Possible mechanisms behind cardiac troponin elevations

Molecular biomarkers in cardio-oncology: Where we stand and where we are heading

Until recently, cardiotoxicity in the setting of a malignant disease was attributed solely to the detrimental effects of chemo- and/or radio-therapy to the heart. On this account, the focus was on the evaluation of well-established cardiac biomarkers for the early detection of myocardial damage. Currently, this view has been revised. Cardiotoxicity is not restricted to a single organ but instead affects the endothelium as a whole. Indeed, it has come into light that not only cancer therapy but also malignant cells per se can impair the cardiovascular system, through a paracrine and endocrine mode of action. Even more intriguingly, a clear interplay between molecular pathways involved in cancer and cardiovascular disease has become prevalent, suggesting a common nominator that governs the pathophysiology of these two entities. Taken together, our strategy in the quest of novel biomarkers in the emerging field of cardio-oncology should be critically reshaped.

Biology of Cardiac Troponins: Emphasis on Metabolism

Understanding of the biology of endo- and exogenous molecules, in particular their metabolism, is not only of great theoretical importance, but also of high practical significance, since many molecules serve as drug targets or markers for the laboratory diagnostics of many human diseases. Thus, cardiac troponin (cTns) molecules have long been used as key markers for the confirmation of diagnosis of myocardial infarction (MI), and with the introduction of contemporary (high sensitivity) test methods, many of our concepts related to the biology of these cardiac markers have changed significantly. In current clinical practice, there are opening new promising diagnostic capabilities of cTns, the understanding and justification of which is closely connected with the theoretical principles of the metabolism of these molecules. However, today, the biology and metabolism of cTns have not been properly investigated; in particular, we do not know the precise mechanisms of release of these molecules from the myocardial cells (MCs) of healthy people and the mechanisms of circulation, and the elimination of cTns from the bloodstream. The main purpose of this manuscript is to systematize information about the biology of cTns, with an emphasis on the metabolism of cTns. The format of this paper, starting with the release of cTns in the blood and concluding with the metabolism/filtration of troponins, provides a comprehensive yet logically easy way for the readers to approach our current knowledge in the framework of understanding the basic mechanisms by which cTns are produced and processed. Conclusions. Based on the analysis of the current literature, the important role of biology and all stages of metabolism (release, circulation, removal) of cTns in laboratory diagnostics should be noted. It is necessary to continue studying the biology and metabolism of cTns, because this will improve the differential diagnosis of MI and i a new application of cTns immunoassays in current clinical practice.

The Effects of a Meldonium Pre-Treatment on the Course of the LPS-Induced Sepsis in Rats

A dysregulated and overwhelming response to an infection accompanied by the exaggerated pro-inflammatory state and metabolism disturbance leads to the fatal outcome in sepsis. Previously we showed that meldonium, an anti-ischemic drug clinically used to treat myocardial and cerebral ischemia, strongly increases mortality in faecal-induced peritonitis (FIP) in rats. We postulated that the same mechanism that is responsible for the otherwise strong anti-inflammatory effects of meldonium could be the culprit of the increased mortality. In the present study, we applied the LPS-induced model of sepsis to explore the presence of any differences from and/or similarities to the FIP model. When it comes to energy production, despite some shared similarities, it is evident that LPS and FIP models of sepsis differ greatly. A different profile of sympathoadrenal activation may account for this observation, as it was lacking in the FIP model, whereas in the LPS model it was strong enough to overcome the effects of meldonium. Therefore, choosing the appropriate model of sepsis induction is of great importance, especially if energy homeostasis is the main focus of the study. Even when differences in the experimental design of the two models are acknowledged, the role of different patterns of energy production cannot be excluded. On that account, our results draw attention to the importance of uninterrupted energy production in sepsis but also call for much-needed revisions of the current recommendations for its treatment.

The ratio of cardiac troponin T to troponin I may indicate non-necrotic troponin release among COVID-19 patients

BACKGROUND

Although cardiac troponin T (cTnT) and troponin I(cTnI) are expressed to similar amount in cardiac tissue, cTnI often reach ten-times higher peak levels compared to cTnT in patients with myocardial necrosis such as in acute myocardial infarction (MI). In contrast, similar levels of cTnT and cTnI are observed in other situations such as stable atrial fibrillation and after strenuous exercise.

OBJECTIVE

Examine cTnT and cTnI levels in relation to COVID-19 disease and MI.

METHODS

Clinical and laboratory data from the local hospital from an observational cohort study of 27 patients admitted with COVID-19 and 15 patients with myocardial infarction (MI) that were analyzed with paired cTnT and cTnI measurement during hospital care.

RESULTS

Levels of cTnI were lower than cTnT in COVID-19 patients (TnI/TnT ratio 0.3, IQR: 0.1-0.6). In contrast, levels of cTnI were 11 times higher compared to cTnT in 15 patients with MI (TnI/TnT ratio 11, IQR: 7-14). The peak cTnI/cTnT ratio among the patients with MI following successful percutaneous intervention were 14 (TnI/TnT ratio 14, IQR: 12-23). The 5 COVID-19 patient samples collected under possible necrotic events had a cTnI/cTnT ratio of 5,5 (IQR: 1,9-8,3).

CONCLUSIONS

In patients with COVID-19, cTnT is often elevated to higher levels than cTnI in sharp contrast to patients with MI, indicating that the release of cardiac troponin has a different cause in COVID-19 patients.

Ultra-high sensitivity cardiac troponin-I concentration and left ventricular structure and function in women with ischemia and no obstructive coronary artery disease

Aims

Women are disproportionally impacted by ischemia and no obstructive coronary artery disease (INOCA), and such women are at increased risk of developing heart failure with preserved ejection fraction (HFpEF), however the mechanisms linking these conditions remain poorly understood. The aim of this study was to determine whether ultra-high sensitivity cardiac troponin I (u-hscTnI), an indicator of cardiomyocyte injury, is associated with abnormalities in myocardial perfusion and left ventricular (LV) structure and function in women with INOCA.

Methods

327 women with INOCA enrolled in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study underwent vasodilator stress cardiac magnetic resonance imaging (CMRI) and u-hscTnI measurements (Simoa HD-1 Analyzer, Quanterix Corporation). Multivariable linear regression was used to evaluate associations between u-hscTnI concentrations and myocardial perfusion (MPRI), LV mass index and feature-tracking derived strain measures of LV function.

Results

u-hscTnI concentrations were quantifiable in 100% of the cohort and ranged from 0.004 to 79.6 pg/mL. In adjusted models, u-hscTnI was associated with LV mass index (+2.03; 95% CI 1.17, 2.89; p < 0.01) and early diastolic radial strain rate (SR) (+0.13; 95% CI 0.01, 0.25; p = 0.03), early diastolic circumferential SR (-0.04; 95% CI -0.08, 0.002; p = 0.06) and early diastolic longitudinal SR (-0.03; 95% CI -0.07, 0.002; p = 0.06). u-hscTnI was not associated with MPRI (p = 0.39) in adjusted models.

Conclusion

Together, these findings support cardiomyocyte injury as a putative pathway towards adverse LV remodeling and dysfunction; however, further research is needed to define the specific mechanism(s) driving myocellular injury in INOCA.

Elevated Myoglobin in Patients With Primary Aldosteronism: A Cross-Sectional Study

OBJECTIVES

Primary aldosteronism (PA) is characterized by the autonomous excessive production of aldosterone in the adrenal cortex. Aldosterone is associated with damages to heart muscle and skeletal muscle. The purpose of this study was to evaluate serum levels of muscle injury markers and their associated factors in patients with primary aldosteronism.

METHODS

We retrospectively enrolled subjects with PA and essential hypertension (EH) who had completed testing for serum high sensitivity troponin T (hs-TnT), creatine kinase isoenzyme MB (CK-MB) and myoglobin from the database of the Chongqing Primary Aldosteronism Study (CONPASS). Univariate and multivariate linear regression analyses were performed to analyze the influencing factors of myocardial injury markers.

RESULTS

In total, 278 patients with PA and 445 patients with EH were enrolled in this study. Compared with EH patients, serum concentrations of hs-TnT [7.0 (4.0-12.0) vs. 6.0 (3.0-11.0) ng/L; p=0.005] and myoglobin [24.2 (21.0-38.1) vs. 21.8 (21.0-31.9) μg/L; p=0.023] were significantly higher among PA patients, while no significant difference of CK-MB was found between two groups [1.4 (1.0-2.0) vs. 1.3 (0.9-1.9) μg/L; p=0.154]. Univariate linear regression analysis showed that myoglobin was negatively correlated with serum potassium (β=-0.31; p<0.01) and positively correlated with plasma aldosterone concentration (β=0.40; p<0.01) in the PA group, while no significant correlation was found between hs-TnT and biochemical parameters. After adjusting for multiple confounders, myoglobin was negatively correlated with serum potassium (β=-0.15; p<0.05) and positively correlated with plasma aldosterone concentration (β=0.34; p<0.01) in the PA group.

CONCLUSIONS

The serum level of myoglobin was significantly increased in PA patients, and myoglobin was independently correlated with plasma aldosterone concentration.

Exercise-Induced Cardiac Troponin Elevations: From Underlying Mechanisms to Clinical Relevance

Supplemental Digital Content is available in the text.

Serological assessment of cardiac troponins (cTn) is the gold standard to assess myocardial injury in clinical practice. A greater magnitude of acutely or chronically elevated cTn concentrations is associated with lower event-free survival in patients and the general population. Exercise training is known to improve cardiovascular function and promote longevity, but exercise can produce an acute rise in cTn concentrations, which may exceed the upper reference limit in a substantial number of individuals. Whether exercise-induced cTn elevations are attributable to a physiological or pathological response and if they are clinically relevant has been debated for decades. Thus far, exercise-induced cTn elevations have been viewed as the only benign form of cTn elevations. However, recent studies report intriguing findings that shed new light on the underlying mechanisms and clinical relevance of exercise-induced cTn elevations. We will review the biochemical characteristics of cTn assays, key factors determining the magnitude of postexercise cTn concentrations, the release kinetics, underlying mechanisms causing and contributing to exercise-induced cTn release, and the clinical relevance of exercise-induced cTn elevations. We will also explain the association with cardiac function, correlates with (subclinical) cardiovascular diseases and exercise-induced cTn elevations predictive value for future cardiovascular events. Last, we will provide recommendations for interpretation of these findings and provide direction for future research in this field.

Troponin I as a Biomarker for Early Detection of Acute Myocardial Infarction

Acute myocardial infarction (AMI) as the main cause of death among cardiovascular diseases is defined as a deficiency of oxygen that generates irreversible tissue necrosis in the heart muscle. For diagnostic measurements, the evaluation of cardiac markers concentration like cardiac triponin I (cTnI) in plasma or saliva thought the use of biosensors has become one of the most commonly applied strategies for prognosis of AMI. Inside this diagnostic devices, electrochemical (ECL) ones have been highly encourage to improve sensing capabilities by using different materials and configurations. In this review, the authors presents a summary of studies that involves cTnI detection using ECL biosensors modified with nanomaterials and related mechanisms.

Cardiac Troponin Is Elevated in Patients with Thyrotoxicosis and Decreases as Thyroid Function Improves and Brain Natriuretic Peptide Levels Decrease

INTRODUCTION

High-sensitive cardiac troponin reflects micro-myocardial injury in the absence of overt myocardial infarction.

OBJECTIVE

This study aimed to clarify how thyrotoxicosis affects cardiac troponin.

METHODS

This was a prospective observational study in Japan. Untreated patients with thyrotoxicosis who visited Ito Hospital were enrolled, and medical treatment was initiated for hyperthyroidism. Thyroid function, high-sensitive troponin I (hsTnI), and brain natriuretic peptide (BNP) were measured at baseline and then every 3 months for 1 year.

RESULTS

Data from a total of 143 patients (median age, 42 years; 32 men and 111 women) were investigated. At baseline, median hsTnI was 1.9 pg/mL and ranged from 0 to 69.6 pg/mL. Five patients (3.5%) had a high hsTnI value that exceeded 26.2 pg/mL, which is used as the cutoff for diagnosis of myocardial infarction, and 22 patients (15.4%) had an intermediate value between 5.0 and 26.2 pg/mL. Multivariable regression analysis showed that significant predictors of the hsTnI value were age (β = 0.20, p = 0.01) and BNP (β = 0.43, p < 0.0001) (R² = 0.27, F = 26.0, p < 0.0001), and significant predictors of the BNP value were age (β = 0.23, p = 0.001), hemoglobin (β = -0.43, p < 0.0001), free T₄ (FT₄) (β = 0.23, p = 0.001), and hsTnI (β = 0.27, p < 0.0001) (R² = 0.49, F = 33.8, p < 0.0001). Correlations were found between a decrease in hsTnI and BNP in the first 3 months (ρ = 0.49, p < 0.0001). A decrease in FT₄ in the first 3 months was weakly correlated with decreases in hsTnI (ρ = 0.32, p = 0.0004) and BNP (ρ = 0.32; p = 0.0003). Of the 27 patients with elevated hsTnI (≥5.0 pg/mL), the hsTnI level was normalized in 20 patients within a year.

CONCLUSIONS

In thyrotoxicosis, the myocardial biomarker hsTnI is elevated in about 20% of patients; hsTnI levels decrease as thyroid function improves and BNP decreases.

Minor troponin T elevation and mortality in patients with atrial fibrillation presenting to the emergency department

BACKGROUND

There are limited data on the association of minor troponin elevation in unselected patients with atrial fibrillation (AF) presenting to the emergency department (ED) with adverse events. In this study, we sought to assess the early and mid-term mortality of these patients.

METHODS

In this observational study, 2911 patients with AF were admitted to the ED. They were divided into 3 groups based on peak high-sensitivity troponin (TnT) levels: normal (<15 ng/L), 15-50 ng/L and 51-100 ng/L. The primary outcomes of this study were all-cause mortality at 30 days and 1 year.

RESULTS

All-cause mortality was 6.7% (n = 196) at 30 days and 22.2% (n = 646) at 1 year. Mortality rate increased along with increasing levels of TnT irrespective of baseline covariates, primary discharge diagnosis and type of AF. A significant association between TnT levels and all-cause mortality was observed. The adjusted hazard ratio (HR) at 30 days was 6.02 (95% CI 2.62-13.83) for TnT 15-50 ng/L and 11.28 (95% CI 4.87-26.12) for TnT 51-100 ng/L (P<.001 for both) compared to TnT <15 ng/L. At 1 year, the adjusted HRs were 3.08 (95% CI 2.15-4.40) and 5.07 (95% CI 3.49-7.35), respectively (P < .001). When patients with TnT <15 ng/L were divided into two groups at the median value, TnT elevation of 10 to 14 ng/L was also associated with increased 1-year mortality (HR 2.51; 95% CI 1.09-5.74; P = .03).

CONCLUSIONS

Among patients with AF admitted to the ED, increased TnT levels were associated with increased early and mid-term all-cause mortality irrespective of baseline covariates and type of AF.

COVID-19 and the cardiovascular system: insights into effects and treatments

Coronavirus disease 2019 (COVID-19), an acute and highly transmissible infectious disease, has reached a pandemic level since 11 March 2020 and continues to challenge the healthcare system worldwide. The pathogenesis of COVID-19 is a complex process involving mechanisms that suppress the host antiviral and innate immune response, while triggering marked activation of coagulation and hyperinflammation leading to cytokine storm in severe COVID-19. This review summarizes current evidence related to COVID-19-associated cardiovascular severe illness and mortality, which encompasses life-threatening clinical manifestations, including myocardial injury, fulminant myocarditis, cardiac arrhythmia, and ischemic stroke. The onset of hypercoagulable state is consistent with increased venous thromboembolism including deep vein thrombosis and pulmonary embolism. Thromboembolic manifestations include arterial thrombotic events such as stroke, myocardial infarction, and limb ischemia. Several treatment strategies have been investigated to mitigate COVID-19-associated cardiovascular clinical manifestations. The prevalence of thrombo-inflammatory syndrome and subsequent cardiovascular dysfunction prompted the implementation of antithrombotic therapy and strategies targeting major pro-inflammatory cytokines involved in COVID-19 cytokine storm. The development of new guidelines for effective treatment strategies requires concerted efforts to refine our understanding of the mechanisms underlying cardiovascular disease and large-scale clinical trials to reduce the burden of COVID-19 hospitalization and mortality.

Genome-wide association study of cardiac troponin I in the general population

Circulating cardiac troponin proteins are associated with structural heart disease and predict incident cardiovascular disease in the general population. However, the genetic contribution to cardiac troponin I (cTnI) concentrations and its causal effect on cardiovascular phenotypes are unclear. We combine data from two large population-based studies, the Trøndelag Health Study and the Generation Scotland Scottish Family Health Study, and perform a genome-wide association study of high-sensitivity cTnI concentrations with 48 115 individuals. We further use two-sample Mendelian randomization to investigate the causal effects of circulating cTnI on acute myocardial infarction (AMI) and heart failure (HF). We identified 12 genetic loci (8 novel) associated with cTnI concentrations. Associated protein-altering variants highlighted putative functional genes: CAND2, HABP2, ANO5, APOH, FHOD3, TNFAIP2, KLKB1 and LMAN1. Phenome-wide association tests in 1688 phecodes and 83 continuous traits in UK Biobank showed associations between a genetic risk score for cTnI and cardiac arrhythmias, metabolic and anthropometric measures. Using two-sample Mendelian randomization, we confirmed the non-causal role of cTnI in AMI (5948 cases, 355 246 controls). We found indications for a causal role of cTnI in HF (47 309 cases and 930 014 controls), but this was not supported by secondary analyses using left ventricular mass as outcome (18 257 individuals). Our findings clarify the biology underlying the heritable contribution to circulating cTnI and support cTnI as a non-causal biomarker for AMI in the general population. Using genetically informed methods for causal inference helps inform the role and value of measuring cTnI in the general population.

An in vivo and in vitro model on the protective effect of corilagin on doxorubicin-induced cardiotoxicity via regulation of apoptosis and PI3-K/AKT signaling pathways

Globally, doxorubicin (DOX)-induced cardio dysfunction is a serious cause of morbidity and mortality in cancerous patients. An adverse event of cardiotoxicity is the main deem to restrict in the clinical application by oncologists. Corilagin (CN) is well known for its antioxidative, anti-fibrosis, and anticancer effects. Herein, we aimed to evaluate the action of CN on DOX-induced experimental animals and H9c2 cells. The myocardium-specific marker, CK-MB, and the influx of mitochondrial calcium levels were measured by using commercial kits. Biochemical indices reflecting oxidative stress and antioxidant attributes such as malondialdehyde, glutathione peroxidase, reduced glutathione, superoxide dismutase, and catalase were also analyzed in DOX-induced cardiotoxic animals. In addition, mitochondrial ROS were measured by DCFH-DA in H9c2 cells under fluorescence microscopy. DOX induction significantly increased oxidative stress levels and also modulated apoptosis/survival protein expressions in myocardial tissues. Western blots were used to measure the expressional levels of Bax/Bcl-2, caspase-3, PI3-K/AKT, and PPARγ signaling pathways. Histological studies were executed to observe morphological changes in myocardial tissues. All of these DOX-induced effects were attenuated by CN (100 mg/kg bw). These in vitro and in vivo results point towards the fact that CN might be a novel cardioprotective agent against DOX-induced cardiotoxicity through modulating cardio apoptosis and oxidative stress.

Stable high-sensitivity cardiac troponin T levels and the association with frailty and prognosis in patients with chest pain

Background

Chronic myocardial injury is defined by stable high-sensitivity cardiac troponin (hs-cTn) levels above the 99th percentile value, which may be a sign of a biologically aged heart. This study investigated the association between frailty and chronic myocardial injury.

Methods

In a cohort of patients with chest pain and stable hs-cTnT levels measured 2011-2014, we included all patients who were assessed by two scoring systems measuring frailty. Adjusted odds ratios (ORs) were calculated to estimate the risk of frailty at different hs-cTnT levels (referent: hs-cTnT ≤ 14 ng/l). Cox regression was used to estimate risks of death and cardiovascular events in relation to frailty status and hs-cTnT levels (referent: non-frail and hs-cTnT ≤ 14 ng/l).

Results

A total of 979 patients were included, of whom 269 (27%) had chronic myocardial injury. The risk of being frail was almost four times higher in patients with chronic myocardial injury, compared with patients in the reference group (hs-cTnT ≥ 30 ng/l: OR: 3.69, 95% CI: 2.02-6.76). During a follow-up of 4.3 years, 275 (28%) patients died. Mortality risks increased with increasing hs-cTnT levels and degree of frailty, being increased four-fold in frail patients with hs-cTnT levels ≥ 30 ng/l (HR: 4.07, 95% CI: 2.42-6.86).

Conclusions

Stable hs-cTnT levels are associated with the degree of frailty, and frailty measurements could help to identify patients with stable hs-cTnT levels who are at a high risk of death. The findings support the hypothesis that chronic myocardial injury could be a marker of a biologically aged heart.

The Effects of a Meldonium Pre-Treatment on the Course of the Faecal-Induced Sepsis in Rats

Sepsis is a life-threatening condition caused by the dysregulated and overwhelming response to infection, accompanied by an exaggerated pro-inflammatory state and lipid metabolism disturbance leading to sequential organ failure. Meldonium is an anti-ischemic and anti-inflammatory agent which negatively interferes with lipid metabolism by shifting energy production from fatty acid oxidation to glycolysis, as a less oxygen-demanding pathway. Thus, we investigated the effects of a four-week meldonium pre-treatment on faecal-induced sepsis in Sprague-Dawley male rats. Surprisingly, under septic conditions, meldonium increased animal mortality rate compared with the meldonium non-treated group. However, analysis of the tissue oxidative status did not provide support for the detrimental effects of meldonium, nor did the analysis of the tissue inflammatory status showing anti-inflammatory, anti-apoptotic, and anti-necrotic effects of meldonium. After performing tissue lipidomic analysis, we concluded that the potential cause of the meldonium harmful effect is to be found in the overall decreased lipid metabolism. The present study underlines the importance of uninterrupted energy production in sepsis, closely drawing attention to the possible harmful effects of lipid-mobilization impairment caused by certain therapeutics. This could lead to the much-needed revision of the existing guidelines in the clinical treatment of sepsis while paving the way for discovering new therapeutic approaches.

Integration of imaging and circulating biomarkers in heart failure: a consensus document by the Biomarkers and Imaging Study Groups of the Heart Failure Association of the European Society of Cardiology

Circulating biomarkers and imaging techniques provide independent and complementary information to guide management of heart failure (HF). This consensus document by the Heart Failure Association (HFA) of the European Society of Cardiology (ESC) presents current evidence-based indications relevant to integration of imaging techniques and biomarkers in HF. The document first focuses on application of circulating biomarkers together with imaging findings, in the broad domains of screening, diagnosis, risk stratification, guidance of treatment and monitoring, and then discusses specific challenging settings. In each section we crystallize clinically relevant recommendations and identify directions for future research. The target readership of this document includes cardiologists, internal medicine specialists and other clinicians dealing with HF patients.

Advances in point-of-care testing for cardiovascular diseases

Point-of-care testing (POCT) is a specific format of diagnostic testing that is conducted without accompanying infrastructure or sophisticated instrumentation. Traditionally, such rapid sample-to-answer assays provide inferior analytical performances to their laboratory counterparts when measuring cardiac biomarkers. Hence, their potentially broad applicability is somewhat bound by their inability to detect clinically relevant concentrations of cardiac troponin (cTn) in the early stages of myocardial injury. However, the continuous refinement of biorecognition elements, the optimization of detection techniques, and the fabrication of tailored fluid handling systems to manage the sensing process has stimulated the production of commercial assays that can support accelerated diagnostic pathways. This review will present the latest commercial POC assays and examine their impact on clinical decision-making. The individual elements that constitute POC assays will be explored, with an emphasis on aspects that contribute to economically feasible and highly sensitive assays. Furthermore, the prospect of POCT imparting a greater influence on early interventions for medium to high-risk individuals and the potential to re-shape the paradigm of cardiovascular risk assessments will be discussed.

Myocardial Injury and the Release of Troponins I and T in the Blood of Patients

BACKGROUND

Cardiac troponin I (cTnI) and cTnT are the established biomarkers of cardiomyocyte damage and the recommended biomarkers for the diagnosis of acute myocardial infarction (MI). High-sensitivity immunochemical diagnostic systems are able to measure the cTn concentrations in the blood of a majority of healthy people. At the same time, the concentration of cTn may be increased not only after MI but also because of other pathologies that might affect myocardium. This effect reduces the clinical specificity of cTn for MI and may complicate the diagnosis.

CONTENT

This review summarizes the existing information regarding the causes and mechanisms that lead to the increase of cTn concentration in blood and the forms of cTn that are present in circulation after MI or other types of myocardial injury.

SUMMARY

Different etiologies of disease associated with increases of cTn above the 99th percentile and various mechanisms of troponin release from myocardium could result in the appearance of different forms of cTn in blood and provide the first clinical evidence of injury. Additional research is needed for the careful characterization of cTn forms that are present in the blood in different clinical settings. That knowledge may lead to the development of immunochemical systems that would differentiate certain forms of troponins and possibly certain types of cardiac disease.

Accuracy of high-sensitive troponin depending on renal function for clinical outcome prediction in patients with acute heart failure

High-sensitive troponin T (hs-TnT) is increasingly used for clinical outcome prediction in patients with acute heart failure (AHF). However, there is an ongoing debate regarding the potential impact of renal function on the prognostic accuracy of hs-TnT in this setting. The aim of the present study was to assess the prognostic value of hs-TnT within 6 h of admission for the prediction of 30-day mortality depending on renal function in patients with AHF. Patients admitted to our institution due to AHF were retrospectively included. Clinical information was gathered from electronic and paper-based patient charts. Patients with myocardial infarction were excluded. A total of 971 patients were enrolled in the present study. A negative correlation between estimated glomerular filtration rate (eGFR) and hsTnT was identified (Pearson r = - 0.16; p < 0.001) and eGFR was the only variable to be independently associated with hsTnT. The area under the curve (AUC) of hs-TnT for the prediction of 30-mortality was significantly higher in patients with an eGFR ≥ 45 ml/min (AUC 0.74) compared to those with an eGFR < 45 ml/min (AUC 0.63; p = 0.049). Sensitivity and specificity of the Youden Index derived optimal cut-off for hs-TnT was higher in patients with an eGFR ≥ 45 ml/min (40 ng/l: sensitivity 73%, specificity 71%) compared to patients with an eGFR < 45 ml/min (55 ng/l: sensitivity 63%, specificity 62%). Prognostic accuracy of hs-TnT in patients hospitalized for AHF regarding 30-day mortality is significantly lower in patients with reduced renal function.

Release Profile of Cardiac Troponin T and Risk Factors of Postoperative Myocardial Injury in Patients Undergoing CABG

Background

Cardiac troponin T (cTnT) is currently one of the important indicators for clinical diagnosis of myocardial injury, which is inevitable in cardiac surgery, especially coronary artery bypass grafting (CABG). Describing the release profile of cTnT and finding out the risk factors of postoperative myocardial injury (PMI) are of great significance. The purposes of this study are to explore the release profile of cTnT in patients undergoing CABG and to search for independent risk factors of PMI.

Methods

In this retrospective study, clinical data of CABG patients were collected. The cTnT was measured at 24 hours before and 6, 12, 24, 48, 72, 96 and 120 hours after operation separately. The release profiles and peak time of cTnT in total cohort and sub-cohorts were observed. Independent risk factors of PMI were explored via univariate and multivariate logistic regression analyses.

Results

In total, 2084 patients were enrolled, including 998 patients in a cTnT group and 1086 patients in a high-sensitive cTnT (hs-cTnT) group. PMI was recognized in 797 patients. In both groups, cTnT showed a trend of rising first and then falling within 120 hours after operation. The peak cTnT appeared within 12–24 hours after operation, while the peak hs-cTnT occurred mostly within 24–48 hours after operation. Univariate logistic analysis showed that body mass index (BMI), New York Heart Association (NYHA) classification, coronary artery disease (CAD) classification, cerebrovascular disease, left ventricular ejection fraction, number of diseased vessels, valvular disease, intra-aortic balloon pump (IABP) implantation, chronic obstructive pulmonary disease, pulmonary hypertension, previous percutaneous coronary intervention (PCI), BMI, bypass graft number, cardiopulmonary bypass, and preoperative cTnT were related risk factors. Multivariate logistic regression analysis showed that NYHA classification, CAD classification, valvular disease, IABP implantation, pulmonary hypertension, previous PCI, bypass graft number, cardiopulmonary bypass, and preoperative cTnT were independent risk factors of PMI.

Conclusion

NYHA classification, CAD classification, valvular disease, IABP implantation, pulmonary hypertension, previous PCI, bypass graft number, cardiopulmonary bypass, and preoperative cTnT are independent risk factors of PMI in patients undergoing CABG.

Cardiac Troponin T: The Impact of Posttranslational Modifications on Analytical Immunoreactivity in Blood up to the Excretion in Urine

Cardiac troponin T (cTnT) is a sensitive and specific biomarker for detecting cardiac muscle injury. Its concentration in blood can be significantly elevated outside the normal reference range under several pathophysiological conditions. The classical analytical method in routine clinical analysis to detect cTnT in serum or plasma is a single commercial immunoassay, which is designed to quantify the intact cTnT molecule. The targeted epitopes are located in the central region of the cTnT molecule. However, in blood cTnT exists in different biomolecular complexes and proteoforms: bound (to cardiac troponin subunits or to immunoglobulins) or unbound (as intact protein or as proteolytic proteoforms). While proteolysis is a principal posttranslational modification (PTM), other confirmed PTMs of the proteoforms include N-terminal initiator methionine removal, N-acetylation, O-phosphorylation, O-(N-acetyl)-glucosaminylation, N(ɛ)-(carboxymethyl)lysine modification and citrullination. The immunoassay probably detects several of those cTnT biomolecular complexes and proteoforms, as long as they have the centrally targeted epitopes in common. While analytical cTnT immunoreactivity has been studied predominantly in blood, it can also be detected in urine, although it is unclear in which proteoform cTnT immunoreactivity is present in urine. This review presents an overview of the current knowledge on the pathophysiological lifecycle of cTnT. It provides insight into the impact of PTMs, not only on the analytical immunoreactivity, but also on the excretion of cTnT in urine as one of the waste routes in that lifecycle. Accordingly, and after isolating the proteoforms from urine of patients suffering from proteinuria and acute myocardial infarction, the structures of some possible cTnT proteoforms are reconstructed using mass spectrometry and presented.

Patients discharged with elevated baseline high-sensitive cardiac troponin T from the emergency department

BACKGROUND

Elevated levels of high-sensitive cardiac troponin T (hs-cTnT) are linked to poor prognosis among emergency department (ED) patients.

OBJECTIVE

Examine the effect of our ED risk assessment among patients with suspected acute coronary syndrome (ACS) and elevated baseline hs-cTnT levels.

DESIGN

Observational cohort study of 16776 ED patients with chest pain or dyspnoea and a hs-cTnT sample analyzed at the time of the ED visit. Of these 1480 patients were sent home with elevated hs-cTnT levels (>14 ng/L).

METHODS

Analysis of clinical and laboratory data from the local hospital and data from the National Board of Health and Welfare.

RESULTS

Admitted patients had 11% and discharged patients had 1.2% 90-day mortality indicating effective risk assessment of patients with suspected ACS. However, if the suspected ACS patient presented with hs-cTnT between 14 and 22 ng/L, the 90-day mortality was 4.1% among discharged and 6.7% among admitted patients. Among discharged patients, an hs-cTnT level above 14 ng/L was a higher independent risk factor for 90-day mortality (HR 3.3, 95% CI 2.9-3.7, p < 0.001) than if the patient was triaged as a high-risk patient (HR 1.6, 95% CI 1.1-1.8, p < 0.001).

CONCLUSIONS

Our ED risk assessment was less effective among patients presenting with elevated hs-cTnT levels.

Tamarindus indica. Linn leaves ameliorates experimental induced heart failure in Wistar rats

OBJECTIVES

Cardiovascular diseases (CVDs) are highly prevalent in various countries, and heart failure accounts for the majority of deaths. The present study focuses on determining the protective effect of ethanol extract of leaves of Tamarindus indica (TIEE) by in vitro and in vivo methods.

METHODS

In vitro cardiotonic activity was determined using Langendorff's heart perfusion assembly. In vivo studies were performed using Doxorubicin (1.5 mg/kg, i.p for seven days) induced cardiotoxicity in rats. These animals were simultaneously treated with the TIEE at a low dose (200 mg/kg, p.o), high dose (400 mg/kg, p.o) and standard drug Digoxin (100 μg/kg, p.o) for seven days. At the end of the study, various parameters like electrocardiogram (ECG) recording, serum levels of serum glutamic pyruvic transaminase (SGPT), lactate dehydrogenase (LDH), creatinine phosphokinase (CPK), and presence of cardiac troponin (cTnI) were determined. Isolated hearts were subjected to histopathological studies.

RESULTS

The TIEE at a concentration of 60 μg/mL showed a significant cardiotonic effect in vitro that was evident by increased force of contraction, heart rate, and cardiac output. In vivo studies revealed that the TIEE decreased the prolongation of QT and RR interval of ECG, lowered the serum enzyme levels like LDH, CPK indicating cardiac protection, and the same was established by the absence of cTnI in blood. Histopathological examinations of heart tissue sections showed improved architecture in the treatment groups when compared with diseased groups.

CONCLUSIONS

The study revealed the cardioprotective activity of T. indica leaf extract by both in vitro and in vivo methods.

Plasma Metabolites Alert Patients With Chest Pain to Occurrence of Myocardial Infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide, and knowing the early warning signs of MI is lifesaving. To expand our knowledge of MI, we analyzed plasma metabolites in MI and non-MI chest pain cases to identify markers for alerting about MI occurrence based on metabolomics. A total of 230 volunteers were recruited, consisting of 146 chest pain patients admitted with suspected MI (85 MIs and 61 non-MI chest pain cases) and 84 control individuals. Non-MI cardiac chest pain cases include unstable angina (UA), myocarditis, valvular heart diseases, etc. The blood samples of all suspected MI cases were collected not longer than 6 h since the onset of chest pain. Gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry were applied to identify and quantify the plasma metabolites. Multivariate statistical analysis was utilized to analyze the data, and principal component analysis showed MI could be clearly distinguished from non-MI chest pain cases (including UA and other cases) in the scores plot of metabolomic data, better than that based on the data constructed with medical history and clinical biochemical parameters. Pathway analysis highlighted an upregulated methionine metabolism and downregulated arginine biosynthesis in MI cases. Receiver operating characteristic curve (ROC) and adjusted odds ratio (OR) were calculated to evaluate potential markers for the diagnosis and prediction ability of MI (MI vs. non-MI cases). Finally, gene expression profiles from the Gene Expression Omnibus (GEO) database were briefly discussed to study differential metabolites' connection with plasma transcriptomics. Deoxyuridine (dU), homoserine, and methionine scored highly in ROC analysis (AUC > 0.91), sensitivity (>80%), and specificity (>94%), and they were correlated to LDH and AST (p < 0.05). OR values suggested, after adjusting for gender, age, lipid levels, smoking, type II diabetes, and hypertension history, that high levels of dU of positive logOR = 3.01, methionine of logOR = 3.48, and homoserine of logOR = 1.61 and low levels of isopentenyl diphosphate (IDP) of negative logOR = -5.15, uracil of logOR = -2.38, and arginine of logOR = -0.82 were independent risk factors of MI. Our study highlighted that metabolites belonging to pyrimidine, methionine, and arginine metabolism are deeply influenced in MI plasma samples. dU, homoserine, and methionine are potential markers to recognize MI cases from other cardiac chest pain cases after the onset of chest pains. Individuals with high plasma abundance of dU, homoserine, or methionine have increased risk of MI, too.

Cardioprotective Effect of Glycyrrhizin on Myocardial Remodeling in Diabetic Rats

Myocardial fibrosis is one of the major complications of long-term diabetes. Hyperglycemia induced cardiomyocyte atrophy is a frequent pathophysiological indicator of diabetic heart. The objective of this study was to investigate the cardioprotective effect of glycyrrhizin (GLC) on myocardial damage in diabetic rats and assess the anti-inflammatory and anti-fibrotic effect of GLC. Our study demonstrates that hyperglycemia can elevate cardiac atrophy in diabetic animals. Type 2 diabetic fatty and the lean control rats were evaluated for cardiac damage and inflammation at 8-12 weeks after the development of diabetes. Western blot and immunohistochemical studies revealed that gap junction protein connexin-43 (CX43), cardiac injury marker troponin I, cardiac muscle specific voltage gated sodium channel NaV1.5 were significantly altered in the diabetic heart. Furthermore, oxidative stress mediator receptor for advanced glycation end-products (RAGE), as well as inflammatory mediator phospho-p38 MAPK and chemokine receptor CXCR4 were increased in the diabetic heart whereas the expression of nuclear factor erythroid-2-related factor 2 (Nrf2), the antioxidant proteins that protect against oxidative damage was reduced. We also observed an increase in the expression of the pleiotropic cytokine, transforming growth factor beta (TGF-β) in the diabetic heart. GLC treatment exhibited a decrease in the expression of phospho-p38 MAPK, RAGE, NaV1.5 and TGF-β and it also altered the expression of CX43, CXCR4, Nrf2 and troponin I. These observations suggest that GLC possesses cardioprotective effects in diabetic cardiac atrophy and that these effects could be mediated through activation of Nrf2 and inhibition of CXCR4/SDF1 as well as TGF-β/p38MAPK signaling pathway.

miR-146a inhibits mitochondrial dysfunction and myocardial infarction by targeting cyclophilin D

Increasing evidence suggests that mitochondrial microRNAs (miRNAs) are implicated in the pathogenesis of cardiovascular diseases; however, their roles in ischemic heart disease remain unclear. Herein, we demonstrate that miR-146a is enriched in the mitochondrial fraction of cardiomyocytes, and its level significantly decreases after ischemic reperfusion (I/R) challenge. Cardiomyocyte-specific knockout of miR-146a aggravated myocardial infarction, apoptosis, and cardiac dysfunction induced by the I/R injury. Overexpression of miR-146a suppressed anoxia/reoxygenation-induced cardiomyocyte apoptosis by inhibiting the mitochondria-dependent apoptotic pathway and increasing the Bcl-2/Bax ratio. miR-146a overexpression also blocked mitochondrial permeability transition pore opening and attenuated the loss of mitochondrial membrane potential and cytochrome c leakage; meanwhile, miR-146a knockdown elicited the opposite effects. Additionally, miR-146a overexpression decreased cyclophilin D protein, not mRNA, expression. The luciferase reporter assay revealed that miR-146a binds to the coding sequence of the cyclophilin D gene. Restoration of cyclophilin D reversed the inhibitory action of miR-146a on cardiomyocyte apoptosis. Furthermore, cardiomyocyte-specific cyclophilin D deletion completely abolished the exacerbation of myocardial infarction and apoptosis observed in miR-146a cardiomyocyte-deficient mice. Collectively, these findings demonstrate that nuclear miR-146a translocates into the mitochondria and regulates mitochondrial function and cardiomyocyte apoptosis. Our study unveils a novel role for miR-146a in ischemic heart disease.

Acute ischemic stroke biomarkers: a new era with diagnostic promise?

Stroke is considered as the first cause of neurological dysfunction and second cause of death worldwide. Recombinant tissue plasminogen activator is the only chemical treatment for ischemic stroke approved by the US Food and Drug Administration. It was the only standard of care for a long time with a very narrow therapeutic window, which usually ranges from 3 to 4.5 h of stroke onset; until 2015, when multiple trials demonstrated the benefit of mechanical thrombectomy during the first 6 h. In addition, recent trials showed that mechanical thrombectomy can be beneficial up to 24 h if the patients meet certain criteria including the presence of magnetic resonance imaging/computed tomography perfusion mismatch, which allows better selectivity and higher recruitment of eligible stroke patients. However, magnetic resonance imaging/computed tomography perfusion is not available in all stroke centers. Hence, physicians need other easy and available diagnostic tools to select stroke patients eligible for mechanical thrombectomy. Moreover, stroke management is still challenging for physicians, particularly those dealing with patients with "wake-up" stroke. The resulting brain tissue damage of ischemic stroke and the subsequent pathological processes are mediated by multiple molecular pathways that are modulated by inflammatory markers and post-transcriptional activity. A considerable number of published works suggest the role of inflammatory and cardiac brain-derived biomarkers (serum matrix metalloproteinase, thioredoxin, neuronal and glial markers, and troponin proteins) as well as different biomarkers including the emerging roles of microRNAs. In this review, we assess the accumulating evidence regarding the current status of acute ischemic stroke diagnostic biomarkers that could guide physicians for better management of stroke patients. Our review could give an insight into the roles of the different emerging markers and microRNAs that can be of high diagnostic value in patients with stroke. In fact, the field of stroke research, similar to the field of traumatic brain injury, is in immense need for novel biomarkers that can stratify diagnosis, prognosis, and therapy.

The Effects of Curcumin Plus Piperine Supplementation in Patients with Acute Myocardial Infarction: A Randomized, Double-Blind, and Placebo-Controlled Trial

BACKGROUND

Acute myocardial infarction (AMI) is a leading cause of death and disability worldwide. Previous investigations have demonstrated that curcumin has a cardioprotective effect and may improve myocardial injury. So this study was performed to assess whether supplementation with curcumin could diminish myocardial injury following AMI.

METHODS

To conduct this randomized, double-blinded, and placebo-controlled clinical trial, seventy-two patients with acute myocardial infarction, aged 18-75 years, were enrolled and randomly divided into the active intervention and control groups. The active intervention group (n = 38) received curcumin capsules with piperine supplement (500 mg/day, 95% curcuminoids) for 8 weeks, whereas the control group (n = 34) received a placebo capsule. At the baseline and end of the study, ejection fraction was assessed, and blood samples were taken from all patients to measure the levels of cardiac troponin I(cTnI), lipid profile, FBG, HbA1C, liver enzymes, renal function parameters, and electrolytes.

RESULTS

In this trial, curcumin supplementation significantly reduced the levels of HbA1C (-0.3 ± 2.2 vs. +1.1 ± 1.3, P = 0.002), LDL (-10.3 ± 20.7 vs. +0.2 ± 22.5, P = 0.039), ALT (-10.2 ± 28.5 vs. +7.3 ± 39.2, P = 0.029), and ALP (+6.4 ± 39.5 vs. +38.0 ± 69.0, P = 0.018) compared to the placebo group. Moreover, the serum concentration of HDL significantly improved in comparison with the placebo group (+4.5 ± 8.9 vs. -1.6 ± 7.7, P = 0.002). However, no substantial difference was perceived between the groups regarding the ejection fraction and serum levels of cTnI, FBG, renal function parameters, and electrolytes.

CONCLUSION

Our results indicated that daily intake of 500 mg of curcumin capsules with piperine supplement for 8 weeks modified lipid profile, liver enzymes, and glycemic status, but did not have any effect on ejection fraction and serum concentration of cardiac troponin I, renal function parameters, and electrolytes in acute myocardial infarction patients.

High sensitivity Troponin-T for prediction of adverse events in patients with COVID-19

BACKGROUND

High sensitivity cardiac troponin-T (hs-TnT) has been associated with mortality in patients hospitalized with COVID-19. We aimed to determine if hs-TnT levels and their timing are independent predictors of adverse events in these patients.

DESIGN

Retrospective chart review was performed for all patients hospitalized at our institution between 23 March 2020 and 13 April 2020 who were found to be COVID-19-positive. Clinical, demographic, and laboratory variables including initial and peak hs-TnT were recorded. Univariable and multivariable analyses were completed for a primary composite endpoint of in-hospital death, intubation, need for critical care, or cardiac arrest.

RESULTS

In the 276 patients analysed, initial hs-TnT above the median (≥17 ng/L) was associated with increased length of stay, need for vasoactive medications, and death, along with the composite endpoint (OR 3.92, p < 0.001). Multivariable analysis demonstrated that elevated initial hs-TnT was independently associated with the primary endpoint (OR 2.92, p = 0.01). Late-peaking hs-TnT (OR 2.19 for each additional day until peak, p < 0.001) was also independently associated with the composite endpoint.

CONCLUSIONS

In patients hospitalized with COVID-19, hs-TnT identifies patients at high risk for adverse in-hospital events, and trends of hs-TnT over time, particularly during the first day, provide additional prognostic information.

Causes of Death in Patients With Acute and Chronic Myocardial Injury

BACKGROUND

Information about causes of death in patients with myocardial injury is limited. The purpose of this study was to explore causes of death in patients with myocardial injury.

METHODS

In a cohort of 22,589 patients, 3853 patients with myocardial injury were identified and categorized into: type 1 myocardial infarction, type 2 myocardial infarction, and nonischemic acute and chronic myocardial injury. We included all 1466/3853 (38%) patients who died during follow-up (3.9 ± 2 years). We estimated rates and adjusted odds ratio (OR) with 95% confidence interval (CI) for causes of death in the 4 categories of myocardial injury using patients without myocardial injury 819/17,932 (4.6%) who died as reference.

RESULTS

The study cohort included 2285 patients. The proportion of cardiovascular deaths was higher in patients with type 1 myocardial infarction (48%), acute (43%), and chronic (45%) myocardial injury and type 2 myocardial infarction (39%) compared with patients without myocardial injury (25%). Adjusted rates for cardiovascular death were similar in patients with myocardial injury. Type 1 myocardial infarction, acute, and chronic myocardial injury was associated with a 77% (OR: 1.77, 95% CI 1.29-2.41), 40% (OR: 1.40, 95% CI: 1.07-1.84), and 36% (OR: 1.36, 95% CI: 1.05-1.76) higher risk of cardiovascular death.

CONCLUSIONS

Patients with type 1 myocardial infarction and acute or chronic myocardial injury have similar proportions and high risks for cardiovascular death. We believe that these findings stress the need for investigating patients without known heart diseases who present with nonischemic myocardial injury, or type 2 myocardial infarction.

The Liver and Kidneys mediate clearance of cardiac troponin in the rat

Cardiac-specific troponins (cTn), troponin T (cTnT) and troponin I (cTnI) are diagnostic biomarkers when myocardial infarction is suspected. Despite its clinical importance it is still not known how cTn is cleared once it is released from damaged cardiac cells. The aim of this study was to examine the clearance of cTn in the rat. A cTn preparation from pig heart was labeled with fluorescent dye or fluorine 18 (¹⁸ F). The accumulation of the fluorescence signal using organ extracts, or the 18 F signal using positron emission tomography (PET) was examined after a tail vein injection. The endocytosis of fluorescently labeled cTn was studied using a mouse hepatoma cell line. Close to 99% of the cTnT and cTnI measured with clinical immunoassays were cleared from the circulation two hours after a tail vein injection. The fluorescence signal from the fluorescently labeled cTn preparation and the radioactivity from the 18F-labeled cTn preparation mainly accumulated in the liver and kidneys. The fluorescently labeled cTn preparation was efficiently endocytosed by mouse hepatoma cells. In conclusion, we find that the liver and the kidneys are responsible for the clearance of cTn from plasma in the rat.

Use of Troponin as a predictor for cardiovascular diseases in patients with type 2 Diabetes Mellitus

People with type 2 diabetes mellitus (T2DM) have two- to four-fold increased cardiovascular mortality in comparison to the general population. With the identification of new therapeutic targets and hypoglycemic drugs for T2DM, the need for a better stratification of CVD risk has emerged to select patients who may need intensive or specific treatment. At present, risk stratification is based on clinical, demographic, and biochemical factors. High sensitivity cardiac troponin (hs-cTn) increases after several ischemic and non-ischemic insults and it is considered a marker of myocardial injury. This review summarizes the main findings about hs-cTn utilization for risk stratification in people with T2DM and no clinical CVD. Several large observational studies have documented the association between hs-cTn and adverse cardiovascular outcomes in both the general population and in patients with T2DM. Lifestyle interventions, and particularly promotion of physical activity and adoption of healthy nutritional habits, have been associated to a significant benefit on hs-cTn release in the general population. Randomized controlled trials suggested that hypoglycemic, anti-hypertensive and lipid-lowering therapy may influence the degree of T2DM-induced cardiac injury. Besides these promising findings, the efficacy of an hs-cTn-based approach for CVD prevention in T2DM patients still requires more investigations.

Intense sport practices and cardiac biomarkers

Biomarkers are well established for the diagnosis of myocardial infarction, heart failure and cardiac fibrosis. Different papers on cardiac biomarker evolution during exercise have been published in the literature and generally show mild to moderate elevations. However, the mechanism responsible for these elevations, reflecting physiological or even pathophysiological changes, still has to be clearly elucidated. There are also indications of higher cardiac risk in poorly trained athletes than in well-trained athletes. Whether regular repetition of intensive exercise might lead, in the longer term, to fibrosis and heart failure remains to be determined. In this review, we summarized the main research about the effects of intense exercise (in particular, running) on cardiac biomarkers (including troponins, natriuretic peptides, etc.). We found that cardiac fibrosis biomarkers seemed to be the most informative regarding the biological impact of intense physical activity.

Etiology of Minor Troponin Elevations in Patients with Atrial Fibrillation at Emergency Department-Tropo-AF Study

Patients with atrial fibrillation (AF) presenting to the emergency department (ED) often have elevated cardiac troponin T (TnT) levels without evidence of type 1 myocardial infarction. We sought to explore the causes and significance of minor TnT elevations in patients with AF at the ED. All patients with AF admitted to the ED of Turku University Hospital between 1 March, 2013 and 11 April, 2016, and at least two TnT measurements, were screened. Overall, 2911 patients with a maximum TnT of 100 ng/L during hospitalization were analyzed. TnT was between 15 and 100 ng/L in 2116 patients. The most common primary discharge diagnoses in this group were AF (18.1%), infection (18.3%), ischemic stroke/transient ischemic attack (10.7%), and heart failure (5.0%). Acute coronary syndrome (ACS) was equally uncommon both in patients with normal TnT and elevated TnT (4.4% vs. 4.5%). Age ≥75 years, low estimated glomerular filtration rate (eGFR), high C-reactive protein (CRP), and hemoglobin <10.0 g/dL, were the most important predictors of elevated TnT. Importantly, TnT elevation was a very frequent (>93%) finding in elderly (≥75 years) AF patients with either low eGFR or high CRP. In conclusion, minor TnT elevations carry limited diagnostic value in elderly AF patients with comorbidities.

Association Between Renal Function and Troponin T Over Time in Stable Chronic Kidney Disease Patients

Background People with reduced glomerular filtration rate (GFR) often have elevated cardiac troponin T (cTnT) levels. It remains unclear how cTnT levels develop over time in those with chronic kidney disease (CKD). The aim of this study was to prospectively study the association between cTnT and GFR over time in older advanced-stage CKD patients not on dialysis. Methods and Results The EQUAL (European Quality Study) study is an observational prospective cohort study in stage 4 to 5 CKD patients aged ≥65 years not on dialysis (incident estimated GFR, <20 mL/min/1.73 m²). The EQUAL cohort used for the purpose of this study includes 171 patients followed in Sweden between April 2012 and December 2018. We used linear mixed models, adjusted for important groups of confounders, to investigate the effect of both measured GFR and estimated GFR on high-sensitivity cTnT (hs-cTnT) trajectory over 4 years. Almost all patients had at least 1 hs-cTnT measurement elevated above the 99th percentile of the general reference population (≤14 ng/L). On average, hs-cTnT increased by 16%/year (95% CI, 13-19; P<0.0001). Each 15 mL/min/1.73 m2 lower mean estimated GFR was associated with a 23% (95% CI, 14-31; P<0.0001) higher baseline hs-cTnT and 9% (95% CI, 5-13%; P<0.0001) steeper increase in hs-cTnT. The effect of estimated GFR on hs-cTnT trajectory was somewhat lower than a previous myocardial infarction (15%), but higher than presence of diabetes mellitus (4%) and male sex (5%). Conclusions In CKD patients, hs-cTnT increases over time as renal function decreases. Lower CKD stage (each 15 mL/min/1.73 m2 lower) is independently associated with a steeper hs-cTnT increase over time in the same range as other established cardiovascular risk factors.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Biomarkers in Stress Related Diseases/Disorders: Diagnostic, Prognostic, and Therapeutic Values

Various internal and external factors negatively affect the homeostatic equilibrium of organisms at the molecular to the whole-body level, inducing the so-called state of stress. Stress affects an organism's welfare status and induces energy-consuming mechanisms to combat the subsequent ill effects; thus, the individual may be immunocompromised, making them vulnerable to pathogens. The information presented here has been extensively reviewed, compiled, and analyzed from authenticated published resources available on Medline, PubMed, PubMed Central, Science Direct, and other scientific databases. Stress levels can be monitored by the quantitative and qualitative measurement of biomarkers. Potential markers of stress include thermal stress markers, such as heat shock proteins (HSPs), innate immune markers, such as Acute Phase Proteins (APPs), oxidative stress markers, and chemical secretions in the saliva and urine. In addition, stress biomarkers also play critical roles in the prognosis of stress-related diseases and disorders, and therapy guidance. Moreover, different components have been identified as potent mediators of cardiovascular, central nervous system, hepatic, and nephrological disorders, which can also be employed to evaluate these conditions precisely, but with stringent validation and specificity. Considerable scientific advances have been made in the detection, quantitation, and application of these biomarkers. The present review describes the current progress of identifying biomarkers, their prognostic, and therapeutic values.

Elevated Cardiac Troponin in Clinical Scenarios Beyond Obstructive Coronary Artery Disease

In this systematic review article, we aim to summarize the most up-to-date evidence regarding elevations of cardiac troponin, especially in clinical scenarios other than obstructive coronary artery disease. The accurate interpretation of raised cardiac troponin is challenging because it relies on unconfirmed postulations and dogmatic knowledge (e.g., the exclusive provenience of cardiac troponin from cardiac myocytes), based on which every troponin elevation is assumed to definitely indicate myocardial damage. Indeed, the investigation of the pathophysiologic mechanism leading to the release in the bloodstream of cardiac biomarkers should be the first step of the diagnostic process to fully understand the clinical significance of the elevated serum levels and identify the best management. A prominent effort should be put in place to identify the contribution of potential confounding factors, both cardiac and non-cardiac in etiology, with the ability to affect synthesis and clearance of cardiac biomarkers. Regardless of the underlying cause, it is well established that cardiovascular biomarkers are increasingly useful to further risk stratification and prognosticate patients. Accordingly, we sought to clarify the meaning and impact of elevated cardiac troponin in those frequently encountered real-world scenarios presenting clinicians with a diagnostic dilemma, with the final goal of facilitating the diagnosis and help optimize individually tailored treatment strategies.

High-sensitive cardiac Troponin T and exercise stress test for evaluation of angiographically significant coronary disease

BACKGROUND

Exercise stress test (EST) has a moderate precision for diagnosis of CAD and could potentially obtain improved accuracy if adding a reliable cardiac biomarker to the test.

OBJECTIVE

We aimed to investigate resting levels and change in hs-cTnT during EST in patients with and without angiographically significant CAD. Moreover, we intended to explore the additive value of hs-cTnT to EST results in diagnosis of stable CAD. We hypothesized that hs-cTnT would be higher in CAD patients and increase diagnostic precision of EST.

METHOD

Patients presenting with symptoms of stable CAD, performed a maximal EST on a bicycle ergometer. Venous blood samples were taken at rest and within 5 min post-exercise. All patients underwent coronary angiography. Significant CAD was defined as having ≥75% stenosis in one or more segments of the coronary arteries.

RESULTS

Out of the 297 participants, significant CAD was found in 111 (37%) patients. Patients with significant CAD compared to without, had higher resting levels of hs-cTnT (median 8.1 vs 5.0 ng/L) and no significant difference in exercise-induced change (median 0.5 vs 0.3 ng/L), p < 0.001 and p = 0.086 respectively. Combined resting hs-cTnT with EST had higher predictive value for significant CAD than EST alone, AUC = 0.751 vs. AUC = 0.637. In an adjusted multivariable regression analysis, resting hs-cTnT >6.0 ng/L was predictive for having significant CAD, OR 2.55 (CI 95% 1.40, 4.65 p = 0.002).

CONCLUSION

In patients with suspected stable CAD, hs-cTnT has a predictive value alone, as well as added to a diagnostic EST for CAD.

Corneal confocal microscopy: ready for prime time

Corneal confocal microscopy is a non-invasive ophthalmic imaging modality, which was initially used for the diagnosis and management of corneal diseases. However, over the last 20 years it has come to the forefront as a rapid, non-invasive, reiterative, cost-effective imaging biomarker for neurodegeneration. The human cornea is endowed with the densest network of sensory unmyelinated axons, anywhere in the body. A robust body of evidence shows that corneal confocal microscopy is a reliable and reproducible method to quantify corneal nerve morphology. Changes in corneal nerve morphology precede or relate to clinical manifestations of peripheral and central neurodegenerative conditions. Moreover, in clinical intervention trials, corneal nerve regeneration occurs early and predicts functional gains in trials of neuroprotection. In view of these findings, it is timely to summarise the knowledge in this area of research and to explain why the case for corneal confocal microscopy is sufficiently compelling to argue for its inclusion as a Food and Drug Administration endpoint in clinical trials of peripheral and central neurodegenerative conditions.

Clinical use of cardiac troponin for acute cardiac care and emerging opportunities in the outpatient setting

Cardiac troponin (cTn) testing has evolved significantly in recent times. Because of increased sensitivity, its use has shifted from a marker used to help diagnose acute myocardial infarction (MI) to a marker than can be used in the outpatient setting, as well as for both detection of myocardial injury and risk-stratification. Its main role remains in the diagnosis of acute MI and the risk-stratification of patients presenting with suspected acute coronary syndrome. The analytical improvements in assays leading to precise high-sensitivity cTn assays have contributed to the development of numerous strategies to identify patients at both low- and high-risk for acute MI within a few hours. These approaches should reduce overcrowding in the emergency room and expedite triaging. The ability of measuring cTn in most patients using high-sensitivity (hs) assays has allowed for the opportunity to examine its use in the detection of cardiotoxicity in patients undergoing chemotherapy, as well as exploring the application in both primary and secondary prevention of coronary artery disease. This particular field of research has become increasingly complex, partly due to the numerous cTn assays available (I and T; point-of-care, contemporary, hs) and an array of approaches in which one can use the test. The purpose of this document is to summarize the analytical and clinical information relevant to cTn assays, in particular, hs-cTn assays, and describe present and future opportunities for use of cTn in acute cardiac care and in the outpatient setting.