from the ED following assessment using an accelerated diagnostic pathway (ADP). Secondary: to determine incidence of 30 day MACE for all ADP patients.

METHODS

Monash Health ED patients thought at low risk for acute myocardial infarction (AMI) or hospital admission are assessed using an ADP, based on arrival and 90 min point-of-care (POC) cardiac troponin I and myoglobin concentration. Other patients are assessed using a traditional pathway of arrival and 6 h central lab cardiac troponin I. Choice of pathway is based on the clinical judgement of the attending ED doctor. To investigate the safety of the ADP component, an observational study of all ADP patients presenting from 6 June 2013 to 30 September 2013 was conducted. After 30 days, occurrence of MACE was determined by examination of hospital records or telephone contact with patients who had not returned.

RESULTS

Of 1547 eligible patients, 1384 (89.5%) were followed up. Of the 1143 discharged patients with follow-up information, 30 day MACE occurred in one (0.09%, 95% CI 0.002-0.5). Of all 1547 patients, 60 patients had a MACE detected: 56 AMI during the initial attendance, four AMI post-discharge (one from ED, three after hospital admission). In total, of the 1328 patients who did not have AMI during the target admission and were followed up, 30 day post-discharge MACE occurred in four patients (0.3%, 95% CI 0.08-0.8).

CONCLUSION

The ADP supports safe, early discharge of low-risk chest pain patients from the ED.

Serum cardiac troponin I concentrations in dogs with systemic inflammatory response syndrome

Background

Myocardial injury can be detected by cardiac troponin I (cTnI) concentration, which appears to be a predictor of short‐term death in critically ill patients. It is unknown if the best prognostic indicator of short‐term survival is cTnI measurement at admission or at later time points.

Hypothesis/Objectives

Measuring cTnI with a high‐sensitivity (HS) test at different time points after admission may be a better short‐term prognostic indicator than a single cTnI measurement at admission in dogs with systemic inflammatory response syndrome (SIRS).

Animals

Prospective, observational clinical study of 60 dogs with SIRS.

Methods

Cardiac troponin I concentration was measured in 133 serum samples, collected at days 1, 2, 3, and 5. Additionally, the acute patient physiologic and laboratory evaluation (APPLE) fast score was evaluated at admission. Prognostic capabilities of cTnI measurement and APPLE fast score for 28‐day mortality were assessed by receiver operating characteristic curve analysis.

Results

Forty‐one dogs with SIRS that survived 28 days had significantly lower serum cTnI concentrations at admission (median, 0.09 ng/mL; P = .004) and at the peak time point (median, 0.23 ng/mL; P = .01) compared to 19 nonsurvivors (median at admission, 0.63 ng/mL; median at peak, 1.22 ng/mL). Area under the curve to predict survival, using cTnI was similar at admission (0.732) and at peak (0.708), and was 0.754 for the APPLE fast score.

Conclusions and Clinical Importance

Increased cTnI concentration in dogs with SIRS is associated with poor outcome. Daily follow‐up measurement of cTnI concentration provides no additional prognostic information for short‐term mortality.

Bedside evaluation of cardiac markers

Accurate and rapid diagnostic tests can help identify high-risk patients with ACS among those presenting to the emergency department with chest pain. Such tests can also differentiate low-risk patients with chest pain who are suitable for early emergency department discharge. In this article, Drs Amsterdam and Deedwania elucidate the varieties of ACS, their pathophysiology, and the methods used for diagnosis. The authors also explore the potential of point-of-care testing for cardiac injury markers in the timely and accurate identification of ACS.

Metabolomics provide new insights on lung cancer staging and discrimination from chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) and lung cancer are widespread lung diseases. Cigarette smoking is a high risk factor for both the diseases. COPD may increase the risk of developing lung cancer. Thus, it is crucial to be able to distinguish between these two pathological states, especially considering the early stages of lung cancer. Novel diagnostic and monitoring tools are required to properly determine lung cancer progression because this information directly impacts the type of the treatment prescribed. In this study, serum samples collected from 22 COPD and 77 lung cancer (TNM stages I, II, III, and IV) patients were analyzed. Then, a collection of NMR metabolic fingerprints was modeled using discriminant orthogonal partial least squares regression (OPLS-DA) and further interpreted by univariate statistics. The constructed discriminant models helped to successfully distinguish between the metabolic fingerprints of COPD and lung cancer patients (AUC training=0.972, AUC test=0.993), COPD and early lung cancer patients (AUC training=1.000, AUC test=1.000), and COPD and advanced lung cancer patients (AUC training=0.983, AUC test=1.000). Decreased acetate, citrate, and methanol levels together with the increased N-acetylated glycoproteins, leucine, lysine, mannose, choline, and lipid (CH3-(CH2)n-) levels were observed in all lung cancer patients compared with the COPD group. The evaluation of lung cancer progression was also successful using OPLS-DA (AUC training=0.811, AUC test=0.904). Based on the results, the following metabolite biomarkers may prove useful in distinguishing lung cancer states: isoleucine, acetoacetate, and creatine as well as the two NMR signals of N-acetylated glycoproteins and glycerol.

Stress cardiac MR imaging compared with stress echocardiography in the early evaluation of patients who present to the emergency department with intermediate-risk chest pain

PURPOSE

To compare the utility and efficacy of stress cardiac magnetic resonance (MR) imaging and stress echocardiography in an emergency setting in patients with acute chest pain (CP) and intermediate risk of coronary artery disease (CAD).

MATERIALS AND METHODS

Written informed consent was obtained from all patients. This HIPAA-compliant study was approved by the institutional review board for research ethics. Sixty patients without history of CAD presented to the emergency department with intermediate-risk acute CP and were prospectively enrolled. Patients underwent both stress cardiac MR imaging and stress echocardiography in random order within 12 hours of presentation. Stress imaging results were interpreted clinically immediately (blinded interpretation was performed months later), and coronary angiography was performed if either result was abnormal. CAD was considered significant if it was identified at angiography (narrowing >50% ) or if a cardiac event (death or myocardial infarction) occurred during follow-up (mean, 14 months ± 5 [standard deviation]). McNemar test was used to compare the diagnostic accuracy of techniques.

RESULTS

Stress cardiac MR imaging and stress echocardiography had similar specificity, accuracy, and positive and negative predictive values (92% vs 96%, 93% vs 88%, 67% vs 60%, and 100% vs 91%, respectively, for clinical interpretation; 90% vs 92%, 90% vs 88%, 58% vs 56%, and 98% vs 94%, respectively, for blinded interpretation). Stress cardiac MR imaging had higher sensitivity at clinical interpretation (100% vs 38%, P = .025), which did not reach significance at blinded interpretation (88% vs 63%, P = .31). However, multivariable logistic regression analysis showed stress cardiac MR imaging to be the strongest independent predictor of significant CAD (P = .002).

CONCLUSION

In patients presenting to the emergency department with intermediate-risk CP, adenosine stress cardiac MR imaging performed within 12 hours of presentation is safe and potentially has improved performance characteristics compared with stress echocardiography. Online supplemental material is available for this article.

Estimation of Ischemia Modified Albumin (IMA) Levels in Patients with Acute Coronary Syndrome

Myocardial ischemia produces free radicals that catalyze a series of oxidative reactions that damage healthy tissues. The N-terminal sequence of albumin is one of the proteins modified by these highly reactive oxygen species and forms the ischemia modified albumin (IMA). This study involves investigations undertaken in different study groups to assess the levels of IMA. Mean serum IMA levels (U/mL) in patients with ST-segment elevated myocardial infarction (92.1 ± 10.6), non-ST-segment elevated myocardial infarction (87.3 ± 5.95) and unstable angina (UA) (88.9 ± 6.16) were significantly higher than non-cardiac chest pain (77.9 ± 6.69) and also healthy subjects (54.7 ± 17.2) (p < 0.001). IMA is a highly sensitive marker and has a high predictive value, which might prove the usefulness of this biomarker for early detection of myocardial ischemia. These data indicate a possible role of the IMA test in the early triage of patients with chest pain.

Heart type fatty acid binding protein: structure, function and biosensing applications for early detection of myocardial infarction

Heart type fatty acid binding protein (HFABP) as an early marker of cardiac injury holds a promising future with studies indicating surpassing performance as compared to myoglobin. As a plasma marker, this cytoplasmic protein owing to its small size (∼15kDa) and water solubility, appears readily in the blood-stream following cardiomyocyte damage, reaching peak levels within 6h of symptom onset. Low plasma levels of HFABP as compared to tissue levels indicate that minute amounts of the protein when released during myocardial infarction leads to a greater proportional rise. These parameters of kinetic release make it an ideal candidate for rapid assessment of acute myocardial infarction (AMI). The need for development of rapid immunoassays and immunotests so as to use HFABP as an early marker for AMI exclusion is tremendous. In the present review, we outline the various immunoassays and immunosensors developed so far for the detection of HFABP in buffer, plasma or whole blood. The principles behind the detection techniques along with their performance parameters compared to standard ELISA techniques are elucidated.

Translational biomarker discovery in clinical metabolomics: an introductory tutorial

Metabolomics is increasingly being applied towards the identification of biomarkers for disease diagnosis, prognosis and risk prediction. Unfortunately among the many published metabolomic studies focusing on biomarker discovery, there is very little consistency and relatively little rigor in how researchers select, assess or report their candidate biomarkers. In particular, few studies report any measure of sensitivity, specificity, or provide receiver operator characteristic (ROC) curves with associated confidence intervals. Even fewer studies explicitly describe or release the biomarker model used to generate their ROC curves. This is surprising given that for biomarker studies in most other biomedical fields, ROC curve analysis is generally considered the standard method for performance assessment. Because the ultimate goal of biomarker discovery is the translation of those biomarkers to clinical practice, it is clear that the metabolomics community needs to start "speaking the same language" in terms of biomarker analysis and reporting-especially if it wants to see metabolite markers being routinely used in the clinic. In this tutorial, we will first introduce the concept of ROC curves and describe their use in single biomarker analysis for clinical chemistry. This includes the construction of ROC curves, understanding the meaning of area under ROC curves (AUC) and partial AUC, as well as the calculation of confidence intervals. The second part of the tutorial focuses on biomarker analyses within the context of metabolomics. This section describes different statistical and machine learning strategies that can be used to create multi-metabolite biomarker models and explains how these models can be assessed using ROC curves. In the third part of the tutorial we discuss common issues and potential pitfalls associated with different analysis methods and provide readers with a list of nine recommendations for biomarker analysis and reporting. To help readers test, visualize and explore the concepts presented in this tutorial, we also introduce a web-based tool called ROCCET (ROC Curve Explorer & Tester, http://www.roccet.ca). ROCCET was originally developed as a teaching aid but it can also serve as a training and testing resource to assist metabolomics researchers build biomarker models and conduct a range of common ROC curve analyses for biomarker studies.

Assessing the clinical utility of biomarkers in medicine

Biomarkers in medicine have gained immense scientific and clinical interest in recent years. Biomarkers are potentially useful in the contexts of primary, secondary and tertiary prevention. Some of the characteristics of an ideal biomarker include that they are safe and easy to measure, are associated with acceptable costs (including those of the follow-up tests), and there is scientific evidence to suggest that biomarker use/modification influences disease outcomes. Additionally, variation in biomarker levels with gender and ethnicity should be elucidated, and the biomarker should have 'good performance characteristics' (i.e., sensitivity, specificity, positive- and negative-predictive values and positive- and negative-likelihood ratios). Risk prediction scores can combine information from several different biomarkers in order to estimate an individual's risk of developing an outcome, such as disease or death. Three commonly employed methods to test if a biomarker will add to traditional risk prediction models are model discrimination, model calibration and risk reclassification. 'Multimarker' strategies serve to integrate information from multiple biomarkers into risk prediction but may be limited by the presence of highly correlated biomarkers, economic costs and selection bias of biomarker candidates in a particular study sample. In the future, integration of biomarkers identified using emerging technologies from the 'omics fields (including genomics, proteomics, metabolomics, lipomics, ribomics and pharmacogenomics) may be useful for the 'personalization' of treatment/disease prevention.

Novel cardiac-specific biomarkers and the cardiovascular continuum

The concept of the cardiovascular continuum, introduced during the early 1990s, created a holistic view of the chain of events connecting cardiovascular-related risk factors with the progressive development of pathological-related tissue remodelling and ultimately, heart failure and death. Understanding of the tissue-specific changes, and new technologies developed over the last 25-30 years, enabled tissue remodelling events to be monitored in vivo and cardiovascular disease to be diagnosed more reliably than before. The tangible product of this evolution was the introduction of a number of biochemical markers such as troponin I and T, which are now commonly used in clinics to measure myocardial damage. However, biomarkers that can detect specific earlier stages of the cardiovascular continuum have yet to be generated and utilised. The majority of the existing markers are useful only in the end stages of the disease where few successful intervention options exist. Since a large number of patients experience a transient underlying developing pathology long before the signs or symptoms of cardiovascular disease become apparent, the requirement for new markers that can describe the early tissue-specific, matrix remodelling process which ultimately leads to disease is evident. This review highlights the importance of relating cardiac biochemical markers with specific time points along the cardiovascular continuum, especially during the early transient phase of pathology progression where none of the existing markers aid diagnosis.

Effect on emergency department efficiency of an accelerated diagnostic pathway for the evaluation of chest pain

OBJECTIVE

To compare ED efficiency measures between a trial period using an accelerated diagnostic pathway (ADP) for chest pain evaluation, and a control period using a traditional diagnostic pathway (TDP).

METHODS

The TDP used cardiac Troponin I assays at arrival and 6 h. The ADP used point-of-care multimarker (myoglobin, creatine kinase-MB fraction and cardiac Troponin I) assays at arrival and 2 h. Outcomes for consecutive eligible patients included ED length of stay (LOS), discharges and admissions within 4 and 8 h, ED occupancy and cardiac cubicle throughput.

RESULTS

There were 413 and 258 eligible patients during the 81 day TDP and 66 day ADP periods. The ED LOS for chest pain patients was reduced in the ADP period for both discharged patients (median 297 [interquartile range {IQR} 230-437]vs 545 [IQR 457-677] min, P < 0.0001) and admitted patients (median 609.5 [IQR 464-857]vs 733.5 [IQR 532-1070] min, P= 0.007). For the whole ED, the percentage of patients discharged or admitted within 4 or 8 h and ED occupancy were similar between periods. Cardiac cubicle throughput increased during the ADP period (217 [95% confidence interval 209.6-224.4]vs 188 [95% confidence interval 174.5-201.8] patients per week, P= 0.005).

CONCLUSIONS

The ADP utilizing point-of-care multimarkers led to significantly shorter ED LOS for both discharged and admitted chest pain patients. This was associated with increased cardiac cubicle throughput, but improvements in other whole ED performance indicators were not demonstrated.

Biomarkers in cardiovascular clinical trials: past, present, future

BACKGROUND

Cardiovascular (CV) clinical trials are instrumental in understanding treatment effects and offer insights into the natural progression of CV disease. Biomarkers are a critical component of patient selection, end point definition, and safety monitoring, and clinical trials provide a platform for the discovery and validation of new biomarkers that may augment the understanding of disease mechanisms, risk stratification, and/or clinical decision-making.

CONTENT

We review the roles that biomarkers have played in CV clinical trials and roles that CV clinical trials have played and will continue to play in the discovery and validation of biomarkers and their implementation in clinical practice. Large biobanks containing multiple specimen types are increasingly being created from patients enrolled in clinical trials, and such biobanks, when coupled with advances in molecular techniques and bioinformatics, promise to accelerate our understanding of CV disease mechanisms and to help fuel the discovery and development of novel therapeutic targets and biomarkers of risk and treatment response.

SUMMARY

The past, present, and future of biomarkers and clinical trials have been and will remain intertwined. Biomarkers were once the workhorses of patient selection and end point definition in clinical trials; more recently, clinical trials have been the proving ground for individual biomarkers. Attention to biobanking and the application of modern informatics and molecular techniques to samples collected within clinical trials will usher in the era of stratified and personalized medicine.

Cardiac biomarkers in acute myocardial infarction

Each year, a large number of patients are seen in the Emergency Department with presentations necessitating investigation for possible acute myocardial infarction. Patients can be stratified by symptoms, risk factors and electrocardiogram results but cardiac biomarkers also have a prime role both diagnostically and prognostically. This review summarizes both the history of cardiac biomarkers as well as currently available (established and novel) assays. Cardiac troponin, our current "gold standard" biomarker criterion for the diagnosis of myocardial infarction has high sensitivity and specificity for this diagnosis and therapies instituted in patients with elevated troponin have been shown to influence outcomes. Other markers of myocardial necrosis, inflammation and neurohormonal activity have also been shown to have either diagnostic or prognostic utility, but none have been shown to be superior to troponin. The measurement of multiple biomarkers and the use of point of care markers may accelerate current diagnostic protocols for the assessment of such patients.

The comparison of cardiac biomarkers positivities in hemodialysis patients without acute coronary syndrome

AIM

We aimed to compare heart-type fatty acid-binding proteins (H-FAB) and other cardiac biomarkers to determine the most reliable cardiac marker in hemodialysis (HD) patients without acute coronary syndrome (ACS).

MATERIALS AND METHODS

Sixty HD patients without ACS were included the study. Blood samples were taken before HD session for measurement of H-FAB, troponin I, troponin T, creatine kinase-MB (CK-MB) isoforms.

RESULTS

Mean age of patients was 55 ± 15 years. Males were 55%. Mean serum level of blood urea nitrogen was 75 ± 15 mg/dL, mean serum level of creatinine was 8.3 ± 2.5 mg/dL, mean serum level of hematocrit was 33 ± 5%, mean ejection fraction was 54 ± 9%, and mean left ventricular mass index (LVMI) was 136 ± 54 g/m(2). H-FAB was positive in 32%, troponin T in 20%, troponin I in 12%, and CK-MB in 5% of all patients. Three or four of all parameters were not positive together in any patient. While 5% of patients had positive troponin T with H-FAB, 3% of patients had positive troponin T with troponin I and 2% of patients had positive troponin I with H-FAB.

CONCLUSION

Our study found that CK-MB had the lowest positivity in the HD patients without ACS. H-FAB had the highest rate of positivity in all markers. If only one marker is assessed it should be CK-MB. But using two parameters in HD patients in ACS diagnosis increases the reliability of diagnosis. If we use two biomarkers it should be CK-MB and troponin I.

Improving patient flow in acute coronary syndromes in the face of hospital crowding

BACKGROUND

The current paradigm for the evaluation of patients with suspected acute coronary syndromes (ACS) in the emergency department (ED) is focused on the identification of patients with active underlying coronary disease. The majority of patients evaluated in the ED setting do not have active underlying cardiac disease.

OBJECTIVE

To measure the effect of bedside point-of-care (POC) cardiac biomarker testing on telemetry unit admissions from the ED. Furthermore, to evaluate the effect telemetry admissions have on ED length of stay (LOS) and overall hospital LOS.

METHODS

Primary data were collected over two 6-month periods in an urban teaching hospital ED. This was an observational cohort study conducted pre- and post-availability of a POC testing platform for cardiac biomarkers. Major measures included number of overall telemetry admissions, ED LOS, hospital LOS, and disposition. Patients were followed at 30 days for significant cardiac events, repeat ED visit or admission, and death.

RESULTS

In the post-implementation period there was a 30% (95% confidence interval [CI] 36-44%) reduction in admissions to telemetry with a 33% (95% CI 26-39%) reduction in ED LOS and a 20% (95% CI 7-34%) reduction in hospital LOS. There was a 62% reduction in overall mortality between the pre-implementation period and the post-implementation period (p=0.001).

CONCLUSION

The focused use of a rapid cardiac disposition protocol can dramatically impact resource utilization, expedite patient flow, and improve short-term outcomes for patients with suspected ACS.

Multi-marker strategies in heart failure: clinical and statistical approaches

Advances in genomics and proteomics promise to transform biomarker research, in which the major challenges will not be the discovery of new markers but rather the optimal selection and validation of a subgroup of clinically useful markers from the large pool of candidates. Critically, the value of new biomarkers panels will need to be assessed in the context of readily available clinical information in order to create more actionable knowledge rather than just greater complexity. Appropriate methodologies for the clinical and statistical evaluation of so called "multi-marker strategies" have not been systematically defined. Although specific criteria for the appropriate clinical and statistical evaluation of multi-marker strategies will vary based on the intended use (e.g., diagnosis vs. screening), the ultimate measure of success is the ability for a biomarker panel to both correct a meaningful portion of misclassification by standard methods (discrimination) and to improve quantification of absolute risk (calibration) in comparison to existing clinical information. Findings should be validated in an independent dataset of the representative patient population before a given multi-marker strategy can be considered for clinical use. Here, we define multi-marker strategies, summarize recent examples of biomarker combinations in heart failure, address key statistical and clinical issues, and discuss future directions for this rapidly evolving field.

Use of multiple biomarkers in heart failure

Biomarkers are becoming increasingly available for clinical use, particularly in the care of patients with heart failure. For health care providers, a major difficulty is how to interpret and apply these increasing amounts of diagnostic and prognostic information. Consequently, the scientific challenge is evolving from the discovery of biomarkers to the selection and validation of select panels of clinically useful markers that balance performance and practicality. Optimal combinations of biomarkers will vary based on the intended use (eg, diagnosis vs prognosis). The final goal must be to generate more actionable knowledge that improves patient management and outcomes, rather than merely creating greater complexity. Here we conceptually define multiple biomarker strategies, provide examples of emerging biomarker panels used in the care of patients with heart failure, and address key statistical and clinical issues for this rapidly evolving field.

The future of point-of-care testing in emergency departments

Emergency physicians and administrators continue to face operational challenges as they attempt to increase emergency department (ED) efficiency and throughput to meet the growing demand for emergency health services. Point-of-care (POC) testing technology can provide clinicians with accurate and reliable results with at least a 50% reduction in turnaround time. Despite the near perfect alignment of POC technology goals with ED operational strategy, there has been a relatively slow adoption of comprehensive POC systems. The authors discuss current market trends for the POC products in the ED and review trends in outcomes data (including operational, clinical and financial). The authors also discuss observed managerial obstacles to implementation. The goal of this paper is to provide readers with a business psychology perspective on the current challenges that organizations face in adopting a new technology and provide an evaluation of the key drivers that influence institutional-level decisions to implement an ED-based POC system. The reader will gain an understanding of the dynamic forces that are slowing the adoption of POC technology. Also, the reader is provided with the authors' future perspectives for POC testing in emergency medicine. The current healthcare system is putting a lot of pressure on EDs to be able to provide efficient care using advanced diagnostic tests. Clinicians and administrators alike must understand the gaps between the clinician's perceived benefit of POC testing and the inconsistent literature on the operational and clinical outcomes before adopting POC systems in ED.

A 2-h diagnostic protocol to assess patients with chest pain symptoms in the Asia-Pacific region (ASPECT): a prospective observational validation study

BACKGROUND

Patients with chest pain contribute substantially to emergency department attendances, lengthy hospital stay, and inpatient admissions. A reliable, reproducible, and fast process to identify patients presenting with chest pain who have a low short-term risk of a major adverse cardiac event is needed to facilitate early discharge. We aimed to prospectively validate the safety of a predefined 2-h accelerated diagnostic protocol (ADP) to assess patients presenting to the emergency department with chest pain symptoms suggestive of acute coronary syndrome.

METHODS

This observational study was undertaken in 14 emergency departments in nine countries in the Asia-Pacific region, in patients aged 18 years and older with at least 5 min of chest pain. The ADP included use of a structured pre-test probability scoring method (Thrombolysis in Myocardial Infarction [TIMI] score), electrocardiograph, and point-of-care biomarker panel of troponin, creatine kinase MB, and myoglobin. The primary endpoint was major adverse cardiac events within 30 days after initial presentation (including initial hospital attendance). This trial is registered with the Australia-New Zealand Clinical Trials Registry, number ACTRN12609000283279.

FINDINGS

3582 consecutive patients were recruited and completed 30-day follow-up. 421 (11.8%) patients had a major adverse cardiac event. The ADP classified 352 (9.8%) patients as low risk and potentially suitable for early discharge. A major adverse cardiac event occurred in three (0.9%) of these patients, giving the ADP a sensitivity of 99.3% (95% CI 97.9-99.8), a negative predictive value of 99.1% (97.3-99.8), and a specificity of 11.0% (10.0-12.2).

INTERPRETATION

This novel ADP identifies patients at very low risk of a short-term major adverse cardiac event who might be suitable for early discharge. Such an approach could be used to decrease the overall observation periods and admissions for chest pain. The components needed for the implementation of this strategy are widely available. The ADP has the potential to affect health-service delivery worldwide.

FUNDING

Alere Medical (all countries), Queensland Emergency Medicine Research Foundation and National Health and Medical Research Council (Australia), Christchurch Cardio-Endocrine Research Group (New Zealand), Medquest Jaya Global (Indonesia), Science International (Hong Kong), Bio Laboratories Pte (Singapore), National Heart Foundation of New Zealand, and Progressive Group (Taiwan).

Testing of low-risk patients presenting to the emergency department with chest pain: a scientific statement from the American Heart Association

The management of low-risk patients presenting to emergency departments is a common and challenging clinical problem entailing 8 million emergency department visits annually. Although a majority of these patients do not have a life-threatening condition, the clinician must distinguish between those who require urgent treatment of a serious problem and those with more benign entities who do not require admission. Inadvertent discharge of patients with acute coronary syndrome from the emergency department is associated with increased mortality and liability, whereas inappropriate admission of patients without serious disease is neither indicated nor cost-effective. Clinical judgment and basic clinical tools (history, physical examination, and electrocardiogram) remain primary in meeting this challenge and affording early identification of low-risk patients with chest pain. Additionally, established and newer diagnostic methods have extended clinicians' diagnostic capacity in this setting. Low-risk patients presenting with chest pain are increasingly managed in chest pain units in which accelerated diagnostic protocols are performed, comprising serial electrocardiograms and cardiac injury markers to exclude acute coronary syndrome. Patients with negative findings usually complete the accelerated diagnostic protocol with a confirmatory test to exclude ischemia. This is typically an exercise treadmill test or a cardiac imaging study if the exercise treadmill test is not applicable. Rest myocardial perfusion imaging has assumed an important role in this setting. Computed tomography coronary angiography has also shown promise in this setting. A negative accelerated diagnostic protocol evaluation allows discharge, whereas patients with positive findings are admitted. This approach has been found to be safe, accurate, and cost-effective in low-risk patients presenting with chest pain.

Upstream treatment of acute coronary syndrome in the ED

Rapid risk stratification, selection of downstream management options, and institution of initial pharmacotherapy are essential to ensure that patients admitted to the emergency department with acute coronary syndromes receive optimal care. A broad range of antiplatelet and antithrombotic medications is available that permits tailoring of initial pharmacotherapy to each patient's risk status. In the urgent setting, thienopyridines (clopidogrel and prasugrel) carry limitations including response variability and increased risk for bleeding in patients requiring subsequent coronary artery bypass graft surgery. Glycoprotein IIb-IIIa receptor inhibitors, although they are highly effective in preventing ischemic events, must be used with care to reduce bleeding risk. Bivalirudin, a relatively new direct thrombin inhibitor, represents another upstream option but is costly and does not have approval for this indication. Simplified institutional management paradigms can streamline the process of selecting appropriate pharmacotherapy and aid in care delivery that will optimize patient outcomes.

Reclassification of cardiovascular risk using integrated clinical and molecular biosignatures: Design of and rationale for the Measurement to Understand the Reclassification of Disease of Cabarrus and Kannapolis (MURDOCK) Horizon 1 Cardiovascular Disease Study

BACKGROUND

Clinical predictive models leave gaps in our ability to stratify cardiovascular risk. High-throughput molecular profiling promises to improve risk classification.

METHODS

Horizon 1 of the Measurement to Understand the Reclassification of Disease of Cabarrus and Kannapolis (MURDOCK) Study was conceived to apply emerging molecular techniques to existing data sets to characterize mechanistic diversity underlying complex human diseases, response to therapy, and prognosis. No previous studies have applied multiple, complementary molecular techniques in combination with well-developed clinical risk models to refine cardiovascular risk prediction. The MURDOCK Cardiovascular Disease Study will assess molecular profiles integrated with clinical data in "clinomic" profiles for cardiovascular risk classification.

CONCLUSION

Herein, we describe the design of and rationale for the MURDOCK Cardiovascular Disease Study.

Time-critical neurological emergencies: the unfulfilled role for point-of-care testing

Background

Neurological emergencies are common and frequently devastating. Every year, millions of Americans suffer an acute stroke, severe traumatic brain injury, subarachnoid hemorrhage, status epilepticus, or spinal cord injury severe enough to require medical intervention.

Aims

Full evaluation of the diseases in the acute setting often requires advanced diagnostics, and treatment frequently necessitates transfer to specialized centers. Delays in diagnosis and/or treatment may result in worsened outcomes; therefore, optimization of diagnostics is critical.

Methods

Point-of-care (POC) testing brings advanced diagnostics to the patient’s bedside in an effort to assist medical providers with real-time decisions based on real-time information. POC testing is usually associated with blood tests (blood glucose, troponin, etc.), but can involve imaging, medical devices, or adapting existing technologies for use outside of the hospital. Noticeably missing from the list of current point-of-care technologies are real-time bedside capabilities that address neurological emergencies.

Results

Unfortunately, the lack of these technologies may result in delayed identification of patients of these devastating conditions and contribute to less aggressive therapies than is seen with other disease processes. Development of time-dependent technologies appropriate for use with the neurologically ill patient are needed to improve therapies and outcomes.

Conclusion

POC-CENT is designed to support the development of novel ideas focused on improving diagnostic or prognostic capabilities for acute neurological emergencies. Eligible examples include biomarkers of traumatic brain injury, non-invasive measurements of intracranial pressure or cerebral vasospasm, and improved detection of pathological bacteria in suspected meningitis.

Future developments in chest pain diagnosis and management

Much of the focus of research on patients with chest pain is directed at technological advances in the diagnosis and management of acute coronary syndrome (ACS), pulmonary embolism (PE), and acute aortic dissection (AAD), despite there being no significant difference at 4 years as regards mortality, ongoing chest pain, and quality of life between patients presenting to the emergency department with noncardiac chest pain and those with cardiac chest pain. This article examines future developments in the diagnosis and management of patients with suspected ACS, PE, AAD, gastrointestinal disease, and musculoskeletal chest pain.

Early Diagnosis of Acute Myocardial Infarction by Bedside Multimarker Test at an Emergency Department in Hong Kong

Introduction

Cardiac biomarker measurement can aid diagnosis of acute myocardial infarction. The present study evaluates the efficacy and efficiency of point-of-care multimarkers measurement of myoglobin, creatine kinase (CK-MB) and troponin in identifying patients with acute myocardial infarction.

Method

We prospectively enrolled consecutive patients (N=105) in the emergency department who were being evaluated for possible acute myocardial infarction. Point-of-care testing (POCT) of myoglobin, CK-MB and troponin I (TnI) was performed in all patients. Central laboratory measurement of troponin I was also performed simultaneously. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio and receiver operating characteristic (ROC) curve were evaluated.

Result

The specificity and positive likelihood ratio of TnI (POCT) and TnI (laboratory) were 98%, 13.0 and 98%, 21.8 respectively. The areas under curve of the ROC curve of TnI (POCT) and TnI (laboratory) were 0.692 and 0.725 respectively.

Conclusion

A high positive likelihood ratio for acute myocardial infarction through point-of-care testing can help timely diagnosis and just-in-time appropriate management for patients presenting with chest pain.

Identification of myocardial injury in the emergency setting

Within the past decade, the use of biomarkers to detect myocardial injury in the emergency department (ED) has been given increasing prominence as evident by the numerous studies and guidelines documenting their use. This review details the scope of the clinical problem, the history of changes in the definition of myocardial infarction (MI) and the new approaches, as well as suggestions for using laboratory biomarkers in the early detection of MI in the ED.

Outcomes associated with small changes in normal-range cardiac markers

INTRODUCTION

Troponin concentrations rising above an institutional cutpoint are used to define acute myocardial necrosis, yet it is uncertain what outcomes are associated with fluctuations in troponin that do not exceed this level. We evaluate the association between troponin fluctuations below an institutional upper limit of normal and acute coronary syndrome (ACS).

MATERIALS AND METHODS

This was a post hoc analysis of the Internet tracking registry of ACS (i*trACS), which describes patients presenting to emergency departments (EDs) with suspected ACS across the spectrum of risk. Patients were included in this registry if they were at least 18 years old and had suspected ACS at the time of their ED visit. Inclusions in this analysis required that patients had at least 1 cardiac marker (creatine kinase-MB [CK-MB], troponin T, or troponin I) drawn twice within 6 hours of presentation, with both measures being below the institution's upper limit of normal. A marker change was defined as either an increase or decrease that exceeded 15% of the institutional upper limit of normal. Acute coronary syndrome was defined as a positive stress test, documented myocardial infarction, coronary revascularization, or death within 30 days of their ED admission.

RESULTS

Of 17,713 patient visits, 2162 met inclusion and exclusion criteria. There were 1872 patient visits with 2 troponin results and 1312 with 2 CK-MB results. Patient visits with increasing troponin had increased odds of ACS compared with those with stable troponin levels (odds ratio, 3.6; 95% confidence interval, 1.4-9.2). Changing CK-MB and decreasing troponin were not associated with increased odds of ACS.

CONCLUSIONS

Small increases in troponin concentration below the upper limit of normal are associated with increased odds of ACS.

Clinical applications of highly sensitive troponin assays

Cardiac troponin is the biomarker of choice for the diagnosis of acute myocardial infarction. Recent consensus recommendations have adopted a concentration of troponin above the 99th percentile of a healthy population to diagnose myocardial infarction. Until recently, there was no assay capable of achieving recommended precision; however, with the development of "highly sensitive" troponin assays, it is now possible to accurately measure troponin concentrations at and below the current 99th percentile of a healthy population. These assays have enormous potential in not only identifying more patients with acute myocardial infarction, and providing superior risk prediction in those so afflicted, in addition highly sensitive troponins assays may be useful for long-term risk assessment of the patient with coronary disease. In this article, we will review the clinical applications, novel concepts, challenges, and limitations of using highly sensitive troponins assays.