Role of serum cardiac troponin T in the diagnosis of acute rheumatic fever and rheumatic carditis

High-sensitivity cardiac troponins in pediatric population

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

Cardiac Biomarkers in Pediatrics: An Undervalued Resource

BACKGROUND

The clinical use of common cardiac biomarkers, such as brain natriuretic peptides and troponins, has traditionally been limited to adult populations in the assessment of heart failure and acute coronary syndrome, respectively. While many have discounted the value of these markers in pediatric populations, emerging evidence suggests they may be useful in the diagnosis and prognostication of many cardiac and noncardiac pathologies in neonates, children, and adolescents, and an increasing number of pediatric hospitals are routinely measuring cardiac markers in their clinical practice.

CONTENT

This review summarizes and critically evaluates the current literature regarding the application of cardiac biomarkers for clinical decision-making in the pediatric population. Main potential clinical indications discussed herein include primary cardiac disease, immune-related conditions, and noncardiac disease. Important diagnostic and interpretative challenges are also described in relation to each potential indication.

SUMMARY

Despite a general lack of clinical awareness regarding the value of cardiac biomarkers in pediatrics, there is increasing literature to support their application in various contexts. Cardiac biomarkers should be considered an undervalued resource in the pediatric population with potential value in the diagnosis and prognosis of myocarditis, congenital heart disease, and heart failure, as well as in the assessment of severity and cardiac involvement in immune-related and other systemic conditions. While interpretation remains challenging in pediatrics due to the age- and sex-specific dynamics occurring throughout growth and development, this should not prevent their application. Future research should focus on defining evidence-based cut-offs for specific indications using the most up-to-date assays.

Rheumatic Myocarditis: A Poorly Recognized Etiology of Left Ventricular Dysfunction in Valvular Heart Disease Patients

Background: Heart failure occurs in ~10% of patients with acute rheumatic fever (RF), and several studies have shown that cardiac decompensation in RF results primarily from valvular disease and is not due to primary myocarditis. However, the literature on this topic is scarce, and a recent case series has shown that recurrent RF can cause ventricular dysfunction even in the absence of valvular heart disease. Methods: The present study evaluated the clinical, laboratory and imaging characteristics of 25 consecutive patients with a clinical diagnosis of myocarditis confirmed by 18F-FDG PET/CT or gallium-67 cardiac scintigraphy and RF reactivation according to the revised Jones Criteria. Patients underwent three sequential echocardiograms at (1) baseline, (2) during myocarditis and (3) post corticosteroid treatment. Patients were divided according to the presence (Group 1) or absence (Group 2) of reduced left ventricular ejection fraction (LVEF) during myocarditis episodes. Results: The median age was 42 (17-51) years, 64% of patients were older than 40 years, and 64% were women. Between Group 1 (n = 16) and in Group 2 (n = 9), there were no demographic, echocardiographic or laboratory differences except for NYHA III/IV heart failure (Group 1: 100.0% vs. Group 2: 50.0%; p = 0.012) and LVEF (30 [25-37] vs. 56 [49-62]%, respectively; p < 0.001), as expected. Group 1 patients showed a significant reduction in LVEF during carditis with further improvement after treatment. There was no correlation between LVEF and valvular dysfunction during myocarditis. Among all patients, 19 (76%) underwent 18F-FDG PET/CT, with a positive scan in 68.4%, and 21 (84%) underwent gallium-67 cardiac scintigraphy, with positive uptake in 95.2%, there was no difference between these groups. Conclusion: Myocarditis due to rheumatic fever reactivation can cause left ventricular dysfunction despite valvular disease, and it is reversible after corticosteroid treatment.

Biomarkers of Cardiac Injury: An Update

Conventional and promising new markers of myocardial injury have become an important diagnostic tool and their prognostic significance is also recognized. In addition, they help identify patients who will derive the most benefit from therapeutic interventions. The literature was searched from the websites of the National Library of Medicine (http://www.ncbi.nlm.nih.gov/) and PubMed Central, the U.S. National Library of Medicine’s digital archive of life sciences journal literature (http://www.pubmedcentral.nih.gov/). The data were accessed from books and journals that published relevant articles in this field. The diagnosis of acute myocardial infarction (AMI) has traditionally relied on the combination of chest pain, ECG features, and elevation in serum markers. However, chest symptoms are frequently atypical or absent and ECG changes may be nonspecific or absent. Hence, the diagnosis of acute coronary syndromes has become increasingly dependent on serum markers of cardiac injury. Among them, creatine kinase (CK) is an effective and widely used test, with the recent CKMB assay offering greater specificity and sensitivity. Cardiac troponins facilitate early and rapid diagnosis, enable effective risk stratification in patients with AMI (with or without traditional criteria for MI), and identify those who will benefit from aggressive medical or surgical intervention. Recent data suggest the potential of myoglobin and CKMB isoforms as sensitive markers in the early hours after symptom onset. Cardiac-specific troponins help in rapid diagnosis, prognostication, and treatment of AMI. Troponins also facilitate early detection of recent infarction owing to their prolonged diagnostic window and also aid in the detection of “microinfarction.” CKMB is used to detect reinfarction or infarct extension, if levels rise again after declining. Finally, novel biochemical markers are receiving attention in ongoing trials. They may prove to be more effective in diagnosis and prognosis than their existing counterparts.

Can troponin T levels be useful in the diagnosis of rheumatic carditis?

Objective:

Acute rheumatic fever (ARF) is an endemic disease observed in children of developing countries. The purpose of this study was to test if it was possible to identify myocardial involvement in cases with rheumatic carditis by the measurement of serum cardiac TnT.

Methods:

30 patients diagnosed as ARF underwent echocardiography and their cardiac troponin T (cTnT) serum levels were measured. Patients were divided into group 1: Arthritis alone, group 2: carditis, and group 3 carditis with congestive heart failure (CHF).

Results:

cTnT serum levels were normal in all except one patient with in group 3. Two patients in carditis (group 2) and three patients in CHF (group 3) had dilation in left ventricular end diastolic diameter.

Conclusions:

Normal cTnT levels in our patient group suggests that inflammation rather than myocardial necrosis is predominant in ARF carditis.

A lab-on-a-chip for rapid blood separation and quantification of hematocrit and serum analytes

In this work, a new lab-on-a-chip for rapid analysis of low volume blood samples was designed, fabricated and demonstrated for integration of serum separation, hematocrit evaluation, and protein quantitation. Blood separation was achieved using microchannel flow-based separation. A novel method for evaluating hematocrit from microfluidic flow-separated blood samples was developed using gray scale analysis of a point-and-shoot digital photograph of separated blood in a micochannel. Protein quantitation was subsequently performed in a high surface area-to-volume ratio microfluidic chemiluminescent immunoassay using cell depleted serum produced by microfluidic flow-based separation of whole blood samples. All three steps were achieved in a single microchannel with separation of blood samples and hematocrit evaluation in less than 1 min, and protein quantitation in 5 min.

Cardiac troponin T in children with acute rheumatic carditis

The existence of cardiac damage in active rheumatic carditis patients is unknown, especially in those without pericarditis. The aim of this study was to determine cardiac myocyte damage using cardiac troponin T (cTnT) measurements in active rheumatic carditis. The levels of creatine kinase MB isoenzyme (CK-MB), cTnT, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), cardiothoracic ratio (CTR), and fractional shortening (FS) were compared using Mann-Whitney U test between 28 patients with active rheumatic carditis and 32 controls (healthy children). Association of cTnT levels with ESR, CRP, and CTR was evaluated with Spearman correlation analysis. ESR, CRP, cTnT levels, and CTR were statistically higher in the patients than in the controls. There were no differences between the groups for CK-MB levels and FS. No relationships were found between cTnT levels and ESR, CRP, and CTR in the patient group. The results of the study suggest that when cTnT levels are within non-pathological range, there is no serious cardiac damage; however, statistically significant increases in cTnT levels may indicate minor damages in patients with active carditis due to acute rheumatic fever.

Myocardial involvement in the hemodynamic abnormalities associated with acute rheumatic fever

BACKGROUND AND AIM

Rheumatic fever is still a common cause of acquired heart disease in children and young adult in many developing countries. The aim was to investigate the role of myocardial involvement in the hemodynamic changes in patients with acute rheumatic fever using cardiac troponin assay and echocardiography.

DESIGN

A prospective cohort study was designed.

PATIENTS AND METHODS

Thirty-four children with acute rheumatic fever, 20 with carditis, and 14 without carditis. Level of cardiac troponin T (cTnT) and echocardiographic measurement of left ventricular function were the main outcome measure.

RESULTS

The level of cardiac troponin in children with carditis was 0.051 ± 0.01 ng/dL, and it was 0.039 ± 0.02 ng/dL in those without carditis. The difference is not significant. In addition, there was no significant difference between the children with carditis and those without carditis regarding left ventricular ejection and shortening fractions.

CONCLUSION

There are no significant echocardiographic measurements abnormalities or cTnT levels elevation suggesting clinically relevant hemodynamic abnormalities due to myocardial involvement during acute rheumatic fever.

Comparison of MB fraction of creatine kinase mass and troponin I serum levels with necropsy findings in acute myocardial infarction

Serum levels of troponin and heart-related fraction of creatine kinase (CK-MB) mass are used as diagnostic and prognostic criteria in myocardial infarction, but the relation between those levels and the necropsy-determined size of necrosis has not been tested in human beings. In this retrospective study, 1-cm-thick transverse sections of the ventricles were cut from the base to the apex in the necropsy hearts of 27 patients aged 47 to 86 years (mean 66, median 69; 19 men). Total and necrotic areas were measured using a computer-linked image analysis system. The weights of the necrotic areas were also calculated. The correlations of the areas and weights of necrotic myocardium with the highest serum values of CK-MB mass and troponin I, which had been quantified during life by chemiluminescence immunoassays, were verified by Pearson's test; results were considered significant at p<or=0.05. Significant correlations were detected between CK-MB mass peak and infarct size (r=0.63, p<0.01) and weight (r=0.69, p<0.01) and between CK-MB mass and highest troponin level (r=0.73, p<0.01); however, the correlations between highest troponin level and myocardial infarct size (r=0.31, p=0.11) and weight (r=0.35, p=0.07) were small and nonsignificant. In conclusion, despite the well-established role of serum levels of troponin as a diagnostic tool for myocardial infarction, their highest values showed poor correlations with the extent of infarct. In contrast, the highest serum level of CK-MB mass was well correlated with myocardial infarct size.