High-Sensitivity Cardiac Troponin I Measurement for Risk Stratification in a Stable High-Risk Population

High-sensitivity Troponin (hs-Tn) for Cardiovascular Risk Prognostication: A Systematic Review and Meta-analysis

BACKGROUND

Chronic low-grade inflammation is involved in coronary atherosclerosis progression whereas recent research efforts suggest that preventative methods should be tailored to the "residual inflammatory risk". As such, modalities for the early identification of the risk have to be investigated.

METHODS

We performed a systematic review and meta-analysis according to the PRISMA guidelines. Any study that presented the prognostic value of high sensitivity troponin (hs-cTn) of vascular inflammation in stable patients without known cardiac heart disease was considered to be potentially eligible. The Medline (PubMed) database was searched up to April 22, 2021. The main endpoint was the difference in c-index (Δ[c-index]) with the use of hs-cTn for major adverse cardiovascular events (MACEs), cardiovascular and all-cause mortality. We calculated I2 to test heterogeneity.

RESULTS

In total, 44 studies and 112,288 stable patients without known coronary heart disease were included in this meta-analysis. The mean follow-up duration of the whole cohort was 6.8 ± 1.1 years. 77,004 (68.5%) of the patients presented at low cardiovascular risk while 35,284 (31.5%) in high. The overall pooled estimate of Δ[c-index] for MACE was 1.4% (95%CI: 0.7-2.1, I2=0%) and for cardiovascular death 1.3% (95%CI: 0.3-2.3, I2=0%). Finally, the overall pooled estimate of Δ[c-index] for all-cause mortality was 3% (95%CI: 1.9-3.9, I2=86%), while high heterogeneity was observed between the studies.

CONCLUSION

The predictive usefulness of changes in hs-cTn measures in stable individuals with either high or low cardiovascular risk, demonstrates that assessing vascular inflammation in addition to clinical risk factors enhances risk prediction for cardiovascular events and allcause mortality. Further prospective studies are necessary to confirm these findings and assist clinical decision-making regarding the most optimal prevention strategy.

High Sensitivity Troponin Level and Benefits of Chronic Total Occlusion Revascularization

Background The survival benefit of revascularization of chronic total occlusion (CTO) of the coronary arteries remains a subject of controversy. We measured high sensitivity troponin-I (hsTn-I) levels as an estimate of myocardial ischemia in patients with stable coronary artery disease, with the hypothesis that (1) patients with CTO have higher levels of hsTn-I than patients without CTO, (2) hsTn-I levels will predict adverse cardiovascular events in patients with CTO, and (3) patients with elevated hsTn-I levels will have a survival benefit from CTO revascularization. Methods and Results In 428 patients with stable coronary artery disease and CTO undergoing coronary angiography, adverse event rates were investigated. Cox proportional hazards models and Fine and Gray subdistribution hazard models were performed to determine the association between hsTn-I level and incident event rates in patients with CTO. HsTn-I levels were higher in patients with compared with those without CTO (median 6.7 versus 5.6 ng/L, P=0.002). An elevated hsTn-I level was associated with higher adverse event rates (adjusted all-cause mortality hazard ratio, 1.19 [95% CI, 1.08-1.32]; P=0.030) for every doubling of hsTn-I level. CTO revascularization was performed in 28.3% of patients. In patients with a high (>median) hsTn-I level, CTO revascularization was associated with substantially lower all-cause mortality (adjusted hazard ratio, 0.26 [95% CI, 0.08-0.88]; P=0.030) compared with those who did not undergo revascularization. In patients with a low ( Collapse

Key Words

• chronic total occlusion
• coronary artery bypass graft
• high sensitivity troponin‐I
• percutaneous coronary intervention

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MESH Headings

• Humans
• Coronary Artery Disease/complications
• Coronary Occlusion
• Risk Factors
• Treatment Outcome
• Percutaneous Coronary Intervention/adverse effects
• Coronary Angiography/adverse effects
• Chronic Disease
• Troponin I

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Grants

• U54 AG062334 NIA NIH HHS
• P01 HL154996 NHLBI NIH HHS
• R33 HL138657 NHLBI NIH HHS
• P01 HL086773 NHLBI NIH HHS
• P30 DK111024 NIDDK NIH HHS
• R01 HL109413 NHLBI NIH HHS
• R01 HL166004 NHLBI NIH HHS
• R61 HL154116 NHLBI NIH HHS
• P20 HL113451 NHLBI NIH HHS
• P01 HL101398 NHLBI NIH HHS

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Affiliation(s)

Daniel A. Gold Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Pratik B. Sandesara Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Vardhmaan Jain Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Matthew E. Gold Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Nishant Vatsa Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Shivang R. Desai Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Malika Elhage Hassan Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Chenyang Yuan Department of Biostatistics and Bioinformatics, Rollins School of Public HealthEmory UniversityAtlantaGA
Yi‐An Ko Department of Biostatistics and Bioinformatics, Rollins School of Public HealthEmory UniversityAtlantaGA
Ayman Alkhoder Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Kiran Ejaz Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Zain Alvi Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Alireza Rahbar Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Gillian Murtagh Abbott Diagnostics, Abbott LaboratoriesAbbott ParkIL
Wissam A. Jaber Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
William J. Nicholson Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Arshed A. Quyyumi Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA

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Storage conditions, sample integrity, interferences, and a decision tool for investigating unusual high-sensitivity cardiac troponin results

The current definition of high-sensitivity cardiac troponin (hs-cTn) assays is laboratory-based and their analytical attributes and characteristics have drawn significant attention in the literature at least partly due to the lower concentration cut-offs and changes in concentrations (i.e., deltas) employed in different algorithms and pathways to manage patient care. We propose that pre-analytical conditions such as sample type, storage conditions, and other interferences may also have a significant impact on hs-cTn concentrations and clinical management. The purpose of this literature review is to provide a summary of important pre-analytical and interference studies affecting hs-cTn concentrations. A breakdown of the literature for the major diagnostic companies providing core laboratory instrumentation (i.e., Abbott, Beckman, Ortho, Roche, and Siemens) is also provided. Finally, three cases are highlighted where knowledge of pre-analytical factors aids the hs-cTn clinically discordant investigations. This review highlights the importance of pre-analytical variables, especially storage condition, sample handling, and blood tubes used (i.e., sample type) when interpreting hs-cTn assays. Additional studies are needed to further elaborate on pre-analytical variables (i.e., centrifugation, sample type, stability) and interferences for all hs-cTn assays in clinical use, as knowledge of these variables may aid in hs-cTn clinically discordant investigations.

Metal-organic frameworks-assisted nonenzymatic cascade amplification multiplexed strategy for sensing acute myocardial infarction related microRNAs

Amplification strategies for multiple microRNAs (miRNAs) detection are pivotal for acute myocardial infarction (AMI). Herein, we rationally developed a metal-organic frameworks-assisted nonenzymatic cascade amplification strategy for simultaneous quantification of three AMI-related miRNAs (miR-21, miR-499 and miR-133a). The fluorescence of the elaborately designed DNA molecular beacons with the respective modification of FAM, TAMRA and Cy5 in the terminal was quenched by a metal-organic framework named Fe-MIL-88. When targets miRNA appeared, they hybridized with the corresponding DNA molecular beacons, and the catalyzed hairpin assembly (CHA) reaction would be triggered, producing "Y" shaped three-branched duplex nanostructure with the targets released, and initiating subsequent another cycle. The "Y" shaped nanostructures could not be adsorbed onto the surface of Fe-MIL-88 due to the weaker affinity between Fe-MIL-88 and "Y" shaped nanostructures. Therefore, the fluorescence of "Y" shaped nanostructures could not be quenched by Fe-MIL-88. In this way, three AMI-related miRNAs were simultaneously detected in the respective ranges of 0.05-30 nM, 0.08-30 nM and 0.1-20 nM with respective limits of detection down to 13, 25 and 40 pM. Furthermore, the method was successfully employed to determine three AMI-related miRNAs in human serum. The strategy offered great opportunity for ultrasensitive detecting multiple AMI-related miRNAs and substantially improving the accuracy of clinical early AMI diagnosis.

Expert consensus on peri-operative myocardial injury screening in noncardiac surgery: A literature review

Peri-operative myocardial injury, detected by dynamic and elevated cardiac troponin (cTn) concentrations, is a common complication of noncardiac surgery that is strongly associated with 30-day mortality. Although active screening for peri-operative myocardial injury has been suggested in recent guidelines, clinical implementation remains tentative due to a lack of examples on how to tackle such an interdisciplinary project at a local level. Moreover, consensus on which assay and cTn cut-off values should be used has not yet been reached, and guidance on whom to screen is lacking. In this article, we aim to summarise local examples of successfully implemented cTn screening practices and review the current literature in order to provide information and suggestions for patient selection, organisation of a screening programme, caveats and a potential management pathway.

A Test in Context: Interpretation of High-Sensitivity Cardiac Troponin Assays in Different Clinical Settings

High-sensitivity cardiac troponin (hs-cTn) assays have the ability to detect minute troponin concentrations and resolve minor changes in biomarker concentrations. Clinically, this allows for the ability to rapidly identify or exclude acute myocardial injury in the setting of acute chest discomfort-thus providing more rapid evaluation for acute myocardial infarction-but the improvements in troponin assays also create avenues for other applications where troponin release from the cardiomyocyte might confer prognostic information. These situations include cardiovascular risk assessment across a wide range of clinical circumstances, including apparently-well individuals, those at risk for heart disease, and those with prevalent cardiovascular disorders. The optimal hs-cTn threshold for each circumstance varies by the assay used and by the population assessed. This review will provide context for how hs-cTn assays might be interpreted depending on the application sought, reviewing results from studies leveraging hs-cTn for applications beyond "acute myocardial infarction diagnostic evaluation."

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.'

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.

Convalescent troponin and cardiovascular death following acute coronary syndrome

OBJECTIVES

High-sensitivity cardiac troponin testing is used in the diagnosis of acute coronary syndromes but its role during convalescence is unknown. We investigated the long-term prognostic significance of serial convalescent high-sensitivity cardiac troponin concentrations following acute coronary syndrome.

METHODS

In a prospective multicentre observational cohort study of 2140 patients with acute coronary syndrome, cardiac troponin I concentrations were measured in 1776 patients at 4 and 12 months following the index event. Patients were stratified into three groups according to the troponin concentration at 4 months using the 99th centile (women>16 ng/L, men>34 ng/L) and median concentration of those within the reference range. The primary outcome was cardiovascular death.

RESULTS

Troponin concentrations at 4 months were measurable in 99.0% (1759/1776) of patients (67±12 years, 72% male), and were ≤5 ng/L (median) and >99th centile in 44.8% (795) and 9.3% (166), respectively. There were 202 (11.4%) cardiovascular deaths after a median of 4.8 years. After adjusting for the Global Registry of Acute Coronary Events score, troponin remained an independent predictor of cardiovascular death (HR 1.4, 95% CI 1.3 to 1.5 per doubling) with the highest risk observed in those with increasing concentrations at 12 months. Patients with 4-month troponin concentrations >99th centile were at increased risk of cardiovascular death compared with those ≤5 ng/L (29.5% (49/166) vs 4.3% (34/795); adjusted HR 4.9, 95% CI 3.8 to 23.7).

CONCLUSIONS

Convalescent cardiac troponin concentrations predict long-term cardiovascular death following acute coronary syndrome. Recognising this risk by monitoring troponin may improve targeting of therapeutic interventions.

TRIAL REGISTRATION NUMBER

ACTRN12605000431628;Results.

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 99^th 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 99^th 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.

Use of High-Sensitivity Cardiac Troponin for the Exclusion of Inducible Myocardial Ischemia: A Cohort Study

BACKGROUND

Many patients with coronary artery disease (CAD) are routinely referred for surveillance stress testing despite recommendations against it.

OBJECTIVE

To determine whether low levels of resting high-sensitivity cardiac troponin I (hs-cTnI) can identify persons without inducible myocardial ischemia.

DESIGN

Observational study.

SETTING

A university-affiliated hospital network.

PATIENTS

Persons with stable CAD: 589 in the derivation group and 118 in the validation cohort.

MEASUREMENTS

Presence of inducible myocardial ischemia was determined by myocardial perfusion imaging with technetium-99m single-photon emission computed tomography during either treadmill or pharmacologic stress testing. Resting plasma hs-cTnI was measured within 1 week of the stress test, and the negative predictive value (NPV) for inducible ischemia was calculated. The derivation cohort was followed for 3 years for incident cardiovascular death and myocardial infarction.

RESULTS

In the derivation cohort, 10 of 101 patients with an hs-cTnI level below 2.5 pg/mL had inducible myocardial ischemia (NPV, 90% [95% CI, 83% to 95%]) and 3 of 101 had inducible ischemia involving at least 10% of the myocardium (NPV, 97% [CI, 92% to 99%]). In the validation cohort, 4 of 32 patients with an hs-cTnI level below 2.5 pg/mL had inducible ischemia (NPV, 88% [CI, 71% to 96%]) and 2 of 32 had ischemia of 10% or greater (NPV, 94% [CI, 79% to 99%]). After a median follow-up of 3 years in the derivation cohort, no adverse events occurred in patients with an hs-cTnI level below 2.5 pg/mL, compared with 33 (7%) cardiovascular deaths or incident myocardial infarctions among those with an hs-cTnI level of 2.5 pg/mL or greater.

LIMITATION

The data may not be applicable to a population without known CAD or to persons with unstable angina, and the modest sample sizes warrant further validation in a larger cohort.

CONCLUSION

Very low hs-cTnI levels may be useful in excluding inducible myocardial ischemia in patients with stable CAD.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Assessing matrix, interferences and comparability between the Abbott Diagnostics and the Beckman Coulter high-sensitivity cardiac troponin I assays

Background:

Analytical evaluation of high-sensitivity cardiac troponin (hs-cTn) assays, with particular attention to imprecision, interferences and matrix effects, at normal cTn concentrations, is of utmost importance as many different clinical algorithms use concentration cutoffs <10 ng/L for decision-making. The objective for the present analytical study was to compare the new Beckman Coulter hs-cTnI assay (Access hsTnI) to Abbott’s hs-cTnI assay in different matrices and for different interferences, with a focus on concentrations <10 ng/L.

Methods:

The limit of blank (LoB) and the limit of detection (LoD) were determined in different matrices for the Beckman hs-cTnI assay. Passing-Bablok regression and difference plots were determined for 200 matched lithium heparin and EDTA plasma samples for the Beckman assay and 200 lithium heparin samples for the Abbott assay. Both EDTA and heparin plasma samples were also evaluated for stability under refrigerated conditions, for endogenous alkaline phosphatase interference and for hemolysis and icterus.

Results:

The Beckman hs-cTnI assay LoB was 0.5 ng/L with the following range of LoDs=0.8–1.2 ng/L, with EDTA plasma yielding lower concentrations as compared to lithium heparin plasma (mean difference=−14.9%; 95% CI=−16.9 to 12.9). Below 10 ng/L, lithium heparin cTnI results from the Beckman assay were on average 1.1 ng/L (95% CI=0.7 to 1.5) higher than the Abbott results, with no difference between the methods when using EDTA plasma (mean difference =−0.1 ng/L; 95% CI=−0.3 to 0.2). Low cTnI concentrations were less effected by interferences in EDTA plasma.

Conclusions:

The Access hsTnI method can reliably detect normal cTnI concentrations with both lithium heparin and EDTA plasma being suitable matrices.

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.

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.

Variability and Error in Cardiac Troponin Testing: An ACLPS Critical Review

OBJECTIVES

To provide a comprehensive overview of the complexities associated with cardiac troponin (cTn) testing. An emphasis is placed on the sources of error, organized into the preanalytical, analytical, and postanalytical phases of the testing pathway. Controversial areas are also explored.

METHODS

A case scenario and review of the relevant literature describing laboratory considerations involving cTn testing are described.

RESULTS

Advanced comprehension of the specific assay used in a given laboratory is necessary for optimal reporting, utilization, and quality monitoring of cTn.

CONCLUSIONS

cTn assays are reliable diagnostic tests for acute myocardial infarction, but understanding their limitations is required for appropriate result interpretation.

The prognostic value of highly sensitive cardiac troponin assays for adverse events in men and women with stable heart failure and a preserved vs. reduced ejection fraction

AIMS

Circulating biomarkers are important in the diagnosis, risk stratification and management of patients with heart failure (HF). Given the current lack of biomarkers in HF with preserved ejection fraction (HFpEF), we aimed to investigate the prognostic performance of the newly developed high-sensitivity (hs) assays for cardiac troponin I (hsTnI) compared with troponin T (hsTnT) for adverse events in HFpEF vs. HF with reduced ejection fraction (HFrEF). Findings in these two HF subgroups were also compared with those in the recently defined HF with mid-range ejection fraction (HFmrEF) subgroup.

METHODS AND RESULTS

Both hsTnI and hsTnT were measured in 1096 patients with HFrEF [left ventricular ejection fraction (LVEF) <50%; n = 853] or HFpEF (LVEF ≥50%; n = 243) enrolled in the Singapore Heart Failure Outcomes and Phenotypes (SHOP) study. Both troponin assays were more strongly associated with the composite endpoint (all-cause mortality or first rehospitalization for HF) in HFpEF than in HFrEF. The hsTnT assay provided the greatest additional prognostic value in HFpEF in comparison with hsTnI and NT-proBNP. TnI was more strongly associated with composite events in men with HFpEF [hazard ratio (HR) 3.33, 95% confidence interval (CI) 1.82-6.09; P < 0.001 per standard deviation (SD) increase in log-transformed hsTnI] than in women with HFpEF (HR 1.35, 95% CI 0.94-1.93; P = 0.10 per SD increase in log-transformed hsTnI).

CONCLUSIONS

There is a potential role for the prognostic use of high-sensitivity troponin assays, particularly hsTnT, in men and women with HFpEF. The predictive association of hsTnI with outcome appears strongest in men with HFpEF.

High-Sensitivity Cardiac Troponin, Statin Therapy, and Risk of Coronary Heart Disease

BACKGROUND

Cardiac troponin is an independent predictor of cardiovascular mortality in individuals without symptoms or signs of cardiovascular disease. The mechanisms for this association are uncertain, and a role for troponin testing in the prevention of coronary heart disease has yet to be established.

OBJECTIVES

This study sought to determine whether troponin concentration could predict coronary events, be modified by statins, and reflect response to therapy in a primary prevention population.

METHODS

WOSCOPS (West of Scotland Coronary Prevention Study) randomized men with raised low-density lipoprotein cholesterol and no history of myocardial infarction to pravastatin 40 mg once daily or placebo for 5 years. Plasma cardiac troponin I concentration was measured with a high-sensitivity assay at baseline and at 1 year in 3,318 participants.

RESULTS

Baseline troponin was an independent predictor of myocardial infarction or death from coronary heart disease (hazard ratio [HR]: 2.3; 95% confidence interval [CI]: 1.4 to 3.7) for the highest (≥5.2 ng/l) versus lowest (≤3.1 ng/l) quarter of troponin (p < 0.001). There was a 5-fold greater reduction in coronary events when troponin concentrations decreased by more than a quarter, rather than increased by more than a quarter, for both placebo (HR: 0.29; 95% CI: 0.12 to 0.72 vs. HR: 1.95; 95% CI: 1.09 to 3.49; p < 0.001 for trend) and pravastatin (HR: 0.23; 95% CI: 0.10 to 0.53 vs. HR: 1.08; 95% CI: 0.53 to 2.21; p < 0.001 for trend). Pravastatin reduced troponin concentration by 13% (10% to 15%; placebo adjusted, p < 0.001) and doubled the number of men whose troponin fell more than a quarter (p < 0.001), which identified them as having the lowest risk for future coronary events (1.4% over 5 years).

CONCLUSIONS

Troponin concentration predicts coronary events, is reduced by statin therapy, and change at 1 year is associated with future coronary risk independent of cholesterol lowering. Serial troponin measurements have major potential to assess cardiovascular risk and monitor the impact of therapeutic interventions.

High-Sensitivity Troponin Release Profile After Cardiac Surgery

BACKGROUND

Postoperative serum troponin levels and perioperative myocardial infarction (MI) rates correlate with mortality and morbidity following cardiac surgery. The objective of this study was to document the release profile of high sensitivity troponin T (hsTnT) following different cardiac operations.

METHODS

Patients undergoing one of five different isolated cardiac surgical procedures (eligible preoperative hsTnT <29ng/L, serum creatinine < 0.2mmol/L) were recruited prospectively. Serum hsTnT was measured at 0, 4, 6, 8, 10, 12, 24 and 72hours after the first surgical insult to myocardium, together with daily electrocardiographs.

RESULTS

There were 10 patients in the on-pump coronary artery bypass group and 5 each in the remaining groups (off-pump coronary artery bypass, open aortic valve replacement, transcutaneous aortic valve implantation and mitral valve replacement). Five additional patients were excluded due to perioperative MI or renal failure. Median [range] of peak hsTnT was 241[99-566], 64[50-136], 353[307-902], 115[112-275], and 918[604-1166] ng/L, respectively. Operations with the lowest peak hsTnT values peaked earliest (four hours) while those with highest values peaked latest (eight hours).

CONCLUSION

After cardiac surgery, the hsTnT profile peaks four to eight hours after the initial surgical insult. The magnitude and timing of the peak correlates to the expected degree of surgically-induced myocardial injury.

Relationship between hsTnI and coronary stenosis in asymptomatic women with rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is a condition associated with accelerated progression of atherosclerosis in affected individuals. Myocardial assessment using exercise testing in such patients, however, is often difficult to perform. Our objective was to determine the factors associated with severe coronary stenosis using computed tomography (CT) angiography of the coronary arteries in asymptomatic patients with RA.

Methods

Forty-four women with RA were examined using CT angiography to detect atherosclerotic involvement and significant coronary stenosis (>50 %). CT findings were correlated with the cardiovascular risk score, and with classical and most recent parameters of atherosclerosis.

Results

CT angiography of the coronary arteries revealed severe stenosis (>70 %) in 9 % of patients. High-sensitivity troponin I level was associated with severe coronary stenosis (odds ratio 6.37; 95 % confidence interval 1.53 − 26.48; P = 0.011). Adjustment for confounders did not alter this result (P = 0.039). In contrast, classical and modified Systemic Coronary Risk Evaluation scores had no value in predicting severe stenosis (P ≥ 0.49).

Conclusion

The present study showed the possible benefits of a coronary CT angiography in women with RA and asymptomatic ischemic coronary heart disease. Increased levels of high-sensitivity troponin I may be a potential indication for this type of examination. However, further studies are needed to confirm these results.

Troponin in Cardiovascular Disease Prevention: Updates and Future Direction

Cardiac troponin has been well described as the preferred biomarker for diagnosis of myocardial infarction due to the high sensitivity and specificity for myocardial injury. Numerous other conditions apart from acute coronary syndrome can also lead to small elevations in troponin levels. However, the use of cTn as prognostic biomarker for the primary assessment of cardiovascular risk in asymptomatic patient has only recently been described. And with the development of newer generations of high-sensitivity cardiac troponin assays that can detect 10-fold lower concentrations of troponin, the potential value cTn in the prevention and management of asymptomatic cardiovascular disease has come to the fore. This review provides an overview of the transition of cardiac troponin as a marker of acute myocardial injury to one that detects sub-clinical injury. Evidence continues to show that high-sensitivity troponin is emerging as one of the most powerful prognostic biomarkers for the assessment of cardiovascular risk in the general population.

Effects of renal denervation on heart failure biomarkers and blood pressure in patients with resistant hypertension

Aim: This multicenter study investigated the effect of renal denervation therapy (RDN) on the heart failure related biomarkers NT-proBNP, ST-2, galectin-3 and hs-TnI. Patients & methods: We included 157 patients with resistant hypertension undergoing RDN. Blood sampling was performed before and 6 months after RDN. Results: Six months after RDN systolic blood pressure (BP) was reduced by 24 mmHg. Biomarker concentrations were not changed after RDN, except a small increase of hs-TnI by 0.3 pg/ml. In individuals with high baseline BP, we observed a BP reduction of 45 mmHg and a decrease of hs-TnI concentrations by 1.2 pg/ml. Conclusion: In this multicenter analysis RDN did significantly reduce systolic BP. However, NT-proBNP, ST-2, galectin-3 and hs-TnI did not correspond to BP reduction 6 months after RDN.

Cardiac troponin as a novel tool for cardiovascular risk prediction in ambulatory populations

Assays for cardiac troponin have become increasingly sensitive, and are now able to detect very low concentrations of circulating cardiac troponin in a substantial proportion of stable patients who are not suspected of having an acute myocardial infarction. These low concentrations of cardiac troponin are frequently well within the range of what is considered normal but are nonetheless associated with a significant increase in the risk of major cardiovascular events, including heart failure, myocardial infarction, and death in patients with and without established cardiovascular disease. The strength and consistency of these associations, and the fact that adding cardiac troponin to traditional risk factors improves the accuracy of existing cardiovascular risk prediction algorithms, raises the possibility of using cardiac troponin for therapeutic decision-making in ambulatory populations. Cardiac troponin is a powerful predictor of cardiovascular risk on the population level, but a specific intervention that can mitigate cardiac troponin-associated risk has not been identified. Thus, the therapeutic implications of cardiac troponin elevations for individual patients remain unclear. Ongoing research seeks to better understand the underlying cause of cardiac troponin release and to identify therapeutic interventions that can effectively mitigate cardiac troponin-associated cardiovascular risk. The development of high-sensitivity assays for cardiac troponin offers the opportunity to gain tremendous insight into the causes and consequences of chronic myocardial injury, and may, in the future, help guide therapy directed at improving the outcomes of ambulatory patients at high risk for cardiovascular events.

Prognostic Value of Undetectable hs Troponin T in Suspected Acute Coronary Syndrome

BACKGROUND

The search for improved strategies for safe and early discharge of patients with suspected acute coronary syndrome in emergency departments is ongoing. This Biomarkers in Cardiology (BIC)-8 biomarker substudy evaluated the usefulness of high-sensitivity troponin T (hsTnT) below or above the limit of detection (LoD) in low-to-intermediate-risk patients with suspected acute coronary syndrome in the emergency department.

METHODS

Patients were categorized into hsTnT ≥ the 99th percentile, between the 99th percentile and LoD, or undetectable hsTnT (<LoD). HsTnT and copeptin were measured at admission, using a copeptin cut-off of 10 pmol/L. The primary endpoint was death and myocardial infarction within 90 days after admission.

RESULTS

Of 882 patients with all biomarker results, 577 (65.4%) had detectable hsTnT levels (≥LoD). Among the 305 patients (34.6%) with undetectable hsTnT, no myocardial infarctions or deaths occurred within 90 days. In patients with detectable hsTnT at admission (≥LoD but ≤99th percentile), the combined endpoint occurred in 1.5% (6/410) of the copeptin-negative patients and in 6.3% (6/96) of copeptin-positive patients within 90 days (hazard ratio 4.39; 95% confidence interval, 1.42-13.61; P = .01). In patients with an initially elevated hsTnT (≥14 ng/L), 9.7% (3/31) of the copeptin-negative patients and 15.4% (4/26) of the copeptin-positive patients experienced the combined endpoint (hazard ratio 1.61; 95% confidence interval, 0.36-7.17; P = .536).

CONCLUSIONS

In low-to-intermediate-risk patients with suspected acute coronary syndrome, undetectable hsTnT values at admission allow a safe discharge without occurrence of death or myocardial infarction within 90 days.

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.

Relationship Between Subclinical Cardiac Troponin I Elevation and Culprit Lesion Characteristics Assessed by Optical Coherence Tomography in Patients Undergoing Elective Percutaneous Coronary Intervention

Background—

The prevalence of subclinical, cardiac troponin I (cTnI) elevation in stable patients undergoing elective percutaneous coronary intervention and its relationship to culprit lesion characteristics assessed by optical coherence tomography (OCT) are unknown.

Methods and Results—

We studied 206 native de novo culprit coronary lesions from 206 patients with stable angina pectoris who underwent OCT before elective percutaneous coronary intervention. Patients were divided into 2 groups according to the presence (cTnI group; n=47; 22.8%) or absence (non-cTnI group; n=159; 77.2%) of cTnI ≥0.03 ng/mL at admission. The clinical and OCT findings were compared between these 2 groups. No significant difference was found in the clinical presentation between the groups except for the serum C-reactive protein levels and presence of multivessel disease. By OCT, cTnI elevation was associated with the presence of thin-cap fibroatheromas, a greater lipid arc, and a longer lipid length. In a multivariable analysis, the presence of positive C-reactive protein levels (odds ratio, 4.38; 95% confidence interval, 1.90–10.08; P =0.001) and OCT-derived thin-cap fibroatheromas (odds ratio, 2.89; 95% confidence interval, 1.22–6.86; P =0.016) were independent predictors of cTnI elevation. Periprocedural myocardial injury, defined as postpercutaneous coronary intervention peak cTnI levels >1.0 ng/mL (5× the upper reference limit), occurred more often in patients with cTnI elevation at admission (cTnI group: 41% versus non-cTnI group: 18%; P =0.001).

Conclusions—

The presence of subclinical cTnI elevation at admission was not uncommon and was associated with OCT-derived unstable plaque morphology in patients undergoing elective percutaneous coronary intervention, and may help to identify patients with stable angina pectoris at high risk for periprocedural myocardial injury.

Impact of Sex on the Prognostic Value of High-Sensitivity Cardiac Troponin I in the General Population: The HUNT Study

BACKGROUND

A new, high-sensitivity assay for cardiac troponin I (hs-cTnI) permits evaluation of the prognostic value of cardiac troponins within the reference interval. Men have higher hs-cTnI concentrations than women, but the underlying pathophysiological mechanisms and prognostic implications are unclear. The aim of this study was to assess the potential impact of sex on the association between hs-cTnI and cardiovascular death.

METHODS

By use of the Architect STAT High-Sensitive Troponin assay, we measured hs-cTnI in 4431 men and 5281 women aged ≥20 years participating in the prospective observational Nord-Trøndelag Health Study (HUNT).

RESULTS

hs-cTnI was detectable in 98.5% of men and 94.7% of women. During a mean follow-up period of 13.9 years, 708 cardiovascular deaths were registered. hs-cTnI was associated with the incidence of cardiovascular death [adjusted hazard ratio (HR) per 1 SD in log hs-cTnI 1.23 (95% CI 1.15–1.31)], with higher relative risk in women than men [HR 1.44 (1.31–1.58) vs 1.10 (1.00–1.20); Pinteraction &lt; 0.001]. This finding was mediated by both lower risk associated with low hs-cTnI concentrations in women than in men and higher risk associated with high concentrations of hs-cTnI in women than in men. Male sex was associated with a higher risk of cardiovascular death [HR 1.28 (1.11–1.49)], but after adjustment for hs-cTnI, this association disappeared [HR 0.87 (0.75–1.02)].

CONCLUSIONS

The prognostic value of hs-cTnI concentrations in the general population is stronger in women than in men. Subtle impairment of cardiovascular status may contribute to higher hs-cTnI concentrations in men, reflecting sex-dependent differences in cardiovascular risk.

A practical approach for the validation and clinical implementation of a high-sensitivity cardiac troponin I assay across a North American city

Objectives

Despite several publications on the analytical performance of high-sensitivity cardiac troponin (hs-cTn) assays, there has been little information on how laboratories should validate and implement these assays into clinical service. Our study provides a practical approach for the validation and implementation of a hs-cTn assay across a large North American City.

Design and methods

Validation for the Abbott ARCHITECT hs-cTnI assay (across 5 analyzers) consisted of verification of limit of blank (LoB), precision (i.e., coefficient of variation; CV) testing at the reported limit of detection (LoD) and within and outside the 99th percentile, linearity testing, cTnI versus hs-cTnI patient comparison within and between analyzers (Passing and Bablok and non-parametric analyses). Education, clinical communications, and memorandums were issued in advance to inform all staff across the city as well as a selected reminder the day before live-date to important users. All hospitals switched to the hs-cTnI assay concurrently (the contemporary cTnI assay removed) with laboratory staff instructed to repeat samples previously measured with the contemporary cTnI assay with the hs-cTnI assay only by physician request.

Results

Across the 5 analyzers and 6 reagent packs the overall LoB was 0.6 ng/L (n=60) with a CV of 33% at an overall mean of 1.2 ng/L (n=60; reported LoD=1.0 ng/L), with linearity demonstrated from 45,005 ng/L to 1.1 ng/L. Precision testing with a normal patient-pool QC material (mean range across 5 analyzers was 3.9–4.4 ng/L) yielded a range of CVs from 7% to 10% (within-run) and CVs from 7% to 18% (between-run) with the high patient-pool QC material (mean range across 5 analyzers was 29.6–36.3 ng/L) yielding a range of CVs from 2% to 5% (within-run) and CVs from 4% to 8% (between-run). There was agreement between hs-cTnI versus cTnI with the patient samples (slope ranges: 0.89–1.03; intercept ranges: 1.9–3.8 ng/L), however, the median CV on patient samples <100 ng/L across the analyzers was 5.6% for hs-cTnI versus 18.7% for the contemporary assay (p<0.001). Following the switch to hs-cTnI testing, no requests for repeat measurements were received.

Conclusions

Validation and implementation of hs-cTnI testing across multiple sites requires collaboration within the laboratories and between hospital laboratories and clinical staff.

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City-wide analytical validation of a high-sensitivity cardiac troponin assay.

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Practical approach to hs-cTnI validation and clinical implementation.

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Clinical support and communication are important for a successful implementation.

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New QC practices and comparability testing for hs-cTnI monitoring.

Decision limits and the reporting of cardiac troponin: Meeting the needs of both the cardiologist and the ED physician

Cardiac troponin is the preferred biomarker for defining the acute coronary syndrome and acute myocardial infarction. Currently, the only decision limit formally endorsed with regard to the cardiac troponins is the 99th percentile. This is a "rule-in" criterion, intended to ensure that only persons with the acute coronary syndrome are reviewed. The 99th percentile is an arbitrary cut point and there are many problems associated with its application, including defining a truly healthy population, the difficulty of standardisation of cardiac troponin assays, especially but not only cardiac troponin I, and the effects of age and sex on this parameter. The Emergency Department (ED) screens many more persons for possible acute coronary syndromes than actually have the condition and their needs are best met by a "rule-out" test that enables them to clear their busy departments of the many persons who do not actually have the condition. The needs of the ED are not optimally met using the 99th percentile. The index of individuality for the cardiac troponins is small and significant changes consistent with an acute coronary syndrome can occur without the 99th percentile being exceeded. It appears that the ED may be better served by use of delta troponin changes rather than the 99th percentile, but there are problems with this approach, particularly in persons who present late when troponin release has plateaued. In addition, there are many non-acute coronary syndrome causes for cardiac troponin release. The needs of the cardiologist and the ED physician are so different that it may be inappropriate for both groups to use the same diagnostic criteria for cardiac troponin, and it is of great importance that cardiac troponin measurement be used as only one part of the assessment of the person presenting with possible acute coronary syndrome.

High-sensitivity troponin: where are we now and where do we go from here?

High-sensitivity troponin (hsTn) assays are used clinically in most parts of the world and are expected to be approved by the US FDA for clinical use in the USA soon. Clinical use of hsTn leads to improvements in the detection of myocardial injury, shorter time to ruling out acute myocardial infarction, improved risk-stratification of patients with heart failure and atrial fibrillation among others. HsTn may also guide strategies for primary and secondary prevention of cardiovascular disease. However, unmet challenges remain, including distinguishing between acute and chronic hsTn elevations, distinguishing between type 1 and type 2 acute myocardial infarction and determining whether to use gender-neutral or gender-specific reference values.

Predictive value of high-sensitivity troponin-I for future adverse cardiovascular outcome in stable patients with type 2 diabetes mellitus

Introduction

High-sensitivity cardiac troponin I(hs-TnI) and T levels(hs-TnT) are sensitive biomarkers of cardiomyocyte turnover or necrosis. Prior studies of the predictive role of hs-TnT in type 2 diabetes mellitus(T2DM) patients have yielded conflicting results. This study aimed to determine whether hs-TnI, which is detectable in a higher proportion of normal subjects than hsTnT, is associated with a major adverse cardiovascular event(MACE) in T2DM patients.

Methods and results

We compared hs-TnI level in stored serum samples from 276 consecutive patients (mean age 65 ± 10 years; 57% male) with T2DM with that of 115 age-and sex-matched controls. All T2DM patients were prospectively followed up for at least 4 years for incidence of MACE including heart failure(HF), myocardial infarction(MI) and cardiovascular mortality. At baseline, 274(99%) patients with T2DM had detectable hs-TnI, and 57(21%) had elevated hs-TnI (male: 8.5 ng/L, female: 7.6 ng/L, above the 99^th percentile in healthy controls). A total of 43 MACE occurred: HF(n = 18), MI(n = 11) and cardiovascular mortality(n = 14). Kaplan-Meier analysis showed that an elevated hs-TnI was associated with MACE, HF, MI and cardiovascular mortality. Although multivariate analysis revealed that an elevated hs-TnI independently predicted MACE, it had limited sensitivity(62.7%) and positive predictive value(38.5%). Contrary to this, a normal hs-TnI level had an excellent negative predictive value(92.2%) for future MACE in patients with T2DM.

Conclusion

The present study demonstrates that elevated hs-TnI in patients with T2DM is associated with increased MACE, HF, MI and cardiovascular mortality. Importantly, a normal hs-TnI level has an excellent negative predictive value for future adverse cardiovascular events during long-term follow-up.

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

IMPORTANCE AND OBJECTIVE

Besides their role in diagnosis of acute myocardial infarction (MI), troponins may be powerful biomarkers for risk stratification in the general population. The objective of our study was to compare the performance of three troponin assays in cardiovascular disease (CVD) risk prediction in a population-based cohort without a history of CVD events.

DESIGN, SETTING AND PARTICIPANTS

Troponin I concentrations were measured using a contemporary-sensitivity, high-sensitivity, and super-sensitivity assay in 7,899 participants of the general-population based FINRISK 1997 cohort. We used Cox proportional hazards regression to determine relative risks, followed by measures of discrimination and reclassification using 10-fold cross-validation to control for over-optimism.

MAIN OUTCOME

As outcome measures we used CVD, MI, ischemic stroke, heart failure (HF), and major adverse cardiac events (MACE). During the follow-up of 14 years 1,074 incident MACE were observed.

RESULTS

Values above the lower limit of detection were observed in 26.4%, 81.5% and 93.9% for the contemporary-sensitivity, high-sensitivity and super-sensitivity assay, respectively. We observed significant associations of troponin concentrations with the risk of future CVD events and the results tended to become stronger with increasing assay sensitivity. For the super-sensitivity assay the multivariate adjusted hazard ratios (per one standard deviation increase) for different outcomes were: MI 1.24 [95% CI 1.11-1.39], stroke 1.14 [1.01-1.28], CVD 1.15 [1.07-1.24], HF 1.28 [1.18-1.39], and MACE 1.18 [1.11-1.25]. In subjects with intermediate risk, we found an improvement of net reclassification for HF (10.2%, p<0.001), and MACE (5.1%, p<0.001).

CONCLUSION

Using a super-sensitivity assay, cardiac troponin was detectable in almost all healthy individuals. Its concentration improved risk prediction and reclassification for cardiovascular endpoints.

High-sensitivity cardiac troponins: no more 'negatives'

According to recently published expert guidelines, cardiac troponins are the only accepted biomarkers to define acute myocardial infarction. New high sensitivity cardiac troponin assays provide exciting opportunities for early rule-out and rule-in strategies and for identifying high-risk patients early in their presentation to guide early treatment and intervention. This review briefly discusses the history of troponin testing, before going on to cover clinical uses of the new highly sensitive assays in the early assessment of acute myocardial infection. Common clinical pitfalls with the use of these assays are discussed, as is the use of highly sensitive troponins more widely as prognostic markers. Likely future developments in this area are discussed.