Heart Failure Risk Assessment Using Biomarkers in Patients With Atrial Fibrillation: Analysis From COMBINE-AF

BACKGROUND

Heart failure (HF) is common among patients with atrial fibrillation (AF), and accurate risk assessment is clinically important.

OBJECTIVES

The goal of this study was to investigate the incremental prognostic performance of N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T (hs-cTnT), and growth differentiation factor (GDF)-15 for HF risk stratification in patients with AF.

METHODS

Individual patient data from 3 large randomized trials comparing direct oral anticoagulants (DOACs) with warfarin (ARISTOTLE [Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation], ENGAGE AF-TIMI 48 [Effective Anticoagulation With Factor Xa Next Generation in Atrial Fibrillation-Thrombolysis In Myocardial Infarction 48], and RE-LY [Randomized Evaluation of Long-Term Anticoagulation Therapy]) from the COMBINE-AF (A Collaboration Between Multiple Institutions to Better Investigate Non-Vitamin K Antagonist Oral Anticoagulant Use in Atrial Fibrillation) cohort were pooled; all patients with available biomarkers at baseline were included. The composite endpoint was hospitalization for HF (HHF) or cardiovascular death (CVD), and secondary endpoints were HHF and HF-related death. Cox regression was used, adjusting for clinical factors, and interbiomarker correlation was addressed using weighted quantile sum regression analysis.

RESULTS

In 32,041 patients, higher biomarker values were associated with a graded increase in absolute risk for CVD/HHF, HHF, and HF-related death. Adjusting for clinical variables and all biomarkers, NT-proBNP (HR per 1 SD: 1.68; 95% CI: 1.59-1.77), hs-cTnT (HR: 1.39; 95% CI: 1.33-1.44), and GDF-15 (HR: 1.20; 95% CI: 1.15-1.25) were significantly associated with CVD/HHF. The discrimination of the clinical model improved significantly upon addition of the biomarkers (c-index: 0.70 [95% CI: 0.69-0.71] to 0.77 [95% CI: 0.76-0.78]; likelihood ratio test, P < 0.001). Using weighted quantile sum regression analysis, the contribution to risk assessment was similar for NT-proBNP and hs-cTnT for CVD/HHF (38% and 41%, respectively); GDF-15 provided a statistically significant but lesser contribution to risk assessment. Results were similar for HHF and HF-related death, individually, and across key subgroups of patients based on a history of HF, AF pattern, and reduced or preserved left ventricular ejection fraction.

CONCLUSIONS

NT-proBNP, hs-cTnT, and GDF-15 contributed significantly and independently to the risk stratification for HF endpoints in patients with AF, with hs-cTnT being as important as NT-proBNP for HF risk stratification. Our findings support a possible future use of these biomarkers to distinguish patients with AF at low or high risk for HF.

Deep Learning-Enhanced Paper-Based Vertical Flow Assay for High-Sensitivity Troponin Detection Using Nanoparticle Amplification

Successful integration of point-of-care testing (POCT) into clinical settings requires improved assay sensitivity and precision to match laboratory standards. Here, we show how innovations in amplified biosensing, imaging, and data processing, coupled with deep learning, can help improve POCT. To demonstrate the performance of our approach, we present a rapid and cost-effective paper-based high-sensitivity vertical flow assay (hs-VFA) for quantitative measurement of cardiac troponin I (cTnI), a biomarker widely used for measuring acute cardiac damage and assessing cardiovascular risk. The hs-VFA includes a colorimetric paper-based sensor, a portable reader with time-lapse imaging, and computational algorithms for digital assay validation and outlier detection. Operating at the level of a rapid at-home test, the hs-VFA enabled the accurate quantification of cTnI using 50 μL of serum within 15 min per test and achieved a detection limit of 0.2 pg/mL, enabled by gold ion amplification chemistry and time-lapse imaging. It also achieved high precision with a coefficient of variation of <7% and a very large dynamic range, covering cTnI concentrations over 6 orders of magnitude, up to 100 ng/mL, satisfying clinical requirements. In blinded testing, this computational hs-VFA platform accurately quantified cTnI levels in patient samples and showed a strong correlation with the ground truth values obtained by a benchtop clinical analyzer. This nanoparticle amplification-based computational hs-VFA platform can democratize access to high-sensitivity point-of-care diagnostics and provide a cost-effective alternative to laboratory-based biomarker testing.

Diagnostic value of a point-of-care cardiac troponin-I assay (i-STAT®) for clinical application in canine and feline cardiology

INTRODUCTION/OBJECTIVES

This study was performed to evaluate the diagnostic value and net benefits, including cost-effectiveness, of a point-of-care analyser (i-STAT®) for measurement of cardiac troponin I (cTnI) in dogs and cats.

ANIMALS, MATERIALS AND METHODS

120 dogs and 120 cats presented with signs of cardiac disease and suspected myocardial insult on cardiac assessment. This was a validation study expressed as agreement between the i-STAT® analyser and two common commercial reference methods (IMMULITE® 2000 and ACCESS® hsTnI).

RESULTS

The comparison between methods showed a negative bias between the i-STAT® and the two commercial cTnI assays. The bias was more evident when the i-STAT® values were compared to the traditional cTnI assay (IMMULITE® 2000), with a calculated difference of -1.14 ng/mL (dogs) and -0.96 ng/mL (cats). However, the bias was distinctly lower when the i-STAT® measurements were compared to the high-sensitivity cTnI assay (ACCESS®), namely -0.3 ng/mL in dogs and -0.17 in cats.

DISCUSSION

The i-STAT® method can reliably detect normal, low and elevated cTnI values, which is fundamental to differentiate pets with and without myocardial damage and, with the rapid availability of results, this confirms the clinical utility of the i-STAT® method.

CONCLUSIONS

cTnI concentrations measured with the i-STAT® have good comparability with those obtained with both commercial assays for low and elevated cTnI values. However, results should be cautiously interpreted for high troponin values, especially if a strict cut-off value is adopted for diagnostic or prognostic purposes in critical clinical conditions, such as myocarditis or acute myocardial ischaemia.

Levels of Small Extracellular Vesicles Containing hERG-1 and Hsp47 as Potential Biomarkers for Cardiovascular Diseases

The diagnosis of cardiovascular disease (CVD) is still limited. Therefore, this study demonstrates the presence of human ether-a-go-go-related gene 1 (hERG1) and heat shock protein 47 (Hsp47) on the surface of small extracellular vesicles (sEVs) in human peripheral blood and their association with CVD. In this research, 20 individuals with heart failure and 26 participants subjected to cardiac stress tests were enrolled. The associations between hERG1 and/or Hsp47 in sEVs and CVD were established using Western blot, flow cytometry, electron microscopy, ELISA, and nanoparticle tracking analysis. The results show that hERG1 and Hsp47 were present in sEV membranes, extravesicularly exposing the sequences 430AFLLKETEEGPPATE445 for hERG1 and 169ALQSINEWAAQTT- DGKLPEVTKDVERTD196 for Hsp47. In addition, upon exposure to hypoxia, rat primary cardiomyocytes released sEVs into the media, and human cardiomyocytes in culture also released sEVs containing hERG1 (EV-hERG1) and/or Hsp47 (EV-Hsp47). Moreover, the levels of sEVs increased in the blood when cardiac ischemia was induced during the stress test, as well as the concentrations of EV-hERG1 and EV-Hsp47. Additionally, the plasma levels of EV-hERG1 and EV-Hsp47 decreased in patients with decompensated heart failure (DHF). Our data provide the first evidence that hERG1 and Hsp47 are present in the membranes of sEVs derived from the human cardiomyocyte cell line, and also in those isolated from human peripheral blood. Total sEVs, EV-hERG1, and EV-Hsp47 may be explored as biomarkers for heart diseases such as heart failure and cardiac ischemia.

High-Sensitivity Cardiac Troponin Assays: Ready for Prime Time!

Rapid and accurate triage of patients presenting with chest pain to an emergency department (ED) is critical to prevent ED overcrowding and unnecessary resource use in individuals at low risk of acute myocardial infarction (AMI) and to efficiently and effectively guide patients at high risk to definite therapy. The use of biomarkers for rule-out or rule-in of suspected AMI has evolved substantially over the last several decades. Previously well-established biomarkers have been replaced by cardiac troponin (cTn). High-sensitivity cTn (hs-cTn) assays represent the newest generation of cTn assays and offer tremendous advantages, including improved sensitivity and precision. Still, implementation of these assays in the United States lags behind several other areas of the world. Within this educational review, we discuss the evolution of biomarker testing for detection of myocardial injury, address the specifics of hs-cTn assays and their recommended use within triage algorithms, and highlight potential challenges in their use. Ultimately, we focus on implementation strategies for hs-cTn assays, as they are now clearly ready for prime time.

Investigating outlier rates of cardiac troponin I and troponin T assays: A systematic review

Objectives

This review aimed to harmoniously summarize and compare outlier rates for various cardiac troponin (cTn) assays, including high-sensitivity-cTn (hs-cTn) assays and contemporary cTn (generation of assays prior to hs-cTn ones) assays, from the published studies.

Methods

The PRISMA guidelines were utilized to perform this systematic review. Five databases, including PubMed, Scopus, Embase, Cochrane Library, and Web of Science, were searched using specific keywords up to June 30th, 2023. Studies reporting specifically calculated outlier rates for cTn assays when conducting in-vitro diagnosis in human samples were included. Selected studies were then further assessed using the GRADE tool.

Results

Thirteen studies were included. The data from the studies were summarized statistically in this review. The results showed substantial evidence of improved analytical robustness or reduced respective mean rates of outliers, critical outliers, and analytical outliers for hs-cTn assays (0.14 %, 0.18 %, and 0.18 %) compared to contemporary cTn assays (0.63 %, 0.71 %, and 0.50 %).

Conclusion

The findings offer promisingly provide a comprehensive reference for laboratory scientists and clinical staff in choosing the most suitable cTn assay for patient care regrading outlier rates. Besides, this review reveals the advancements of hs-cTn assays with lower outlier rates than contemporary cTn assays. The emerging challenges for continuously improving analytical robustness of cTn assays are also elaborated.

Theoretical analysis of immunochromatographic assay and consideration of its operating parameters for efficient designing of high-sensitivity cardiac troponin I (hs-cTnI) detection

Troponin is the American College of Cardiology and American Heart Association preferred biomarker for diagnosing acute myocardial infarction (MI). We provide a modeling framework for high sensitivity cardiac Troponin I (hs-cTnI) detection in chromatographic immunoassays (flow displacement mode) with an analytical limit of detection, i.e., LOD < 10 ng/L. We show that each of the various control parameters exert a significant influence over the design requirements to reach the desired LOD. Additionally, the design implications in a multiplexed fluidic network, as in the case of Simple Plex™ Ella instrument, are significantly affected by the choice of the number of channels or partitions in the network. We also provide an upgrade on the existing LOD equation to evaluate the necessary minimum volume to detect a particular concentration by considering the effects of stochastics and directly incorporating the target number of copies in each of the partitions in case of multiplexed networks. Even though a special case of cTnI has been considered in this study, the model and analysis are analyte agnostic and may be applied to a wide class of chromatographic immunoassays. We believe that this contribution will lead to more efficient designing of the immunochromatographic assays.

Cardiac troponin as a prognosticator of mortality in patients with sepsis: A systematic review and meta-analysis

BACKGROUND

The impact of cardiac troponin on the short-term and long-term prognosis of patients with sepsis remains uncertain. Therefore, we conducted a meta-analysis to investigate the role of cardiac troponin as a potential indicator for sepsis mortality.

METHODS

We performed a comprehensive search for articles published before November 2022 using Google Scholar, PubMed, and Web of Science. Inclusion criteria for the studies were: (1) investigation of cardiac troponin, and (2) investigation of sepsis. Exclusion criteria included: (1) inability to obtain or calculate hazard ratio (HR) and 95% confidence interval (CI) for the relationship between cardiac troponin level and sepsis mortality, and (2) reviews, meta-analyses, and case reports. Analysis of HRs and 95% CIs for the association between cardiac troponin level and sepsis mortality was conducted using STATA 12.0 software.

RESULTS

Our study included 24 prospective studies (comprising 20,457 sepsis patients) and 4 retrospective studies (comprising 1416 sepsis patients). Meta-analysis demonstrated that elevated cardiac troponin levels were significantly associated with increased sepsis mortality using a random effects model (HR = 1.57, 95% CI 1.41-1.75). Moreover, elevated cardiac troponin levels were also significantly associated with increased hospital mortality of sepsis (HR = 1.35, 95% CI 1.19-1.53) and long-term mortality of sepsis (HR = 1.96, 95% CI 1.51-2.55) using the random effects model.

CONCLUSIONS

Overall, our finding revealed that elevated cardiac troponin for sepsis patients was a predictor of hospital and long-term mortality. Clinicians may treat septic patients with elevated cardiac troponin more cautious to avoid extra death. Moreover, large clinical studies are warranted to validate this association.

Acute dyspnea in the emergency department: a clinical review

Acute dyspnea represents one of the most frequent symptoms leading to emergency room evaluation. Its significant prognostic value warrants a careful evaluation. The differential diagnosis of dyspnea is complex due to the lack of specificity and the loose association between its intensity and the severity of the underlying pathological condition. The initial assessment of dyspnea calls for prompt diagnostic evaluation and identification of optimal monitoring strategy and provides information useful to allocate the patient to the most appropriate setting of care. In recent years, accumulating evidence indicated that lung ultrasound, along with echocardiography, represents the first rapid and non-invasive line of assessment that accurately differentiates heart, lung or extra-pulmonary involvement in patients with dyspnea. Moreover, non-invasive respiratory support modalities such as high-flow nasal oxygen and continuous positive airway pressure have aroused major clinical interest, in light of their efficacy and practicality to treat patients with dyspnea requiring ventilatory support, without using invasive mechanical ventilation. This clinical review is focused on the pathophysiology of acute dyspnea, on its clinical presentation and evaluation, including ultrasound-based diagnostic workup, and on available non-invasive modalities of respiratory support that may be required in patients with acute dyspnea secondary or associated with respiratory failure.

The clinical importance of high-sensitivity cardiac troponin measurements for risk prediction in non-cardiac surgery

INTRODUCTION

The global healthcare burden associated with surgery is substantial, with many patients experiencing perioperative complications. Cardiac troponin I and T measured with high-sensitivity assays are cardiac specific biomarkers that associate closely with adverse outcomes in most patient populations. Perioperative physiological stress can induce troponin release from cardiomyocytes, a condition known as perioperative myocardial injury (PMI). PMI is associated with increased risk of poor short- and long-term outcomes, and current European guidelines recommend screening for PMI in at-risk individuals undergoing non-cardiac surgery.

AREAS COVERED

In this review we summarize current knowledge of the prognostic attributes of cardiac troponins, as well as the challenges associated with their application as biomarkers in the perioperative phase.

EXPERT OPINION

Measurement of circulating levels of cardiac troponins identify individuals at increased risk of poor postoperative outcomes. Systematic screening of at-risk individuals undergoing non-cardiac surgery will result in a large proportion of patients in need of further diagnostic workup to establish the exact nature of their PMI. The lack of concrete evidence of clinical benefit and the increased cost associated with such a strategy is concerning and underscore the need for further research.

Biomarkers in Heart Failure: From Research to Clinical Practice

The aim of this narrative review is to summarize contemporary evidence on the use of circulating cardiac biomarkers of heart failure (HF) and to identify a promising biomarker model for clinical use in personalized point-of-care HF management. We discuss the reported biomarkers of HF classified into clusters, including myocardial stretch and biomechanical stress; cardiac myocyte injury; systemic, adipocyte tissue, and microvascular inflammation; cardiac fibrosis and matrix remodeling; neurohumoral activation and oxidative stress; impaired endothelial function and integrity; and renal and skeletal muscle dysfunction. We focus on the benefits and drawbacks of biomarker-guided assistance in daily clinical management of patients with HF. In addition, we provide clear information on the role of alternative biomarkers and future directions with the aim of improving the predictive ability and reproducibility of multiple biomarker models and advancing genomic, transcriptomic, proteomic, and metabolomic evaluations.

Cardiac Troponin I in Patients Undergoing Percutaneous and Surgical Myocardial Revascularization: Comparison of Analytical Methods

The myocardial infarction (MI) types 4a and 5 guidelines recommend cardiac troponin (cTn) diagnostic decision limits of 5 and 10 times the 99th percentile, respectively. Different cTn kits elicit different responses, so the MI diagnosis is still challenging. The study aimed to establish the cutoff values and the accuracy of three different cTnI kits in the diagnosis of post-procedural MI. We analyzed 115 patients with multivessel stable chronic coronary artery disease; 26 underwent percutaneous coronary intervention, and 89 underwent coronary artery bypass graft. Delayed-enhancement magnetic resonance imaging was performed before and after each intervention for definitive MI diagnoses. Two contemporary and one high-sensitivity cTnI immunoassays were used. ROC curves determined the accuracy of each assay. Low accuracy was observed after applying the current guidelines recommendations. The three cTnI assays accuracies improved when adjusted by the new ROC cutoffs, reaching 82% for MI type 5 for all assays, and 78%, 88%, and 87% for MI type 4 for Siemens, Beckman, and Abbott, respectively. The ultrasensitive and contemporary tests’ accuracy for MI types 4a and 5 diagnoses are equivalent when adjusted for these new cutoffs. The hs-cTnI assays had lower accuracy than contemporary tests for MI types 4a and 5 diagnoses.

Device-measured movement behaviors and cardiac biomarkers in older adults without major cardiovascular disease: the Seniors-ENRICA-2 study

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP) are biomarkers of myocardial infarction and heart failure, respectively, and indicate cardiovascular risk. Since low physical activity (PA) and sedentary behavior (SB) are also associated with higher cardiovascular risk, and this association could be a consequence of higher levels of cardiac biomarkers, we examined the association of device-measured movement behaviors with hs-cTnT and NT-proBNP in older men and women without major cardiovascular disease (CVD).

METHODS

We used data from 1939 older adults from the Seniors-ENRICA-2 study. Accelerometers were used to assess time spent in sleep, SB, light PA (LPA), and moderate-to-vigorous PA (MVPA). Linear regression models were fitted separately in eight strata defined by sex, by median total PA time, and by the presence of subclinical cardiac damage according to cardiac biomarkers levels.

RESULTS

In the less active men with subclinical cardiac damage, spending 30 min/day more of MVPA was associated with a mean percentage difference (MPD) (95% confidence interval) in hs-cTnT of - 13.1 (- 18.3, - 7.5); MPDs in NT-proBNP per 30 min/day increment were 5.8 (2.7, 8.9) for SB, - 19.3 (- 25.4, - 12.7) for LPA and - 23.1 (- 30.7, - 14.6) for MVPA. In women with subclinical cardiac damage who were less physically active, 30 min/day more of SB, LPA and MVPA were associated with MPDs in hs-cTnT of 2.1 (0.7, 3.6), - 5.1 (- 8.3, - 1.7) and - 17.5 (- 22.9, - 11.7), respectively, whereas in those more active, LPA and MVPA were associated with MPDs of 4.1 (1.2, 7.2) and - 5.4 (- 8.7, - 2.0), respectively. No associations were found with NT-proBNP in women.

CONCLUSIONS

The relationship between movement behaviors and cardiac biomarkers in older adults without major CVD depends on sex, subclinical cardiac damage and PA level. More PA and less SB were generally related to lower cardiac biomarkers levels among less active individuals with subclinical cardiac damage, with greater benefits for hs-cTnT in women than men and no benefits for NT-proBNP in women.

Judging the clinical suitability of analytical performance of cardiac troponin assays

New millennium diagnostic criteria for acute myocardial infarction precipitated a revolutionary shift from an approach based primarily on electrocardiography and clinical symptoms to a strategy based on biomarkers, and preferably cardiac troponins (cTn) I and T. In the last 20 years, clinical recommendations have strengthened the role of cTn and led to the development of highly sensitive (hs-cTn) assays, which are now leading players in all current clinical practice guidelines. To optimize the clinical use of these hs-cTn assays, focus on their analytical aspects has become increasingly important, emphasizing the need for the establishment of suitable analytical performance by the definition and implementation of appropriate specifications. An accurate estimate of measurement uncertainty, together with the acquisition of the highest analytical quality when very low concentrations of hs-cTn are measured, are essential requirements and should represent a practical laboratory standard in assuring optimal clinical use. Additional goals for further improving the quality of laboratory information should be the establishment of robust data concerning biological variation of cTn and the resolution of practical challenges opposed to the harmonization of cTn I results obtained by differing commercial measuring systems.

Severity of Illness Scores and Biomarkers for Prognosis of Patients with Coronavirus Disease 2019

The spectrum of disease severity and the insidiousness of clinical presentation make it difficult to recognize patients with coronavirus disease 2019 (COVID-19) at higher risk of worse outcomes or death when they are seen in the early phases of the disease. There are now well-established risk factors for worse outcomes in patients with COVID-19. These should be factored in when assessing the prognosis of these patients. However, a more precise prognostic assessment in an individual patient may warrant the use of predictive tools. In this manuscript, we conduct a literature review on the severity of illness scores and biomarkers for the prognosis of patients with COVID-19. Several COVID-19-specific scores have been developed since the onset of the pandemic. Some of them are promising and can be integrated into the assessment of these patients. We also found that the well-known pneumonia severity index (PSI) and CURB-65 (confusion, uremia, respiratory rate, BP, age ≥ 65 years) are good predictors of mortality in hospitalized patients with COVID-19. While neither the PSI nor the CURB-65 should be used for the triage of outpatient versus inpatient treatment, they can be integrated by a clinician into the assessment of disease severity and can be used in epidemiological studies to determine the severity of illness in patient populations. Biomarkers also provide valuable prognostic information and, importantly, may depict the main physiological derangements in severe disease. We, however, do not advocate the isolated use of severity of illness scores or biomarkers for decision-making in an individual patient. Instead, we suggest the use of these tools on a case-by-case basis with the goal of enhancing clinician judgment.

Associations between elevated high-sensitive cardiac troponin t and outcomes in patients with acute abdominal pain

PURPOSE

The purpose of this study was to determine outcomes in patients presenting to emergency department (ED) with acute abdominal pain and suspected occult myocardial injury [OMI (high-sensitive cardiac troponin T, hs-cTnT level > 14 ng/L)] without clinical signs of myocardial ischaemia. We hypothesized that OMI is a common entity associated with poor outcomes.

METHODS

After institutional research ethics committee approval, a retrospective review was performed on patients subjected to extended use of hs-cTnT measurements during two months period in patients admitted to ED with a chief complaint of abdominal pain, aged 30 years or older and triaged to red, orange, or yellow categories. Primary outcomes were 30-day, six-month, and one-year mortality, respectively. Adjusted mortality rates were compared using the Cox proportional hazard regression model.

RESULTS

Overall, 1000 consecutive patients were screened. A total of 375 patients were subjected to hs-cTnT measurement and 156 of them (41.6%) experienced OMI. None of the patients had acute myocardial infarction diagnosed in the ED. Patients with OMI had a significantly higher 30-day, six-month and one-year mortality compared to the normal hs-cTnT level group [12.8% (20/156) vs. 3.7% (8/219), p = 0.001, 34.0% (53/156) vs. 6.9% (15/219), p < 0.001 and 39.1% (61/156) vs. 9.1 (20/219), p < 0.001, respectively]. OMI was an independent risk factor for mortality at every time point analyzed.

CONCLUSION

Our investigation noted OMI in older patients with co-morbidities and in higher triage category presenting with abdominal pain to ED, respectively. OMI is an independent risk factor for poor outcomes that warrants appropriate screening and management strategy. Our results support the use of hs-cTnT as a prognostication tool in this subgroup of ED patients.

Intact Transition Epitope Mapping-Force Differences between Original and Unusual Residues (ITEM-FOUR)

Antibody-based point-of-care diagnostics have become indispensable for modern medicine. In-depth analysis of antibody recognition mechanisms is the key to tailoring the accuracy and precision of test results, which themselves are crucial for targeted and personalized therapy. A rapid and robust method is desired by which binding strengths between antigens and antibodies of concern can be fine-mapped with amino acid residue resolution to examine the assumedly serious effects of single amino acid polymorphisms on insufficiencies of antibody-based detection capabilities of, e.g., life-threatening conditions such as myocardial infarction. The experimental ITEM-FOUR approach makes use of modern mass spectrometry instrumentation to investigate intact immune complexes in the gas phase. ITEM-FOUR together with molecular dynamics simulations, enables the determination of the influences of individually exchanged amino acid residues within a defined epitope on an immune complex's binding strength. Wild-type and mutated epitope peptides were ranked according to their experimentally determined dissociation enthalpies relative to each other, thereby revealing which single amino acid polymorphism caused weakened, impaired, and even abolished antibody binding. Investigating a diagnostically relevant human cardiac Troponin I epitope for which seven nonsynonymous single nucleotide polymorphisms are known to exist in the human population tackles a medically relevant but hitherto unsolved problem of current antibody-based point-of-care diagnostics.

ECG and Biomarker Profile in Patients with Acute Heart Failure: A Pilot Study

Background: Biomarkers, electrocardiogram (ECG) and Holter ECG are basic, accessible and feasible cardiac investigations. The combination of their results may lead to a more complex predictive model that may improve the clinical approach in acute heart failure (AHF). The main objective was to investigate which ECG parameters are correlated with the usual cardiac biomarkers (prohormone N-terminal proBNP, high-sensitive cardiac troponin I) in patients with acute heart failure, in a population from Romania. The relationship between certain ECG parameters and cardiac biomarkers may support future research on their combined prognostic value. Methods: In this prospective case-control study were included 49 patients with acute heart failure and 31 participants in the control group. For all patients we measured levels of prohormone N-terminal proBNP (NT-proBNP), high-sensitive cardiac troponin I (hs-cTnI) and MB isoenzyme of creatine phosphokinase (CK-MB) and evaluated the 12-lead ECG and 24 h Holter monitoring. Complete clinical and paraclinical evaluation was performed. Results: NT-proBNP level was significantly higher in patients with AHF (p < 0.001). In patients with AHF, NT-proBNP correlated with cQTi (p = 0.027), pathological Q wave (p = 0.029), complex premature ventricular contractions (PVCs) (p = 0.034) and ventricular tachycardia (p = 0.048). Hs-cTnI and CK-MB were correlated with ST-segment modification (p = 0.038; p = 0.018) and hs-cTnI alone with complex PVCs (p = 0.031). Conclusions: The statistical relationships found between cardiac biomarkers and ECG patterns support the added value of ECG in the diagnosis of AHF. We emphasize the importance of proper ECG analysis of more subtle parameters that can easily be missed. As a non-invasive technique, ECG can be used in the outpatient setting as a warning signal, announcing the acute decompensation of HF. In addition, the information provided by the ECG complements the biomarker results, supporting the diagnosis of AHF in cases of dyspnea of uncertain etiology. Further studies are needed to confirm long-term prognosis in a multi-marker approach.

Association of Serial High-Sensitivity Cardiac Troponin T With Subsequent Cardiovascular Events in Patients Stabilized After Acute Coronary Syndrome: A Secondary Analysis From IMPROVE-IT

Importance

Studies have demonstrated an association between single measures of high-sensitivity troponin (hsTn) and future cardiovascular events in patients with chronic coronary syndromes. However, limited data exist regarding the association between changes in serial values of hsTn and subsequent cardiovascular events in this patient population.

Objective

To evaluate the association between changes in high-sensitivity troponin T (hsTnT) and subsequent cardiovascular events in patients stabilized after acute coronary syndrome (ACS).

Design, Setting, and Participants

This is a secondary analysis from the Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT), a randomized clinical trial of ezetimibe vs placebo on a background of simvastatin in 18 144 patients hospitalized for an ACS across 1147 sites in 39 countries. The current biomarker substudy includes the 6035 participants consenting to the biomarker substudy with available hsTnT at months 1 and 4. Data were collected from October 26, 2005, through July 8, 2010, with the database locked October 21, 2014. Data were analyzed from February 28, 2021, through August 14, 2022.

Main Outcomes and Measures

The outcomes of interest were cardiovascular death, myocardial infarction (MI), stroke, or hospitalization for heart failure (HHF). Associations of absolute and relative changes in hsTnT between month 1 and month 4 as a function of the starting month 1 hsTnT and the composite outcome were examined using landmark analyses.

Results

Of 6035 patients in this analysis (median [IQR] age, 64 [57-71]), 1486 (24.6%) were female; 361 (6.0%) were Asian; 121 were (2.0%) Black; 252 (4.2%) were Spanish descent; 4959 were (82.2%) White; and 342 (5.7%) reported another race (consolidated owing to small numbers), declined to respond, or were not asked to report race owing to regulatory prohibitions. Most patients (4114 [68.2%]) had stable hsTnT values (change <3 ng/L), with 1158 (19.2%) and 763 (12.6%) having changes of 3 to less than 7 ng/L and 7 ng/L or more, respectively. After adjustment for clinical risk factors and stratification by the starting month 1 hsTnT level, an absolute increase in hsTnT of 7 ng/L or more was associated with a more than 3-fold greater risk of the composite outcome (adjusted hazard ratio [aHR], 3.33; 95% CI, 1.99-5.57; P < .001), whereas decreases of 7 ng/L or more were associated with similar to lower risk (aHR, 0.51; 95% CI, 0.26-1.03; P = .06) compared with stable values. There was a stepwise association moving from larger absolute decreases (aHR, 0.51; 95% CI, 0.26-1.03) to larger absolute increases (aHR, 3.33; 95% CI, 1.99-5.57) in hsTnT with future risk of the composite outcome (P trend <.001). A similar association was observed when analyzed on the basis of relative percent and continuous change.

Conclusions and Relevance

Among stable patients post-ACS, changes in hsTnT were associated with a gradient of risk of subsequent cardiovascular events across the range of starting hsTnT values. Serial assessment of hsTnT may refine risk stratification with the potential to guide therapy decisions in this patient population.

Trial Registration

ClinicalTrials.gov Identifier: NCT00202878.

Early Diagnosis of Chemotherapy-Linked Cardiotoxicity in Breast Cancer Patients Using Conventional Biomarker Panel: A Prospective Study Protocol

The prognosis of cancer treatment depends on, among other aspects, the cardiotoxicity of chemotherapy. This research aims to create a feasible algorithm for the early diagnosis of antitumor therapy cardiotoxicity in breast cancer patients. The paper represents a protocol for a prospective cohort study with N 120 eligible participants admitted for treatment with anthracyclines and/or trastuzumab. These patients will be allocated into four risk groups regarding potential cardiotoxic complications. Patients will be examined five times every three months for six biomarkers,: cardiac troponin I (cTnI), brain natriuretic peptide (BNP), C-reactive protein (CRP), myeloperoxidase (MPO), galectin-3 (Gal-3), and D-dimer, simultaneously with echocardiographic methods, including speckle tracking. The adjusted relative risk (aOR) of interrupting an entire course of chemotherapy due to cardiotoxic events will be assessed using multiple analyses of proportional Cox risks. The Cox model will also assess associations between baseline biomarker values and time to cardiotoxic events. Moreover, partly conditional survival models will be applied to determine associations between repeated assessments of changes in biomarkers from baseline and time to cancer therapy-related cardiac dysfunction. All models will be adjusted for cancer therapy regimen, baseline LVEF, groups at risk, baseline biomarker values, and age. The decision-tree and principal component analysis (PCA) methods will also be applied. Thus, feasible patterns will be detected.

Novel Biomarkers of Heart Failure in Pediatrics

Novel biomarkers of heart failure are the subject of numerous studies. Biomarkers of heart failure can be determined in the blood and in the urine. Seven groups of biomarkers of heart failure based on pathophysiological mechanisms are presented in this review, namely biomarkers of myocardial stretch, myocyte injury, myocardial remodeling, biomarkers of inflammation, renal dysfunction, neurohumoral activation, and oxidative stress. Studies of biomarkers in the pediatric population are scarce, therefore, further investigation is needed for reliable prognostic and therapeutic implications. The future of biomarker use is in multimarker panels that include a combination of biomarkers with different pathophysiological mechanisms in order to improve their diagnostic and prognostic predictive value.

Metabolic Pathway of Cardiospecific Troponins: From Fundamental Aspects to Diagnostic Role (Comprehensive Review)

Many molecules of the human body perform key regulatory functions and are widely used as targets for the development of therapeutic drugs or as specific diagnostic markers. These molecules undergo a significant metabolic pathway, during which they are influenced by a number of factors (biological characteristics, hormones, enzymes, etc.) that can affect molecular metabolism and, as a consequence, the serum concentration or activity of these molecules. Among the most important molecules in the field of cardiology are the molecules of cardiospecific troponins (Tns), which regulate the processes of myocardial contraction/relaxation and are used as markers for the early diagnosis of ischemic necrosis of cardiomyocytes (CMC) in myocardial infarction (MI). The diagnostic value and diagnostic capabilities of cardiospecific Tns have changed significantly after the advent of new (highly sensitive (HS)) detection methods. Thus, early diagnostic algorithms of MI were approved for clinical practice, thanks to which the possibility of rapid diagnosis and determination of optimal tactics for managing patients with MI was opened. Relatively recently, promising directions have also been opened for the use of cardiospecific Tns as prognostic markers both at the early stages of the development of cardiovascular diseases (CVD) (arterial hypertension (AH), heart failure (HF), coronary heart disease (CHD), etc.), and in non-ischemic extra-cardiac pathologies that can negatively affect CMC (for example, sepsis, chronic kidney disease (CKD), chronic obstructive pulmonary disease (COPD), etc.). Recent studies have also shown that cardiospecific Tns are present not only in blood serum, but also in other biological fluids (urine, oral fluid, pericardial fluid, amniotic fluid). Thus, cardiospecific Tns have additional diagnostic capabilities. However, the fundamental aspects of the metabolic pathway of cardiospecific Tns are definitively unknown, in particular, specific mechanisms of release of Tns from CMC in non-ischemic extra-cardiac pathologies, mechanisms of circulation and elimination of Tns from the human body, mechanisms of transport of Tns to other biological fluids and factors that may affect these processes have not been established. In this comprehensive manuscript, all stages of the metabolic pathway are consistently and in detail considered, starting from release from CMC and ending with excretion (removal) from the human body. In addition, the possible diagnostic role of individual stages and mechanisms, influencing factors is analyzed and directions for further research in this area are noted.

Multiplex Label-Free Kinetic Characterization of Antibodies for Rapid Sensitive Cardiac Troponin I Detection Based on Functionalized Magnetic Nanotags

Express and highly sensitive immunoassays for the quantitative registration of cardiac troponin I (cTnI) are in high demand for early point-of-care differential diagnosis of acute myocardial infarction. The selection of antibodies that feature rapid and tight binding with antigens is crucial for immunoassay rate and sensitivity. A method is presented for the selection of the most promising clones for advanced immunoassays via simultaneous characterization of interaction kinetics of different monoclonal antibodies (mAb) using a direct label-free method of multiplex spectral correlation interferometry. mAb-cTnI interactions were real-time registered on an epoxy-modified microarray glass sensor chip that did not require activation. The covalent immobilization of mAb microdots on its surface provided versatility, convenience, and virtually unlimited multiplexing potential. The kinetics of tracer antibody interaction with the “cTnI—capture antibody” complex was characterized. Algorithms are shown for excluding mutual competition of the tracer/capture antibodies and selecting the optimal pairs for different assay formats. Using the selected mAbs, a lateral flow assay was developed for rapid quantitative cTnI determination based on electronic detection of functionalized magnetic nanoparticles applied as labels (detection limit—0.08 ng/mL, dynamic range > 3 orders). The method can be extended to other molecular biomarkers for high-throughput screening of mAbs and rational development of immunoassays.

The Importance of Cardiac Troponin Metabolism in the Laboratory Diagnosis of Myocardial Infarction (Comprehensive Review)

The study of the metabolism of endogenous molecules is not only of great fundamental significance but also of high practical importance, since many molecules serve as drug targets and/or biomarkers for laboratory diagnostics of diseases. Thus, cardiac troponin molecules have long been used as the main biomarkers for confirmation of diagnosis of myocardial infarction, and with the introduction of high-sensitivity test methods, many of our ideas about metabolism of these cardiac markers have changed significantly. In clinical practice, there are opening new promising diagnostic capabilities of cardiac troponins, the understanding and justification of which are closely connected with the fundamental principles of the metabolism of these molecules. Our current knowledge about the metabolism of cardiac troponins is insufficient and extremely disconnected from various literary sources. Thus, many researchers do not sufficiently understand the potential importance of cardiac troponin metabolism in the laboratory diagnosis of myocardial infarction. The purpose of this comprehensive review is to systematize information about the metabolism of cardiac troponins and during the discussion to focus on the potential impact of cTns metabolism on the laboratory diagnosis of myocardial infarction. The format of this comprehensive review includes a sequential consideration and analysis of the stages of the metabolic pathway, starting from possible release mechanisms and ending with elimination mechanisms. This will allow doctors and researchers to understand the significant importance of cTns metabolism and its impact on the laboratory diagnosis of myocardial infarction.

PMVEMA-coated upconverting nanoparticles for upconversion-linked immunoassay of cardiac troponin

Surface engineering of upconverting nanoparticles (UCNPs) is crucial for their bioanalytical applications. Here, an antibody specific to cardiac troponin I (cTnI), an important biomarker for acute myocardial infection, was covalently immobilized on the surface of UCNPs to prepare a label for the detection of cTnI biomarker in an upconversion-linked immunoassay (ULISA). Core-shell UCNPs (NaYF₄:Yb,Tm@NaYF₄) were first coated with poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) and then conjugated to antibodies. The morphology (size and uniformity), hydrodynamic diameter, chemical composition, and amount of coating on the of UCNPs, as well as their upconversion luminescence, colloidal stability, and leaching of Y³⁺ ions into the surrounding media, were determined. The developed ULISA allowed reaching a limit of detection (LOD) of 0.13 ng/ml and 0.25 ng/ml of cTnI in plasma and serum, respectively, which represents 12- and 2-fold improvement to conventional enzyme-linked immunosorbent based on the same immunoreagents.

Circulating and Platelet MicroRNAs in Cardiovascular Risk Assessment and Antiplatelet Therapy Monitoring

Micro-ribonucleic acids (microRNAs) are small molecules that take part in the regulation of gene expression. Their function has been extensively investigated in cardiovascular diseases (CVD). Most recently, miRNA expression levels have been suggested as potential biomarkers of platelet reactivity or response to antiplatelet therapy and tools for risk stratification for recurrence of ischemic evens. Among these, miR-126 and miR-223 have been found to be of particular interest. Despite numerous studies aimed at understanding the prognostic value of miRNA levels, no final conclusions have been drawn thus far regarding their utility in clinical practice. The aim of this review is to critically appraise the evidence on the association between miRNA expression, cardiovascular risk and on-treatment platelet reactivity as well as provide insights on future developments in the field.

Features of the Metabolisms of Cardiac Troponin Molecules-Part 1: The Main Stages of Metabolism, Release Stage

Cardiac troponins (cTns) have long been the most valuable and specific biomarkers for detecting ischemic myocardial cells (MCs) injury, which is one of the key signs of myocardial infarction (MI). Modern methods (highly sensitive and ultra-sensitive immunoassays (hs-cTns)) of detection are an important and indispensable tool for the early diagnosis of MI and the choice of patient management protocols. Timely diagnosis of MI can significantly improve the prognosis of patients. However, in real clinical practice, doctors often face a significant problem when using cTns-the difficulty of differential diagnosis due to frequent and unexplained increases in the concentration of cTns in blood serum. In addition, there is conflicting information that may potentially affect the diagnostic capabilities and value of cTns: the influence of certain biological factors (diurnal rhythm, gender and age) on serum cTns levels; extra-cardiac expression of cTns; the possibilities of non-invasive diagnosis of MI; and other pathological conditions that cause non-ischemic injury to MCs. To solve these problems, it is necessary to concentrate on studying the metabolism of cTns. The review of our current knowledge about cTns metabolism consists of two parts. In this (first) part of the manuscript, the main stages of cTns metabolism are briefly described and the mechanisms of cTns release from MCs are considered in detail.

Serum Myoglobin Is Associated With Postoperative Acute Kidney Injury in Stanford Type A Aortic Dissection

Background

The correlation between rhabdomyolysis and postoperative acute kidney injury has been reported in several surgical procedures. As a good predictor of rhabdomyolysis-related acute kidney injury, an elevated serum myoglobin level was often observed after total aortic arch replacement combined with frozen elephant trunk implantation. However, the correlation between serum myoglobin and acute kidney injury in such patients had not been established.

Methods

Totally 398 stanford type A aortic dissection patients who underwent total aortic arch replacement combined with frozen elephant trunk implantation were enrolled in this retrospective study. The correlations between serum myoglobin and acute kidney injury as well as the 30-day mortality were assessed.

Results

Overall, 268(67.3%) patients had acute kidney injury (KDIGO stage 1 or higher) and 75(18.8%) had severe acute kidney injury (KDIGO stage 2&3). Patients who developed acute kidney injury had higher level of perioperative serum myoglobin than patients without acute kidney injury. After adjusting for known acute kidney injury risk factors, logarithmically transformed preoperative serum myoglobin [OR = 1.58 (95% CI, 1.26–1.95), P < 0.001] and postoperative day 1 serum myoglobin [OR = 3.47 (95%CI, 2.27–5.29), P < 0.001] were associated with severe acute kidney injury. These correlation persisted after adjustment for decline in filtration via change in serum creatinine (ΔCr) and biomarkers of cardiac and kidney injury, including N-terminal prohormone of brain natriuretic peptide, cardiac troponin I, creatine kinase-MB, serum creatinine and Cystatin C. Compared with the clinical model, sMb considerably improved the risk discrimination and reclassification for AKI.

Conclusion

For stanford type A aortic dissection patients underwent total aortic arch replacement with frozen elephant trunk implantation, serum myoglobin can improve postoperative acute kidney injury risk classification. Rhabdomyolysis may be an important supplement to the existing knowledge on the mechanism of acute kidney injury.

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.

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.

Diagnostic Performance of Novel Troponin Algorithms for the Rule-Out of Non-ST-Elevation Acute Coronary Syndrome

BACKGROUND

The European Society of Cardiology (ESC) rule-out algorithms use cutoffs optimized for exclusion of non-ST elevation myocardial infarction (NSTEMI). We investigated these and several novel algorithms for the rule-out of non-ST elevation acute coronary syndrome (NSTE-ACS) including less urgent coronary ischemia.

METHOD

A total of 1504 unselected patients with suspected NSTE-ACS were included and divided into a derivation cohort (n = 988) and validation cohort (n = 516). The primary endpoint was the diagnostic performance to rule-out NSTEMI and unstable angina pectoris during index hospitalization. The secondary endpoint was combined MI, all-cause mortality (within 30 days) and urgent (24 h) revascularization. The ESC algorithms for high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI) were compared to different novel low-baseline (limit of detection), low-delta (based on the assay analytical and biological variation), and 0-1-h and 0-3-h algorithms.

RESULTS

The prevalence of NSTE-ACS was 24.8%, 60.0% had noncardiac chest pain, and 15.2% other diseases. The 0-1/0-3-h algorithms had superior clinical sensitivity for the primary endpoint compared to the ESC algorithm (validation cohort); hs-cTnT: 95% vs 63%, and hs-cTnI: 87% vs 64%, respectively. Regarding the secondary endpoint, the algorithms had similar clinical sensitivity (100% vs 94%-96%) but lower clinical specificity (41%-19%) compared to the ESC algorithms (77%-74%). The rule-out rates decreased by a factor of 2-4.

CONCLUSION

Low concentration/low-delta troponin algorithms improve the clinical sensitivity for a combined endpoint of NSTEMI and unstable angina pectoris, with the cost of a substantial reduction in total rule-out rate. There was no clear benefit compared to ESC for diagnosing high-risk events.

Troponin interference with special regard to macrocomplex formation

Biomarkers, such as troponin-T and troponin-I, are regarded as the gold standard laboratory parameter for diagnosing many cardiological diseases. These parameters have been approved for clinical use. Many cardiological guidelines recommend the analysis of troponins in the majority of cardiological disease diagnoses and to also gain prognostic information. Nonetheless, many medical circumstances could cause false troponin elevations. In this article, we focus on troponin artifacts, particularly macro-immune complex formation, as important interference factors. Therefore, we performed a literature search from 2006 to 06/2021.

New insights from the MESA study: increased high-sensitivity troponins as a cardiovascular risk factor

The most recent high-sensitivity assays for troponins I and T (hs-TnI and hs-TnT) have made it possible to detect blood concentrations up to 10 times lower than previous assays, making troponins detectable even in asymptomatic subjects without manifest cardiovascular disease. For this reason, hs-Tn, initially introduced as markers of myocardial damage in an acute setting, have also become possible markers of subclinical myocardial damage in baseline conditions. In fact, recent evidence suggests that hs-TnT and hs-TnI predict the risk of future cardiovascular events also in the context of primary prevention, and offer incremental information when added to current risk stratification models. The different association highlighted with different outcome measures, such as coronary heart disease, atherosclerotic cardiovascular disease, heart failure, and death from all causes, seems to indicate that the risk observed in asymptomatic subjects with high levels of hs-Tn is an expression of subclinical damage secondary to multiple pathophysiological mechanisms, and not only to atherothrombosis. However, the ability of hs-TnT and hs-TnI (until now used interchangeably), to provide differential predictive information, and not redundant with respect to more traditional factors, remains to be definitively clarified, both for the purpose of predicting specific outcomes and for the implementation of specific preventive strategies. To date, evidences available allow us to hypothesize their role more as markers than as risk factors.

The Main Causes and Mechanisms of Increase in Cardiac Troponin Concentrations Other Than Acute Myocardial Infarction (Part 1): Physical Exertion, Inflammatory Heart Disease, Pulmonary Embolism, Renal Failure, Sepsis

The causes and mechanisms of increased cardiac troponin T and I (cTnT and cTnI) concentrations are numerous and are not limited to acute myocardial infarction (AMI) (ischemic necrosis of cardiac myocytes). Any type of reversible or irreversible cardiomyocyte injury can result in elevated serum cTnT and cTnI levels. Researchers and practitioners involved in the diagnosis and treatment of cardiovascular disease, including AMI, should know the key causes and mechanisms of elevated serum cTnT and cTnI levels. This will allow to reduce or completely avoid diagnostic errors and help to choose the most correct tactics for further patient management. The purpose of this article is to discuss the main causes and mechanisms of increase in cardiac troponins concentrations in frequently occurring physiological (physical exertion, psycho-emotional stress) and pathological conditions (inflammatory heart disease, pulmonary embolism, chronic renal failure and sepsis (systemic inflammatory response)) not related to myocardial infarction.

Elevation Mechanisms and Diagnostic Consideration of Cardiac Troponins under Conditions Not Associated with Myocardial Infarction. Part 1

Although cardiac troponins are considered the most specific biomarkers for the diagnosis of acute myocardial infarction (AMI), their diagnostic consideration goes far beyond the detection of this dangerous disease. The mechanisms of cardiac troponin elevation are extremely numerous and not limited to ischemic necrosis of cardiac myocytes. Practitioners should be well aware of the underlying pathological and physiological conditions that can lead to elevated serum levels of cardiac troponins to avoid differential diagnostic errors, which will be greatly increased if clinicians rely on laboratory data alone. This article presents a classification of the main causes of an elevation in cardiac troponins and discusses in detail the mechanisms of such elevation and the diagnostic consideration of cardiac troponins in some conditions not associated with AMI, such as physical exertion, inflammatory heart diseases (myocarditis and endocarditis), pulmonary embolism (PE), renal failure, and systemic inflammation (sepsis).

External validation of a high-sensitive troponin I algorithm for rapid evaluation of acute myocardial infarction in a Danish cohort

AIMS

An accelerated diagnostic algorithm for ruling-in or ruling-out myocardial infarction (MI) after 1 hour (1 h) has recently been derived and internally validated for the Siemens ADVIA Centaur TNIH assay. We aimed to validate the diagnostic performance of the TNIH 0 h/1 h algorithm ad modum Boeddinghaus in a Danish cohort.

METHODS AND RESULTS

Patients with chest pain suggestive of MI were prospectively enrolled. High-sensitive troponin I (TNIH) was measured at admission (0 h) and after 30 minutes (30 m), 1 h, and 3 hours (3 h). We externally validated the TNIH 0 h/1 h algorithm ad modum Boeddinghaus in Danish patients. Moreover, we applied the algorithm using the second TNIH measurement at 30 m instead of 1 h. We enrolled 1003 patients: median (Q1-Q3) age 64 (52-74) years, 42% female, and 23% with previous MI. Myocardial infarction was the final diagnosis in 9% of patients. Median (Q1-Q3) times from admission to 30 m and 1 h blood draw were 35 min (30-37 min) and 67 min (62-75 min), respectively. Using the 0 h and 1 h results, 468 (47%) patients were assigned to rule-out, 104 (10%) to rule-in, and 431 (43%) to the observational zone. This resulted in a negative predictive value of 100% (95% confidence interval: 99.2-100%), sensitivity of 100% (95.9-100%), positive predictive value of 79.8 (70.8-87.0%), and specificity of 97.7% (96.5-98.6%). The diagnostic performance after 30 m was similar.

CONCLUSIONS

The TNIH 0 h/1 h algorithm ad modum Boeddinghaus performed excellently for rule-out of MI in a Danish cohort. The Boeddinghaus algorithm also performed excellently after only 30 m.

TRIAL REGISTRATION NUMBER

NCT03634384.

TRIAL REGISTRY NAME AND URL

Rapid Use of High-Sensitive Cardiac Troponin I for Ruling-in and Ruling-out Acute Myocardial Infarction (RACING-MI), https://clinicaltrials.gov/ct2/show/NCT03634384.

Biological Variation of Cardiac Troponins in Health and Disease: A Systematic Review and Meta-analysis

BACKGROUND

Many studies have assessed the biological variation (BV) of cardiac-specific troponins (cTn), reporting widely varying within-subject BV (CVI) estimates. The aim of this study was to provide meta-analysis-derived BV estimates for troponin I (cTnI) and troponin T (cTnT) for different sampling intervals and states of health.

METHODS

Relevant studies were identified by a systematic literature search. Studies were classified according to their methodological quality by the Biological Variation Data Critical Appraisal Checklist (BIVAC). Meta-analyses of BIVAC-compliant studies were performed after stratification by cTn isoform, exclusion of results below the limit of detection, states of health, and sampling interval to deliver reference change values (RCV), index of individuality (II) and analytical performance specifications (APS) for these settings.

RESULTS

Sixteen and 15 studies were identified for cTnI and cTnT, respectively, out of which 6 received a BIVAC grade A. Five studies had applied contemporary cTnI assays, but none contemporary cTnT. High-sensitivity (hs-) cTnI and cTnT delivered similar estimates in all settings. Long-term CVI estimates (15.1; 11.3%) derived from healthy individuals were higher than short-term (4.3%; 5.3%) for hs-cTnI and hs-cTnT, respectively, although confidence intervals overlapped. Estimates derived from diseased subjects were similar to estimates in healthy individuals for all settings.

CONCLUSIONS

This study provides robust estimates for hs-cTnI and hs-cTnT applicable for different clinical settings and states of health, allowing for the use of RCV both to aid in the diagnosis of myocardial injury and for prognosis. BV-based APS appear too strict for some currently available technologies.

FCER1G and PTGS2 Serve as Potential Diagnostic Biomarkers of Acute Myocardial Infarction Based on Integrated Bioinformatics Analyses

This study aimed to explore the potential diagnostic biomarkers and mechanisms underlying acute myocardial infarction (AMI). We downloaded four datasets (GSE19339, GSE48060, GSE66360, and GSE97320) from the Gene Expression Omnibus database and combined them as an integrated dataset. A total of 153 differentially expressed genes (DEGs) were analyzed by the linear models for microarray analysis (LIMMA) package. Weighted gene co-expression network analysis was used to screen for the significant gene modules. The intersection of DEGs and genes in the most significant module was termed "common genes" (CGs). CGs were mainly enriched in "inflammatory response," "neutrophil chemotaxis," and "IL-17 signaling pathway" through functional enrichment analyses. Subsequently, 15 genes were identified as the hub genes in the protein-protein interaction network. The Fc fragment of IgE receptor Ig (FCER1G) and prostaglandin-endoperoxide synthase 2 (PTGS2) showed significantly increased expression in AMI patients and mice at the 12-h time point in our experiments. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of FCER1G and PTGS2. The area under ROC curve of FCER1G and PTGS2 was 77.6% and 80.7%, respectively. Moreover, the micro (mi)RNA-messenger (m)RNA network was also visualized; the results showed that miRNA-143, miRNA-144, and miRNA-26 could target PTGS2 in AMI progression.

Big Tests in Little People

Can laboratory tests that are routinely used in adult patients also be used in pediatric patients? Does the current literature support the routine use of troponin, brain natriuretic peptide, D-dimer, and lactate in children? Adult problems such as acute coronary syndrome and pulmonary embolism are rare in pediatrics, and there is a paucity of literature on how blood tests commonly used to help diagnose these conditions in adults play a role in the diagnosis and management of children. This article presents the literature about 4 common blood tests and examines the clinical applications of each.

Predictors associated with increased troponin in acute decompensated and chronic heart failure patients

Background: Myocardial injury (INJ) expressed by elevated high-sensitivity troponin (hs-Tn) is common in heart failure (HF), due to cardiovascular and non-cardiac conditions. The mechanisms of INJ in acute decompensated HF (ADHF) versus chronic HF (CHF) are still debated. This study’s purpose was to evaluate the determinants of elevated hs-TnT in ADHF and CHF.

Methods: We retrospectively analyzed consecutive HF patients with hs-TnT measured on admission, hospitalized in a tertiary-care hospital. Rehospitalizations, acute coronary syndromes, embolisms, infections, autoimmunity and malignancy were excluded. Cut-off point for hs-TnT was 14 ng/L.

Results: Our study included 488 HF patients, 56.55% with ADHF. Mean age was 72.52±10.09 years. 53.89% were females. 67.75% ADHF and 45.75% CHF patients had elevated hs-TnT. Median hs-TnT was higher in ADHF versus CHF (21.05[IQR 12.74-33.81] vs 13.20[IQR 7.93-23.25], p<0.0001). In multivariable analysis in ADHF and CHF, log10NT-proBNP (HR=5.30, 95%CI 2.71–10.38, p<0.001, respectively HR=5.49, 95%CI 1.71–17.57, p=0.004) and eGFR (HR=0.72, 95%CI 0.62–0.85, p<0.001, respectively HR=0.71, 95%CI 0.55–0.93, p=0.014) were independent predictors for increased hs-TnT. Independent factors associated with elevated hs-TnT in ADHF were male sex (HR=2.52, 95%CI 1.31-4.87, p=0.006) and chronic pulmonary obstructive disease (COPD) (HR=10.57, 95%CI 1.26-88.40, p=0.029), while in CHF were age (HR=2.68, 95%CI 1.42-5.07, p=0.002) and previous stroke (HR=5.35, 95%CI 0.98-29.20, p=0.053).

Conclusion: HF severity, expressed by NT-proBNP levels, and kidney disease progression, expressed by eGFR, were independent predictors associated with increased hs-TnT in both ADHF and CHF. Specific independent predictors were also indentified in ADHF (male sex, COPD) and CHF (age, history of stroke).

Cardiac-specific troponins in uncomplicated pregnancy and pre-eclampsia: A systematic review

Background

The risk of myocardial infarction (MI) increases during pregnancy, particularly in women with pre-eclampsia. MI is diagnosed by measuring high blood levels of cardiac-specific troponin (cTn), although this may be elevated in women with pre-eclampsia without MI, which increases diagnostic uncertainty. It is unclear how much cTn is elevated in uncomplicated and complicated pregnancy, which may affect whether the existing reference intervals can be used in pregnant women. Previous reviews have not investigated high-sensitivity troponin in pregnancy, compared to older, less sensitive methods.

Methods

Electronic searches using the terms “troponin I” or “troponin T”, and “pregnancy”, “pregnancy complications” or “obstetrics”. cTn levels were extracted from studies of women with uncomplicated pregnancies or pre-eclampsia.

Results

The search identified ten studies with 1581 women. Eight studies used contemporary methods that may be too insensitive to use reliably in this clinical setting. Two studies used high-sensitivity assays, with one reporting an elevation in troponin I (TnI) in pre-eclampsia compared to uncomplicated pregnancy, and the other only examining women with pre-eclampsia.

Seven studies compared cTn between women with pre-eclampsia or uncomplicated pregnancy using any assay. Seven studies showed elevated TnI in pre-eclampsia compared to uncomplicated pregnancy or non-pregnant women. One study measured troponin T (TnT) in pregnancy but did not examine pre-eclampsia.

Conclusion

TnI appears to be elevated in pre-eclampsia, irrespective of methodology, which may reflect the role of cardiac stress in this condition. TnI may be similar in healthy pregnant and non-pregnant women, but we found no literature reporting pregnancy-specific reference intervals using high-sensitivity tests. This limits broader application of cTn in pregnancy. There is a need to define reference intervals for cTn in pregnant women, which should involve serial sampling throughout pregnancy, with careful consideration for gestational age and body mass index, which cause dynamic changes in normal maternal physiology.

High-sensitivity troponins in dialysis patients: variation and prognostic value

Background

Dialysis patients have a high prevalence of cardiovascular mortality but also elevated cardiac troponins (cTns) even without signs of cardiac ischaemia. The study aims to assess variation and prognostic value of high-sensitivity cTnI and cTnT in prevalent dialysis patients.

Methods

In 198 prevalent haemodialysis (HD) and 78 peritoneal dialysis (PD) patients, 4-monthly serum troponin I and T measurements were obtained. Reference change values (RCVs) were used for variability assessment and competing-risk regression models for survival analyses; maximal follow-up was 50 months.

Results

HD and PD patients had similar troponin levels [median (interquartile range) troponin I: 25 ng/L (14–43) versus 21 ng/L (11–37), troponin T: 70 ng/L (44–129) versus 67 ng/L (43–123)]. Of troponin I and T levels, 42% versus 98% were above the decision level of myocardial infarction. RCVs were +68/−41% (troponin I) and +29/−23% (troponin T). Increased variability of troponins related to higher age, male sex, protein-energy wasting and congestive heart failure, but not ischaemic heart disease or dialysis form. Elevated troponin T, but not troponin I, predicted death after adjusting for confounders.

Conclusions

A large proportion of prevalent dialysis patients without current established or ongoing cardiac events have elevated levels of high-sensitivity cTns. Mortality risk was doubled in patients with persistently high troponin T levels. The large intraindividual variation of cTns suggests that serial measurements and reference change levels may be used to improve diagnostic utility. However, evidence-based recommendations require more data from large studies of dialysis patients with cardiac events.

Intraoperative factors contributory to myocardial injury in high-risk patients undergoing abdominal surgery in a South Indian population

Background and Aims:

Myocardial injury after non-cardiac surgery (MINS) is associated with high postoperative mortality. We sought to examine the intraoperative variables associated with MINS among high-risk patients undergoing abdominal surgery at a South Indian Centre.

Methods:

A retrospective analysis of patients who underwent abdominal surgery, aged >45 years with one of five factors: hypertension, diabetes mellitus, previous coronary artery disease (CAD), stroke, or peripheral vascular disease or all patients >65 years of age was undertaken. Forty-six patients with raised troponin Group P (Trop I > 0.03 ng/d) were compared with 125 troponin-negative patients Group N (Trop I < 0.012 ng/dL) as well as 51 with intermediate levels Group I (Trop I > 0.012 and < 0.03 ng/dL). We evaluated the association of pre and intraoperative factors on MINS using logistic regression to identify the explanatory variables.

Results:

Demographics were similar among the three groups. In-hospital mortality was significantly higher in group P (P = 0.005).The use of vasopressors (OR 2.6; 95% CI 1.2–5.5), female gender, (OR 2.3; 95%CI 1.1–4.7), associated CAD (OR 2.8;95% CI 1.1–7.4), and fresh frozen plasma (FFP) transfusion (OR 12.1;95% CI 1.3–11.7) were associated with MINS in regression analysis between group P versus group N. Female gender (OR2.3; 95% CI 1.2–4.5), postoperative mechanical ventilation (OR 3.5; 95% CI 1.2–10.4), and perioperative hypothermia (OR 4.5; 95% CI 1.3–14.9) were significant between Group P and Group I with Group N.

Conclusions:

Female patients with CAD undergoing abdominal surgery, needing vasopressors and transfusion of plasma are at high risk for MINS with higher hospital mortality and merit vigilant monitoring postoperatively.

How to choose a point-of-care testing for troponin

BACKGROUND

Point-of-care (POC) cTn assays are needed when the central laboratory is unable to provide timely results to the emergency department. Many POC devices are available. The prospect of choosing them is daunting. In order to provide a quick decision-making reference for POC cTn device selection comparing them to the central laboratory, seven POC devices commonly employed by emergency department were evaluated.

METHODS

Firstly, we reviewed all devices package inserts. Secondly, we evaluated several POC cTn assays for imprecision, linearity, and correlation with central laboratory assays according to CLSI EP protocols. The linear regression analyses were performed only for the detectable concentrations. Five cTnI devices (Alere Triage, BioMerieux Vidas, Mitsubishi Pathfast, ReLIA TZ-301, and Radiometer AQT90) were evaluated against a contemporary cTnI assay (Beckman Access II Accu TnI). Two cTnT assays (Radiometer AQT90 and Roche Cobas h232) were compared to a high-sensitivity (hs) cTnT method (Roche Cobas e601).

RESULTS

For cTn levels around the 99th percentile upper reference limits (URLs) of the comparator assays, imprecision could not be assessed for the Alere, BioMerieux, and Cobas h232 as they gave undetectable readings due to a lack of assay sensitivity. Imprecision (CV) was unacceptably high for the ReLIA (33.3%). On account of this precision metric, these four assays were deemed unsuitable. Regression analyses showed acceptable linearity for all the POC devices. The correlation coefficients for ReLIA, BioMerieux, Cobas h232, and Radiometer cTnT were >0.95. Unlike the cTnT devices, the cTnI assays employ different capture and detection antibodies leading to non-commutable results. The POC cTn results were concordant with their comparator-Radiometer cTnT 90%, Pathfast cTnI 85%, and Radiometer cTnI 75%.

CONCLUSION

Our study provides the procedure and essential data to guide selection of a POC cTn device. Of the point-of-care devices, methods evaluated Radiometer AQT90 (cTnI and cTnT) and Pathfast might be considered.

Automated, Universal, and Mass-Producible Paper-Based Lateral Flow Biosensing Platform for High-Performance Point-of-Care Testing

Paper-based lateral flow assays (LFAs) are among the most widely used biosensing platforms for point-of-care testing (POCT). However, the conventional colloidal gold label of LFAs show low sensitivity and limited quantitative capacity. Alternatively, the use of enzyme/chemical reaction-based signal amplification with structural modifications has enhanced analytical capacity but requires multiple user interventions as a trade-off, increasing complexity, test imprecision, and time. These platforms are also difficult to manufacture, limiting their practical applications. In this study, within the current LFA production framework, we developed a highly sensitive, automated, universal, and manufacturable LFA biosensing platform by (i) incorporating gold nanoparticles into a polymer-networked peroxidase with an antibody as a new scheme for enhanced enzyme conjugation and (ii) integrating a mass-producible and time-programmable amplification part based on a water-swellable polymer for automating the sequential reactions in the immunoassay and signal amplification, without compromising performance, simplicity, and production feasibility. We applied this platform to evaluate cardiac troponin I (cTnI), a gold-standard biomarker for myocardial infarction diagnosis. Quantitative analysis of cTnI in clinical setting remains limited to the laboratory-based high-end and costly standard equipment. Coupled with an enzyme-catalyzed chemiluminescence method, this platform enables automated, cost-effective (0.66 USD per test), and high-performance testing of human cTnI in serum samples within 20 min with a detection range of 6 orders of magnitude, detection limit of 0.84 pg mL^-1 (595-fold higher than conventional cTnI-LFA), and a coefficient of variation of 2.9-8.5%, which are comparable to the standard equipment and acceptable for clinical use. Moreover, cTnI analysis results using clinical serum/plasma samples revealed a strong correlation (R² = 0.991) with contemporary standard equipment, demonstrating the practical application of this platform for high-performance POCT.

Clinical and Biomarker Predictors of Expanded Heart Failure Outcomes in Patients With Type 2 Diabetes Mellitus After a Recent Acute Coronary Syndrome: Insights From the EXAMINE Trial

Background Improved heart failure (HF) risk stratification after a recent acute coronary syndrome may identify those who can benefit from therapies that reduce HF risk. We aimed to identify clinical and biomarker predictors for expanded HF outcomes in patients with type 2 diabetes mellitus after recent acute coronary syndrome. Methods and Results The EXAMINE (Examination of Cardiovascular Outcomes with Alogliptin versus Standard of Care) trial was a multicenter, non-inferiority, double-masked, placebo-controlled study which randomized 5380 patients with type 2 diabetes mellitus after recent acute coronary syndrome to alogliptin or placebo. Baseline biomarkers were measured in 5154 patients: NT-proBNP (N-terminal pro-B-type natriuretic peptide), high-sensitivity troponin I, adiponectin, growth-differentiation-factor-15, and galectin-3. Our primary outcome was cardiovascular) death, HF hospitalization, elevated NT-proBNP during follow-up, or loop diuretics initiation. The association between clinical variables, biomarkers, and outcomes were assessed using Cox regression models. In the study population, the median age was 61.0 years, 67.7% were men, and 28.0% had baseline HF (median follow-up was 18 months). In multivariable analyses, NT-proBNP had the strongest association with the primary outcome (per log2, hazard ratio 1.24; Wald χ2 67.4; P<0.0001) followed by a prior HF history (hazard ratio 1.42; Wald χ2 20.8; P<0.0001). A model with clinical variables and biomarkers allowed for risk prediction for expanded HF outcomes (C-statistic=0.72). Discrimination results were similar for cardiovascular death or HF hospitalization. Conclusions Among patients with type 2 diabetes mellitus after recent acute coronary syndrome, the use biomarkers such as N-terminal pro-B-type natriuretic peptide and clinical variables enables risk stratification for expanded HF outcomes. Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00968708.

A comparison of cardiac troponin T delta change methods and the importance of the clinical context in the assessment of acute coronary syndrome

Background

The management of patients presenting with symptoms suggestive of acute coronary syndrome is a significant challenge for clinicians. Guidelines for the diagnosis of acute myocardial infarction require a rise and/or fall of cardiac troponin, along with other criteria. Knowing what constitutes a significant delta change from baseline is still unclear and the literature is varied.

Methods

We compared three methods for determining cardiac troponin delta changes (relative, absolute and z-scores) for detecting acute myocardial infarction in 806 patients presenting to an emergency department with symptoms suggestive of acute coronary syndrome. Blood specimens were collected at admission and 2, 3, 4 and 6 h postadmission and tested on the Roche Elecsys high-sensitivity troponin T assay.

Results

A positive diagnosis for acute myocardial infarction was found in 39 (4.8%) patients. ROC AUC showed better performance for the absolute and z-score delta change (0.959–0.988 and 0.956–0.988, respectively) compared with relative delta change (0.921–0.960) at all time points in the diagnosis of acute myocardial infarction. Optimal timing for the second sample was at 4–6 h postadmission.

Conclusions

Although not statistically significant, the results show a trend of absolute and z-score delta change performing better than relative delta change for the diagnosis of acute myocardial infarction. The z-score approach allows for a single cut-off value across multiple high-sensitivity assays which could be useful in the clinical setting. Our study also highlighted the importance of interpreting cardiac troponin changes in the clinical context with a combination of the patient’s clinical history and electrocardiogram.