Comparison of three troponins as predictors of future cardiovascular events--prospective results from the FINRISK and BiomaCaRE studies

A systematic review and meta-analysis evaluating the association of high sensitivity troponin levels with outcomes in patients with stable coronary artery disease

BACKGROUND

High-sensitivity cardiac troponins (Hs-cTns) are reliable indicators of myocardial injury, but their relationship with cardiovascular outcomes remains less understood. This study explores the association between adverse cardiac events and Hs-cTnT levels exceeding 14 ng/L in patients with stable CAD.

METHODS

Thirteen pertinent studies were identified using specific keywords from a pool of 208 articles retrieved from PubMed, Scopus, and Google Scholar, spanning 2013 to 2023. The primary outcomes included all-cause mortality (ACM), myocardial infarction (MI), cardiovascular death (CVD), rehospitalization due to decompensated heart failure (RDHF), need for revascularization, and stroke. Comprehensive meta-analysis (CMA) was employed to analyze the data for odds ratios (OR) and 95% confidence intervals (CI). Heterogeneity was assessed using I2 statistics, and both qualitative assessment (Newcastle-Ottawa Scale) and quantitative analysis (Egger's and Beggs test, funnel plots) were conducted.

RESULTS

The analysis included 29,115 participants (74.72% male) with a mean age of 68.34 years. It revealed a significantly elevated risk of ACM among stable CAD patients with Hs-cTnT levels >14 ng/L compared to those with levels <14 ng/L (11.2% vs. 3.3%; OR = 5.46; 95% CI = 1.53-19.54; p = 0.009). Similarly, higher risks were observed for MI (10.9% vs 3.6%; OR = 3.12; 95% CI = 0.98-9.95, p = 0.053), CVD (8.1% vs. 2.1%; OR = 3.37; 95% CI = 1.74-6.50; p < 0.0001), and RDHF (6.62% vs. 0.92%; OR = 9.46; 95% CI = 4.65-19.24; p < 0.0001). Notably, major adverse cardiovascular events (MACE) exhibited a stronger association with Hs-cTnT levels (18.2% vs 7.81%; OR = 1.89; 95% CI = 0.80-4.43; I2 = 97%; p = 0.14) compared to Hs-cTnI levels (20.1% vs 21.1%; OR = 1.30; 95% CI = 1.03-1.64; I2 <0.0001%; p = 0.03).

CONCLUSION

Elevated levels of Hs-cTnT (>14 ng/L) are significantly associated with increased risks of RDHF and ACM in patients with stable CAD. Further large-scale prospective studies are warranted to refine risk assessment strategies and mitigate cardiovascular mortality in this population.

High sensitivity troponin I as a biomarker for cardiac allograft vasculopathy: Evaluation of diagnostic potential and clinical utility

INTRODUCTION

Cardiac allograft vasculopathy (CAV) limits long-term survival in heart transplant (HTx) recipients. The use of biomarkers in CAV surveillance has been studied, but none are used in clinical practice. The predictive value of high-sensitivity troponin I (hsTnI) has not been extensively investigated in HTx recipients.

METHODS

HTx patients undergoing surveillance coronary angiograms and enrolled in the Emory Cardiovascular Biobank had plasma hsTnI measured. CAV grade was assessed using ISHLT nomenclature. Multivariable cumulative link mixed modeling was performed to determine association between hsTnI level and CAV grade. Patients were followed for adverse outcomes over a median 10-year period. Kaplan-Meier survival analysis and Cox proportional hazard modeling were performed.

RESULTS

Three hundred and seventy-two angiograms were analyzed in 156 patients at a median 8.9 years after transplant. hsTnI levels were positively correlated with concurrent CAV grade after adjustment for age, age at transplant, sex, BMI, hypertension, diabetes, hyperlipidemia, estimated glomerular filtration rate, and history of acute cellular rejection (p = .016). In an adjusted Cox proportional hazard model, initial hsTnI level above the median (4.9 pg/mL) remained a predictor of re-transplantation or death (hazard ratio 1.82; 95% confidence interval 1.16-2.90; p = .01).

CONCLUSION

An elevated hsTnI level reflects severity of CAV and is associated with poor long-term outcomes in patients with HTx.

Aggregate Clinical and Biomarker-Based Model Predicts Adverse Outcomes in Patients With Coronary Artery Disease

Despite guideline-based therapy, patients with coronary artery disease (CAD) are at widely variable risk for cardiovascular events. This variability demands a more individualized risk assessment. Herein, we evaluate the prognostic value of 6 biomarkers: high-sensitivity C-reactive protein, heat shock protein-70, fibrin degradation products, soluble urokinase plasminogen activator receptor, high-sensitivity troponin I, and B-type natriuretic peptide. We then develop a multi-biomarker-based cardiovascular event prediction model for patients with stable CAD. In total, 3,115 subjects with stable CAD who underwent cardiac catheterization at Emory (mean age 62.8 years, 17% Black, 35% female, 57% obstructive CAD, 31% diabetes mellitus) were randomized into a training cohort to identify biomarker cutoff values and a validation cohort for prediction assessment. Main outcomes included (1) all-cause death and (2) a composite of cardiovascular death and nonfatal myocardial infarction (MI) within 5 years. Elevation of each biomarker level was associated with higher event rates in the training cohort. A biomarker risk score was created using optimal cutoffs, ranging from 0 to 6 for each biomarker exceeding its cutoff. In the validation cohort, each unit increase in the biomarker risk score was independently associated with all-cause death (hazard ratio 1.62, 95% confidence interval [CI] 1.45 to 1.80) and cardiovascular death/MI (hazard ratio 1.52, 95% CI 1.35 to 1.71). A biomarker risk prediction model for cardiovascular death/MI improved the c-statistic (∆ 6.4%, 95% CI 3.9 to 8.8) and net reclassification index by 31.1% (95% CI 24 to 37), compared with clinical risk factors alone. Integrating multiple biomarkers with clinical variables refines cardiovascular risk assessment in patients with CAD.

Enhancement of Bottle Gourd Oil Activity via Optimized Self-Dispersing Lipid Formulations (SDLFs) to Mitigate Isoproterenol-Evoked Cardiac Toxicity in Rats via Modulating BMP, MMP2, and miRNA-21 and miRNA-23a Genes' Expression

Bottle gourd (BG) oil (family Cucurbitaceae) has several pharmacological activities including a reduction of the hazard of cardiovascular and atherosclerosis conditions. This work aimed to develop and optimize self-dispersing lipid formulations (SDLFs) of BG oil by applying a full 32 factorial design. The formulation variables (oil concentration and surfactant mixture ratio) showed an obvious impact on the characters of the prepared BG-SDLFs including droplet size (DS), polydispersity index (PDI), emulsification time (ET), and transmission percentage (Tr%). The optimum BG-SDLF composed of 30% oil and Tween 80/Cremophor® RH40 (1:1) showed good emulsification characteristics and a better drug release profile compared with BG oil. In vivo study in isoproterenol-injected rats showed that BG oil and the optimized BG-SDLF improved cardiac function, by elevating the miRNA-23a gene expression level and decreasing miRNA-21 gene expression. They also caused the inhibition of the plasma B-type natriuretic peptide (BNP), N-terminal proatrial natriuretic peptide (NT-pro-BNP), cystatin c, galectin-3, lipoprotein-associated phospholipase A2 (Lp-PLA2), matrix metallopeptidase 2 (MMP2), cardiac troponin I (cTnI), and cardiac troponin T (cTnT). Our study demonstrated that BG oil and the optimized BG-SDLF provided a cardioprotection against isoproterenol-induced cardiac toxicity with better results in groups treated with the optimized BG-SDLF.

Ultrasensitive Troponin I and Incident Cardiovascular Disease

BACKGROUND

To examine the association of ultrasensitive cTnI (cardiac troponin I) with incident cardiovascular disease events (CVDs) in the primary prevention setting.

METHODS

cTnI was analyzed in the baseline plasma (2008-2012) of CVD-free volunteers from the Paris Prospective Study III using a novel ultrasensitive immunoassay (Simoa Troponin-I 2.0 Kit, Quanterix, Lexington) with a limit of detection of 0.013 pg/mL. Incident CVD hospitalizations (coronary heart disease, stroke, cardiac arrhythmias, deep venous thrombosis or pulmonary embolism, heart failure, or arterial aneurysm) were validated by critical review of the hospital records. Hazard ratios were estimated per log-transformed SD increase of cTnI in Cox models using age as the time scale.

RESULTS

The study population includes 9503 participants (40% women) aged 59.6 (6.3) years. cTnI was detected in 99.6% of the participants (median value=0.63 pg/mL, interquartile range, 0.39-1.09). After a median follow-up of 8.34 years (interquartile range, 8.0-10.07), 516 participants suffered 612 events. In fully adjusted analysis, higher cTnI (per 1 SD increase of log cTnI) was significantly associated with CVD events combined (hazard ratio, 1.18 [1.08-1.30]). Among all single risk factors, cTnI had the highest discrimination capacity for incident CVD events (C index=0.6349). Adding log cTnI to the SCORE 2 (Systematic Coronary Risk Evaluation) risk improved moderately discriminatory capacity (C index 0.698 versus 0.685; bootstrapped C index difference: 0.0135 [95% CI, 0.0131-0.0138]), and reclassification of the participants (categorical net reclassification index, 0.0628 [95% CI, 0.023-0.102]). Findings were consistent using the US pooled cohort risk equation.

CONCLUSIONS

Ultrasensitive cTnI is an independent marker of CVD events in the primary prevention setting.

Clinical implications of cardiac troponin-I in patients with hypertensive crisis visiting the emergency department

OBJECTIVES

Cardiac troponin-I (cTnI) is a representative marker of myocardial injury. Elevation of cTnI is frequently observed in patients with hypertensive crisis, but few studies have examined its prognostic significance in hypertensive crisis. We aimed to determine whether cTnI could predict all-cause mortality in patients with hypertensive crisis visiting the emergency department (ED).

METHODS

This observational study included patients aged ≥18 years who visited an ED between 2016 and 2019 for hypertensive crisis, defined as systolic blood pressure (BP) ≥180 mmHg and/or diastolic BP ≥110 mmHg. Among 6467 patients, 3938 who underwent a cTnI assay were analysed.

RESULTS

Among the 3938 patients, 596 (15.1%) had cTnI levels above the 99th percentile upper reference limit (elevated cTnI >40 ng/L) and 600 (15.2%) had cTnI levels between the detection limit (≥10 ng/L) and the 99th percentile upper reference limit (detectable cTnI). The 3-year all-cause mortality in the elevated, detectable and undetectable cTnI groups were 41.6%, 36.5% and 12.8%, respectively. After adjusting for confounding variables, elevated cTnI patients (adjusted hazard ratio [HR], 2.01; 95% confidence interval [CI], 1.61-2.52) and detectable cTnI patients (adjusted HR, 1.64; 95% CI, 1.32-2.04) showed a significantly higher risk of 3-year all-cause mortality than did patients with undetectable cTnI.

CONCLUSIONS

In patients with hypertensive crisis, elevated cTnI levels provide useful prognostic information and permit the early identification of patients with an increased risk of death. Moreover, putatively normal but detectable cTnI levels also significantly correlated with a higher risk of all-cause mortality. Intensive treatment and follow-up strategies are needed for patients with hypertensive crisis with elevated and detectable cTnI levels.Key messagesCardiac troponin-I level was an independent prognostic factor for all-cause mortality in patients with hypertensive crisis.Detectable but normal range cardiac troponin-I, which was considered clinically insignificant, also had a prognostic impact on all-cause mortality comparable to elevated cardiac troponin-I levels.

Prognostic Value of High-Sensitivity Cardiac Troponin in Women

High-sensitivity cardiac troponin assays have become the gold standard for diagnosing acute and chronic myocardial injury. The detection of troponin levels beyond the 99th percentile is included in the fourth universal definition of myocardial infarction, specifically recommending the use of sex-specific thresholds. Measurable concentrations below the proposed diagnostic thresholds have been shown to inform prognosis in different categories of inpatients and outpatients. However, clinical investigations from the last twenty years have yielded conflicting results regarding the incremental value of using different cut-offs for men and women. While advocates of a sex-specific approach claim it may help reduce gender bias in cardiovascular medicine, particularly in acute coronary syndromes, other groups question the alleged incremental diagnostic and prognostic value of sex-specific thresholds, ultimately asserting that less is more. In the present review, we aimed to synthesize our current understanding of sex-based differences in cardiac troponin levels and to reappraise the available evidence with regard to (i) the prognostic significance of sex-specific diagnostic thresholds of high-sensitivity cardiac troponin assays compared to common cut-offs in both men and women undergoing cardiovascular disease risk assessment, and (ii) the clinical utility of high-sensitivity cardiac troponin assays for cardiovascular disease prevention in women.

Circulating cardiac biomarkers improve risk stratification for incident cardiovascular disease in community dwelling populations

Background

Plasma cardiac markers may assist in prediction of incident cardiovascular disease.

Methods

The incremental value of cardiac Troponins (T and I) and NT-proBNP added to risk factors in the PREDICT score for incident cardiovascular disease (CVD) in primary care, was assessed in 4102 asymptomatic participants in a randomised controlled trial of Vitamin D (ViDA). Findings were corroborated in 2528 participants in a separate community-based observational registry of CVD-free volunteers (HVOLS).

Findings

Hazard ratios for first cardiovascular events adjusted for PREDICT risk factors, comparing fifth to first quintiles of marker plasma concentrations, were 2.57 (95% CI 1.47-4.49); 3.01 (1.66-5.48) and 3.38 (2.04-5.60) for hs-cTnI, hs-cTnT and NT-proBNP respectively. The C statistic for discrimination of the primary endpoint increased from 0.755 to 0.771 (+0.016, p = 0.01). Cardiac marker data correctly reclassified risk upwards in 6.7% of patients and downwards in 3.3%. These findings were corroborated by results from HVOLS.

Interpretation

Increments in plasma cardiac biomarkers robustly and reproducibly predicted increased hazard of incident CVD, independent of established risk factors, in two community-dwelling populations. Cardiac markers may augment risk assessment for onset of CVD in primary care.

Funding

ViDA was funded by the Health Research Council of New Zealand (grant 10/400) and the Accident Compensation Corporation. HVOLS was funded by the Health Research Council of NZ Programme Grants (grants 02/152 and 08/070) and by grants from the Heart Foundation of NZ and the Christchurch Heart Institute Trust. Roche Diagnostics provided in-kind support for NT-proBNP and hs-cTnT assays and Abbott Laboratories for hs-cTnI assays.

High-sensitivity troponins for outcome prediction in the general population: a systematic review and meta-analysis

BACKGROUND

High-sensitivity (hs) assays allow to measure cardiac troponin T and I (cTnT/I) even in healthy individuals. The higher hs-cTn values, the higher the ongoing cardiomyocyte damage, and then reasonably the risk of developing symptomatic cardiac disease.

METHODS

We retrieved all studies evaluating the prognostic value of hs-cTnT or I in the general population. We calculated pooled hazard ratio (HR) values for all-cause and cardiovascular death, cardiovascular events and heart failure (HF) hospitalization.

RESULTS

We included 24 studies for a total of 203,202 subjects; 11 studies assessed hs-cTnT and 14 hs-cTnI. One standard deviation (SD) increase in baseline hs-cTn was associated with a 23% higher risk of all-cause death (HR 1.226, 95% CI 1.083-1.388, p<0.001, I²=88.5%); all these studies measured hs-cTnI. In an exploratory analysis on 3 studies with 25,760 subjects, hs-cTn predicted cardiovascular death (HR 1.822, 95% CI 1.241-2.674, p=0.002, I²=87.2%). After synthesizing 9 studies with 58,565 subjects, hs-cTn predicted cardiovascular events (HR 1.328, 95% CI 1.167-1.513, p<0.001, I²=93.8%). Both hs-cTnT (HR 1.627, 95% CI 1.145-2.311, p<0.001) and hs-cTnI (HR 1.260, 95% CI 1.115-1.423, p<0.001; p for interaction <0.001). Furthermore, in 10 studies with 61,467 subjects, hs-cTn predicted HF hospitalization (HR 1.493, 95% CI 1.368-1.630, p<0.001, I²=76.6%). Both hs-cTnT (HR 1.566, 95% CI 1.303-1.883, p<0.001) and hs-cTnI (HR 1.467, 95% CI 1.321-1.628, p<0.001) were associated with HF hospitalization (p for interaction <0.001).

CONCLUSIONS

hs-cTn values hold strong prognostic value in subjects from the general population, predicting the risk of all-cause and cardiovascular mortality, cardiovascular events, and HF hospitalization.

Genetically Predicted Cardiac Troponin I Concentrations and Risk of Stroke and Atrial Fibrillation

OBJECTIVES

Observational studies have shown that elevated circulating cardiac troponin I (cTnI) concentrations were linked to higher risk of stroke and atrial fibrillation, but the causality remains unclear. Therefore, we used mendelian randomization to assess the potential causal effects of cTnI concentrations on the risk of stroke, its subtypes and atrial fibrillation.

MATERIALS AND METHODS

The instrumental variables for circulating cTnI concentrations were selected from a genome-wide association study meta-analysis of 48,115 European individuals. We examined the associations of circulating cTnI concentrations with stroke, ischemic stroke, ischemic stroke subtypes (cardioembolic, large artery, small vessel stroke), intracerebral hemorrhage and atrial fibrillation.

RESULTS

Genetically predicted elevated circulating cTnI concentrations were associated with higher risk of cardioembolic stroke (odds ratio [OR], 1.80; 95% confidence interval [CI], 1.20-2.68; P = 0.004), but not associated with large artery stroke, small vessel stroke, total stroke, ischemic stroke and intracerebral hemorrhage. Additionally, we also found that elevated cTnI concentrations were causally linked to higher risk of atrial fibrillation (OR, 1.30; 95% CI, 1.10-1.53; P = 0.003).

CONCLUSIONS

This study provides evidence that genetically predicted circulating cTnI concentrations are causally linked to higher risk of cardioembolic stroke and atrial fibrillation.

A systematic review of the status and methodological considerations for estimating risk of first ever stroke in the general population

AIMS

The methodological quality of development, validation, and modification of those models have not been evaluated via a thoroughly literature review. This study aims to describe the overall status and evaluate the methodological quality of risk prediction models for stroke incidence in the general population.

METHODS

We searched the database of EMBASE and MEDLINE by the combination of subject words and key words to collect the research on stroke risk prediction model in the general population. The retrieval time was from the establishment of the database to September 2019. It should be mentioned that risk of bias for each model was assessed, and data on population characteristics and model performance was also extracted.

RESULTS

The search screened 11,386 peer-reviewed publications and 57 citation searching, of which 48 were included in the review, describing the development of 51 prediction models, 47 external validation models, and 12 modification models. Among 51 development models, the predicted outcome concentrated on fatal or non-fatal stroke (n = 37, 73%). Thirty-nine development models (76%) were without internal validation. C-statistic or AUC was adopted for discrimination in 80% models, and Hosmer-Lemeshow test (n = 25, 49%) was also performed for calibration. Twenty-six development models (53%) were externally validated, among which only 2 (8%) were validated by independent researchers. Risk prediction performance was improved when models were modified by adding novel risk factors, such as the internal carotid artery plaque and intima-media thickness.

CONCLUSION

Models for predicting stroke occurrence need further external validation, recalibration, or modification in different populations, to help interpret those models in the practice of stroke prevention.

Clinical Application of High-Sensitivity Troponin Testing in the Atherosclerotic Cardiovascular Disease Framework of the Current Cholesterol Guidelines

Importance

The 2018 American Heart Association/American College of Cardiology (AHA/ACC) cholesterol management guidelines identified 2 distinct groups of patients with atherosclerotic cardiovascular disease (ASCVD) prompting different treatment recommendations.

Objective

To investigate whether the addition of high-sensitivity troponin (hsTn) testing to guideline-derived ASCVD risk can improve risk classification and downstream treatment recommendations.

Design, Setting, and Participants

A prospective cohort biomarker substudy was performed that included 8635 patients enrolled in the Prevention of Cardiovascular Events in Patients with Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin-Thrombolysis in Myocardial Infarction 54 (PEGASUS-TIMI 54) trial. Patients were assigned to risk groups of either very high-risk ASCVD or lower-risk ASCVD based on their cardiovascular history and comorbidities, in line with the 2018 AHA/ACC cholesterol management guidelines criteria. Patients were also classified on the basis of hsTnI level (ARCHITECT assay; Abbott) using cut points of 2 ng/L (limit of detection) and 6 ng/L (risk threshold), followed by joint classification on the basis of clinical features and hsTnI level. The setting was a nested prospective cohort study in a completed multinational trial. Participants were all patients who had a myocardial infarction 1 to 3 years before enrollment, were at least 50 years of age, and had at least 1 high-risk feature. The study dates were October 2010 to December 2014. The dates of analysis were June 2019 to January 2020.

Main Outcomes and Measures

The primary end point was a composite of cardiovascular death, myocardial infarction, or stroke.

Results

Among 8635 patients enrolled in the PEGASUS-TIMI 54 trial, the median age was 65 years (interquartile range, 58-71 years), and 6614 (76.6%) were men; 8340 (96.6%) were White individuals and 176 (2.0%) were Black individuals. Patients meeting clinical criteria for the very high-risk ASCVD group had a primary end point 3-year event rate of 8.8% compared with 5.0% in the lower-risk ASCVD group (hazard ratio, 2.01; 95% CI, 1.58-2.57; P < .001). When patients in the very high-risk ASCVD group were further risk stratified by hsTnI level, 614 of 6789 patients (9.0%) with an undetectable hsTnI level had a 3-year event rate of 2.7% (<1% per year), which was less than the overall rate in the lower-risk ASCVD group. Analogously, in the lower-risk ASCVD group, 417 of 1846 patients (22.6%) with an hsTnI level exceeding 6 ng/L had an event rate of 9.1%, comparable to the overall rate in the very high-risk ASCVD group. The addition of hsTnI to guideline-derived ASCVD risk led to a net reclassification index at event rate of 0.15 (95% CI, 0.10-0.21). Overall, use of hsTnI reclassified 1031 of 8635 patients (11.9%) (1 in 11 with very high-risk ASCVD and 1 in 4 with lower-risk ASCVD).

Conclusions and Relevance

The findings of this cohort substudy suggest that a strategy incorporating hsTn into a guideline-derived ASCVD risk algorithm provides enhanced risk stratification and reclassifies 11.9% of patients into a more appropriate risk group. This application of hsTn testing might be used to optimize the care of patients with ASCVD.

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

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

Clinical relevance of biological variation of cardiac troponins

The high-sensitivity immunoassays for cardiac troponin I (hs-cTnI) and cardiac troponin T (hs-cTnT) are recommended by all the most recent international guidelines as gold standard laboratory methods for the detection of myocardial injury and diagnosis of acute myocardial infarction (AMI). In this review article, the Authors aimed at discussing the relevant biochemical, physiological, and clinical issues related to biological variability of cTnI and cTnT. Cardiac troponins, measured with hs-cTn methods, show a better clinical profile than the other cardio-specific biomarkers (such as the natriuretic peptides, BNP and NT-proBNP). In particular, the hs-cTn methods are characterized by a low intra-individual index of variation (<0.6) and reduced analytical imprecision (about 5% CV) at the clinical cut-off value (i.e., the 99th percentile URL value). Moreover, recent studies have reported that differences between two hs-cTn measured values (RCV) >30% can be considered statistically significant. These favourable biological characteristics and analytical performance of hs-cTn methods significantly improved the accuracy in the diagnostic process of acute coronary syndromes (ACS) in patients admitted to emergence department. In addition, several studies have demonstrated the clinical usefulness of cardiovascular risk evaluation with hs-cTn methods in some groups of patients with clinical conditions at high cardiovascular risk (such as systemic hypertension, severe obesity, diabetes mellitus, renal insufficiency, and chronic obstructive pulmonary disease). However, screening programs in the general population with hs-cTn methods for cardiovascular risk stratification require further investigation to define the optimal target populations, timing of measurement, and preventive interventions.

Is the true clinical value of high-sensitivity troponins as a biomarker of risk? The concept that detection of high-sensitivity troponin 'never means nothing'

INTRODUCTION

High-sensitivity troponin (hs-cTn) assays are central to the diagnosis of myocardial infarction (MI). Their increased sensitivity has facilitated rapid pathways for the exclusion of MI. However, hs-cTn is now more readily detectable in patients without symptoms typical of MI, in whom a degree of myocardial injury is assumed. Recently, the practice of using the 99^th centile of hs-cTn as a working 'upper reference limit' has been challenged. There is increasing evidence that hs-cTn may provide useful prognostic information, regardless of any suspicion of MI, and as such these assays may have potential as a general biomarker for mortality. This raises the concept that detection of hs-cTn 'never means nothing.'

AREAS COVERED

In this review, we will evaluate the evidence for the use of hs-cTn assays outside their common clinical indication to rule out or diagnose acute MI.

EXPERT OPINION

The data presented suggest that hs-cTn testing may in the future have a generalized role as a biomarker of mortality risk and may be used less as a test for ruling in acute MI, but will remain a frontline test to exclude that diagnosis in ED. Further, the data suggest that the detection of hs-cTn 'never means nothing.'

Evidence on clinical relevance of cardiovascular risk evaluation in the general population using cardio-specific biomarkers

In recent years, the formulation of some immunoassays with high-sensitivity analytical performance allowed the accurate measurement of cardiac troponin I (cTnI) and T (cTnT) levels in reference subjects. Several studies have demonstrated the association between the risk of major cardiovascular events and cardiac troponin concentrations even for biomarker values within the reference intervals. High-sensitivity cTnI and cTnT methods (hs-cTn) enable to monitor myocardial renewal and remodelling, and to promptly identify patients at highest risk ofheart failure. An early and effective treatment of individuals at higher cardiovascular risk may revert the initial myocardial remodelling and slow down heart failure progression. Specific clinical trials should be carried out to demonstrate the efficacy and efficiency of the general population screening by means of cost-benefit analysis, in order to better identify individuals at higher risk for heart failure (HF) progression with hs-cTn methods.

High-Sensitivity Cardiac Troponin I Improves Cardiovascular Risk Prediction in Older Men: HIMS (The Health in Men Study)

Background

The Framingham Risk Score estimates the 10‐year risk of cardiovascular events. However, it performs poorly in older adults. We evaluated the incremental benefit of adding high‐sensitivity cardiac troponin I (hs‐cTnI) to the Framingham Risk Score.

Methods and Results

The HIMS (Health in Men Study) is a cohort study of community‐dwelling men aged 70 to 89 years in Western Australia. Participants were identified from the electoral roll, with a subset undergoing plasma analysis. Hs‐cTnI (Abbott Architect i2000SR) was measured in 1151 men without prior cardiovascular disease. The Western Australia Data Linkage System was used to identify incident cardiovascular events. After 10 years of follow‐up, 252 men (22%) had a cardiovascular event (CVE+) and 899 did not (CVE–). The Framingham Risk Score placed 148 (59%) CVE+ and 415 (46%) CVE– in the high‐risk category. In CVE– men, adding hs‐cTnI affected the risk categories of 244 (27.2%) men, with 64.8% appropriately reclassified to a lower and 35.2% to a higher category, which decreased the number of high‐risk men in the CVE– to 39%. In CVE+ men, adding hs‐cTnI affected the risk categories of 61 (24.2%), with 50.8% appropriately reclassified to a higher and 49.2% to a lower category and 82.5% remaining above the 15% risk treatment threshold. The net reclassification index was 0.305 (P<0.001). Adding hs‐cTnI increased the C‐statistic modestly from 0.588 (95% CI, 0.552–0.624) to 0.624 (95% CI, 0.589–0.659) and improved model fit (likelihood ratio test, P<0.001).

Conclusions

Adding hs‐cTnI to the Framingham Risk Score provided incremental prognostic benefit in older men, especially aiding reclassification of individuals into a lower risk category.

Association Between High-Sensitivity Cardiac Troponin and Risk of Stroke in 96 702 Individuals: A Meta-Analysis

Background and Purpose- Our study aim was to estimate risk of incident stroke based on levels of hs-cTn (high-sensitivity cardiac troponin), a specific biomarker indicating myocardial injury, in the general population, patients with atrial fibrillation, and patients with previous stroke. Methods- Embase, PubMed, and Web of Science were searched until March 14, 2019 to identify relevant articles. Randomized controlled trials and cohort studies assessing the risk of incident stroke based on hs-cTn were eligible. Pooled adjusted hazard ratios including 95% CI were calculated using a random-effects model due to study heterogeneity per population, coding of hs-cTn (categorical/continuous data), per hs-cTn subunit (T or I), for low risk of bias, and for all-cause and ischemic stroke separately. Results- We included 17 articles with 96 702 participants. In studies conducted in the general population (n=12; 77 780 participants), the pooled adjusted hazard ratio for incident stroke was 1.25 (CI, 1.10-1.40) for high versus low hs-cTn (as defined by included studies) during an average follow-up of 1 to 20 years (median 10). When categorical data were used, this was increased to 1.58 (CI, 1.26-1.90). The results were robust when accounting for stroke classification (all-cause stroke/ischemic stroke), hs-cTn subunit, risk of bias, and coding of hs-cTn. In patients with atrial fibrillation (4 studies; 18 725 participants), the pooled adjusted hazard ratio for incident stroke was 1.95 (CI, 1.29-2.62) for high versus low hs-cTn. Due to lack of data (one study, 197 participants), no meta-analysis could be performed in patients with previous stroke. Conclusions- This meta-analysis suggests that hs-cTn can be regarded as a risk marker for incident stroke, with different effect size in different subgroups. More research about the association between hs-cTn and incident stroke in high-risk populations is needed, especially in patients with history of ischemic stroke.

Association Between Plasma Neutrophil Gelatinase-Associated Lipocalin and Cardiac Disease Hospitalizations and Deaths in Older Women

Background

Neutrophil gelatinase‐associated lipocalin (NGAL) or lipocalin 2 may promote atherosclerosis and plaque instability leading to increased risk of cardiac events. We investigated the relationships between plasma NGAL, cardiovascular disease biomarkers, and long‐term cardiac events.

Methods and Results

The study population consisted of 1131 ambulant older white women (mean age 75 years) without clinical coronary heart disease (CHD) and measures of plasma NGAL in the Perth Longitudinal Study of Ageing Women with 14.5‐year CHD and heart failure hospitalizations or death (events) captured using linked records. Over 14.5 years, 256 women had CHD events, while 118 had heart failure events. Per SD increase in log‐transformed NGAL there was a 35% to 37% increase in relative hazards for CHD and heart failure events in unadjusted analyses, which remained significant after adjustment for conventional risk factors for CHD events (hazard ratio 1.29, 95% CI 1.13–1.48, P<0.001) but not heart failure (P>0.05). Women in the highest 2 quartiles of NGAL had higher relative hazards for CHD events compared with women in the lowest quartile hazard ratio 1.61, 95% CI 1.08–2.39, P=0.019 and hazard ratio 1.97, 95% CI 1.33–3.93, P=0.001, respectively. These associations were independent of high‐sensitivity cardiac troponin I, homocysteine, and estimated renal function. NGAL correctly reclassified 1 in 4 women who sustained a CHD event up in risk and 1 in 10 women without CHD events down in risk.

Conclusions

NGAL was associated with increased risk of long‐term CHD events, independent of conventional risk factors and biomarkers. These findings provide mechanistic insight into the role of NGAL with cardiac events.

Revisiting the Biological Variability of Cardiac Troponin: Implications for Clinical Practice

The diagnosis of acute myocardial injury requires a rise and/or fall of cardiac troponin (cTn) on serial testing, with at least one concentration above the 99th percentile value of a normal reference population according to the recently published Fourth Universal Definition of Myocardial Infarction.1 However, the magnitude of change in cTn that constitutes a significant rise and/or fall was again not specified in detail. High-sensitivity cardiac troponin (hs-cTn) assays can measure ten-fold lower concentrations of cTn with more precision than older assays, and can accurately quantify cTn in more than 50% of healthy individuals with a coefficient of variation of less than 10% at the 99th percentile. These hs-cTn assays are also able to detect the normal variations in cTn results that are due to biological variability. Understanding and quantifying the normal variations in cTn is important as this would allow significant changes to be better defined. Numerous studies have sought to investigate the biological variability of cTn over the last ten years. Such studies are usually conducted in healthy individuals, however individuals with chronic cardiac disease or chronic renal failure have also been examined. These studies have yielded varying results in regards to significant change values for cTn. In light of the recent redefinition for myocardial infarction, the purpose of this mini-review is to revisit the biological variability of cTn. In particular, we outline concepts for determining a significant change value, review the results of previous studies on the biological variation of cTn and discuss potential considerations for clinical practice.

Prognostic Value of a Novel and Established High-Sensitivity Troponin I Assay in Patients Presenting with Suspected Myocardial Infarction

: High-sensitivity troponin has proven to be a promising biomarker for the prediction of future adverse cardiovascular events. We aimed to assess the prognostic value of high-sensitivity troponin I (hs-TnI) on admission in patients with suspected acute myocardial infarction (AMI) analyzed by a novel (Singulex Clarity cTnI) and established hs-TnI assay (ARCHITECT STAT hs-TnI, Abbott). Hs-TnI was measured in a total of 2332 patients from two prospective cohort studies presenting to the emergency department with suspected AMI. The prognostic impact for overall and cardiovascular mortality of both hs-TnI assays was assessed in the total patient cohort as well as in the subgroups of patients with AMI (n = 518) and without AMI (non-AMI) (n = 1814). Patients presenting with highest hs-TnI levels showed higher overall and cardiovascular mortality rates compared to those with lower troponin levels, irrespective of the assay used. Both hs-TnI assays indicated association with overall mortality according to adjusted hazard ratio (HR) among the entire study population (HR for Singulex assay: 1.16 (95% CI 1.08-1.24) and HR for Abbott assay: 1.17 (95% CI 1.09-1.25)). This finding was particularly pronounced in non-AMI patients, whereas no association between hs-TnI and overall mortality was found in AMI patients for either assay. In non-AMI patients, both assays equally improved risk prediction for cardiovascular mortality beyond conventional cardiovascular risk factors. Hs-TnI is independently predictive for adverse outcomes in patients with suspected AMI, especially in the subset of patients without confirmed AMI. There was no difference between the established and the novel assay in the prediction of mortality.

Diagnostic Accuracy of a High-Sensitivity Cardiac Troponin Assay with a Single Serum Test in the Emergency Department

OBJECTIVES

We sought to evaluate diagnostic accuracy of a high-sensitivity cardiac troponin I (hs-cTnI) assay for acute coronary syndromes (ACS) in the emergency department (ED). The assay has high precision at low concentrations and can detect cTnI in 96.8% of healthy individuals.

METHODS

In successive prospective multicenter studies (“testing” and “validation”), we included ED patients with suspected ACS. We drew blood for hs-cTnI [Singulex Clarity® cTnI; 99th percentile, 8.67 ng/L; limit of detection (LoD), 0.08 ng/L] on arrival. Patients also underwent hs-cTnT (Roche Elecsys) testing over ≥3 h. The primary outcome was an adjudicated diagnosis of ACS, defined as acute myocardial infarction (AMI; prevalent or incident), death, or revascularization within 30 days.

RESULTS

The testing and validation studies included 665 and 2470 patients, respectively, of which 94 (14.1%) and 565 (22.9%) had ACS. At a 1.5-ng/L cutoff, hs-cTnI had good sensitivity for AMI in both studies (98.7% and 98.1%, respectively) and would have “ruled out” 40.1% and 48.9% patients. However, sensitivity was lower for ACS (95.7% and 90.6%, respectively). At a 0.8-ng/L cutoff, sensitivity for ACS was higher (97.5% and 97.9%, ruling out 28.6% patients in each cohort). The hs-cTnT assay had similar performance at the LoD (24.6% ruled out; 97.2% sensitivity for ACS).

CONCLUSIONS

The hs-cTnI assay could immediately rule out AMI in 40% of patients and ACS in &gt;25%, with similar accuracy to hs-cTnT at the LoD. Because of its high precision at low concentrations, this hs-cTnI assay has favorable characteristics for this clinical application.

Cardiac Troponin T and Troponin I in the General Population

BACKGROUND

There is great interest in widening the use of high-sensitivity cardiac troponins for population cardiovascular disease (CVD) and heart failure screening. However, it is not clear whether cardiac troponin T (cTnT) and troponin I (cTnI) are equivalent measures of risk in this setting. We aimed to compare and contrast (1) the association of cTnT and cTnI with CVD and non-CVD outcomes, and (2) their determinants in a genome-wide association study.

METHODS

High-sensitivity cTnT and cTnI were measured in serum from 19 501 individuals in Generation Scotland Scottish Family Health Study. Median follow-up was 7.8 years (quartile 1 to quartile 3, 7.1-9.2). Associations of each troponin with a composite CVD outcome (1177 events), CVD death (n=266), non-CVD death (n=374), and heart failure (n=216) were determined by using Cox models. A genome-wide association study was conducted using a standard approach developed for the cohort.

RESULTS

Both cTnI and cTnT were strongly associated with CVD risk in unadjusted models. After adjusting for classical risk factors, the hazard ratio for a 1 SD increase in log transformed troponin was 1.24 (95% CI, 1.17-1.32) and 1.11 (1.04-1.19) for cTnI and cTnT, respectively; ratio of hazard ratios 1.12 (1.04-1.21). cTnI, but not cTnT, was associated with myocardial infarction and coronary heart disease. Both cTnI and cTnT had strong associations with CVD death and heart failure. By contrast, cTnT, but not cTnI, was associated with non-CVD death; ratio of hazard ratios 0.77 (0.67-0.88). We identified 5 loci (53 individual single-nucleotide polymorphisms) that had genome-wide significant associations with cTnI, and a different set of 4 loci (4 single-nucleotide polymorphisms) for cTnT.

CONCLUSIONS

The upstream genetic causes of low-grade elevations in cTnI and cTnT appear distinct, and their associations with outcomes also differ. Elevations in cTnI are more strongly associated with some CVD outcomes, whereas cTnT is more strongly associated with the risk of non-CVD death. These findings help inform the selection of an optimal troponin assay for future clinical care and research in this setting.

Evaluation of analytical performance of immunoassay methods for cTnI and cTnT: From theory to practice

Current guidelines worldwide recommend cardiac troponins I (cTnI) and T (cTnT) as the biomarkers of choice for the differential diagnosis of acute coronary syndrome (ACS), and the measurement of the 99th upper reference population limit (URL) value for cardiac troponins, with an imprecision of ≤10 CV%. Measuring the 99th URL of cTnI and cTnT is a challenging analytical task due to low biomarker concentrations present in healthy subjects. Therefore, since the year 2006, several manufacturers have established new generation cTnI and cTnT immunoassays with an improved analytical sensitivity in accordance with the quality specifications described in international guidelines, the more recent of which state that only immunoassays that meet the required quality specifications should be considered "high-sensitivity" methods. For the early diagnosis of ACS, and for the stratification of cardiovascular risk in cardiac patients and the general population, high-sensitivity methods should be employed. It is therefore important for laboratory professionals and clinicians to gain a thorough understanding of the analytical performances of immunoassay methods for cTnI and cTnT, especially at low to normal concentration ranges. The aim of the present study was to analyze critical aspects related to definition, analytical performance, pathophysiological interpretations, and the clinical relevance of high-sensitivity cardiac troponin assays.

Ultrasensitive Detection of Clostridioides difficile Toxins A and B by Use of Automated Single-Molecule Counting Technology

Current tests for the detection of Clostridioides (formerly Clostridium) difficile free toxins in feces lack sensitivity, while nucleic acid amplification tests lack clinical specificity. We have evaluated the Singulex Clarity C. diff toxins A/B assay (currently in development), an automated and rapid ultrasensitive immunoassay powered by single-molecule counting technology, for detection of C. difficile toxin A (TcdA) and toxin B (TcdB) in stool. The analytical sensitivity, analytical specificity, repeatability, and stability of the assay were determined. In a clinical evaluation, frozen stool samples from 311 patients with suspected C. difficile infection were tested with the Clarity C. diff toxins A/B assay, using an established cutoff value. Samples were tested with the Xpert C. difficile/Epi assay, and PCR-positive samples were tested with an enzyme immunoassay (EIA) (C. Diff Quik Chek Complete). EIA-negative samples were further tested with a cell cytotoxicity neutralization assay. The limits of detection for TcdA and TcdB were 0.8 and 0.3 pg/ml in buffer and 2.0 and 0.7 pg/ml in stool, respectively. The assay demonstrated reactivity to common C. difficile strains, did not show cross-reactivity to common gastrointestinal pathogens, was robust against common interferents, allowed detection in fresh and frozen stool samples and in samples after three freeze-thaw cycles, and provided results with high reproducibility. Compared to multistep PCR and toxin-testing procedures, the Singulex Clarity C. diff toxins A/B assay yielded 97.7% sensitivity and 100% specificity. The Singulex Clarity C. diff toxins A/B assay is ultrasensitive and highly specific and may offer a standalone solution for rapid detection and quantitation of free toxins in stool.

Ultrasensitive quantification of cardiac troponin I by a Single Molecule Counting method: analytical validation and biological features

AIM

To evaluate analytical and biological characteristics of the Singulex Clarity® cTnI assay, based upon Single Molecule Counting technology.

METHODS

Assay's analytical sensitivity, precision, linearity, hook effect, cross-reactivity or interference by endogenous and exogenous substances, stability, 99th reference percentile [p99th] in EDTA plasma were evaluated in single or multi-site studies.

RESULTS

Detection limit was 0.12 ng/L. Sensitivity was 0.14 ng/L at 20% CV (functional sensitivity) and 0.53 ng/L at 10% CV. Imprecision was 3.16%-10.0% in a multi-lot, single-site study, and 5.5%-12.0% in a single-lot, multi-site study; assay was linear from 0.08 to 25,000 ng/L. No hook effect was observed; any cross-reactivity/interference exceeded the 10%. Healthy subjects were recruited using clinical history, normal NT-proBNP and eGFR (n = 560) or plasma creatinine (n = 535) as inclusion criteria. cTnI was detectable in 96.8% of healthy subjects. The p99th were 8.01 (eGFR used) and 8.15 ng/L (plasma creatinine); both were measured with ≤5.7% CV. Median cTnI were significantly higher in older and male than in young and female subjects.

CONCLUSIONS

The Singulex Clarity cTnI assay show analytical features and % detection in healthy subjects that improve the corresponding values of most of the existing high-sensitivity cTnI assays.

High-Sensitivity Troponin I Levels and Coronary Artery Disease Severity, Progression, and Long-Term Outcomes

Background

The associations between high‐sensitivity troponin I (hsTnI) levels and coronary artery disease (CAD) severity and progression remain unclear. We investigated whether there is an association between hsTnI and angiographic severity and progression of CAD and whether the predictive value of hsTnI level for incident cardiovascular outcomes is independent of CAD severity.

Methods and Results

In 3087 patients (aged 63±12 years, 64% men) undergoing cardiac catheterization without evidence of acute myocardial infarction, the severity of CAD was calculated by the number of major coronary arteries with ≥50% stenosis and the Gensini score. CAD progression was assessed in a subset of 717 patients who had undergone ≥2 coronary angiograms >3 months before enrollment. Patients were followed up for incident all‐cause mortality and incident cardiovascular events. Of the total population, 11% had normal angiograms, 23% had nonobstructive CAD, 20% had 1‐vessel CAD, 20% had 2‐vessel CAD, and 26% had 3‐vessel CAD. After adjusting for age, sex, race, body mass index, smoking, hypertension, diabetes mellitus history, and renal function, hsTnI levels were independently associated with the severity of CAD measured by the Gensini score (log 2 ß=0.31; 95% confidence interval, 0.18–0.44; P<0.001) and with CAD progression (log 2 ß=0.36; 95% confidence interval, 0.14–0.58; P=0.001). hsTnI level was also a significant predictor of incident death, cardiovascular death, myocardial infarction, revascularization, and cardiac hospitalizations, independent of the aforementioned covariates and CAD severity.

Conclusions

Higher hsTnI levels are associated with the underlying burden of coronary atherosclerosis, more rapid progression of CAD, and higher risk of all‐cause mortality and incident cardiovascular events. Whether more aggressive treatment aimed at reducing hsTnI levels can modulate disease progression requires further investigation.

High-Sensitivity Cardiac Troponin and New-Onset Heart Failure: A Systematic Review and Meta-Analysis of 67,063 Patients With 4,165 Incident Heart Failure Events

OBJECTIVES

The aim of this study was to systematically collate and appraise the available evidence regarding the association between high-sensitivity cardiac troponin (hs-cTn) and incident heart failure (HF) and the added value of hs-cTn in HF prediction.

BACKGROUND

Identification of subjects at high risk for HF and early risk factor modification with medications such as angiotensin-converting enzyme inhibitors may delay the onset of HF. Hs-cTn has been suggested as a prognostic marker for the incidence of first-ever HF in asymptomatic subjects.

METHODS

PubMed, Embase, and Web of Science were systematically searched for prospective cohort studies published before January 2017 that reported associations between hs-cTn and incident HF in subjects without baseline HF. Study-specific multivariate-adjusted hazard ratios (HRs) were pooled using random-effects meta-analysis.

RESULTS

Data were collated from 16 studies with a total of 67,063 subjects and 4,165 incident HF events. The average age was 57 years, and 47% were women. Study quality was high (Newcastle-Ottawa score 8.2 of 9). In a comparison of participants in the top third with those in the bottom third of baseline values of hs-cTn, the pooled multivariate-adjusted HR for incident HF was 2.09 (95% confidence interval [CI]: 1.76 to 2.48; p < 0.001). Between-study heterogeneity was high, with an I² value of 80%. HRs were similar in men and women (2.29 [95% CI: 1.64 to 3.21] vs. 2.18 [95% CI: 1.68 to 2.81]) and for hs-cTnI and hs-cTnT (2.09 [95% CI: 1.53 to 2.85] vs. 2.11 [95% CI: 1.69 to 2.63]) and across other study-level characteristics. Further adjustment for B-type natriuretic peptide yielded a similar HR of 2.08 (95% CI: 1.64 to 2.65). Assay of hs-cTn in addition to conventional risk factors provided improvements in the C index of 1% to 3%.

CONCLUSIONS

Available prospective studies indicate a strong association of hs-cTn with the risk of first-ever HF and significant improvements in HF prediction.

Biomarkers to Predict Cardiovascular Death

This article reviews biomarkers that have been shown to identify subjects at increased risk for cardiovascular death within the general population, in those with established coronary artery disease, and in those with heart failure. Use of biomarkers for risk stratification for sudden cardiac death continues to evolve. It seems that a multimarker strategy for risk stratification using simple measures of circulating proteins and usual clinical risk factors, particularly in patients with known coronary artery disease, can be used to identify patients at near-term risk of death. Whether similar strategies in the general population will prove to be cost-effective needs to be investigated.

High-sensitivity cardiac troponin I and risk of cardiovascular disease in an Australianpopulation-based cohort

Objective

High-sensitivity cardiac troponin I (hs-cTnI) is an emerging biomarker for cardiovascular risk. We examined hs-cTnI as a predictor of mortality and cardiovascular outcomes in an Australian population-based cohort and evaluated if a sex difference exists.

Methods

Serum hs-cTnI was measured in the Busselton Health Study 1994/1995 Cohort (n=3939). Outcome measures were total and cardiovascular mortality, cardiovascular disease (CVD) and coronary heart disease (CHD) events, heart failure and stroke.

Results

Hs-cTnI was detectable (>1.2 ng/L) in 66.1% of participants (males 81.8%, females 54.4%) at baseline. There were 886 deaths (including 361 from CVD) and 940 CVD events during 20-year follow-up. Adjusting for Framingham Risk Score variables, hs-cTnI was a significant predictor of total mortality (HR (95% CI): 1.16 (1.09 to 1.24)), CVD mortality (1.33 (1.23 to 1.44)), CVD events (1.18 (1.11 to 1.25)), CHD events (1.11 (1.03 to 1.20)), heart failure (1.44 (1.31 to 1.58)) and stroke (1.13 (1.03 to 1.24)) per doubling of hs-cTnI at baseline. HRs remained significant in CVD-free individuals at baseline (n=3215), except for CHD events. There were no significant interactions between sex and hs-cTnI as a predictor of outcomes. Compared with individuals with hs-cTnI ≤1.2 ng/L, men with hs-cTnI ≥6.0 ng/L and women with hs-cTnI ≥4.0 ng/L had an HR of 2.18 (1.42 to 3.37) and 1.84 (1.30 to 2.62), respectively, for any CVD event, which persisted in the CVD-free subgroup.

Conclusions

Cardiac troponin I, measured with a high-sensitive assay, is an independent predictor of fatal and non-fatal CVD events and may help identify at-risk individuals in a general population.

Cardiovascular Biomarkers in Hypertensive Patients with Medical Treatment-Results from the Randomized TEAMSTA Protect I Trial

BACKGROUND

High blood pressure (BP) is associated with an increased rate of cardiovascular events and mortality. Cardiovascular biomarkers are able to predict long-term risk in the general population, particularly in diseased cohorts. We undertook an investigation of the effect of 2 different antihypertensive treatments on cardiovascular biomarkers in a randomized trial.

METHODS

The TEAMSTA study included 481 hypertensive patients. They were randomized to either 80-mg telmisartan + 5-mg amlodipine (TA) or 40-mg olmesartan + 12.5-mg hydrochlorothiazide (OH). The trial was performed as a prospective, randomized, double-blinded, controlled, single-center study. We measured BP, high-sensitivity cardiac troponin I (hs-cTnI), high-sensitivity cardiac troponin T (hs-cTnT), B-type natriuretic peptide (BNP), and N-terminal-pro-BNP (NT-proBNP) before randomization and after 6 months.

RESULTS

Individuals were randomized into 2 groups: 230 individuals to the OH-group and 251 to the TA-group. After 6 months of treatment, a reduction in BP (systolic/diastolic) was seen, from 135.2/85.2 mmHg to 122.5/75.7 mmHg with similar effects in both groups. hs-cTnT concentrations were measureable in 26.2% of the study population, while hs-cTnI was detected in 98.3%. hs-cTnI concentrations were significantly reduced from 4.6 to 4.2 ng/L in the overall population, from 4.7 to 4.4 ng/L in the OH-group, and from 4.6 to 4.0 ng/L in the TA-group (all P < 0.001). No significant changes of hs-cTnT were observed. BNP and NT-proBNP concentrations decreased from 15.0 to 12.4 ng/L (P < 0.001) and from 64.8 to 53.3 ng/L (P < 0.001), respectively, after 6 months.

CONCLUSIONS

The reduction in BP was associated with a decrease of high-sensitivity troponin I, BNP, and NT-proBNP concentrations, which might represent a cardiovascular risk reduction.

CLINICAL TRIAL REGISTRATION

EudraCT 2009-017010-68.

High-Sensitivity Cardiac Troponin Concentration and Risk of First-Ever Cardiovascular Outcomes in 154,052 Participants

BACKGROUND

High-sensitivity assays can quantify cardiac troponins I and T (hs-cTnI, hs-cTnT) in individuals with no clinically manifest myocardial injury.

OBJECTIVES

The goal of this study was to assess associations of cardiac troponin concentration with cardiovascular disease (CVD) outcomes in primary prevention studies.

METHODS

A search was conducted of PubMed, Web of Science, and EMBASE for prospective studies published up to September 2016, reporting on associations of cardiac troponin concentration with first-ever CVD outcomes (i.e., coronary heart disease [CHD], stroke, or the combination of both). Study-specific estimates, adjusted for conventional risk factors, were extracted by 2 independent reviewers, supplemented with de novo data from PROSPER (Pravastatin in Elderly Individuals at Risk of Vascular Disease Study), then pooled by using random effects meta-analysis.

RESULTS

A total of 28 relevant studies were identified involving 154,052 participants. Cardiac troponin was detectable in 80.0% (hs-cTnI: 82.6%; hs-cTnT: 69.7%). In PROSPER, positive associations of log-linear shape were observed between hs-cTnT and CVD outcomes. In the meta-analysis, the relative risks comparing the top versus the bottom troponin third were 1.43 (95% confidence interval [CI]: 1.31 to 1.56) for CVD (11,763 events), 1.67 (95% CI: 1.50 to 1.86) for fatal CVD (7,775 events), 1.59 (95% CI: 1.38 to 1.83) for CHD (7,061 events), and 1.35 (95% CI: 1.23 to 1.48) for stroke (2,526 events). For fatal CVD, associations were stronger in North American studies (p = 0.010) and those measuring hs-cTnT rather than hs-cTnI (p = 0.027).

CONCLUSIONS

In the general population, high cardiac troponin concentration within the normal range is associated with increased CVD risk. This association is independent of conventional risk factors, strongest for fatal CVD, and applies to both CHD and stroke.

Association Between High-Sensitivity Cardiac Troponin I and Cardiac Events in Elderly Women

Background

Elderly women are at high risk of coronary heart disease (CHD) and heart failure. High‐sensitivity assays allow detection of cardiac troponin I (hsTnI) well below diagnostic cutoffs for acute coronary syndrome. We investigated the association between these levels with future cardiac events in community‐based ambulant white women aged over 70 years initially recruited for a 5‐year randomized, controlled trial of calcium supplements.

Methods and Results

This was a prospective study of 1081 elderly women without clinical CHD at baseline (1998) or hsTnI above the diagnostic cutoffs for acute coronary syndrome with 14.5‐year follow‐up hospitalization and mortality (events). Two hundred forty‐three (22%) women had CHD events, 163 (15%) myocardial infarction or CHD death (hard CHD), and 109 (10%) heart failure. In 99.6% of available serum samples, hsTnI was above the level of detection (median, 4.5 ng/L; interquartile range, 3.6–5.8). After adjusting for Framingham risk factors, each SD natural log‐transformed hsTnI increase was associated with an increased hazard for CHD (hazard ratio, 1.34; 95% CI, 1.18–1.53; P<0.001) hard CHD (hazard ratio, 1.51; 95% CI, 1.29–1.76; P<0.001), and heart failure (hazard ratio, 1.65; 95% CI, 1.36–1.99; P<0.001). Step‐wise increases in relative hazards were observed with increasing quartiles of hsTnI (P for trend, <0.001), whereas the addition of hsTnI to conventional risk factors modestly improved discrimination indices: Harrell's c‐statistic, net reclassification, and integrated discrimination (P<0.05).

Conclusions

Cardiac troponin I is independently associated with future cardiac events in elderly women without apparent clinical manifestations. The addition of cardiac troponin I to conventional risk factors may modestly improve risk prediction in this setting.

Troponin I and T in relation to cardiac injury detected with electrocardiography in a population-based cohort - The Maastricht Study

Interest in high-sensitivity cardiac troponin I(hs-cTnI) and T(hs-cTnT) has expanded from acute cardiac care to cardiovascular disease(CVD) risk stratification. Whether hs-cTnI and hs-cTnT are interchangeable in the ambulant setting is largely unexplored. Cardiac injury is a mechanism that may underlie the associations between troponin levels and mortality in the general population. In the population-based Maastricht Study, we assessed the correlation and concordance between hs-cTnI and hs-cTnT. Multiple regression analyses were conducted to assess the association of hs-cTnI and hs-cTnT with electrocardiographic (ECG) changes indicative of cardiac abnormalities. In 3016 eligible individuals(mean age,60 ± 8years;50.6%,men) we found a modest correlation between hs-cTnI and hs-cTnT(r = 0.585). After multiple adjustment, the association with ECG changes indicative of cardiac abnormalities was similar for both hs-cTn assays(OR,hs-cTnI:1.72,95%CI:1.40-2.10;OR,hs-cTnT:1.60,95%CI:1.22–2.11). The concordance of dichotomized hs-cTnI and hs-cTnT was κ = 0.397(≥sex-specific 75^th percentile). Isolated high levels of hs-cTnI were associated with ECG changes indicative of cardiac abnormalities(OR:1.93,95%CI:1.01–3.68), whereas isolated high levels of hs-cTnT were not(OR:1.07,95%CI:0.49–2.31). In conclusion, there is a moderate correlation and limited concordance between hs-cTnI and hs-cTnT under non-acute conditions. These data suggest that associations of hs-cTnI and hs-cTnT with cardiac injury detected by ECG are driven by different mechanisms. This information may benefit future development of CVD risk stratification algorithms.

Frontal plane T-wave axis orientation predicts coronary events: Findings from the Moli-sani study

BACKGROUND AND AIMS

The orientation of the frontal plane T-wave axis (T axis) is a reliable measure of ventricular repolarisation. We investigated the association between T-axis and the risk of coronary heart disease (CHD), heart failure (HF), atrial fibrillation (AF), stroke and cardiovascular (CVD) mortality.

METHODS

A sample of 21,287 Moli-sani participants randomly recruited from the general adult (≥35 y) Italian population, free of CVD disease, were followed for a median of 4.4 years. T-axis was measured from a standard 12-lead resting ECG.

RESULTS

After adjusting for CVD risk factors, subjects with abnormal T-axis showed an increase in the risk of both CHD (Hazard Ratio (HR) = 2.65; 95% CI = 1.67-4.21), HF (HR = 2.56; 1.80-3.63), AF (HR = 2.48; 1.56-3.94) and CVD mortality (HR = 2.83; 1.50-5.32). The association with CHD and HF, but not with AF or CVD death, remained significant after further adjustment for ECG abnormalities. Subjects with abnormal T-axis showed higher levels of subclinical inflammation, hs-troponin I and hs-NT-proBNP (p < 0.001 for all). However, further adjustment for troponin I and/or NT-proBNP determined a reduction of HRs ranging from 12.1 to 24.0% for CHD, while additional adjustment for inflammation markers did not change any association.

CONCLUSIONS

An abnormal T-axis orientation is associated with an increased risk of both CHD and HF, independently of common CVD risk factors and other ECG abnormalities. This association was partially explained by increased hs-troponin I and hs-NT-proBNP levels.

Ultra-sensitive troponin I is an independent predictor of incident coronary heart disease in the general population

Troponins are sensitive markers of myocardial injury and predictive of cardiovascular events, but conventional assays fail to detect slightly elevated troponins in a considerable proportion of the general population. Using a novel ultrasensitive assay, we explored the relationship of troponin levels with the incidence of coronary heart disease (CHD) in a case-cohort sample (mean age 52.5 ± 0.2 years, 51.5% women) comprising 803 CHD cases and 1942 non-cases. Ultrasensitive troponin I was detectable in 99.9% of available case-cohort samples. In an age- and sex-adjusted model, individuals in the highest quartile of the troponin distribution had a more than threefold increased risk for CHD events compared to those in the bottom quartile [hazard ratio, HR, 3.11; 95% confidence interval (CI) 2.15-4.49]. In a model adjusting for cardiovascular risk factors including C-reactive protein, cystatin C and N-terminal pro brain natriuretic peptide, individuals in the highest troponin I quartile still showed a hazard ratio of 2.58 (95% CI 1.66-4.00) for incident CHD as compared to those in the lowest quartile. Ultrasensitive troponin I was detectable in almost all individuals of a study sample reflecting middle-aged to elderly European general population. Ultrasensitive troponin concentrations exhibit an independent, graded, positive relation with incident CHD.

Early diagnosis of acute myocardial infarction using high-sensitivity troponin I

Objective

There is a clinical need for early and accurate diagnosis of acute myocardial infarction (AMI). Current European Society of Cardiology (ESC) guidelines recommend diagnosis of non-ST-elevation AMI based on serial troponin measurements. We aimed to challenge the ESC guidelines using 1) a high-sensitivity troponin I (hs-TnI) baseline cutoff, 2) an absolute hs-TnI change after 1 hour and 3) additional application of an ischemic ECG.

Methods

1,516 patients with suspected AMI presenting to the emergency department were included. Hs-TnI was measured directly at admission, after 1 and 3 hours. We investigated baseline concentrations, absolute changes of hs-TnI and additional application of an ischemic ECG to diagnose AMI. A positive predictive value (PPV) of more than 85% was targeted.

Results

The median age of the study population was 65 years; 291 patients were diagnosed with AMI. The PPV of the 3-hours ESC algorithm was 85.5% (CI 79.7, 90.1) and 65.8% (CI 60.5,70.8) for the 1-hour algorithm. Using a high baseline hs-TnI concentration of 150 ng/L resulted in a PPV of 87.8% (CI 80.9,92.9). Alternatively, a hs-TnI change of 20 ng/L after 1 hour, resulted in a PPV of 86.5% (80.9,91.0), respectively for the diagnosis of AMI. Additional use of an ischemic ECG increased the PPV to 90.5% (CI 83.2,95.3), while reducing the efficacy.

Conclusion

The diagnosis of AMI based on hs-TnI is challenging. The application of absolute hs-TnI changes after 1 hour may facilitate rapid rule-in of patients.

Trial registration

www.clinicaltrials.gov (NCT02355457).

Higher prevalence of detectable troponin I among cocaine-users without known cardiovascular disease

BACKGROUND

While cocaine use is an established risk factor for acute cardiovascular complications, associations between cocaine use and markers of cardiac injury outside of acute hospital presentation remain poorly characterized. We leveraged advances in cardiac troponin (cTnI) testing to assess low but clinically meaningful levels of cardiac injury among cocaine users and non-users.

METHODS

We conducted a case control study comparing cTnI levels by the presence of cocaine among patients presenting for non-cardiac care in an urban safety net hospital. Samples were chosen sequentially among those for which urine drug screens were ordered by providers hospital-wide.

RESULTS

During 2015, 14% of all hospital drug screens ordered were cocaine-positive. Among unique persons providing cocaine-positive (N=100) and cocaine-negative (N=100) samples, 37% were female, 45% were African-American and the median age was 51. Detectable cTnI (> 0.02ng/mL) was observed in 21 samples (11%). It was more common in subjects using cocaine (Adjusted OR=2.81; 95% CI=1.03-7.65), but not other drugs. Moreover, there was a significant correlation between concentrations of cTnI and the cocaine metabolite, benzoylecgonine (Spearman Correlation=0.34, p<0.01).

CONCLUSIONS

Among urban safety net hospital patients, 11% had detectable cTnI, and cTnI concentration was significantly correlated with benzoylecgonine concentration. While these preliminary results require additional confirmation, they suggest the potential utility of considering cocaine use as more than just an episodic exposure leading to acute cardiac events. The consideration of cocaine use as an ongoing chronic exposure leading to subclinical cardiac injury may improve risk-stratification and patient outcomes in populations where cocaine use is high.

Prognostic value of basal high-sensitive cardiac troponin levels on mortality in the general population: A meta-analysis

Interest in the use of cardiac troponin T (cTnT) and cardiac troponin I (cTnI) has expanded from diagnosis of acute myocardial infarction to risk assessment for morbidity and mortality. Although cTnT and cTnI were shown to have equivalent diagnostic performance in the setting of suspected acute myocardial infarction, potential prognostic differences are largely unexplored.The aim of this study is to quantify and compare the relationship between cTnT and cTnI, and cardiovascular and all-cause mortality in the general population.Medline, Embase, and the Cochrane Library (from inception through October 2016) were searched for prospective observational cohort studies reporting on the prognostic value of basal high-sensitive cTnT and/or cTnI levels on cardiovascular and all-cause mortality in the general population. Data on study characteristics, participants' characteristics, outcome parameters, and quality [according to the Effective Public Health Practice Project (EPHPP) "Quality Assessment Tool For Quantitative Studies] were retrieved. Hazard ratios per standard deviation increase in basal cardiac troponin level (HR per 1-SD; retrieved from the included articles or estimated) were pooled using a random-effects model.On a total of 2585 reviewed citations, 11 studies, with data on 65,019 participants, were included in the meta-analysis. Random effects pooling showed significant associations between basal cardiac troponin levels and HR for cardiovascular and all-cause mortality [HR per 1-SD 1.29 (95% confidence interval, 95% CI, 1.20-1.38) and HR per 1-SD 1.18 (95% CI, 1.11-1.26), respectively]. Stratified analyses showed higher HRs for cTnT than cTnI [cardiovascular mortality: cTnT HR per 1-SD 1.37 (95% CI, 1.23-1.52); and cTnI HR per 1-SD 1.21 (95% CI, 1.16-1.26); all-cause mortality: cTnT HR per 1-SD 1.31 (955 CI, 1.13-1.53); and cTnI HR per 1-SD 1.14 (95% CI, 1.06-1.22)]. These differences were significant (P < 0.01) in meta-regression analyses for cardiovascular mortality but did not reach statistical significance for all-cause mortality.Elevated, basal cTnT, and cTnI show robust associations with an increased risk of cardiovascular and all-cause mortality during follow-up in the general population.Systematic review registration number PROSPERO CRD42014006964.

Troponin I and cardiovascular risk prediction in the general population: the BiomarCaRE consortium

Aims

Our aims were to evaluate the distribution of troponin I concentrations in population cohorts across Europe, to characterize the association with cardiovascular outcomes, to determine the predictive value beyond the variables used in the ESC SCORE, to test a potentially clinically relevant cut-off value, and to evaluate the improved eligibility for statin therapy based on elevated troponin I concentrations retrospectively.

Methods and results

Based on the Biomarkers for Cardiovascular Risk Assessment in Europe (BiomarCaRE) project, we analysed individual level data from 10 prospective population-based studies including 74 738 participants. We investigated the value of adding troponin I levels to conventional risk factors for prediction of cardiovascular disease by calculating measures of discrimination (C-index) and net reclassification improvement (NRI). We further tested the clinical implication of statin therapy based on troponin concentration in 12 956 individuals free of cardiovascular disease in the JUPITER study. Troponin I remained an independent predictor with a hazard ratio of 1.37 for cardiovascular mortality, 1.23 for cardiovascular disease, and 1.24 for total mortality. The addition of troponin I information to a prognostic model for cardiovascular death constructed of ESC SCORE variables increased the C-index discrimination measure by 0.007 and yielded an NRI of 0.048, whereas the addition to prognostic models for cardiovascular disease and total mortality led to lesser C-index discrimination and NRI increment. In individuals above 6 ng/L of troponin I, a concentration near the upper quintile in BiomarCaRE (5.9 ng/L) and JUPITER (5.8 ng/L), rosuvastatin therapy resulted in higher absolute risk reduction compared with individuals <6 ng/L of troponin I, whereas the relative risk reduction was similar.

Conclusion

In individuals free of cardiovascular disease, the addition of troponin I to variables of established risk score improves prediction of cardiovascular death and cardiovascular disease.

High-sensitivity cardiac troponin I and incident coronary heart disease among asymptomatic older adults

OBJECTIVE

High-sensitivity cardiac troponin I (hs-cTnI) is a novel biomarker of myocardial injury and ischaemia. Our objective was to ascertain correlates of hs-cTnI and its incremental prognostic utility for incident coronary heart disease (CHD) among older asymptomatic subjects.

METHODS

We performed a cohort study among 1135 asymptomatic control participants in the ADVANCE (Atherosclerotic Disease, VAscular FunctioN and GenetiC Epidemiology) study at Kaiser Permanente Northern California and Stanford University, with follow-up through 31 December 2014. Hs-cTnI was measured in stored baseline (2002-2004) serum samples.

RESULTS

After a median follow-up of 11.3 years, 164 CHD events were documented. The most significant correlates of hs-cTnI were black race, body mass index, hypertension, LDL cholesterol and estimated glomerular filtration rate (eGFR) (R(2)=0.16) After adjustment for race/ethnicity, education level, diabetes status, ATP-III Framingham risk score (FRS), C reactive protein and eGFR, each 1 SD increment of log-transformed Hs-cTnI was associated with 1.11 (95% CI 1.01 to 1.23, p=0.04) increased hazard of CHD. The c-statistic increased to 0.70 from 0.68 (p=0.16) and the category-based net reclassification index was 18% (95% CI 8% to 30%) after adding hs-cTnI to the model containing the ATP-III FRS.

CONCLUSIONS

Hs-cTnI conveys incremental prognostic information for incident CHD among asymptomatic older adults.

Novel biomarkers for cardiovascular risk assessment: current status and future directions

Cardiovascular disease (CVD) is the leading cause of mortality in the modern world. Traditional risk algorithms may miss up to 20% of CVD events. Therefore, there is a need for new cardiac biomarkers. Many fields of research are dedicated to improving cardiac risk prediction, including genomics, transcriptomics and proteomics. To date, even the most promising biomarkers have only demonstrated modest associations and predictive ability. Few have undergone randomized control trials. A number of biomarkers are targets to new therapies aimed to reduce cardiovascular risk. Currently, some of the most promising risk prediction has been demonstrated with panels of multiple biomarkers. This article reviews the current state and future of proteomic biomarkers and aggregate biomarker panels.

Fully automated ultrasensitive digital immunoassay for cardiac troponin I based on single molecule array technology

BACKGROUND

The association between increases in cardiac troponin and adverse cardiac outcomes is well established. There is a growing interest in exploring routine cardiac troponin monitoring as a potential early indicator of adverse heart health trends. Prognostic use of cardiac troponin measurements requires an assay with very high sensitivity and outstanding analytical performance. We report development and preliminary validation of an investigational assay meeting these requirements and demonstrate its applicability to cohorts of healthy individuals and patients with heart failure.

METHODS

On the basis of single molecule array technology, we developed a 45-min immunoassay for cardiac troponin I (cTnI) for use on a novel, fully automated digital analyzer. We characterized its analytical performance and measured cTnI in healthy individuals and heart failure patients in a preliminary study of assay analytical efficacy.

RESULTS

The assay exhibited a limit of detection of 0.01 ng/L, a limit of quantification of 0.08 ng/L, and a total CV of 10% at 2.0 ng/L. cTnI concentrations were well above the assay limit of detection for all samples tested, including samples from healthy individuals. cTnI was significantly higher in heart failure patients, and exhibited increasing median and interquartile concentrations with increasing New York Heart Association classification of heart failure severity.

CONCLUSIONS

The robust 2-log increase in sensitivity relative to contemporary high-sensitivity cardiac troponin immunoassays, combined with full automation, make this assay suitable for exploring cTnI concentrations in cohorts of healthy individuals and for the potential prognostic application of serial cardiac troponin measurements in both apparently healthy and diseased individuals.