Cardiac troponin I measured with a very high sensitivity assay predicts subclinical carotid atherosclerosis: The Akershus Cardiac Examination 1950 Study

Determinants of Cardiac Myosin Binding Protein C in the General Population

BACKGROUND

Cardiac myosin binding protein C (cMyC) is a novel, cardiac-specific biomarker with an early release profile after acute ischemic myocardial injury. Whether cMyC reflects chronic myocardial injury and left ventricular remodelling in the general population is unknown. The aims of the study were to test the hypotheses that cMyC concentrations are associated with cardiovascular risk factors, biomarkers of chronic myocardial injury, and imaging biomarkers of cardiac anatomy, function, and fibrosis.

METHODS

Circulating cMyC and cardiac troponin I and T concentrations were measured in 3672 individuals from the general population, born in 1950, who underwent echocardiography. One-hundred-ninety-nine participants with measured cMyC completed a cardiovascular magnetic resonance (CMR) examination for assessment of myocardial fibrosis.

RESULTS

Circulating cMyC was measurable in 99.6% of study participants and in 99.0% of CMR substudy participants. cMyC was positively associated with left ventricular mass and left atrial volume and inversely associated with renal function and indices of left ventricular systolic and diastolic function. In participants with available late gadolinium enhancement images for the assessment of focal fibrosis (n = 197), cMyC was positively associated with indices of focal myocardial fibrosis.

CONCLUSIONS

In the general population, circulating cMyC concentrations are associated with cardiovascular risk factors, reflect left ventricular remodelling, including focal myocardial fibrosis, and systolic and diastolic dysfunction independently of traditional risk factors.

Accelerated Vascular Aging as a Possible Mechanism of Troponin I Release in the Absence of Clinically Manifested Myocardial Injury

BACKGROUND

We examined the association between clusters of vascular aging manifestations and ultrasensitivity cardiac troponin I in individuals without cardiovascular disease.

METHODS AND RESULTS

A cross-sectional analysis was conducted using baseline data from PPS-3 (Paris Prospective Study III), a French cohort of 10 157 participants. Cardiac troponin I was measured with an ultrasensitive immunoassay with a limit of detection of 0.013 pg/mL. Vascular aging manifestations were assessed via echotracking of the right common carotid artery to measure structural and functional parameters. Hierarchical clustering was used to identify clusters of vascular aging. Multinomial regression assessed the association between vascular aging clusters and cardiac troponin I quintiles. The study included 8722 cardiovascular disease-free participants (mean±SD age, 59.5±6.3 years; 39% women). Three vascular aging clusters were identified. Cluster 1 (n=4158; 47.4%) was characterized as healthy vascular aging with the lowest arteriosclerosis and atherosclerosis indices; cluster 2 (n=2237; 25.5%) was characterized by the highest arteriosclerosis indices, including increased pulse wave velocity, β index, and Young elastic modulus and lowest distensibility coefficient; and cluster 3 (n=2377; 27.0%) was characterized by the highest atherosclerosis indices, including more frequent plaque prevalence and greater intima-media thickness. Compared with healthy vascular aging, arteriosclerosis and atherosclerosis clusters showed a graded positive association with cardiac troponin I quintiles, independent of traditional risk factors. The adjusted odds ratio for belonging to the highest quintile (quintile 5 versus quintile 1) was 1.55 (95% CI, 1.31-1.92) for arteriosclerosis and 2.66 (95% CI, 2.18-3.23) for atherosclerosis clusters.

CONCLUSIONS

Vascular aging manifestations of arteriosclerosis and atherosclerosis may partly explain the release of troponin I into the bloodstream in adults without clinical cardiovascular disease.

REGISTRATION

URL: https://clinicaltrials.gov; Unique identifier: NCT00741728.

Prognostic value of biomarkers of ischaemia in patients with peripheral arterial disease following endovascular revascularisation

Background: Our aim was to evaluate the prognostic value of detectable high-sensitivity cardiac troponin I (hs-cTnI) and ischaemia-modified albumin (IMA) in predicting all-cause death or non-fatal ischaemic events in patients with PAD after endovascular revascularisation of the lower limbs. Patients and methods: Patients who underwent successful endovascular revascularisation for chronic limb-threatening ischaemia (CLTI) or disabling intermittent claudication (IC) were prospectively included. Pre-procedural levels of hs-cTnI and IMA were measured, and patients were followed for one year for the occurrence of the composite outcome of all-cause death, non-fatal myocardial infarction, new-onset angina, non-fatal ischaemic stroke, transient ischaemic attack, or progression of PAD. Outcomes were evaluated using survival analyses. Results: A total of 487 patients concluded the study, of whom 175 (35.9%) experienced the composite outcome. When considering only the clinical presentation of PAD and biomarker values, in patients with CLTI, hs-cTnI above the limit of detection (LoD) conferred an increased risk of the composite outcome compared to hs-cTnI below the LoD (p=0.004), while for IMA we found no significant difference. Outcomes of patients with CLTI and hs-cTnI or IMA below the LoD did not differ from those of patients with IC (p=0.07 and p=0.462, respectively). When adjusting for clinical characteristics and common cardiovascular risk factors in multivariate Cox survival analysis, neither biomarker improved prognostic performance, however IMA emerged as an independent predictor of the composite outcome in patients with CLTI. Conclusions: In patients with PAD who underwent successful endovascular procedure, neither IMA nor hs-cTnI improved risk stratification beyond clinical determinants. However, detection of IMA was an independent predictor of major cardiovascular events or death in patients with CLTI.

Prognostication in emergency room patients: comparing ultrasensitive and contemporary quantification of cardiac troponin levels below the 99th percentile

Introduction

Cardiac troponin levels below the 99th percentile improve the predictive efficacy for cardiovascular events when associated with relevant clinical variables. However, whether ultra-sensitive analytical methods improve this predictive efficacy over less sensitive or contemporary analytical methods remains unknown.

Methods

This retrospective observational study involved consecutive patients who presented to the emergency department for suspected acute coronary syndrome and underwent measurement of ultra-sensitive cardiac troponin I (Singulex) and contemporary cardiac troponin I (Siemens) with levels below the 99th percentile. The clinical characteristics of these patients were analysed, and the efficacy of both analytical methods for predicting cardiovascular events over a 4-year follow-up period was compared.

Results

In total, 838 patients were analysed (mean age, 62.9 ± 16.6 years; 42.2% women). Their cumulative incidence of the composite cardiovascular event (death, readmission for myocardial infarction, and readmission for heart failure) was 25.9% over the 4-year follow-up. Both Singulex cardiac troponin I (analysed by quartiles) and Siemens cardiac troponin (analysed as detectable/undetectable) improved the predictive efficacy for the combined event over clinical variables [Harrell's C-index (95% confidence interval): 0.77 (0.74-0.80) vs. 0.79 (0.76-0.81) and 0.77 (0.74-0.80) vs. 0.78 (0.75-0.81), respectively; p = 0.018]. However, there were no statistically significant difference between the two predictive models that included the aforementioned troponin assays.

Conclusions

Detectable levels of cardiac troponin using a contemporary analytical method or those near the 99th percentile using an ultra-sensitive analytical method improve the predictive efficacy for cardiovascular events, with no differences between the two methods.

Cardiac Troponin Serum Concentration Measurement Is Useful Not Only in the Diagnosis of Acute Cardiovascular Events

Cardiac troponin serum concentration is the primary marker used for the diagnosis of acute coronary syndrome. Moreover, the measurement of cardiac troponin concentration is important for risk stratification in patients with pulmonary embolism. The cardiac troponin level is also a general marker of myocardial damage, regardless of etiology. The purpose of this study is to conduct a literature review and present the most important information regarding the current state of knowledge on the cardiac troponin serum concentration in patients with chronic cardiovascular disease (CVD), as well as on the relationships between cardiac troponin serum concentration and features of subclinical cardiovascular dysfunction. According to research conducted to date, patients with CVDs, such as chronic coronary syndrome, chronic lower extremities' ischemia, and cerebrovascular disease, are characterized by higher cardiac troponin concentrations than people without a CVD. Moreover, the literature data indicate that the concentration of cardiac troponin is correlated with markers of subclinical dysfunction of the cardiovascular system, such as the intima-media thickness, pulse wave velocity, ankle-brachial index, coronary artery calcium index (the Agatston score), and flow-mediated dilation. However, further research is needed in various patient subpopulations and in different clinical contexts.

Cardiospecific Troponins as Laboratory Biomarkers of Myocardial Cell Injury in Hypertension: A Mini-Review

To date, it is well known that a significant number of diseases of cardiovascular genesis (coronary heart disease, myocardial infarction, cardiomyopathy, Takotsubo syndrome, heart failure, etc.) and extra-cardiac genesis (renal failure, chronic obstructive pulmonary disease, sepsis, diabetes mellitus, etc.) cause injury to contractile cells of the heart muscle (myocardial cells). The most sensitive and specific criteria for proving myocardial cell injury are cardiospecific troponins (CSTns) - CSTnI and CSTnT. According to the current clinical recommendations of the European, American, and Russian Cardiological Communities, CSTnI and CSTnT are the main biomarkers for early diagnosis of myocardial infarction. Hypertension is one of the most dangerous and common risk factors for the development of cardiovascular pathologies and is associated with a high risk of dangerous cardiovascular complications. Therefore, there is an urgent need to search for new biomarkers for the timely assessment of the prognosis of patients with hypertension. This mini-review aims to substantiate the possibilities of using the cardiomarkers (CSTnI and CSTnT) to assess the prognosis of patients suffering from hypertension and to discuss potential mechanisms that cause injury to myocardial cells and increase serum levels of CSTnI and CSTnT. This is a narrative mini-review, which was prepared using the following databases: Pubmed/Medline, PubMed Central, Embase, Scopus, and Web of Science. The following keywords were used in the literature search: "myocardial cells", "injury", "damage", and "hypertension" in combination with the terms "mechanisms of injury" "predictive significance", "cardiac troponins", or "cardiospecific troponins".

Association between high-sensitivity cardiac troponin I and fall-related hospitalisation in women aged over 70 years

OBJECTIVE

To examine the association between high-sensitivity cardiac troponin I (hs-cTnI), a biomarker of myocardial injury, muscle function decline and 14.5-year fall-related hospitalisation risk in women aged over 70 years.

METHODS

1179 ambulatory community-dwelling women aged over 70 years with subclinical levels of hs-cTnI (ie, <15.6 ng/L), who were followed up for 14.5 years, were included. Samples for hs-cTnI were obtained in 1998. Fall-related hospitalisations were retrieved from linked health records. Muscle function measures, including handgrip strength and the Timed-Up-and-Go (TUG) test, were assessed in 1998 and 2003.

RESULTS

Mean±SD age was 75.2±2.7 years. Over 14.5 years of follow-up, 40.4% (476 of 1179) experienced fall-related hospitalisation. Participants were categorised into four approximate hs-cTnI quartiles: quartile 1 (<3.6 ng/L), quartile 2 (3.6-4.4 ng/L), quartile 3 (4.5-5.8 ng/L) and quartile 4 (≥5.9 ng/L). Compared with those in Q1, women in Q4 were likely to experience fall-related hospitalisation (36.0% vs 42.8%). In a multivariable-adjusted model that accounted for CVD and fall risk factors, compared with women in Q1, those in Q4 had a 46% higher risk of fall-related hospitalisation (HR 1.46, 95% CI 1.08 to 1.98). Additionally, women in Q4 had slower TUG performance compared with those in Q1 (10.3 s vs 9.5 s, p=0.032).

CONCLUSION

Elevated level of hs-cTnI was associated with slower TUG performance and increased fall-related hospitalisation risk. This indicates subclinical level of hs-cTnI can identify clinically relevant falls, emphasising the need to consider cardiac health during fall assessment in women aged over 70 years.

TRIAL REGISTRATION NUMBER

ACTRN12617000640303.

Sex differences in diagnostic modalities of atherosclerosis in the macrocirculation

Asymptomatic atherosclerosis begins early in life and may progress in a sex-specific manner to become the major cause of cardiovascular morbidity and death. As diagnostic tools to evaluate atherosclerosis in the macrocirculation, we discuss imaging methods (in terms of computed tomography, positron emission tomography, intravascular ultrasound, magnetic resonance imaging, and optical coherence tomography), along with derived scores (Agatston, Gensini, Leaman, Syntax), and also hemodynamic indices of vascular stiffness (including flow-mediated dilation, shear stress, pulse pressure, augmentation index, arterial distensibility), assessment of plaque properties (composition, erosion, rupture), stenosis measures such as fractional flow reserve. Moreover, biomarkers including matrix metalloproteinases, vascular endothelial growth factors and miRNAs, as well as the impact of machine learning support, are described. Special attention is given to age-related aspects and sex-specific characteristics, along with clinical implications. Knowledge gaps are identified and directions for future research formulated.

Digital detection of proteins

This paper reviews methods for detecting proteins based on molecular digitization, i.e., the isolation and detection of single protein molecules or singulated ensembles of protein molecules. The single molecule resolution of these methods has resulted in significant improvements in the sensitivity of immunoassays beyond what was possible using traditional "analog" methods: the sensitivity of some digital immunoassays approach those of methods for measuring nucleic acids, such as the polymerase chain reaction (PCR). The greater sensitivity of digital protein detection has resulted in immuno-diagnostics with high potential societal impact, e.g., the early diagnosis and therapeutic intervention of Alzheimer's Disease. In this review, we will first provide the motivation for developing digital protein detection methods given the limitations in the sensitivity of analog methods. We will describe the paradigm shift catalyzed by single molecule detection, and will describe in detail one digital approach - which we call digital bead assays (DBA) - based on the capture and labeling of proteins on beads, identifying "on" and "off" beads, and quantification using Poisson statistics. DBA based on the single molecule array (Simoa) technology have sensitivities down to attomolar concentrations, equating to ∼10 proteins in a 200 μL sample. We will describe the concept behind DBA, the different single molecule labels used, the ways of analyzing beads (imaging of arrays and flow), the binding reagents and substrates used, and integration of these technologies into fully automated and miniaturized systems. We provide an overview of emerging approaches to digital protein detection, including those based on digital detection of nucleic acids labels, single nanoparticle detection, measurements using nanopores, and methods that exploit the kinetics of single molecule binding. We outline the initial impact of digital protein detection on clinical measurements, highlighting the importance of customized assay development and translational clinical research. We highlight the use of DBA in the measurement of neurological protein biomarkers in blood, and how these higher sensitivity methods are changing the diagnosis and treatment of neurological diseases. We conclude by summarizing the status of digital protein detection and suggest how the lab-on-a-chip community might drive future innovations in this field.

High sensitivity troponins: A potential biomarkers of cardiovascular risk for primary prevention

There have been several approaches to building charts for CV risk, all of which have both strengths and limitations. Identifying early organ damage provides relevant information and should be included in risk charts, although the direct relationship with risk is imprecise, variability between operators at the time to assess, and low availability in some healthcare systems, limits its use. Biomarkers, like troponin (cTns) isoforms cTnI and cTnT, a cardiac specific myocyte injury marker, have the great advantage of being relatively reproducible, more readily accessible, and applicable to different populations. New and improved troponin assays have good analytical performance, can measure very low levels of circulating troponin, and have low intra individual variation, below 10 %. Several studies have analyzed the blood levels in healthy subjects and their predictive value for cardiovascular events in observational, prospective and post-hoc studies. All of them offered relevant information and shown that high sensitivity hs-cTnI has a place as an additional clinical marker to add to current charts, and it also reflects sex- and age-dependent differences. Although few more questions need to be answered before recommend cTnI for assessing CV risk in primary prevention, seems to be a potential strong marker to complement CV risk charts.

Hypertension as One of the Main Non-Myocardial Infarction-Related Causes of Increased Cardiospecific Troponins: From Mechanisms to Significance in Current Medical Practice

It is well known that many pathological conditions of both cardiovascular diseases (CVDs) (coronary heart disease, myocardial infarction, arrhythmias, myocarditis, cardiomyopathy, etc.) and non-cardiac (sepsis, anemia, kidney diseases, diabetes mellitus, etc.) origin in the course of their development cause injury to contractile cardiac muscle cells - myocardial cells (MCs). One of the most sensitive and specific criteria for detecting MC injury are cardiospecific troponins (CTs), which are regulatory protein molecules that are released into the blood serum from MC upon their death or injury. Current methods for determining CTs are called high-sensitive ones, and their main advantage is a very low minimum detectable concentration (limit of detection) (average 1 - 10 ng/L or less), which allows early detection of minor MC injury at the earliest stages of CVDs, and therefore they can change the understanding of disease development mechanisms and open up new diagnostic possibilities. One of the most common and dangerous early diseases of the cardiovascular system is hypertension (HT). The novelty of this article lies in the discussion of a new diagnostic direction - predicting the risk of developing CVDs and their dangerous complications in patients with HT by determining the concentration of CTs. In addition, pathophysiological mechanisms underlying MC injury and the release of CTs into the bloodstream and the elimination of CTs into the urine are proposed. This information will contribute to additional fundamental and clinical research to verify the new diagnostic possibility of using CTs in clinical practice (for the management of patients with HT).

Cardiac Troponins as Biomarkers of Cardiac Myocytes Damage in Case of Arterial Hypertension: From Pathological Mechanisms to Predictive Significance

BACKGROUND

Many pathological conditions of both cardiovascular and non-cardiac origin in the course of their development cause damage to contractile cardiac muscle cells-cardiac myocytes (CMCs). One of the most sensitive and specific criteria for detecting CMCs are cardiac troponins (CTs), which are regulatory protein molecules that are released into the blood serum from CMCs upon their death or damage. New (high-sensitive) methods for detecting CTs allow the detection of minor CMCs damages at the earliest stages of cardiovascular diseases and can therefore change the understanding of disease development mechanisms and open up new diagnostic possibilities. One of the most common and dangerous early diseases of the cardiovascular system is arterial hypertension. The purpose of this paper is to summarize the pathophysiological mechanisms underlying CMCs damage and CTs release into the bloodstream in the case of arterial hypertension and to state the clinical significance of increased CTs levels in patients with arterial hypertension.

MATERIALS AND METHODS

This is a descriptive review, which was prepared using the following databases: Embase, Pubmed/Medline and Web of Science. The following key words were used in the literature search: "myocardial injury" and "arterial hypertension" in combination with the terms "cardiac troponins" and "mechanisms of increase".

CONCLUSIONS

According to a literature analysis, CMCs damage and CTs release in the case of arterial hypertension occur according to the following pathophysiological mechanisms: myocardial hypertrophy, CMCs apoptosis, damage to the CMC cell membrane and increase in its permeability for CTs molecules, as well as changes in the glomerular filtration rate. Most often, increased CTs serum levels in case of arterial hypertension indicate an unfavorable prognosis. Data on the CTs predictive significance in case of arterial hypertension open the prospects for the use of these biomarkers in the choice of patient management plans.