Serum Cardiac Troponin T, But Not Troponin I, Is Elevated in Idiopathic Inflammatory Myopathies: Figure 1

Advances in the diagnosis of myocarditis in idiopathic inflammatory myopathies: an overview of diagnostic tests

Cardiac involvement in idiopathic inflammatory myopathies (IIM) purports to worse clinical outcomes, and therefore early identification is important. Research has focused on blood biomarkers and basic investigations such as ECG and echocardiography, which have the advantage of wide availability and low cost but are limited in their sensitivity and specificity. Imaging the myocardium to directly look for inflammation and scarring has therefore been explored, with a number of new methods for doing this gaining wider research interest and clinical availability. Cardiovascular magnetic resonance (CMR) with contemporary multiparametric mapping techniques and late gadolinium enhancement imaging, is an extremely valuable and increasingly used non-invasive imaging modality for the diagnosis of myocarditis. The recently updated CMR-based Lake Louise Criteria for the diagnosis of myocarditis incorporate the newer T1 and T2 mapping techniques, which have greatly improved the diagnostic accuracy for IIM myocarditis.18F-FDG-PET/CT is a well-utilized imaging modality in the diagnosis of malignancies in IIM, and it also has a role for the diagnosis of myocarditis in multiple systemic inflammatory diseases. Endomyocardial biopsy, however, remains the gold standard technique for the diagnosis of myocarditis and is necessary for the diagnosis of specific cases of myocarditis. This article provides an overview of the important tests and imaging modalities that clinicians should consider when faced with an IIM patient with potential myocarditis.

Elevated high-sensitivity cardiac troponin T serum concentration in subjects with spinal cord injury

BACKGROUND

The biochemical analysis of high-sensitivity cardiac troponins (hs-cTn) from peripheral blood specimens has been established as biomarker for myocardial injury. Independently of myocardial injury, increased serum hs-cTn concentrations have been described in patients with myopathies. The relevance and frequency of noncardiac hs-cTn elevations in spinal cord injury (SCI) is unknown. Our study aimed to 1) determine the frequency of increased hs-cTn concentrations of supposedly noncardiac origin above the 99th percentile (upper reference limit, URL) in an unselected SCI population and 2) compare the two protagonist analytes cTnT and cTnI with respect to these noncardiac elevations.

METHODS

In this monocentric, cross-sectional study, we sampled blood from n = 30 SCI subjects without cardiac symptoms to test for hs-cTnT and hs-cTnI serum concentrations.

RESULTS

18/30 (60%) of SCI subjects showed increased hs-cTnT concentrations above the URL of 14 ng/l (p < 0.001). In 4 subjects (22.2%) concentrations were >50 ng/l. Moreover, 3 of these four subjects fulfilled the 6-h troponin dynamics criterion for acute myocardial injury in serial hs-cTnT testing. In contrast, no subject demonstrated increased hs-cTnI concentrations according to the URL of 40 ng/l. 6-h troponin dynamics were also unremarkable for hs-cTnI testing.

CONCLUSIONS

SCI subjects frequently have increased hs-cTnT concentrations without clinical and hs-cTnI evidence of myocardial injury. Clinicians must be aware of cTnT "skeletal muscle false-positives" in SCI, which applies to elevated baseline cTnT concentrations and troponin dynamics in serial measurements. In case of diagnostic uncertainty, simultaneous analysis of cTnI might be helpful.

The use of high-sensitivity cardiac troponin I in assessing cardiac involvement and Disease prognosis in idiopathic inflammatory myopathy

OBJECTIVES

Cardiac involvement is one of the most serious complications of idiopathic inflammatory myopathy (IIM) that indicates poor prognosis. However, there is a lack of effective biomarkers for the identification of cardiac involvement and the prediction of prognosis in IIM. Here, we aimed to explore the value of different cardiac biomarkers in IIM patients.

METHODS

A total of 142 IIM patients in the Department of Rheumatology and Immunology, Ruijin Hospital from July 2019 to October 2022 were included in this study. The clinical characteristics, laboratory tests, treatments and prognosis were recorded. The disease activity was assessed according to the core set measures. The correlations of the serum cardiac biomarkers levels with disease activity were analyzed by the Spearman correlation test. Risk factors for cardiac involvement were evaluated by multivariate logistic regression analysis.

RESULTS

Higher high-sensitivity cardiac troponin I (hs-cTnI) levels were associated with cardiac involvement (n = 41) in IIM patients [adjusted OR 7.810 (95% CI: 1.962-31.097); p = 0.004], independent of other serum cardiac biomarkers. The abnormal hs-cTnI had the highest AUC for distinguishing of cardiac involvement in IIM patients (AUC = 0.848, 95% CI: 0.772,0.924; p < 0.001). Besides, we found that high serum levels of hs-cTnI were significantly correlated with disease activity. Moreover, patients with higher serum levels of hs-cTnI tended to suffer from poor prognosis.

CONCLUSIONS

Serum hs-cTnI testing may play a role in screening for cardiac involvement in IIM patients. Abnormal levels of serum hs-cTnI were associated with increased disease activity and poor prognosis.

Cardiovascular manifestations in idiopathic inflammatory myopathies

Cardiovascular involvement in idiopathic inflammatory myopathies (IIM) is an understudied area which is gaining increasing recognition in recent times. Recent advances in imaging modalities and biomarkers have allowed the detection of subclinical cardiovascular manifestations in IIM. However, despite the availability of these tools, the diagnostic challenges and underestimated prevalence of cardiovascular involvement in these patients remain significant. Notably, cardiovascular involvement remains one of the leading causes of mortality in patients with IIM. In this narrative literature review, we outline the prevalence and characteristics of cardiovascular involvement in IIM. Additionally, we explore investigational modalities for early detection of cardiovascular involvement, as well as newer approaches in screening to facilitate timely management. Key points • Cardiac involvement in IIM in majority cases is subclinical and a major cause of mortality. • Cardiac magnetic resonance imaging is sensitive for detection of subclinical cardiac involvement.

Cardiac involvement in polymyositis and dermatomyositis: diagnostic approaches

Polymyositis (PM) and dermatomyositis (DM) are rare idiopathic inflammatory myopathies (IIM). Myocardial involvement in patients with IIM is an unfavorable prognostic factor and one of the most common cause of mortality in this group of patients. The purpose of this review is to present current knowledge on cardiovascular manifestations observed in IIM. Data published in English until December 2021 were selected. Clinical symptoms suggesting cardiac involvement are non-specific and require a differential diagnosis in accordance with cardiological guidelines. Troponin I is specific to cardiac injury and should be preferred to other markers to evaluate the myocardium in IIM. Abnormalities in electrocardiography are common in IIM, especially non-specific changes of the ST-T segment. In standard echocardiography left ventricular diastolic dysfunction is reported frequently. New diagnostic technologies can reveal clinically silent myocardial abnormalities. However, the prognostic value of subclinical impairment of myocardial function require further studies.

The rise and fall of troponin in a patient with polymyositis

Troponins are an excellent sensitive marker for myocardial ischaemic damage. However, there are several non-ischaemic cardiac and non-cardiac reasons for troponin elevation. Many cases of troponin T elevation and some troponin I cases have been reported in the literature due to inflammatory muscle disease. Here, we report a woman in her 50s who initially presents with fatigue and weakness, and is found to have elevated troponin T. The patient was appropriately worked up for cardiac causes with ECG and echocardiogram. She had positive antinuclear antibodies, antineutrophil cytoplasmic antibody and myositis panel. The elevation of troponins was attributed to polymyositis and treated with methotrexate and prednisone with recovery of patient's symptoms. This article emphasises the struggle of diagnosis in a patient with no reported medical history, having low to moderate risk of silent myocardial infarction.

Case report of elevation of high-sensitivity cardiac troponin T in the absence of cardiac involvement in immune checkpoint inhibitor-associated myositis

Background

Immune checkpoint inhibitors (ICIs) have markedly improved outcome in various types of cancer. ICI-associated myocarditis is one of the most severe immune-related adverse events. In particular, high concentrations of cardiac troponin T (cTnT) are associated with a high risk of death and early detection and vigorous therapy with high-dose steroids may improve survival. However, chronic skeletal muscle disorders have been suggested as a non-cardiac source of elevated high-sensitivity cardiac troponin T (hs-cTnT) concentrations.

Case summary

Here, we present the case of a 72-year-old patient with metastatic melanoma treated with nivolumab and ipilimumab, who developed symptomatic myositis [creatine kinase (CK) max. 3113 U/L]. Due to substantially elevated concentrations of hs-cTnT (max. 1128 ng/L, normal <14 ng/L, Elecsys), the patient was referred to the cardio-oncology unit for evaluation of concomitant myocarditis. The patient did not report any cardiac symptoms and there were no clinical signs of congestion or rhythm abnormalities. Concentrations of NT-proBNP were within the normal range. Echocardiography showed normal cardiac dimensions and normal systolic and diastolic function. Cardiac magnetic resonance imaging confirmed these findings and also showed no evidence of acute or post-inflammatory myocardial tissue changes. Absence of relevant cardiomyocyte injury was supported by determination of normal levels of cardiac troponin I concentrations and made endomyocardial biopsy in this severely ill patient unnecessary.

Discussion

Our observation documents ICI-induced myositis as an alternative non-cardiac cause of hs-cTnT elevation. A global cardiologic approach employing clinical and cardiac magnetic resonance imaging data as well as NT-proBNP and cardiac troponin I helps to identify false positive hs-TnT elevation under ICI therapy.

Cardiovascular Abnormalities in Juvenile Dermatomyositis: A Scoping Review for the Clinical Rheumatologists

Juvenile dermatomyositis (JDM) is a common form of inflammatory myositis in children. Vasculopathy and endothelial dysfunction play significant roles in the pathogenesis of JDM. Cardiac involvement in JDM is often underestimated, and it may be a potential indicator of poor prognosis. Cardiac dysfunction in JDM can occur both in the acute and chronic stages of the disease. Amongst the acute complications, acute congestive heart failure (CHF), myocarditis, arrhythmia, and complete heart block are common. However, these remain unrecognized due to a lack of overt clinical manifestations. Increased rates of cardiovascular abnormalities have been noted with anti-SRP and anti-Jo 1 auto-antibody positivity. Long-term follow-up studies in JDM have shown an increased prevalence of hypertension, atherosclerosis, coronary artery disease, and metabolic syndrome in adolescence and adulthood. Monitoring of body-mass index, blood pressure, and laboratory evaluation of fasting glucose and lipid profile may help in identifying metabolic syndrome in children with JDM. Steroid-sparing agents, daily exercise, and a healthy diet may reduce such long-term cardiac morbidities. Current use of multimodality imaging such as stress-echocardiography, contrast-enhanced echocardiography, cardiac magnetic resonance imaging, and positron emission tomography has increased the diagnostic yield of subclinical heart disease during acute and chronic stages of JDM. This review elaborates on different aspects of cardiac dysfunction in JDM. It also emphasizes the importance of cardiac screening in long-term follow-up of children with JDM.

Skeletal Muscle Disorders: A Noncardiac Source of Cardiac Troponin T

BACKGROUND

Cardiac troponin (cTn) T and cTnI are considered cardiac specific and equivalent in the diagnosis of acute myocardial infarction. Previous studies suggested rare skeletal myopathies as a noncardiac source of cTnT. We aimed to confirm the reliability/cardiac specificity of cTnT in patients with various skeletal muscle disorders (SMDs).

METHODS

We prospectively enrolled patients presenting with muscular complaints (≥2 weeks) for elective evaluation in 4 hospitals in 2 countries. After a cardiac workup, patients were adjudicated into 3 predefined cardiac disease categories. Concentrations of cTnT/I and resulting cTnT/I mismatches were assessed with high-sensitivity (hs-) cTnT (hs-cTnT-Elecsys) and 3 hs-cTnI assays (hs-cTnI-Architect, hs-cTnI-Access, hs-cTnI-Vista) and compared with those of control subjects without SMD presenting with adjudicated noncardiac chest pain to the emergency department (n=3508; mean age, 55 years; 37% female). In patients with available skeletal muscle biopsies, TNNT/I1-3 mRNA differential gene expression was compared with biopsies obtained in control subjects without SMD.

RESULTS

Among 211 patients (mean age, 57 years; 42% female), 108 (51%) were adjudicated to having no cardiac disease, 44 (21%) to having mild disease, and 59 (28%) to having severe cardiac disease. hs-cTnT/I concentrations significantly increased from patients with no to those with mild and severe cardiac disease for all assays (all P<0.001). hs-cTnT-Elecsys concentrations were significantly higher in patients with SMD versus control subjects (median, 16 ng/L [interquartile range (IQR), 7-32.5 ng/L] versus 5 ng/L [IQR, 3-9 ng/L]; P<0.001), whereas hs-cTnI concentrations were mostly similar (hs-cTnI-Architect, 2.5 ng/L [IQR, 1.2-6.2 ng/L] versus 2.9 ng/L [IQR, 1.8-5.0 ng/L]; hs-cTnI-Access, 3.3 ng/L [IQR, 2.4-6.1 ng/L] versus 2.7 ng/L [IQR, 1.6-5.0 ng/L]; and hs-cTnI-Vista, 7.4 ng/L [IQR, 5.2-13.4 ng/L] versus 7.5 ng/L [IQR, 6-10 ng/L]). hs-cTnT-Elecsys concentrations were above the upper limit of normal in 55% of patients with SMD versus 13% of control subjects (P<0.01). mRNA analyses in skeletal muscle biopsies (n=33), mostly (n=24) from individuals with noninflammatory myopathy and myositis, showed 8-fold upregulation of TNNT2, encoding cTnT (but none for TNNI3, encoding cTnI) versus control subjects (n=16, P_Wald<0.001); the expression correlated with pathological disease activity (R=0.59, P_t-statistic<0.001) and circulating hs-cTnT concentrations (R=0.26, P_t-statistic=0.031).

CONCLUSIONS

In patients with active chronic SMD, elevations in cTnT concentrations are common and not attributable to cardiac disease in the majority. This was not observed for cTnI and may be explained in part by re-expression of cTnT in skeletal muscle.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT03660969.

Consider Myocarditis When Patients Treated with Immune Checkpoint Inhibitors Present with Ocular Symptoms

Immune checkpoint inhibitors (ICIs) have been associated with neurological immune related adverse events (irAE-N) and patients with ICI toxicity may present with neurological or ocular symptoms. Furthermore, patients on ICI may initially present to oncology or neurology. We report a case series of 3 patients treated with ICIs presenting with diplopia or ptosis, found to have concurrent myocarditis in addition to immune-related myopathy (irMyopathy) or myasthenia gravis (irMG). None of the patients described cardiac symptoms, underscoring the importance of screening for myocarditis in patients presenting with diplopia and/or other neuromuscular symptoms which may suggest either irMyopathy or irMG.

False-Positive Causes in Serum Cardiac Troponin Levels

Cardiac troponins (cTns) are the most valuable and specific markers of cardiovascular diseases, including acute myocardial infarction. These biomarkers can also be used to assess the degree of myocardial damage in non-cardiac diseases that can negatively affect the cells of cardiac muscle tissue. However, in everyday clinical practice, doctors often encounter with false-positive cases of increased cTns. False-positive cases of increased cTns can contribute to incorrect diagnosis and subsequent inadequate treatment, which causes significant harm to the patient. This review discusses some common causes of a false-positive increase in the level of cTns in the blood serum. Such causes are fibrin clots, heterophilic antibodies, alkaline phosphatase, rheumatoid factor, and cross-reactions of diagnostic (anti-cTn) antibodies with skeletal troponins. Detailed attention is focused on the mechanisms of false-positive increase, and ways to identify and combat these false-positive causes of increased cTns. This has an important practical significance in modern clinical practice.

Hsp90 Levels in Idiopathic Inflammatory Myopathies and Their Association With Muscle Involvement and Disease Activity: A Cross-Sectional and Longitudinal Study

Background

Heat shock proteins (Hsp) are chaperones playing essential roles in skeletal muscle physiology, adaptation to exercise or stress, and activation of inflammatory cells. We aimed to assess Hsp90 in patients with idiopathic inflammatory myopathies (IIM) and its association with IIM-related features.

Methods

Hsp90 plasma levels were analyzed in a cross-sectional cohort (277 IIM patients and 157 healthy controls [HC]) and two longitudinal cohorts to assess the effect of standard-of-care pharmacotherapy (n=39 in early disease and n=23 in established disease). Hsp90 and selected cytokines/chemokines were measured by commercially available ELISA and human Cytokine 27-plex Assay.

Results

Hsp90 plasma levels were increased in IIM patients compared to HC (median [IQR]: 20.2 [14.3–40.1] vs 9.8 [7.5–13.8] ng/mL, p<0.0001). Elevated Hsp90 was found in IIM patients with pulmonary, cardiac, esophageal, and skeletal muscle involvement, with higher disease activity or damage, and with elevated muscle enzymes and crucial cytokines/chemokines involved in the pathogenesis of myositis (p<0.05 for all). Plasma Hsp90 decreased upon pharmacological treatment in both patients with early and established disease. Notably, Hsp90 plasma levels were slightly superior to traditional biomarkers, such as C-reactive protein and creatine kinase, in differentiating IIM from HC, and IIM patients with cardiac involvement and interstitial lung disease from those without these manifestations.

Conclusions

Hsp90 is increased systemically in patients with IIM. Plasma Hsp90 could become an attractive soluble biomarker of disease activity and damage and a potential predictor of treatment response in IIM.

Some Common Causes of False Positive Increases in Serum Levels of Cardiac Troponins

Cardiac troponin molecules (cTnI and cTnT) are the most valuable and in-demand biomarkers for detecting various types of myocardial damage (reversible and irreversible, ischemic, inflammatory, toxic, etc.) in current clinical practice. These biomarkers are widely used for early diagnosis of acute myocardial infarction (AMI) and risk stratification of patients suffering from a number of cardiac (such as myocarditis, heart failure, cardiomyopathy, etc.) and extra-cardiac diseases (such as sepsis, renal failure, pulmonary embolism, neurological pathologies, etc.) that negatively affect the cells of cardiac muscle tissue. However, in daily routine clinical activities, internists and cardiologists often encounter cases of false increases in the concentrations of cardiospecific troponins. A false increase in the concentration of troponins contributes to an incorrect diagnosis and incorrect therapy, which can harm the patient. A false increase in the concentration of troponins contributes to an incorrect diagnosis and incorrect therapy, which can harm the patient, therefore, internists and cardiologists should be well aware of the main reasons and mechanisms for false-positive results cTnI and cTnT. This review article mainly focuses on the causes of falsepositive increases in serum levels of cTnI and cTnT, which provide helpful clues for the accurate diagnosis of AMI and evidence for the differential diagnosis.

Variability of high-sensitivity cardiac troponin T and I in asymptomatic patients receiving hemodialysis

Variation of high-sensitivity cardiac troponin I and T (hs-cTn) during hemodialysis has been observed. Observational studies demonstrated the increased incidence of adverse cardiovascular events after long compared to short interdialytic intervals. Therefore, we aimed to compare variation of hs-cTnI and hs-cTnT before and after hemodialysis and between short and long interdialytic intervals. We enrolled 200 asymptomatic patients receiving regular hemodialysis. The hs-cTnI and hs-cTnT levels were measured before and after hemodialysis on the day after short and long interdialytic intervals. Mean age was 62.3 ± 14.8 years (Male 55.5%). Prevalence of increased hs-cTnI and hs-cTnT was 34.5% and 99.0%, respectively. The median ± interquartile range of hs-cTnT increased significantly after hemodialysis during short and long interdialytic intervals. However, hs-cTnI level did not increase after hemodialysis during short and long intervals. We found that levels of hs-cTnI and T did not differ between short interdialytic and long interdialytic intervals. We demonstrated higher prevalence of elevated hs-cTnT in patients with regular hemodialysis compared to hs-cTnI. The rise of hs-cTnT was observed immediately after hemodialysis but no significant change of hs-cTnI was noted. Accordingly, hs-cTnI may be preferable as a diagnostic marker in patients with suspected acute myocardial infarction than hs-cTnT.

Defining cardiac involvement in idiopathic inflammatory myopathies: a systematic review

OBJECTIVE

Recent advances in cardiac magnetic resonance imaging (CMR) and other diagnostic techniques have made it easier to identify subclinical cardiac inflammation and dysfunction in the idiopathic inflammatory myopathies (IIM). Herein, we systematically review the literature regarding cardiac involvement in IIM.

METHODS

We searched Medline and EMBASE from 1990-2020 using keywords related to IIM and cardiac disease. We included English language studies in adults with any immune-mediated, inflammatory muscle pathology.

RESULTS

We identified 10425 potentially relevant abstracts, of which 29 were included. Most frequently these included patients with polymyositis or dermatomyositis without symptomatic myocarditis. Five categories of cardiac investigation were used in these patients: cardiac enzyme testing, electrocardiography (ECG), transthoracic echocardiography (TTE), CMR and nuclear medicine testing. Patients with clinical myocarditis had universally abnormal cardiac troponin levels and ECG. Elevated cardiac troponin T was more common than troponin I (cTnI) and may correlate with disease activity, whereas cTnI was more specific for cardiac involvement. Non-specific ECG changes were common. The major finding on TTE was abnormal ejection fraction. Gross systolic dysfunction was unusual, but subclinical systolic dysfunction was reported in several studies. Abnormal diastolic function was common and may be associated with disease duration. Late gadolinium enhancement (reflecting regional necrosis or scar) and abnormal myocardial mapping parameters (reflecting myocardial inflammation, fibrosis and oedema) were frequently identified on CMR, suggesting significant subclinical myocardial pathology (despite typically normal ejection fraction).

CONCLUSION

Abnormal cardiac investigations are commonly found in asymptomatic IIM patients, which has potential prognostic and treatment implications.

Cardiac troponin T is elevated and increases longitudinally in ALS patients

Objective: To test whether high-sensitivity cardiac troponin T (hs-cTnT) could act as a diagnostic or prognostic biomarker in ALS, comparing hs-cTnT to neurofilament light (NfL). Methods: We performed a case-control study, including 150 ALS patients, 28 ALS mimics, and 108 healthy controls, and a follow-up study of the ALS patients, during 2014-2020 in Stockholm, Sweden. We compared concentrations of hs-cTnT in plasma and NfL in the cerebrospinal fluid between cases and controls. To evaluate the diagnostic performance, we calculated the area under the curve (AUC). Hazard ratios (HRs) were estimated from Cox models to assess associations between hs-cTnT and NfL at ALS diagnosis and risk of death. The longitudinal analysis measured changes of hs-cTnT and NfL since ALS diagnosis. Results: We noted higher levels of hs-cTnT in ALS patients (median: 16.5 ng/L) than in ALS mimics (11 ng/L) and healthy controls (6 ng/L). Both hs-cTnT and NfL could distinguish ALS patients from ALS mimics, with higher AUC noted for NfL (AUC 0.88; 95%CI 0.79-0.97). Disease progression correlated weakly with hs-cTnT (Pearson's r = 0.18, p = 0.04) and moderately with NfL (Pearson's r = 0.41, p < 0.001). Shorter survival was associated with higher levels of NfL at diagnosis (HR 1.08, 95%CI 1.04-1.11), but not hs-cTnT. hs-cTnT increased (12.61 ng/L per year, 95%CI 7.14-18.06) whereas NfL decreased longitudinally since ALS diagnosis. Conclusions: NfL is a stronger diagnostic and prognostic biomarker than hs-cTnT for ALS. However, hs-cTnT might constitute a disease progression biomarker as it increases longitudinally. The underlying causes for this increase need to be investigated.

Cardiac troponins: are there any differences between T and I?

The most recent international guidelines recommend the measurement of cardiac troponin I (cTnI) and cardiac troponin T (cTnT) using high-sensitivity methods (hs-cTn) for the detection of myocardial injury and the differential diagnosis of acute coronary syndromes. Myocardial injury is a prerequisite for the diagnosis of acute myocardial infarction, but also a distinct entity. The 2018 Fourth Universal Definition of Myocardial Infarction states that myocardial injury is detected when at least one value above the 99th percentile upper reference limit is measured in a patient with high-sensitivity methods for cTnI or cTnT. Not infrequently, increased hs-cTnT levels are reported in patients with congenital or chronic neuromuscular diseases, while the hs-cTnI values are often in the normal range. Furthermore, some discrepancies between the results of laboratory tests for the two troponins are occasionally found in individuals apparently free of cardiac diseases, and also in patients with cardiac diseases. In this review article, authors discuss the biochemical, pathophysiological and analytical mechanisms which may cause discrepancies between hs-cTnI and hs-cTnT test results.

Elevated Cardiac Troponin T in Patients with Lupus Myositis Presenting with Noncardiac Chest Pain

Patients with systemic lupus erythematosus (SLE) presenting with chest pain pose a unique diagnostic challenge, with causes ranging from cardiopulmonary disease to esophageal disorders and musculoskeletal chest wall pain. The most common biomarkers for myocardial injury are cardiac troponin T and I (cTnT and cTnI) due to their high sensitivity for the early detection of myocardial infarction. In the idiopathic inflammatory myopathies, cTnT is commonly elevated, and this reflects skeletal muscle breakdown rather than myocardial damage. Similar observations have not been reported in SLE myositis to date. We present two cases of patients with SLE and associated myositis who presented with chest pain and elevated cTnT. Both patients had a normal cTnI, transthoracic echocardiogram, and cardiac magnetic resonance imaging, likely indicating noncardiac chest pain. Clinicians should be aware that the specificity of cTnT might be lower in SLE myositis and that cTnI elevation may be more specific in detecting myocardial insult.

Identification of characteristics of overt myocarditis in adult patients with idiopathic inflammatory myopathies

Background

Myocarditis is a rare complication of idiopathic inflammatory myopathies (IIMs), which is usually underestimated because of limited applications of endomyocardial biopsy and cardiovascular magnetic resonance (CMR) in clinical routines.

Methods

From January 2014 to January 2019, 62 patients with initial untreated IIMs were enrolled, including 31 cases with myocarditis (case group) and 31 cases without cardiac involvement (control group). Myocarditis secondary to IIMs was defined based on definitions of IIMs. All medical data were retrieved from electrical medical records of PUMCH. The differences between two groups in symptoms, serum levels of cardiac troponin I (cTnI), creatine kinase-isozyme and N-terminal pro-brain natriuretic peptide (NT-proBNP) were analyzed. The comparisons of arrhythmia, left ventricular ejection fraction (LVEF) and restrictive diastolic dysfunction between two groups were conducted in the analysis of electrocardiogram and electrocardiogram. Besides, CMR data were analyzed to explore the characteristics of CMR in the identification of myocarditis. Meanwhile, 31 patients with myocarditis were divided into two subgroups based on the activity of anti-mitochondrial antibody M2 (AMA-M2), and the differences between two subgroups in the above tests were also analyzed.

Results

Compared with control group, patients with myocarditis exhibited shorter disease durations (defined as the period from onset symptoms of IIM to diagnosis of IIM), more symptoms associated with IIMs, more manifestations of heart failure, and higher frequency of positive AMA-M2 antibody (P<0.05). Patients with myocarditis exhibited elevated levels of cTnI, creatine kinase-isozyme and NT-proBNP compared with control group. In case group, the area under the curve indicating myocarditis for CK-MB, cTnI, and NT-proBNP was 0.654, 0.915 and 0.973, with optimal cut-off values of 24.4 µg/L, 0.1 ng/L and 531 pg/L, respectively. Ventricular arrhythmia, atrial arrhythmia, abnormal Q wave and left anterior fascicular block (LAFB) were showed in 76.7%, 53.3%, 74.2% and 51.6% of patients in case group (P<0.01). Patients of case group were featured as decreased LVEF and restrictive diastolic dysfunction compared with control group (P<0.05). Analyzing CMR data of patients of case group, the basal segments (74.2%) and mid-cavity segments (71.0%) were the most frequently involved areas of late gadolinium-enhancement (LGE), while intramural LGE (54.8%) and subendocardial LGE (51.6%) were reported more commonly than subepicardial LGE (19.4%). In patients with myocarditis and positive AMA-M2 antibody, LVEF and right ventricular ejection factor (RVEF) were decreased, and more cases presented diffuse LGE than those with negative AMA-M2 antibody (P<0.05).

Conclusions

Symptoms of heart failure and arrhythmias, elevated levels of cTnI and NT-proBNP, and positive AMA-M2 antibody play an important role in the identification of myocarditis in IIMs. Most frequently involved areas of LGE were found in the ventricular septal, basal and mid-cavity segments, as well as in the sub-endocardium and intramural myocardium. Diffuse LGE is common in the detection, which is correlated with AMA-M2 antibody in patients with myocarditis related to IIMs.

Interleukin-33/suppression of tumorigenicity 2 (IL-33/ST2) axis in idiopathic inflammatory myopathies and its association with laboratory and clinical parameters: a pilot study

Idiopathic inflammatory myopathies (IIM) are rare connective tissue diseases, which can lead to internal organ involvement. IL-33/ST2 pathway is involved in the pathogenesis of numerous diseases including autoimmune disorders. IL-33 fulfils cardioprotective function, while soluble ST2 (sST2) is a decoy receptor that reduces protective impact of IL-33. The aim of the study was to evaluate the concentrations of sST2 and IL-33 in sera of patients with IIM and evaluate its associations with the clinical course of the disease. Patients with IIM as well as age- and sex-matched healthy controls were recruited. Concentrations of sST2 and IL-33 were assessed with ELISA in sera of both patients and controls. Patients were asked to fill in the questionnaires concerning clinical symptoms and physical functioning. Concentrations of sST2 and IL-33 were correlated with the results of laboratory tests and clinical symptoms. Concentrations of sST2 were significantly higher in IIM group than in healthy subjects (median sST2 in IIM 26.51 vs in healthy controls 21.39; p = 0.03). In the majority of patients, IL-33 concentrations did not exceed the detection limit. Anti-SRP-positive patients presented significantly higher concentrations of sST2 as compared to anti-SRP-negative patients (p = 0.04). In patients with anti-Ro52 antibodies, sST2 concentrations were significantly lower than in anti-Ro52-negative patients (p = 0.02). Concentrations of sST2 correlated with the degree of disability evaluated with Health Assessment Questionnaire. sST2 is increased in patients with IIM and its concentration correlates with the degree of disability. In patients with anti-SRP antibodies, levels of sST2 are exceptionally high.

Cardiovascular complications in patients with idiopathic inflammatory myopathies: does heart matter in idiopathic inflammatory myopathies?

This review presents a detailed study of original researches and previously published reviews concerning cardiovascular involvement in idiopathic inflammatory myopathies (IIM). We aimed to summarize the current knowledge on the cardiac involvement in IIM, evaluate its impact on mortality and indicate areas still awaiting to be investigated. We searched MEDLINE database (until January 2019) and the reference lists of articles. Selection criteria included only published data, available in English, both original researches and reviews. Articles related to cardiovascular involvement in IIM were selected and analysed. The references were also screened, and relevant articles were included. Cardiovascular involvement is frequent in IIM but typically remains subclinical. Among far less prevalent symptomatic forms, congestive heart failure is the most common. Myocardium and conduction system seems to be predominantly affected. High rate of left ventricular diastolic dysfunction was observed. Non-specific changes of ST-T segment were the most common abnormalities in electrocardiography. Patients with IIM were more frequently affected by atrial fibrillation as compared with other autoimmune diseases. Increased risk of myocardial infarction was observed; furthermore, patients often develop comorbidities that enhance cardiovascular risk. Since cardiovascular disorders remain one of the major causes of death and subclinical involvement is frequent, active screening is justified. Growing availability of the novel imaging techniques may facilitate diagnosis. Correlation between myocardial involvement and the type of autoantibodies and impact of different therapeutic options on the progression of cardiovascular lesions require further studies.

Elevated Cardiac Troponin T in Patients With Skeletal Myopathies

BACKGROUND

Cardiac troponins are often elevated in patients with skeletal muscle disease who have no evidence of cardiac disease.

OBJECTIVES

The goal of this study was to characterize cardiac troponin concentrations in patients with myopathies and derive insights regarding the source of elevated troponin T measurements.

METHODS

Cardiac troponin T (cTnT) and cardiac troponin I (cTnI) concentrations were determined by using high sensitivity assays in 74 patients with hereditary and acquired skeletal myopathies. Patients underwent comprehensive cardiac evaluation, including 12-lead electrocardiogram, 24-h electrocardiogram, cardiac magnetic resonance imaging, and coronary artery computed tomography. cTnT and cTnI protein expression was determined in skeletal muscle samples of 9 patients and in control tissues derived from autopsy using antibodies that are used in commercial assays. Relevant Western blot bands were subjected to liquid chromatography tandem mass spectrometry for protein identification.

RESULTS

Levels of cTnT (median: 24 ng/l; interquartile range: 11 to 54 ng/l) were elevated (>14 ng/l) in 68.9% of patients; cTnI was elevated (>26 ng/l) in 4.1% of patients. Serum cTnT levels significantly correlated with creatine kinase and myoglobin (r = 0.679 and 0.786, respectively; both p < 0.001). Based on cTnT serial testing, 30.1% would have fulfilled current rule-in criteria for myocardial infarction. Noncoronary cardiac disease was present in 23%. Using cTnT antibodies, positive bands were found in both diseased and healthy skeletal muscle at molecular weights approximately 5 kDa below cTnT. Liquid chromatography tandem mass spectrometry identified the presence of skeletal troponin T isoforms in these bands.

CONCLUSIONS

Measured cTnT concentrations were chronically elevated in the majority of patients with skeletal myopathies, whereas cTnI elevation was rare. Our data indicate that cross-reaction of the cTnT immunoassay with skeletal muscle troponin isoforms was the likely cause.

Biomarkers in Inflammatory Myopathies-An Expanded Definition

Biomarkers as parameters of pathophysiological conditions can be of outmost relevance for inflammatory myopathies. They are particularly warranted to inform about diagnostic, prognostic, and therapeutic questions. As biomarkers become more and more relevant in daily routine, this review focusses on relevant aspects particularly addressing myopathological features. However, the level of evidence to use them in daily routine at presence is low, still since none of them has been validated in large cohorts of patients and rarely in independent biopsy series. Hence, they should be read as mere expert opinions. The evaluation of biomarkers as well as key biological parameters is an ongoing process, and we start learning about relevance of them, as we must recognize that pathophysiology of myositis is biologically incompletely understood. As such this approach should be considered an essay toward expansion of the definition “biomarker” to myositis, an emerging field of interest in biomedical research.

Troponins in scuba divers with immersion pulmonary edema

Immersion pulmonary edema (IPE) is a serious complication of water immersion during scuba diving. Myocardial ischemia can occur during IPE that worsens outcome. Because myocardial injury impacts the therapeutic management, we aim to evaluate the profile of cardiac markers (creatine phosphokinase (CPK), brain natriuretic peptide (BNP), highly sensitive troponin T (TnT-hs) and ultrasensitive troponin I (TnI-us) of divers with IPE. Twelve male scuba divers admitted for suspected IPE were included. The collection of blood samples was performed at hospital entrance (T0) and 6 h later (T0 + 6 h). Diagnosis was confirmed by echocardiography or computed-tomography scan. Mean ± S.D. BNP (pg/ml) was 348 ± 324 at T0 and 223 ± 177 at T0 + 6 h (P<0.01), while mean CPK (international units (IUs)), and mean TnT-hs (pg/ml) increased in the same times 238 ± 200 compared with 545 ± 39, (P=0.008) and 128 ± 42 compared with 269 ± 210, (P=0.01), respectively; no significant change was observed concerning TnI-us (pg/ml): 110 ± 34 compared with 330 ± 77, P=0.12. At T0 + 6 h, three patients had high TnI-us, while six patients had high TnT-hs. Mean CPK was correlated with TnT-hs but not with TnI-us. Coronary angiographies were normal. The increase in TnT during IPE may be secondary to the release of troponin from non-cardiac origin. The measurement of TnI in place of TnT permits in some cases to avoid additional examinations, especially unnecessary invasive investigations.

Using serum troponins to screen for cardiac involvement and assess disease activity in the idiopathic inflammatory myopathies

Objectives

Limitations in the methods available for identifying cardiac involvement and accurately quantifying disease activity in the idiopathic inflammatory myopathies (IIMs) may contribute to poor outcomes. We investigated the utility of different serum muscle damage markers [total creatine kinase (CK), cardiac troponin T (cTnT) and cardiac troponin I (cTnI)] to address these issues.

Methods

We assessed disease activity and cardiac involvement using the International Myositis Assessment and Clinical Studies Group core set measures in 123 participants with confirmed adult-onset IIM from the UK and Denmark. Total CK, cTnT and cTnI were measured. Associations were assessed using logistic regression and Spearman's ranked correlation.

Results

Cardiac involvement (n = 18) was associated with higher cTnI levels, independent of overall disease activity [adjusted odds ratio 1.03 (95% CI 1.01, 1.05); P = 0.002]. An abnormal cTnI had the highest specificity and positive predictive value for cardiac involvement (95% and 62%, respectively). In those with a normal CK but elevated cTnT or cTnI, an association with increased disease activity scores was observed. Serum cTnT correlated with the physician (ρ = 0.39) and patient-assessed (ρ = 0.28) global visual analogue scales and HAQ (ρ = 0.41) more strongly than CK or cTnI levels. cTnT was the only marker to correlate with manual muscle testing scores (ρ = -0.24).

Conclusion

Serum cTnI testing may have a role in screening for cardiac involvement in IIMs. Abnormal levels of serum cTnT and cTnI are associated with increased disease activity, including in those with a normal CK.

Is it cardiac involvement mimicking acute myocardial infarction in idiopathic inflammatory myopathy?

Idiopathic inflammatory myopathy (IIM) comprises a group of rare systemic diseases characterized by progressive weakness of the symmetrical proximal limb muscles, elevated muscle enzymes, inflammation or necrosis on muscle biopsy. IIM may impair the function of multiple organs, particularly the heart. However, it rarely manifests as acute myocardial infarction (AMI) at initial presentation. The present study described the case of a 39-year-old woman with AMI, whose muscle biopsy on the left arm conformed to polymyositis. Coronary arteriography showed irregularities in the left descending and right coronary artery (25% diameter reduction in middle segment). It was concluded that AMI was the chief manifestation of IIM at initial presentation. Furthermore, to the best of our knowledge, the present study was the first to provide a systematic literature review to assess AMI in IIM patients and discuss the possible causes of AMI.

What to do when you question cardiac troponin values

High-sensitivity cardiac troponin assays enable cardiac troponin measurement with a high degree of analytical sensitivity and a low level of analytical imprecision at the low measuring range. One of the most important advantages of these new assays is that they allow novel, more rapid approaches for ruling in or ruling out acute myocardial infarctions. The increase in the early diagnostic sensitivity of high-sensitivity cardiac troponin assays comes at the cost of a reduced acute myocardial infarction specificity of the biomarker, because more patients with other causes of acute or chronic myocardial injury without overt myocardial ischaemia are detected than with previous cardiac troponin assays. Increased troponin concentrations that do not fit with the clinical presentation are seen in the daily routine, mainly as a result of a variety of pathologies, and if tested in the same sample, even discrepancies between high-sensitivity cardiac troponin I and troponin T test results may sometimes be found as well. In addition, analytically false-positive test results occasionally may occur since no assay is perfect. In this review, we summarise the biochemical, pathophysiological and analytical background of the work-up for such a clinical setting.

Elevated plasma levels of cardiac troponin-I predict left ventricular systolic dysfunction in patients with myotonic dystrophy type 1: A multicentre cohort follow-up study

Objective

High sensitivity plasma cardiac troponin-I (cTnI) is emerging as a strong predictor of cardiac events in a variety of settings. We have explored its utility in patients with myotonic dystrophy type 1 (DM1).

Methods

117 patients with DM1 were recruited from routine outpatient clinics across three health boards. A single measurement of cTnI was made using the ARCHITECT STAT Troponin I assay. Demographic, ECG, echocardiographic and other clinical data were obtained from electronic medical records. Follow up was for a mean of 23 months.

Results

Fifty five females and 62 males (mean age 47.7 years) were included. Complete data were available for ECG in 107, echocardiography in 53. Muscle Impairment Rating Scale score was recorded for all patients. A highly significant excess (p = 0.0007) of DM1 patients presented with cTnI levels greater than the 99^th centile of the range usually observed in the general population (9 patients; 7.6%). Three patients with elevated troponin were found to have left ventricular systolic dysfunction (LVSD), compared with four of those with normal range cTnI (33.3% versus 3.7%; p = 0.001). Sixty two patients had a cTnI level < 5ng/L, of whom only one had documented evidence of LVSD. Elevated cTnI was not predictive of severe conduction abnormalities on ECG, or presence of a cardiac device, nor did cTnI level correlate with muscle strength expressed by Muscle Impairment Rating Scale score.

Conclusions

Plasma cTnI is highly elevated in some ambulatory patients with DM1 and shows promise as a tool to aid cardiac risk stratification, possibly by detecting myocardial involvement. Further studies with larger patient numbers are warranted to assess its utility in this setting.

Elevation of cardiac troponin T in patients with amyotrophic lateral sclerosis

Limited evidence suggests that specificity of cardiac troponin T (cTnT), a highly sensitive biomarker of myocardial injury, is reduced in patients with skeletal myopathies. Whether amyotrophic lateral sclerosis (ALS)-the most common motor neuron disease-could be also associated with abnormal plasma or serum cTnT levels remains unclear. Our objective was to assess cTnT levels in patients with ALS without known cTnT elevating conditions. Among ALS patients seen at our institution until 2012 we identified those who had their cTnT measured. Patients who suffered from conditions known to elevate cTnT were excluded. A case-control analysis comparing cTnT levels of these ALS patients to matched non-ALS controls fulfilling the same inclusion criteria was performed. We included 40 ALS patients of whom 27 (68 %) patients had a positive cTnT. In the control group (n = 40), 2 (5 %) tested as cTnT positive (p < 0.001). Among the ALS patients who underwent cTnT evaluation on more occasions (n = 7; median follow-up = 1.08 years), 2 (29 %) patients tested positive during the initial measurement while 6 (86 %) of them had positive cTnT at the subsequent evaluations. ALS patients with increased cTnT had been diagnosed with ALS significantly earlier than those without the elevation. Our findings raise the possibility that ALS may cause cTnT elevations. Further studies are needed to confirm these findings, clarify the pathophysiological mechanism, and establish the significance of cTnT elevations in patients with ALS.

Cardiac involvement in adult and juvenile idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) include the main subgroups polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM) and juvenile DM (JDM). The mentioned subgroups are characterised by inflammation of skeletal muscles leading to muscle weakness and other organs can also be affected as well. Even though clinically significant heart involvement is uncommon, heart disease is one of the major causes of death in IIM. Recent studies show an increased prevalence of traditional cardiovascular risk factors in JDM and DM/PM, which need attention. The risk of developing atherosclerotic coronary artery disease is increased twofold to fourfold in DM/PM. New and improved diagnostic methods have in recent studies in PM/DM and JDM demonstrated a high prevalence of subclinical cardiac involvement, especially diastolic dysfunction. Interactions between proinflammatory cytokines and traditional risk factors might contribute to the pathogenesis of cardiac dysfunction. Heart involvement could also be related to myocarditis and/or myocardial fibrosis, leading to arrhythmias and congestive heart failure, demonstrated both in adult and juvenile IIM. Also, reduced heart rate variability (a known risk factor for cardiac morbidity and mortality) has been shown in long-standing JDM. Until more information is available, patients with IIM should follow the same recommendations for cardiovascular risk stratification and prevention as for the corresponding general population, but be aware that statins might worsen muscle symptoms mimicking myositis relapse. On the basis of recent studies, we recommend a low threshold for cardiac workup and follow-up in patients with IIM.

Sporadic inclusion body myositis: A review of recent clinical advances and current approaches to diagnosis and treatment

Sporadic inclusion body myositis is the most frequent acquired myopathy of middle and later life and is distinguished from other inflammatory myopathies by its selective pattern of muscle involvement and slowly progressive course, and by the combination of inflammatory and degenerative muscle pathology and multi-protein deposits in muscle tissue. This review summarises the findings of recent studies that provide a more complete picture of the clinical phenotype and natural history of the disease and its global prevalence and genetic predisposition. Current diagnostic criteria, including the role of electrophysiological and muscle imaging studies and the recently identified anti-5'-nucleotidase (anti-cN1A) antibody in diagnosis are also discussed as well as current trends in the treatment of the disease.

Drug-Induced Rhabdomyolysis with Elevated Cardiac Troponin T

The essential role of cardiac troponin in the diagnosis of acute myocardial infarction has led to the development of high-sensitivity assays, which are able to detect very small amounts of myocardial necrosis. The high-sensitivity cardiac troponin T assay, however, is not entirely specific for myocardial injury. This case report describes a 48-year-old woman, who, two years after cardiac transplantation, presented with rhabdomyolysis. During the course of the disease, her troponin T level was elevated on repeated occasions, but other definitive evidence of myocardial injury was not found. Asymptomatic cardiac troponin T elevations during rhabdomyolysis may be due to either cardiac involvement or false positive results stemming from skeletal muscle injury.

A prospective assessment of cardiac biomarkers for hemodynamic stress and necrosis and the risk of falls among older people: the ActiFE study

Falls are related to a complex interaction of risk factors. We examined if cardiac biomarkers for hemodynamic stress (N-terminal pro Brain Natriuretic Peptide-NT-proBNP), and for necrosis [high sensitive (hs) cardiac troponins T (cTnT) and I (cTnI)] are associated with falls in older people. Biomarkers were measured at baseline in a cohort of 1506 community-dwelling adults ≥65 years. Falls were assessed prospectively in a falls calendar (median 370 days). Cox-proportional hazards models evaluated the association of each biomarker with the incidence of the first fall accounting for established confounders. We observed 430 incident falls among 1327 participants and an effect modification by sex for all biomarkers. In multivariable analyses among men a one unit increment of log-transformed hs-cTnI was associated with a hazard ratio (HR) of 1.26 (95 % CI 1.04, 1.53). Men with hs-cTnT ≥ 14 ng/L had a HR of 1.74 (95 % CI 1.15, 2.61) compared to those with undetectable hs-cTnT levels. In women cTn were not associated with falls. We did not detect an association between NT-proBNP and the risk of fall. Our results suggest that cardiac troponins may not only identify subjects at risk for cardiovascular diseases, but also help to understand the underlying complex pathophysiology of falls.

Rhabdomyolysis in association with simvastatin and dosage increment in clarithromycin

Clarithromycin is the most documented cytochrome P450 3A4 (CYP3A4) inhibitor to cause an adverse interaction with simvastatin. This particular case is of interest as rhabdomyolysis only occurred after an increase in the dose of clarithromycin. The patient developed raised cardiac biomarkers without any obvious cardiac issues, a phenomenon that has been linked to rhabdomyolysis previously. To date, there has been no reported effect of rhabdomyolysis on the structure and function of cardiac muscle. Clinicians need to be aware of prescribing concomitant medications that increase the risk of myopathy or inhibit the CYP3A4 enzyme. Our case suggests that troponin elevation could be associated with statin induced rhabdomyolysis, which may warrant further studies.

Cardiac troponin testing in idiopathic inflammatory myopathies and systemic sclerosis-spectrum disorders: biomarkers to distinguish between primary cardiac involvement and low-grade skeletal muscle disease activity

Primary cardiac involvement, an under-recognised manifestation of the idiopathic inflammatory myopathies (IIM) and systemic sclerosis (SSc)-spectrum disorders, is associated with significant mortality. Within these two conditions, traditional skeletal muscle enzyme testing may not effectively distinguish between skeletal and cardiac muscle involvement, especially in patients with subclinical cardiac disease. Accurate biomarkers are thus required to screen for cardiac disease, to better inform both therapeutic decision-making and treatment response. The widespread uptake of cardiac troponin testing has revolutionised the management of acute coronary syndromes. While cardiac troponin I (cTnI) appears specific to the myocardium, cardiac troponin T (cTnT) is also expressed by skeletal muscle, including regenerating skeletal muscle tissue. There is increasing interest about the role of cardiac troponins as a putative biomarker of primary cardiac involvement in IIM and SSc-spectrum disorders. Herewith we discuss subclinical cardiac disease in IIM and SSc-spectrum disorders, the respective roles of cTnI and cTnT testing, and the re-expression of cTnT within regenerating skeletal muscle tissue. There remains wide variation in access to cardiac troponin testing nationally and internationally. We propose two pragmatic clinical pathways using cardiac troponins, preferably measuring concomitant cTnT followed by confirmatory (cardiac) cTnI to screen patients for subclinical cardiac disease and/or low-grade skeletal muscle disease activity, and also an agenda for future research.

Sex-specific associations of established and emerging cardiac biomarkers with all-cause mortality in older adults: the ActiFE study

BACKGROUND

N-terminal pro B-type natriuretic peptide (NT-proBNP) has strong prognostic value for all-cause mortality in the general population. High-sensitivity assays now allow detection of cardiac troponins even in asymptomatic populations. We examined the association between NT-proBNP, high-sensitivity cardiac troponin T (hs-cTnT), and hs-cTnI and all-cause mortality in older adults.

METHODS

We conducted a longitudinal cohort study [Activity and Function in the Elderly in Ulm (ActiFE Ulm)] including 1506 community-dwelling adults ≥65 years old with NT-proBNP, hs-cTnT, and hs-cTnI measured at baseline. We evaluated the associations between log-transformed biomarker concentrations and 4-year total mortality, accounting for possible confounders, with Cox proportional hazards models.

RESULTS

We observed 125 deaths among 1422 participants (median follow-up 4 years). We detected effect modification by sex for all biomarkers (all P values <0.05) expressed as hazard ratio (HR) for death per 1-unit increment of ln(biomarker concentration) in women (n = 618, 37 deaths) compared with men (n = 804, 88 deaths): HR 2.97 (95% CI 2.04-4.33) vs 1.73 (1.40-2.13) for NT-proBNP; 3.67 (2.31-5.81) vs 2.15 (1.61-2.87) for hs-cTnT; and 3.32 (2.13-5.18) vs 1.92 (1.55-2.38) for hs-cTnI. Among 777 participants with undetectable hs-cTnT (<5 ng/L), hs-cTnI remained associated with all-cause mortality in age- and sex-adjusted analysis.

CONCLUSIONS

NT-proBNP, hs-cTnT, and hs-cTnI were independently associated with all-cause mortality in older adults. The strength of these associations varied between men and women, emphasizing the need for additional sex-specific research among older people.

Troponin assays in the assessment of the equine myocardium

In 2000, troponin assays were adopted as the test of choice for detection of myocardial injury in man. This decision was made after extensive testing and followed a 60 year search for a biomarker of myocardial damage with sufficient analytical sensitivity and specificity. This has led to proliferation of assays for use in human medicine, each requiring extensive testing and validation before it could be made available on the open market for human use. The search for ever-more analytically sensitive assays and for a standard reference material continues. The adoption of troponin testing in veterinary medicine followed shortly after its development for use in man, providing a much-needed means of detecting and monitoring myocardial damage in horses. However, application of these tests in veterinary medicine has exclusively involved use of assays designed for and clinically validated in human patients. There is no mandated requirement for test validation in veterinary medicine and, while many of these assays have been shown to be capable of detecting equine troponin, the wide diversity of available tests, lack of validation, absence of protocols for their use and lack of standardisation make their application problematic. The objective of this review article is to address this issue, offering guidance where data are available and encouraging caution where there are none. Ultimately, the overall goal of this review is to examine critically the use of troponin assays in the horse and to promote the accurate and appropriate interpretation of valid results.