Are troponins confusing?

Association of H-FABP with cardiovascular events: A systematic review

The research aimed to evaluate the association between heart-type fatty acid binding protein (H-FABP) and cardiovascular events. We systematically reviewed research that has been conducted to assess this relationship, aiming to determine how useful H-FABP could be as a biomarker for cardiovascular diseases, especially in the initial phases of acute myocardial infarction (AMI) and acute coronary syndrome (ACS). Our goal was to validate its diagnostic accuracy and clinical relevance. We systematically searched through PubMed, Web of Science, and Google Scholar databases to find pertinent publications related to cardiovascular diseases and H-FABP, using various permutations, abbreviations, and language variations of MeSH keywords. The final analysis included 12 studies in total. The final study comprised twelve studies, and it was concluded that H-FABP demonstrated high sensitivity (64.3-91.5) and specificity (73-100) for diagnosing Acute Myocardial Infarction (AMI) and Acute Coronary Syndrome (ACS), especially within the first hours of symptom onset. H-FABP demonstrates potential in enhancing the overall diagnostic accuracy during the initial hours following the manifestation of symptoms. However, the existing data do not provide sufficient evidence to recommend the regular utilization of H-FABP as a preliminary risk assessment approach in individuals who present with suspected cardiac events. Additional investigations, with well-defined prospective cohorts, are needed to validate the results observed.

Low-attenuation coronary plaque burden and troponin release in chronic coronary syndrome: A mediation analysis

BACKGROUND

Coronary low-attenuation plaque (LAP) burden is a strong predictor of myocardial infarction in patients with stable chest pain. We aimed to assess the relationship between LAP burden and circulating levels of high-sensitivity cardiac troponin T (hs-cTnT), and to explore the potential underlying etiology in patients undergoing clinically indicated coronary CT angiography (CCTA).

METHODS

A comprehensive metabolic and lipid panel, as well as C-reactive protein (CRP) and hs-cTnT tests were obtained from consecutive patients with stable chest pain at the time of CCTA. Qualitative and quantitative coronary plaque analysis, CT-derived fractional flow reserve (FFR) calculation, and pericoronary adipose tissue (PCAT) attenuation measurement around the right coronary artery were performed on CCTA images. Linear regression analyses were performed to identify independent associations with hs-cTnT concentration and mediation analysis was used to assess whether ischemia or markers of inflammation mediate hs-cTnT elevation.

RESULTS

In total, 114 patients (56.3 ​± ​10.6 years, 44.7 ​% female) were enrolled. In multivariable analysis, age (β ​= ​0.04 [95%CI: 0.02; 0.06], p ​< ​0.001), female sex (β ​= ​-0.77 [95%CI: -1.20; 0.33], p ​< ​0.001), and LAP burden (β ​= ​0.03 [95%CI: 0.001; 0.06], p ​= ​0.04) were independently associated with hs-cTnT levels. Mediation analysis, on the other hand, did not identify a significant mediating effect of lesion-specific ischemia based on CT-FFR, circulating CRP levels, or PCAT values between LAP burden and hs-cTnT levels (all p ​> ​0.05).

CONCLUSION

Although ischemia and inflammation have previously been proposed to mediate the association between LAP burden and hs-cTnT levels, our results did not confirm the role of these pathophysiological pathways in patients with stable chest pain.

Coronary low-attenuation plaque and high-sensitivity cardiac troponin

OBJECTIVE

In patients with acute chest pain who have had myocardial infarction excluded, plasma cardiac troponin I concentrations ≥5 ng/L are associated with risk of future adverse cardiovascular events. We aim to evaluate the association between cardiac troponin and coronary plaque composition in such patients.

METHODS

In a prespecified secondary analysis of a prospective cohort study, blinded quantitative plaque analysis was performed on 242 CT coronary angiograms of patients with acute chest pain in whom myocardial infarction was excluded. Patients were stratified by peak plasma cardiac troponin I concentration ≥5 ng/L or <5 ng/L. Associations were assessed using univariable and multivariable logistic regression analyses.

RESULTS

The cohort was predominantly middle-aged (62±12 years) men (69%). Patients with plasma cardiac troponin I concentration ≥5 ng/L (n=161) had a higher total (median 33% (IQR 0-47) vs 0% (IQR 0-33)), non-calcified (27% (IQR 0-37) vs 0% (IQR 0-28)), calcified (2% (IQR 0-8) vs 0% (IQR 0-3)) and low-attenuation (1% (IQR 0-3) vs 0% (IQR 0-1)) coronary plaque burden compared with those with concentrations <5 ng/L (n=81; p≤0.001 for all). Low-attenuation plaque burden was independently associated with plasma cardiac troponin I concentration ≥5 ng/L after adjustment for clinical characteristics (adjusted OR per doubling 1.62 (95% CI 1.17 to 2.32), p=0.005) or presence of any visible coronary artery disease (adjusted OR per doubling 1.57 (95% CI 1.07 to 2.37), p=0.026).

CONCLUSION

In patients with acute chest pain but without myocardial infarction, plasma cardiac troponin I concentrations ≥5 ng/L are associated with greater burden of low-attenuation coronary plaque.

The Limits of Cardiac Performance: Can Too Much Exercise Damage the Heart?

Routine moderate-intensity physical activity confers numerous cardiovascular benefits and reduces all-cause mortality. However, the health impact of exercise doses that exceed contemporary physical activity guidelines remains incompletely understood, and an emerging body of literature suggests that high levels of exercise may have the capacity to damage the cardiovascular system. This review focuses on the contemporary controversies regarding high-dose exercise and cardiovascular morbidity and mortality. We discuss the limitations of available studies, explore potential mechanisms that may mediate exercise-related cardiac injury, and highlight the gaps in knowledge for future research.

Sensitive miRNA markers for the detection and management of NSTEMI acute myocardial infarction patients

Background

NSTEMI patients will benefit greatly with better biomarker screening to detect and prognose the disease. Using miRNAs, we evaluated the clinical utility in acute myocardial infarction (AMI) patients during disease onset and therapy.

Methods

A total of 145 NSTEMI patients and 30 healthy volunteers with no history of cardiovascular disease (CVD) were recruited. miRNA levels in plasma were measured during disease manifestation and serially during treatment phase. Levels of multiple candidates (miR-1, miR-133, miR-208, miR-499) were analysed. The miRNA levels were directly compared between NSTEMI and healthy volunteers.

Results

Cardiac related miRNAs levels demonstrated significant increase compared with healthy controls. miR-499 exhibited the highest elevation with more than 6.03-fold change compared with healthy participants. Conventional cTnT measurements were in good agreement to miRNA relative expressions. In serial measurements, miR-499 demonstrated large fluctuations and could be linked to the secondary complications. In contrast, miR-133 showed insignificant variations in mean levels during serial sampling.

Conclusions

miRNA is a potentially sensitive biomarker for NSTEMI AMI patients for disease detection and treatment monitoring. The sensitivities were comparable to cTnT for diagnostic accuracy and patients with sustained or higher levels were correlated to secondary complications.

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.

Acute "Pseudoischemic" ECG Abnormalities after Right Pneumonectomy

New onset of electrocardiographic (ECG) abnormalities can occur after lung surgery due to the changes in the position of structures and organs in the chest cavity. The most common heart rhythm disorder is atrial fibrillation. So-called “pseudoischemic” ECG changes that mimic classic ECG signs of acute myocardial ischemia are also often noticed. We report the case of a 68-year-old male, with no prior cardiovascular disease, who underwent extensive surgical resection for lung cancer. On a second postoperative day, clinical and electrocardiographic signs of acute myocardial ischemia occurred. According to clinical course, diagnostic procedures, and therapeutic response, we excluded acute coronary syndrome. We concluded that physical lesion of the pericardium, caused by extended pneumonectomy with resection of the pericardium, provoked the symptoms and ECG signs that mimic acute coronary syndrome. Our final diagnosis was postpericardiotomy syndrome after extended pneumonectomy and further treatment with nonsteroidal anti-inflammatory drugs (NSAIDs) was recommended. It is necessary to consider possibility that nature of ECG changes after extended pneumonectomy could be “pseudoischemic.”

microRNA assays for acute coronary syndromes

microRNAs are promising biomarkers for diverse cardiovascular diseases. While quantification of the small non-coding RNAs is routinely performed in the research laboratory, clinical-grade assessment of microRNAs in central laboratory environments or point-of-care testing is still in its infancy. In this review, we provide an overview on microRNAs as biomarkers for acute coronary syndromes and highlight promising technical approaches for microRNA-based assays systems.

Type 2 myocardial infarction: the chimaera of cardiology?

The term type 2 myocardial infarction first appeared as part of the universal definition of myocardial infarction. It was introduced to cover a group of patients who had elevation of cardiac troponin but did not meet the traditional criteria for acute myocardial infarction although they were considered to have an underlying ischaemic aetiology for the myocardial damage observed. Since first inception, the term type 2 myocardial infarction has always been vague. Although attempts have been made to produce a systematic definition of what constitutes a type 2 myocardial infarction, it has been more often characterised by what it is not rather than what it is. Clinical studies that have used type 2 myocardial infarction as a diagnostic criterion have produced disparate incidence figures. The range of associated clinical conditions differs from study to study. Additionally, there are no agreed or evidence-based treatment strategies for type 2 myocardial infarction. The authors believe that the term type 2 myocardial infarction is confusing and not evidence-based. They consider that there is good reason to stop using this term and consider instead the concept of secondary myocardial injury that relates to the underlying pathophysiology of the primary clinical condition.

Influence of repeated bouts of table tennis training on cardiac biomarkers in children

It is documented that exercise can increase serum cardiac troponins in adults and adolescents; however, there is a lack of related studies concerning the release of cardiac troponins in children. This study investigated the influence of table tennis training on cardiac biomarkers in children. Twenty-eight male children performed six 10-min forehand exercise sessions with 5-min recovery intervals. Serum cardiac troponin T (cTnT) and I (cTnI), and creatinine kinase isoenzyme MB (CK-MB) were assessed before exercise, immediately after the last 10 min of exercise (PEI), 4 h post-exercise (PE4), 24 h post-exercise (PE24), and 48 h post-exercise (PE48). Cardiac function was measured using an ultrasound system (GE Vivid7 Dimension) at rest state. Serum cTnT, cTnI, and CK-MB were significantly elevated from the PEI sample point, and returned to baseline at the PE48 sample point in children. Serum cTnT in four (14.29%), nine (32.14%), and two (7.14%) subjects at the PEI, PE4, and PE24 sample points, respectively, exceeded the cutoff for myocardial injury. At the PE4 sample point, cTnT in five subjects (17.86%) exceeded the cutoff for acute myocardial infarction. Serum cTnI in two (14.29%), seven (25%), and two (7.14 %) subjects at the PEI, PE4, and PE24 timepoints, respectively, exceeded the cutoff for myocardial injury. cTnI in two subjects (7.14%) exceeded the cutoff for acute myocardial infarction at the PE4 timepoint in children. Repeated bouts of table tennis forehand training can significantly increase the release of serum cardiac troponins in some children.

Myocardial involvement during ischemia-induced acute liver failure in the pig

OBJECTIVE

The objective of this experimental study was to investigate a possible myocardial involvement in acute liver failure.

MATERIALS AND METHODS

A porcine model of acute liver failure induced by hepatic devascularization was used. Twenty animals were allocated to the Acute Liver Failure (ALF) or Control Group (CG). Serum cardiac troponin I (cTnI), MB isoenzyme of creatine kinase (CK-MB), and also hemodynamic variables were measured and compared before surgery (T1), at 4 hr (T2), and at 7 hr (T3) after the end of surgery.

RESULTS

Data from 10 pigs in the ALF and 7 in the CG were analyzed. In the ALF group, cTnI increased from 0.3 ± 0.055 to 0.35 ± 0.696 and 0.39 ± 0.06 ng/ml at T1, T2, and T3 time points, respectively (p < .001). In the CG, cTnI was not significantly changed from 0.29 ± 0.07, to 0.31 ± 0.01, and 0.31 ± 0.11 ng/ml at T1, T2, and T3 time points, respectively (p = .895). A statistically significant difference was found in cTnI between the groups at T3 (z = -2.93, p = .002). CK-MB increased significantly in both groups: in ALF group, CK-MB changed from 3.43 ± 0.53 to 4.33 ± 0.73 and 7.14 ± 1.12 ng/ml at T1, T2, and T3 time points, respectively (p < .001). In the CG, CK-MB changed from 3.6 ± 0.597 to 4.6 ± 1.07 and 6.2 ± 1.17 ng/ml at T1, T2, and T3 time points, respectively, (p = .001). Mean arterial pressure (MAP) was significantly reduced in the ALF group.

CONCLUSIONS

In a porcine model of acute liver failure, a significant increase of cTnI serum levels was found, indicating that a subclinical myocardial damage may occur as a result of heart involvement in the multiple organ dysfunction.

Troponins in acute kidney injury

AIM

To investigate and describe cardiac troponins in subjects with acute kidney injury (AKI).

METHODS

A prospective observational study of troponin in subjects presenting with AKI in a tertiary hospital. Creatine kinase-MB (CKMB), troponin I (Abbott Laboratories), and troponin T (Roche 4th generation) were measured. Patients with conditions known to cause elevated troponin levels were excluded.

RESULTS

Nineteen subjects were enrolled in the study. Six subjects had troponin I and T concentrations above the 99th percentile of a reference population. There was high concordance of result between troponin I and troponin T. However, the concordance of elevated troponin levels with CKMB was less marked at 45%. Statistically significant factors associated with elevated troponin levels were age over 60 years, abnormal electrocardiogram, and history of previous ischemic heart disease.

CONCLUSION

This is the first study able to demonstrate impaired renal function occurring acutely, without known confounders, results in elevated troponin levels. This suggests that impaired renal function disease influences plasma troponin levels in AKI as well as in chronic kidney failure.

Diagnostic accuracy of heart-type fatty acid-binding protein for the early diagnosis of acute myocardial infarction

OBJECTIVE

The aim of this study was to evaluate the diagnostic efficacy of multiple tests-heart-type fatty acid-binding protein (H-FABP), cardiac troponin I (cTnI), creatine kinase-MB, and myoglobin-for the early detection of acute myocardial infarction among patients who present to the emergency department with chest pain.

METHODS

A total of 1128 patients provided a total of 2924 venous blood samples. Patients with chest pain were nonselected and treated according to hospital guidelines. Additional cardiac biomarkers were assayed simultaneously at serial time points using the Cardiac Array (Randox Laboratories Ltd, Crumlin, United Kingdom).

RESULTS

Heart-type fatty acid-binding protein had the greatest sensitivity at 0 to 3 hours (64.3%) and 3 to 6 hours (85.3%) after chest pain onset. The combination of cTnI measurement with H-FABP increased sensitivity to 71.4% at 3 to 6 hours and 88.2% at 3 to 6 hours. Receiver operating characteristic curves demonstrated that H-FABP had the greatest diagnostic ability with area under the curve at 0 to 3 hours of 0.841 and 3 to 6 hours of 0.894. The specificity was also high for the combination of H-FABP with cTnI at these time points. Heart-type fatty acid-binding protein had the highest negative predictive values of all the individual markers: 0 to 3 hours (93%) and 3 to 6 hours (97%). Again, the combined measurement of cTnI with H-FABP increased the negative predictive values to 94% at 0 to 3 hours, 98% at 3 to 6 hours, and 99% at 6 to 12 hours.

CONCLUSION

Testing both H-FABP and cTnI using the Cardiac Array proved to be both a reliable diagnostic tool for the early diagnosis of myocardial infarction/acute coronary syndrome and also a valuable rule-out test for patients presenting at 3 to 6 hours after chest pain onset.

High-sensitivity troponin assays in the evaluation of patients with acute chest pain in the emergency department

Evaluating patients with acute chest pain presenting to the emergency department remains an ongoing challenge. The spectrum of etiologies in acute chest pain ranges from minor disease entities to life-threatening diseases, such as pulmonary embolism, acute aortic dissection or acute myocardial infarction (MI). The diagnosis of acute MI is usually made integrating the triad of patient history and clinical presentation, readings of 12-lead ECG and measurement of cardiac troponins (cTn). Introduction of high-sensitivity cTn assays substantially increases sensitivity to identify patients with acute MI even at the time of presentation to the emergency department at the cost of specificity. However, the proportion of patients presenting with cTn positive, non-vascular cardiac chest pain triples with the implementation of new sensitive cTn assays increasing the difficulty for the emergency physician to identify those patients who are at need for invasive diagnostics. The main objectives of this mini-review are 1) to discuss elements of disposition decision made by the emergency physician for the evaluation of chest pain patients, 2) to summarize recent advances in assay technology and relate these findings into the clinical context, and 3) to discuss possible consequences for the clinical work and suggest an algorithm for the clinical evaluation of chest pain patients in the emergency department.

Exercise-induced cardiac troponin elevation: evidence, mechanisms, and implications

Regular physical exercise is recommended for the primary prevention of cardiovascular disease. Although the high prevalence of physical inactivity remains a formidable public health issue, participation in exercise programs and recreational sporting events, such as marathons and triathlons, is on the rise. Although regular exercise training reduces cardiovascular disease risk, recent studies have documented elevations in cardiac troponin (cTn) consistent with cardiac damage after bouts of exercise in apparently healthy individuals. At present, the prevalence, mechanism(s), and clinical significance of exercise-induced cTn release remains incompletely understood. This paper will review the biochemistry, prevalence, potential mechanisms, and management of patients with exercise-induced cTn elevations.

Ischemia modified albumin: a novel biomarker for the detection of cardiac ischemia

SUMMARY

The diagnosis of cardiac ischemia remains a challenge in contemporary emergency medicine. A blood-borne biomarker is an attractive alternative to cardiac imaging or stress testing as it would be cheaper and logistically faster to obtain. A number of candidate biomarkers have been proposed for the detection of cardiac ischemia; however, only Ischemia Modified Albumin (IMA) has been released for clinical use. IMA is a good discriminator between ischemic and non-ischemic patients. Changes in IMA concentration have shown to occur during coronary angioplasty-induced ischemia. Clinical studies indicate that IMA appears to offer on admission an early test which can be combined with electrocardiographic findings and cardiac troponin measurements for the early exclusion of acute coronary syndrome. IMA is an independent predictor of short and long term adverse outcomes in patients with acute chest pain. However, this test is relatively new and uncertainties remain. Elevations of IMA occur in conditions other than chest pain, thus questioning its specificity. The mechanism of IMA formation and the precise entity being measured are not fully known. Nevertheless, IMA measurement remains the only current clinical biomarker which may be used for the diagnosis of patients suspected of cardiac ischemia.

Diagnosis and Management of Patients with Suspected Acute Myocardial Infarction

Patients admitted with suspected acute myocardial infarction (MI) constitute a diagnostic, prognostic and therapeutic challenge for the treating physician. Elevation of a marker of myocardial necrosis together with ischemic symptoms and/or ischemic ECG changes are mandatory for the diagnosis of acute MI. Troponin T or I is the preferred marker of myocardial necrosis. The diagnostic process should start as soon as possible. The introduction of prehospital ECG recordings and prehospital administration of thrombolytic treatment in case of ST-segment elevation MI, have been shown to decrease the time from onset of symptoms till treatment considerably, which also translates into saved lives. In contrast, data of the value of prehospital analyses of biochemical markers are still limited. In patients without ST-segment elevation on admission the diagnosis is dependent on repeated measurements of markers of myocardial damage, which together with other biochemical markers (e.g. CRP and BNP/NT-proBNP) also are useful for risk assessment. Patients identified to be at low risk of future cardiac events might be discharged early and, on the contrary, a more intense treatment might be started in patients identified to be at high risk. An elevated troponin concentration is shown to identify patients who benefit from antithrombotic therapy and invasive procedures. Several different risk scoring models based on a combination of clinical variables, ECG-changes and biochemical markers, have been shown to further improve risk assessment and selection of treatment.

[Perioperative myocardial damage in non-cardiac surgery patients]

Perioperative myocardial damage occurs with a high incidence depending on the operative procedure and the patients examined and is considered to be among the most relevant risk factors for increased perioperative morbidity and mortality in patients undergoing non-cardiac surgery. The pathophysiology of myocardial damage in the perioperative period is still not well understood. Both ischemia with and without acute coronary occlusion and non-ischemic stimuli can put a substantial strain on the heart in the perioperative period. However, in many cases the clinical presentation does not allow a clear differentiation between ischemic and non-ischemic myocardial damage. In the majority of cases perioperative myocardial infarctions occur with only mild or even without any clinical symptoms. This is probably due to a considerable difference in phenotype and pathophysiology between perioperative and non-perioperative myocardial infarctions. As a result of this unexplained etiology of perioperative myocardial infarction it remains an open question whether the contemporary diagnostic and therapeutic recommendations for the acute coronary syndrome can be extrapolated to the perioperative situation. The present review reflects the current state of knowledge and presents an optional approach to the diagnosis and therapy of perioperative myocardial injury.

Present and Future Biochemical Markers for Detection of Acute Coronary Syndrome

The use of biochemical markers in the diagnosis and management of patients with acute coronary syndrome has increased continually in recent decades. The development of highly sensitive and cardiac-specific troponin assays has changed the view on diagnosis of myocardial infarction and also extended the role of biochemical markers of necrosis into risk stratification and guidance for treatment. The consensus definition of myocardial infarction places increased emphasis on cardiac marker testing, with cardiac troponin replacing creatine kinase MB as the "gold standard" for diagnosis of myocardial infarction. Along with advances in the use of more cardiac-specific markers of myocardial necrosis, biochemical markers that are involved in the progression of atherosclerotic plaques to the vulnerable state or that signal the presence of vulnerable plaques have recently been identified. These markers have variable abilities to predict the risk of an individual for acute coronary syndrome. The aim of this review is to provide an overview of the well-established markers of myocardial necrosis, with a special focus on cardiac troponin I, together with a summary of some of the potential future markers of inflammation, plaque instability, and ischemia.

The role of biomarkers in the early detection of anthracycline-induced cardiotoxicity in children: a review of the literature

Anthracycline-induced cardiotoxicity can cause serious health problems for an increasing number of children surviving childhood malignancies. Early detection of cardiac failure is critically important for the prevention and management of anthracycline-induced cardiotoxicity. The aim of this research was to determine the role of biomarkers in the early detection of anthracycline-induced cardiotoxicity in children. A literature review is presented of studies regarding the use of the biomarkers B-type natriuretic peptide (BNP), N-terminal pro-BNP (NT-pro-BNP), cardiac troponin T (cTnT), and cardiac troponin I (cTnI) in relation with anthracycline-induced cardiotoxicity in children. Six of 14 studies in children showed a significant relation between elevated biomarkers BNP, NT-pro-BNP, and cTnT and cardiac dysfunction. Six studies, although small, suggest that BNP, NT-pro-BNP, and cTnT might be useful markers in the early detection of anthracycline-induced cardiotoxicity.

Prospective study of cardiac troponin I release in patients with upper gastrointestinal bleeding

BACKGROUND AND AIM

The rate of cardiac injury in upper gastrointestinal hemorrhage is unclear. The aims of this study were to determine prospectively the risk of cardiac troponin I release and associated adverse cardiac events in patients with acute upper gastrointestinal hemorrhage.

METHODS

From January to September 2003, we prospectively studied patients with documented hematemesis and melena referred to the gastroenterology unit in a tertiary teaching hospital in Melbourne, Australia. Serial assays for cardiac troponin I were performed at 0, 12 and 24 h. Serial creatine kinase levels and electrocardiographs were also performed. Clinical and biochemical data were collected. The primary endpoint was a troponin level >0.5 microg/L within 24 h of recruitment. Various clinical variables were then compared between the groups of patients with or without troponin rise.

RESULTS

A total of 156 patients were included in the study. The mean age was 67 years (range 19-96). There were 104 (67%) male patients. A troponin level of greater than 0.5 microg/L was found in 30/156 (19%); 126 (81%) patients had normal troponin levels. Age greater than 65 years, signs of hemodynamic instability at presentation, a recent history of cardiac disease, cardiovascular compromise following endoscopy, and re-bleeding were associated with troponin release.

CONCLUSION

Upper gastrointestinal bleeding is associated with a risk of cardiac injury of up to 19%. Troponin assay could be used to screen for cardiac damage, especially in elderly patients who present with hemodynamic instability.

Troponin I in the intensive care unit setting: from the heart to the heart

When measured in the plasma, cardiac troponins T (cTnT) and I (cTnI) are considered to be highly specific markers of myocardial cell damage; however, research has demonstrated that troponin elevation may associated with causes other than coronary artery disease. In the intensive care unit (ICU) setting, increased cTnI levels are quite common findings and when documented, even on admission, intensivists should bear in mind that this laboratory finding holds a prognostic role independent of the reason for ICU admission. The mechanism(s) (such as demand ischemia, myocardial strain, etc.) and not simply the cause (i.e., renal failure) of the increment in serum cTnI should be investigated to better tailor the therapeutical regimen in the single patient. In this review, we therefore consider the nonthrombotic causes of troponin elevation in the critical setting.

Best practice in primary care pathology: review 7

This seventh best-practice review examines four series of common primary care questions in laboratory medicine: (1) blood count abnormalities 2; (2) cardiac troponins; (3) high-density lipoprotein cholesterol; and (4) viral diseases 2. The review is presented in a question-answer format, with authorship attributed for each question series. The recommendations are a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by Medline Embase searches to identify relevant primary research documents. The recommendations are not standards, but form a guide to be set in the clinical context. Most are consensus based rather than evidence based. They will be updated periodically to take account of new information.

Biomarkers of cardiovascular damage

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis. This may then result in cardiac remodelling. Serum biomarkers are available which can be used for diagnosis of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The problems with potential ischaemia markers are specificity and the reference diagnostic standard against which they can be judged. To date, only one, ischaemia-modified albumin(R), has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, have become recognised as the diagnostic reference standard for myocardial necrosis. The sensitive nature of these tests has also revealed that myocardial necrosis is also found in a range of other clinical situations, highlighting the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B-type natriuretic peptides can be shown to be diagnostic and prognostic in both ACS and detecting the sequelae of post-infarction myocardial insufficiency. The role of the B-type natriuretic peptides in detection of cardiac failure, both acute and chronic, is well defined but remains the subject of further studies, in ACS.

Biomarkers of Cardiovascular Damage and Dysfunction—An Overview

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis and subsequent cardiac remodelling. Cardiac biomarkers can be used for diagnosis and assessment of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The challenges with potential ischaemia markers are specificity and the diagnostic reference standard for assessment. To date, only one, ischaemia modified albumin, has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, has become the diagnostic standard as the biomarker of myocardial necrosis. The sensitive nature of troponin measurement has also revealed that myocardial necrosis is also found in a range of other clinical situations. This illustrates the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B type natriuretic peptides can be shown to be diagnostic and prognostic for both acute ACS and detecting the sequelae of post infarction myocardial insufficiency. The role of the B type natriuretic peptides in detection of cardiac failure, acute and chronic, is well defined. Their role in ACS remains the subject of further studies.

Prognostic Significance of Raised Cardiac Troponin T in Patients Presenting with Acute Limb Ischaemia

OBJECTIVE

To study the relation between serum cardiac troponin T (cTnT) and mortality in patients presenting with acute limb ischaemia secondary to an embolism.

MATERIAL AND METHODS

A two years prospective study of all patients admitted to the vascular unit with a diagnosis of acute limb ischaemia secondary to an embolism. On admission all patients had an ECG. A blood sample was taken for measurement of cTnT, CRP, serum biochemistry, full blood count and clotting. All embolectomies were performed under local anaesthesia. Patients were followed until discharge from hospital and up to twelve months after surgery.

RESULTS

There were 37 patients with lower limb and 2 patients with upper limb ischaemia. Twenty four patients were female and fifteen were male, with the mean age of 76 years (50-95) for women and 84 years (77-90) for men. Seventeen patients (44%) had a raised cTnT. The patients with raised cTnT were older than those with normal cTnT [86y (77-92) vs 77y (51-95), p = 0.01, t test]. The mean cTnT was 0.20 microg/L (range: 0.11-0.27). Only two patients with raised cTnT gave a history of chest pains. All of the patients with an elevated cTnT had also raised CRP. There was no significant difference in the serum creatinine in the group of patients with elevated cTnT compared to those with normal cTnT [112 micromol/L (range 98-159) vs 119 micromol/L (range: 47-177), p = ns]. The cumulative survival for cTnT+ patients at 7 days was 53% and that of cTnT- patients was 100%. The cumulative survival for cTnT+ and cTnT- patients was statistically different (p = 0.0000, chi2 = 13.1, Log Rank test). Using regression analysis, an elevated cTnT was found to be an independent predictor of outcome.

CONCLUSION

A significant proportion of patients presenting with an acutely ischaemic limb have an elevated cTnT. An elevated cTnT may be an early marker of overall disease severity and a predictor of outcome.

Diagnostic and prognostic role of cardiac troponin I (cTnI) measured on the DPC Immulite

OBJECTIVE

To evaluate the diagnostic and prognostic role of the Immulite cTnI assay for the detection of acute coronary syndromes (ACS).

POPULATION

150 males and 63 females with a median age of 63 years, range 28 to 88, and an interquartile range of 18 years were admitted within 24 h of chest pain and non-ST segment elevation ACS were studied. The median onset of symptoms was 3 h (range 0-23).

METHODS

Venous samples were taken on admission (t = 0) and at 24 h (t = 24). The serum samples were assayed for CK, CK-MB and cTnT on an Elecsys 1010 (Roche Diagnostics, Lewes, UK). The cTnT assay CV was 5.5% at 0.32 microg/l and 5.4% at 6.0 microg/l, and the detection limit was 0.01 microg/l with an upper limit of 25 microg/l. For cTnI using the Immulite (DPC, Gwynedd, Wales), the detection limit was 0.1 microg/l, and the upper limit was 180 microg/l. Final diagnostic categorization was performed by both WHO and European Society of Cardiology criteria using cTnT as the diagnostic cardiac biomarker. Patients were followed for the major adverse cardiac events (MACE), endpoints cardiac death, AMI or need for urgent revascularization. ROC curves were constructed using final diagnosis. Outcome prediction was assessed by ROC curves and Kaplan-Meier survival curves.

RESULTS

Both methods had equivalent diagnostic efficiency using WHO criteria for AMI. When ESC criteria were used the AUC for admission and 24 h cTnT and cTnI values were 0.945 vs. 0.910, P = 0.20 and 0.998 vs. 0.937, P = 0.005, respectively. Both methods predicted outcome as either death or MI or MACE and were not significantly different.

CONCLUSION

The Immulite cTnI assay can be used for diagnosis and risk stratification in patients admitted with non-ST segment elevation acute coronary syndromes.

The Antibody Configurations of Cardiac Troponin I Assays May Determine Their Clinical Performance

Background: Previous studies have shown superior clinical performance of the cardiac troponin I (cTnI) assay from Beckman-Coulter Diagnostics. This assay had a unique combination of monoclonal antibodies with 2 monoclonal antibodies directed against epitopes near the NH2 terminus of the heart-specific region of troponin I. The approach has been adopted by the new cTnI assay from Abbott Diagnostics. The aim of our study was to investigate whether this approach affects the clinical performance of cTnI assays.

Methods: Cardiac troponin concentrations were measured in a random sample of patients with unstable coronary artery disease included in the GUSTO IV trial (n = 696) by the AccuTnI (Beckman-Coulter Diagnostics), Architect cTnI (Abbott Diagnostics), Immulite 2500 cTnI (Diagnostics Products Corporation), and Elecsys 2010 cTnT (Roche Diagnostics) assays and related to the 1-year mortality. The primary cutoff concentrations were based on the 99th percentile upper reference limits and an imprecision (CV) ≤10%.

Results: The sensitivities of the AccuTnI and Architect cTnI assays in identifying patients who died within 1 year were equal and were significantly higher (P &lt;0.05) than those of the Immulite 2500 cTnI and the Elecsys cTnT assays. The concordance between the AccuTnI and Architect cTnI assays was 97%, but concordances between the Architect cTnI and the Elecsys cTnT assays were 89%–92% with more at-risk patients (P &lt;0.01 to P &lt;0.001) identified by the Architect cTnI assay.

Conclusions: The Architect cTnI assay has clinical performance similar to that of the AccuTnI, probably as a result of the inclusion of a monoclonal antibody against troponin I epitope 41–49 in the assay.

Utility of admission cardiac troponin and "Ischemia Modified Albumin" measurements for rapid evaluation and rule out of suspected acute myocardial infarction in the emergency department

OBJECTIVE

To assess if the combination of cardiac troponin (cTn) and Ischemia Modified Albumin (IMA) can be used for early exclusion of acute myocardial infarction (AMI).

METHODS

Prospective consecutive admissions to the emergency department (ED) with undifferentiated chest pain were assessed clinically and by electrocardiography. A total of 539 patients (335 men, 204 women; median age 51.9 years) considered at low risk of AMI had blood drawn on admission. If the first sample was less than 12 hours from onset of chest pain, a second sample was drawn two hours later, at least six hours from onset of chest pain. Creatine kinase MB isoenzyme (CKMB) mass was measured on the first sample and CKMB mass and cTnT on the second sample. An aliquot from the first available sample was frozen and subsequently analysed for IMA. If cTnT had not been measured on the original sample cTnI was measured (n = 189).

RESULTS

Complete data were available for 538/539 patients. IMA or cTn was elevated in the admission sample of all patients with a final diagnosis of AMI (n = 37) with IMA alone elevated in 2/37, cTn alone in 19/37, and both in 16/37. In 173/501 patients in whom AMI was excluded both tests were negative. In the non-AMI group 22 patients had elevation of both IMA and cTn in the initial sample, suggesting ischaemic disease.

CONCLUSION

Admission measurement of cardiac troponin plus IMA can be used for early classification of patients presenting to the ED to assist in patient triage.

The exciting story of cardiac biomarkers: from retrospective detection to gold diagnostic standard for acute myocardial infarction and more

This paper reviews the history of the contribution of the laboratory medicine to clinical cardiology and discusses the most important steps in this field. Until 20 years ago, the clinical laboratory only placed at the cardiologist's disposal a few assays for the retrospective detection of cardiac tissue necrosis, such as enzymatic methods for creatine kinase and lactate dehydrogenase activities. However, in the latter part of the 20th century, highly sensitive and specific assays, such as cardiac troponins, as well as assays for markers of myocardial function, such as cardiac natriuretic peptides, rapidly changed the scenario of clinical management of patients with cardiac diseases, assigning to the laboratory a pivotal role in the overall diagnostic flow. This is witnessed by the recent incorporation of these markers into international guidelines and in the redefinition of myocardial infarction. For the foreseeable future, new serum markers of myocardial ischemic, i.e. reversible, injury or related to coronary plaque instability and disruption are expected.

Two cases of inflammatory muscle disease presenting with raised serum concentrations of troponin T

Troponins T and I are highly sensitive markers of myocardial injury. However, non-cardiac disorders, such as pulmonary embolism, renal failure, subarachnoid haemorrhage, sepsis, eclampsia, chemotherapy, and inflammatory muscle conditions (dermatomyositis and polymyositis), can also result in raised serum troponin concentrations. This article describes two cases that occurred within a month of each other in Craigavon Area Hospital, whereby conditions unrelated to myocardial ischaemia resulted in raised concentrations of cardiac markers. The first patient, in retrospect, underwent unnecessary investigation as an inpatient in the cardiac ward. Experience gained from this case led to more appropriate consultation and management of the second patient.

Troponin I as a predictor of coronary heart disease and mortality in 70-year-old men: a community-based cohort study

BACKGROUND

Cardiac troponin I (cTnI), a standard for detection of myocardial damage, has recently been reported to predict acute myocardial infarction or death in patients with unstable coronary heart disease (CHD). Cardiac TnI concentrations increase with age in subjects free from clinical signs of CHD, suggesting silent myocardial damage. We investigated the association between cTnI and future CHD and mortality in a community-based cohort of men.

METHODS AND RESULTS

A community-based study was conducted from August 1991 to May 1995 among 1203 men in Uppsala, Sweden, aged 70 years at baseline with a follow-up of up to 10.4 years with the use of registry data (National Board of Health and Welfare, Sweden). CHD was defined with the use of data taken from the Cause of Death Registry or from first-time hospitalization for CHD as recorded in the Hospital Discharge Registry. Cardiac TnI concentrations were measured blinded for outcome, in frozen baseline plasma samples, with the use of the AccuTnI from Beckman Coulter, Inc. Hazard ratios (HRs) from Cox proportional hazards are presented with 95% confidence intervals (CIs) for a 1-SD increase. In men free from cardiovascular disease (CVD), cTnI predicted death (HR, 1.26; 95% CI, 1.08 to 1.46; P=0.003) or first CHD event (HR, 1.31; 95% CI, 1.11 to 1.54; P=0.001) after adjustment for conventional risk factors: total and HDL cholesterol, plasma glucose, body mass index, smoking, and systolic blood pressure.

CONCLUSIONS

In this first longitudinal report, cTnI was shown to predict death and first CHD event in men free from CVD at baseline, indicating the importance of silent cardiac damage in the development of CHD and mortality.

The new definition of myocardial infarction and the impact of troponin determination on clinical practice

OBJECTIVE

To discuss the more controversial clinical and laboratory aspects in the application of the new biochemical diagnostic standard for myocardial infarction, 4 years after its introduction, and to make some suggestions, which could allow for a more realistic application of the new definition in the current clinical practice.

METHODS

Studies published in the last 4 years in the most important cardiology and laboratory medicine journals (including proceedings of the international meetings), discussing advantages and limits of the new definition of myocardial infarction, were reviewed and pertinent data were discussed and compared with similar information available in literature.

RESULTS AND CONCLUSIONS

Although the exact status of implementation of the new definition of myocardial infarction cannot yet be known, the trend toward such recommendation is evolving significantly, even if at different rates in different countries. To make the transition smoother, major educational efforts are required to disseminate the conceptual reasoning behind the new guidelines. On the other hand, more knowledge is needed for some relevant issues, such as the different analytical performance of cardiac troponin assays or the prognostic significance of biomarker changes after a percutaneous coronary intervention.

The clinical relevance of raised cardiac troponin I in the absence of significant angiographic coronary artery disease

OBJECTIVES

Cardiac troponins are highly sensitive and specific markers of myocardial cell injury. We wished to determine the clinical relevance of raised troponins in the absence of significant angiographic coronary artery disease.

DESIGN AND METHODS

We assessed patients admitted to our hospital over the past 3 years with troponin-positive chest pain and no angiographically significant coronary disease.

RESULTS

The study included 67 patients, all of whom had symptoms of "chest pain" and elevated (>0.2 microg/L) troponin I on admission. Thirty-four (51%) patients had alternative causes for myocyte injury other than coronary ischaemia. In the remaining 33 (49%) patients we could find no other associated features or diagnoses. Follow up was obtained in 29 (88%) of these 33 patients (mean follow up 58+/-13 weeks, range 17-156 weeks). During the follow up period, three (4.5%) patients were readmitted with further ischaemic events.

CONCLUSIONS

Myocardial damage can occur in the absence of significant angiographic coronary disease and other causes of raised troponins should be considered according to the clinical presentation. Troponin-positive cases with angiographically "normal" coronary arteries can re-present with future cardiac events and should still be considered for aggressive risk management.

Cardiac troponins in intensive care

The cardiac troponins are integral components of the myofibrillary apparatus and they regulate muscle contraction. The measurement of cardiac troponins has replaced other biomarkers for the specific detection of myocardial necrosis and for the diagnosis of myocardial infarction. The tissue specificity plus sensitivity of the measurement technology has meant that cardiac damage can be detected in circumstances other than conventional acute coronary syndromes. The ability to specifically detect cardiac damage as part of multiple organ failure in intensive care patients has been shown to provide prognostic information, but it is unclear whether this is a dependent or an independent marker of outcome.

Biomarkers of cardiac disease

The challenge of medical practice today is to identify individuals who are at risk of developing disease, determine the severity of the disease and distinguish the responders from the nonresponders to therapy (individualized medicine). Advances in molecular genetics and biology have shifted the paradigm for identification of markers from large-scale epidemiologic studies to studies on genomic- and proteomic-based techniques. Consequently, a large number of biologic markers, referred to as biomarkers, are being identified and validated to serve for risk stratification, prognostication and individualization of therapy. Identification of biomarkers for cardiovascular diseases could also provide insight into the pathogenesis of the phenotype, which is fundamental for the development of specific therapies. The list of biomarkers for cardiovascular disease is expanding rapidly. Nonetheless, the field is in the early stages of evolution and large-scale clinical studies are required to validate the utility of newly identified biomarkers in diagnosis, risk stratification and treatment of cardiovascular diseases. Selected biomarkers for coronary atherosclerosis, acute coronary syndromes and heart failure are discussed in this review.

Impact of marathon running on cardiac structure and function in recreational runners

The present study examined the relationship between LV (left ventricular) function, markers of cardiac-specific damage and markers of oxidative stress in recreational runners following a marathon. Runners (n=52; 43 male and nine female; age, 35±10 years; height, 1.74±0.08 m; body mass, 75.9±8.9 kg) were assessed pre- and immediately post-marathon. LV function was assessed using standard M-mode two-dimensional Doppler echocardiography and TDI (tissue-Doppler imaging) echocardiography. Serum was analysed for cTnT (cardiac troponin-T), TEAC (Trolox equivalent antioxidant capacity; a measure of total antioxidant capacity), MDA (malondealdehyde) and 4-HNE (4-hydroxynonenal). A strong relationship was observed between standard and TDI echocardiography for all functional measures. Diastolic function was altered post-marathon characterized by a reduction in E (peak early diastolic filling: 0.79±0.11 compared with 0.64±0.16 cm/s; P<0.001), an increase in A (peak late diastolic filling: 0.48±0.11 compared with 0.60±0.12 cm/s; P<0.001) and a resultant decrease in E/A (ratio of E to A; 1.71±0.48 compared with 1.10±0.31; P<0.001). Ejection fraction remained unchanged post-marathon. Thirty-two runners presented with cTnT values above the lower limit of detection for the assay (0.01 μg/l), and 20 runners presented post-marathon with cTnT values above the acute myocardial infarction cut-off value (0.05 μg/l). No significant correlations were observed between cTnT and any functional measurements. MDA (2.90±1.58 compared with 3.59±1.47 μmol/l) and TEAC (1.80±0.12 compared with 1.89±0.21 mmol/l) were significantly increased post-marathon, but were unrelated to changes in function or cTnT. In conclusion, the present study demonstrated a reduction in diastolic function and widespread evidence of minimal cardiac damage following a marathon in recreational runners. The mechanism(s) underpinning the altered function and appearance of cTnT appear unrelated to reactive oxygen species.

Cardiac troponin elevations among critically ill patients

PURPOSE OF THE REVIEW

Elevated levels of cardiac troponins, indicative of the presence of cardiac injury, have been reported in critically ill patients. In this review, the incidence, significance, and clinical relevance of elevated troponin levels among this group of patients will be discussed.

RECENT FINDINGS

It has been shown that elevated cardiac troponin levels can be present among critically ill septic patients without evidence of myocardial ischemia. Recent studies show that elevated troponin levels are also present in a diverse group of critically ill patients without sepsis or septic shock. In addition, several but not all studies show that the mortality rate of troponin-positive patients is significantly higher compared with troponin-negative patients.

SUMMARY

Elevated troponin levels are not only present in patients suffering from acute coronary syndromes but can also be present in critically ill patients. Even minor elevations are specific for myocardial injury. However, every elevated troponin level in the critically ill patient should not be rigorously diagnosed or treated as a myocardial infarction.

The effect of dexrazoxane on myocardial injury in doxorubicin-treated children with acute lymphoblastic leukemia

BACKGROUND

Doxorubicin chemotherapy is very effective in children with acute lymphoblastic leukemia (ALL) but also injures myocardial cells. Dexrazoxane, a free-radical scavenger, may protect the heart from doxorubicin-associated damage.

METHODS

To determine whether dexrazoxane decreases doxorubicin-associated injury of cardiomyocytes, we randomly assigned 101 children with ALL to receive doxorubicin alone (30 mg per square meter of body-surface area every three weeks for 10 doses) and 105 to receive dexrazoxane (300 mg per square meter) followed immediately by doxorubicin. Serial measurements of serum cardiac troponin T were obtained in 76 of 101 patients in the doxorubicin group and 82 of 105 patients in the group given dexrazoxane and doxorubicin. A total of 2377 serum samples (mean, 15.1 samples per patient) were obtained before, during, and after treatment with doxorubicin. Troponin T levels were evaluated in a blinded fashion to determine whether they were elevated (>0.01 ng per milliliter)--the primary end point--or extremely elevated (>0.025 ng per milliliter).

RESULTS

Elevations of troponin T occurred in 35 percent of the patients (55 of 158). Patients treated with doxorubicin alone were more likely than those who received dexrazoxane and doxorubicin to have elevated troponin T levels (50 percent vs. 21 percent, P<0.001) and extremely elevated troponin T levels (32 percent vs. 10 percent, P<0.001). The median follow-up was 2.7 years. The rate of event-free survival at 2.5 years was 83 percent in both groups (P=0.87 by the log-rank test).

CONCLUSIONS

Dexrazoxane prevents or reduces cardiac injury, as reflected by elevations in troponin T, that is associated with the use of doxorubicin for childhood ALL without compromising the antileukemic efficacy of doxorubicin. Longer follow-up will be necessary to determine the influence of dexrazoxane on echocardiographic findings at four years and on event-free survival.