Predicting myocardial infarction and other serious cardiac outcomes using high-sensitivity cardiac troponin T in a high-risk stable 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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Cardiovascular Biomarkers: Lessons of the Past and Prospects for the Future

Cardiovascular diseases (CVDs) are a major healthcare burden on the population worldwide. Early detection of this disease is important in prevention and treatment to minimise morbidity and mortality. Biomarkers are a critical tool to either diagnose, screen, or provide prognostic information for pathological conditions. This review discusses the historical cardiac biomarkers used to detect these conditions, discussing their application and their limitations. Identification of new biomarkers have since replaced these and are now in use in routine clinical practice, but still do not detect all disease. Future cardiac biomarkers are showing promise in early studies, but further studies are required to show their value in improving detection of CVD above the current biomarkers. Additionally, the analytical platforms that would allow them to be adopted in healthcare are yet to be established. There is also the need to identify whether these biomarkers can be used for diagnostic, prognostic, or screening purposes, which will impact their implementation in routine clinical practice.

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.

Can the Addition of NT-proBNP and Glucose Measurements Improve the Prognostication of High-Sensitivity Cardiac Troponin Measurements for Patients with Suspected Acute Coronary Syndrome?

Guidelines published in 2021 have supported natriuretic peptide (NP) testing for the prognostication in patients with acute coronary syndrome (ACS) and for the diagnosis of chronic and acute heart failure (HF). Our objective was to determine if the addition of N-terminal pro B-type NP (NT-proBNP) and glucose to high-sensitivity cardiac troponin (hs-cTn) could better identify emergency department (ED) patients with potential ACS at low- and high-risk for a serious cardiovascular outcome over the next 72 h. The presentation sample in two different ED cohorts which enrolled patients with symptoms suggestive of ACS within six hours of pain onset (Cohort-1, n = 126 and Cohort-2, n = 143) that had Abbott hs-cTnI, Roche hs-cTnT, NT-proBNP and glucose were evaluated for NT-proBNP alone and combined with hs-cTn and glucose for the primary outcome (composite which included death, myocardial infarction, HF, serious arrhythmia and refractory angina) via receiver-operating characteristic (ROC) curve analyses with area under the curve (AUC) and diagnostic estimates derived. The AUC for NT-proBNP for the primary outcome was 0.68 (95% confidence interval (CI): 0.59-0.76) and 0.75 (95%CI: 0.67-0.82) in Cohort-1 and 2, respectively, with the 125 ng/L cutoff yielding a higher sensitivity (≥75%) as compared to the 300 ng/L cutoff (≥58%). Using the 125 ng/L cutoff for NT-proBNP with the published glucose and hs-cTn cutoffs for risk-stratification produced a new score (GuIDER score for Glucose, Injury and Dysfunction in the Emergency-setting for cardiovascular-Risk) and yielded higher AUCs as compared to NT-proBNP (p < 0.05). GuIDER scores of 0 and 5 using either hs-cTnI/T yielded sensitivity estimates of 100% and specificity estimates > 92% for the primary outcome. A secondary analysis assessing MI alone in the overall population (combined Cohorts 1 and 2) also achieved 100% sensitivity for MI with a GuIDER cutoff ≥ 2, ruling-out 48% (Roche) and 38% (Abbott) of the population at presentation for MI. Additional studies are needed for the GuIDER score in both the acute and ambulatory setting to further refine the utility, however, the preliminary findings reported here may present a pathway forward for inclusion of NP testing for ruling-out serious cardiac events and MI in the emergency setting.

Clinical chemistry score versus high-sensitivity cardiac troponin I and T tests alone to identify patients at low or high risk for myocardial infarction or death at presentation to the emergency department

BACKGROUND

Testing for high-sensitivity cardiac troponin (hs-cTn) may assist triage and clinical decision-making in patients presenting to the emergency department with symptoms of acute coronary syndrome; however, this could result in the misclassification of risk because of analytical variation or laboratory error. We sought to evaluate a new laboratory-based risk-stratification tool that incorporates tests for hs-cTn, glucose level and estimated glomerular filtration rate to identify patients at risk of myocardial infarction or death when presenting to the emergency department.

METHODS

We constructed the clinical chemistry score (CCS) (range 0-5 points) and validated it as a predictor of 30-day myocardial infarction (MI) or death using data from 4 cohort studies involving patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome. We calculated diagnostic parameters for the CCS score separately using high-sensitivity cardiac troponin I (hs-cTnI) and high-sensitivity cardiac troponin T (hs-cTnT).

RESULTS

For the combined cohorts (n = 4245), 17.1% of participants had an MI or died within 30 days. A CCS score of 0 points best identified low-risk participants: the hs-cTnI CCS had a sensitivity of 100% (95% confidence interval [CI] 99.5%-100%), with 8.9% (95% CI 8.1%-9.8%) of the population classified as being at low risk of MI or death within 30 days; the hs-cTnT CCS had a sensitivity of 99.9% (95% CI 99.2%-100%), with 10.5% (95% CI 9.6%-11.4%) of the population classified as being at low risk. The CCS had better sensitivity than hs-cTn alone (hs-cTnI < 5 ng/L: 96.6%, 95% CI 95.0%-97.8%; hs-cTnT < 6 ng/L: 98.2%, 95% CI 97.0%-99.0%). A CCS score of 5 points best identified patients at high risk (hs-cTnI CCS: specificity 96.6%, 95% CI 96.0%-97.2%; 11.2% [95% CI 10.3%-12.2%] of the population classified as being at high risk; hs-cTnT CCS: specificity 94.0%, 95% CI 93.1%-94.7%; 13.1% [95% CI 12.1%-14.1%] of the population classified as being at high risk) compared with using the overall 99th percentiles for the hs-cTn assays (specificity of hs-cTnI 93.2%, 95% CI 92.3-94.0; specificity of hs-cTnT 73.8%, 95% CI 72.3-75.2).

INTERPRETATION

The CCS score at the chosen cut-offs was more sensitive and specific than hs-cTn alone for risk stratification of patients presenting to the emergency department with suspected acute coronary syndrome. Study registration: ClinicalTrials.gov, nos. NCT01994577; NCT02355457.

Variability in High-Sensitivity Cardiac Troponin T Testing in Stable Patients With and Without Coronary Artery Disease

BACKGROUND

High-sensitivity cardiac troponin T (hs-cTnT) is used to diagnosis acute myocardial infarction, often based on values exceeding the 99th percentile threshold (14 ng/L) of normal populations. The short- and long-term variability of hs-cTnT in stable patients with or without coronary artery disease (CAD) is unknown.

METHODS

Prospective cohort study of 75 stable patients with CAD and 3 differing clinical profiles (stable angina [SA]; remote myocardial infarction [MI]; repetitive acute coronary syndrome [ACS]) and 25 controls without angiographic CAD, each with 15 hs-cTnT measurements over 1 year.

RESULTS

Individual results (1491 measurements) did not vary over within-day, daily, weekly, monthly, seasonal, or yearly time windows. The overall median was 2.8 ng/L (interquartile range [IQR] 5.2 ng/L) with the highest median (6.3 ng/L) and variability (IQR 6. 9 ng/L) in the repetitive ACS group. Diabetes, impaired renal function, and raised C-reactive protein were independent predictors of higher hs-cTnT values (average increase by 8.5 ng/L [95% CI, 5.0-11.9], 5.0 ng/L [95% CI, 2.0-8.1] and 4.0 ng/L (95% CI, 1.0-7.0), respectively). The 99th percentile value of all hs-cTnT measurements in the combined stable patients with CAD was 39 ng/L compared with 14 ng/L in the non-CAD patients.

CONCLUSIONS

Individual hs-cTnT readings in both patients with and without CAD were stable over hours, days, weeks, and months. Diabetes, poor renal function, and elevated C-reactive protein were independent predictors of higher median and IQR hs-cTnT values, often exceeding conventional thresholds. These findings highlight the need for caution and clinical contextualization in the interpretation of hs-cTnT results.

Elevated High-Sensitivity Troponin I in the Stabilized Phase after an Acute Coronary Syndrome Predicts All-Cause and Cardiovascular Mortality in a Highly Admixed Population: A 7-Year Cohort

Background

High-sensitivity cardiac troponin I (hs-cTnI) has played an important role in the risk stratification of patients during the in-hospital phase of acute coronary syndrome (ACS), but few studies have determined its role as a long-term prognostic marker in the outpatient setting.

Objective

To investigate the association between levels of hs-cTnI measured in the subacute phase after an ACS event and long-term prognosis in a highly admixed population.

Methods

We measured levels of hs-cTnI in 525 patients 25 to 90 days after admission for an ACS event; these patients were then divided into tertiles according to hs-cTnI levels and followed for up to 7 years. We compared all-cause and cardiovascular mortality using Cox proportional hazards models and adopting a significance level of 5%.

Results

After a median follow-up of 51 months, patients in the highest tertile had a greater hazard ratio (HR) for all-cause mortality after adjustment for age, sex, known cardiovascular risk factors, medication use, and demographic factors (HR: 3.84, 95% CI: 1.92-8.12). These findings persisted after further adjustment for estimated glomerular filtration rate < 60 ml/min/1.73 m² and left ventricular ejection fraction < 0.40 (HR: 6.53, 95% CI: 2.12-20.14). Cardiovascular mortality was significantly higher in the highest tertile after adjustment for age and sex (HR: 5.65, 95% CI: 1.94-16.47) and both in the first (HR: 4.90, 95% CI: 1.35-17.82) and second models of multivariate adjustment (HR: 5.89, 95% CI: 1.08-32.27).

Conclusions

Elevated hs-cTnI levels measured in the stabilized phase after an ACS event are independent predictors of all-cause and cardiovascular mortality in a highly admixed population.

Usefulness of Higher Levels of Cardiac Troponin T in Patients With Stable Angina Pectoris to Predict Risk of Acute Myocardial Infarction

In patients with stable angina, the association between high-sensitivity cardiac troponin T (hs-cTnT) and incident acute myocardial infarction (AMI), as well as pathophysiologic mechanisms accounting for an adverse prognosis, remain to be determined. We explored the association between hs-cTnT and future AMI among 3,882 patients evaluated for suspected stable angina pectoris and investigated to which extent hs-cTnT attenuated the relations between traditional coronary heart disease (CHD) risk factors and AMI. Associations between increasing hs-cTnT categories (≤3, 4 to 9, 10 to 19, and 20 to 30 ng/L) and risk of AMI were studied by Cox regression. We investigated whether the associations between traditional CHD risk factors and future AMI were influenced by adjusting for hs-cTnT. Median age was 62 years. During median (25th to 75th percentile) 8 (6.4 to 8.7) years of follow-up, 460 (11.8%) experienced an AMI. There was a strong association between hs-cTnT categories and risk of AMI. The relation was somewhat attenuated, but still present, when adjusting for potential confounders, traditional CHD risk factors, previous peripheral vascular disease, and percutaneous coronary intervention or coronary bypass surgery. Moreover, hs-cTnT slightly attenuated the risk relations between traditional CHD risk factors and incident AMI, but each risk factor remained significantly associated with AMI. In conclusion, among patients with suspected stable angina, hs-cTnT was positively related to incident AMI.

Cardiac Troponin T Concentrations, Reversible Myocardial Ischemia, and Indices of Left Ventricular Remodeling in Patients with Suspected Stable Angina Pectoris: a DOPPLER-CIP Substudy

BACKGROUND

Cardiac troponin T concentrations measured with high-sensitivity assays (hs-cTnT) provide important prognostic information for patients with stable coronary artery disease (CAD). However, whether hs-cTnT concentrations mainly reflect left ventricular (LV) remodeling or recurrent myocardial ischemia in this population is not known.

METHODS

We measured hs-cTnT concentrations in 619 subjects with suspected stable CAD in a prospectively designed multicenter study. We identified associations with indices of LV remodeling, as assessed by cardiac MRI and echocardiography, and evidence of myocardial ischemia diagnosed by single positron emission computed tomography.

RESULTS

Median hs-cTnT concentration was 7.8 ng/L (interquartile range, 4.8–11.6 ng/L), and 111 patients (18%) had hs-cTnT concentrations above the upper reference limit (&gt;14 ng/L). Patients with hs-cTnT &gt;14 ng/L had increased LV mass (144 ± 40 g vs 116 ± 34 g; P &lt; 0.001) and volume (179 ± 80 mL vs 158 ± 44 mL; P = 0.006), lower LV ejection fraction (LVEF) (59 ± 14 vs 62 ± 11; P = 0.006) and global longitudinal strain (14.1 ± 3.4% vs 16.9 ± 3.2%; P &lt; 0.001), and more reversible perfusion defects (P = 0.001) and reversible wall motion abnormalities (P = 0.008). Age (P = 0.009), estimated glomerular filtration rate (P = 0.01), LV mass (P = 0.003), LVEF (P = 0.03), and evidence of reversible myocardial ischemia (P = 0.004 for perfusion defects and P = 0.02 for LV wall motion) were all associated with increasing hs-cTnT concentrations in multivariate analysis. We found analogous results when using the revised US upper reference limit of 19 ng/L.

CONCLUSIONS

hs-cTnT concentrations reflect both LV mass and reversible myocardial ischemia in patients with suspected stable CAD.

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.

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.

Impact of Sex on Cardiac Troponin Concentrations—A Critical Appraisal

BACKGROUND

The use of sex-specific cutoffs for cardiac troponin (cTn) is currently debated. Although endorsed by scientific working groups, concerns have been raised that sex-specific cutoffs may have only a small clinical effect at the cost of increased complexity in decision-making.

METHODS

We reviewed studies investigating the interrelations between high-sensitivity (hs) cTn results and sex, diagnoses, and outcome. Investigated populations included community-dwelling subjects and patients with stable angina, congestive heart failure, or acute chest pain including those with acute coronary syndromes.

RESULTS

Men usually have higher hs-cTn concentrations compared with women, regardless of the assessed population or the applied assay. The distribution and prognostic implications of hs-cTn concentrations indicate that women have a broader cardiovascular risk panorama compared with men, particularly at lower hs-cTn concentrations. At higher concentrations, particularly above the 99th percentile, this variation is often attenuated. Sex-specific hs-cTn 99th percentiles have so far shown clinical net benefit in only 1 study assessing patients with chest pain. However, several methodological aspects need to be considered when interpreting study results, e.g., issues related to the determination of the 99th percentiles, the selection bias, and the lack of prospective and sufficiently powered analyses.

CONCLUSIONS

Available studies do not show a consistent clinical superiority of sex-specific hs-cTn 99th percentiles. This may reflect methodological aspects. However, from a pathobiological perspective, the use of sex-specific hs-cTn 99th percentiles makes sense for the ruling in of myocardial infarction. We propose a new approach to hs-cTn 99th cutoffs taking into account the analytical properties of the used assays.

Rule-In and Rule-Out of Myocardial Infarction Using Cardiac Troponin and Glycemic Biomarkers in Patients with Symptoms Suggestive of Acute Coronary Syndrome

BACKGROUND

Early rule-in/rule-out of myocardial infarction (MI) in patients presenting to the emergency department (ED) is important for patient care and resource allocation. Given that dysglycemia is a strong risk factor for MI, we sought to explore and compare different combinations of cardiac troponin (cTn) cutoffs with glycemic markers for the early rule-in/rule-out of MI.

METHODS

We included ED patients (n = 1137) with symptoms suggestive of acute coronary syndrome (ACS) who had cTnI, high-sensitivity cTnI (hs-cTnI), hs-cTnT, glucose, and hemoglobin A_1c (Hb A_1c) measurements. We derived rule-in/rule-out algorithms using different combinations of ROC-derived and literature cutoffs for rule-in and rule-out of MI within 7 days after presentation. These algorithms were then tested for MI/cardiovascular death and ACS/cardiovascular death at 7 days. ROC curves, sensitivity, specificity, likelihood ratios, positive and negative predictive values (PPV and NPV), and CIs were determined for various biomarker combinations.

RESULTS

MI was diagnosed in 133 patients (11.7%; 95% CI, 9.8-13.8). The algorithms that included cTn and glucose produced the greatest number of patients ruled out/ruled in for MI and yielded sensitivity ≥99%, NPV ≥99.5%, specificity ≥99%, and PPV ≥80%. This diagnostic performance was maintained for MI/cardiovascular death but not for ACS/cardiovascular death. The addition of hemoglobin A_1c (Hb A_1c) (≥6.5%) to these algorithms did not change these estimates; however, 50 patients with previously unknown diabetes may have been identified if Hb A_1c was measured.

CONCLUSIONS

Algorithms incorporating glucose with cTn may lead to an earlier MI diagnosis and rule-out for MI/cardiovascular death. Addition of Hb A_1c into these algorithms allows for identification of diabetes. Future studies extending these findings are needed for ACS/cardiovascular death. ClinicalTrials.gov identifier: NCT01994577.

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.

Determinants of minimal elevation in high-sensitivity cardiac troponin T in the general population

OBJECTIVES

To study the relationship between cardiovascular risk factors and detectable cardiac troponin-T using a highly sensitive assay (hs-cTnT) among persons without a history of cardiovascular disease.

DESIGN AND METHODS

We examined the cross-sectional associations between cardiovascular risk factors and hs-cTnT in 9593 participants (mean age 65.6 (SD, 5.6), 41% female, 22% black) free of cardiovascular disease in a community-based cohort, through the Atherosclerosis Risk in Communities (ARIC) Study. We used multivariable logistic regression to characterize the association between cardiovascular risk factors and detectable (≥3.0 to 13.9ng/L) and elevated (≥14.0ng/L) hs-cTnT.

RESULTS

hs-cTnT was detectable in 59% and elevated in 7% of the study population. Among persons with ideal cardiovascular health, hs-cTnT was detectable in 44%. In models adjusting for significant determinants of hs-cTnT concentration, detectable hs-cTnT was more frequent among males, blacks and persons with diabetes and hypertension and less frequent among statin users, current smokers and drinkers. Other risk factors associated with detectable hs-cTnT were older age, lower kidney function and higher body mass index. These risk factors were associated with elevated hs-cTnT in a similar pattern.

CONCLUSION

In a community-based sample without cardiovascular disease hs-cTnT is detectable in most adults, even among those with ideal cardiovascular health. Although most traditional cardiovascular risk factors were significant determinants of detectable and elevated hs-cTnT, the associations were particularly robust for sex, age, race, hypertension and diabetes.

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.

Laboratory medicine as the science that underpins medicine: the “high-sensitivity” troponin paradigm

The availability of so-called high-sensitivity troponin assays (hsTn) has scored a compelling goal for laboratory medicine, allowing the safe clinical application of international recommendations for the definition of acute myocardial infarction (AMI). However, the introduction of hsTn has not been welcomed by clinicians, claiming an increase in false-positive results. Here we critically trace back the steps following the introduction of hsTn by referring to the 5-year practical experience in our academic hospital and to suitable information available in the literature. In agreement with published data, we found that hsTn introduction was associated with an increased number of AMI diagnoses, whereas the test volume, the revascularization rate, and the proportion of cases with negative angiography findings remained virtually unchanged. Fast-track protocols for ruling out AMI have been further optimized to recommend sampling at presentation and after 3 h only. We focus on a cost-effective use of hsTn that can account for all clinical variables increasing the pre-test probability in order to ensure that tests are ordered only for patients at medium to high risk for acute coronary syndrome (ACS). To guide interpretation of results, hsTn typical release patterns suggestive for AMI should be identified by evaluating the significance of concentration changes. hsTn have markedly shortened the time to rule out or rule in AMI and has the potential to improve the prognostic assessment of critical patients in clinical contexts different from ACS.

Calprotectin and cardiovascular events. A narrative review

OBJECTIVES

Calprotectin, also known as S100A8/A9 complex, is currently considered as a valid biomarker for diagnosis, follow-up and therapeutic monitoring of inflammatory bowel diseases. The attractive evidence that this protein may be actively produced and released by leukocytes (especially neutrophils) and by nonmyeloid cardiovascular cell types has paved the way to a series of studies that have assessed its biology in the setting of cardiovascular disease. The aim of this review was thus to investigate the diagnostic and prognostic utility of this biomarker in cardiovascular disease and in particular in myocardial infarction.

DESIGN AND METHODS

We performed a systematic, electronic search on Medline, Scosus and Web of Science, using the keywords "calprotectin" or "S100A8/A9" or "MRP-8/14" and "myocardial infarction" or "acute coronary syndrome" or "cardiovascular disease", from inception to June 2013. The bibliographic references of articles published in English, French and Italian were reviewed for additional relevant studies.

RESULTS

The data of the current scientific literature seems to confirm that calprotectin is actively secreted in the setting of cardiac ischemia and its concentration is significantly associated with the prognosis. Nevertheless, the evidence provided by recent articles that have assessed its performance for diagnosing acute myocardial infarction, either alone or in combination with troponin, supports the hypothesis that this biomarker may be of limited value for enabling a better or faster diagnosis of cardiac ischemia. Even its putative role as an independent prognostic biomarker of cardiovascular morbidity and death is still largely uncertain.

CONCLUSIONS

It can hence be concluded that calprotectin does not currently meet the requirements for efficient diagnosis and prognostication of patients with cardiovascular disease.

The COSEHC™ Global Vascular Risk Management quality improvement program: first follow-up report

The Global Vascular Risk Management (GVRM) Study is a 5-year prospective observational study of 87,863 patients (61% females) with hypertension and associated cardiovascular risk factors began January 1, 2010. Data are gathered electronically and cardiovascular risk is evaluated using the Consortium for Southeastern Hypertension Control™ (COSEHC™)-11 risk score. Here, we report the results obtained at the completion of 33 months since study initiation. De-identified electronic medical records of enrolled patients were used to compare clinical indicators, antihypertensive medication usage, and COSEHC™ risk scores across sex and diabetic status subgroups. The results from each subgroup, assessed at baseline and at regular follow-up periods, are reported since the project initiation. Inference testing was performed to look for statistically significant differences between goal attainments rates between sexes. At-goal rates for systolic blood pressure (SBP) were improved during the 33 months of the study, with females achieving higher goal rates when compared to males. On the other hand, at-goal control rates for total and low-density lipoprotein (LDL) cholesterol (chol) were better in males compared to females. Diabetic patients had lower at-goal rates for SBP and triglycerides but higher rates for LDL-chol. The LDL-chol at-goal rates were higher for males, while high-density lipoprotein (HDL)-chol rates were higher for females. Utilization of antihypertensive medications was similar during and after the baseline period for both men and women. Patients taking two or more antihypertensive medications had higher mean COSEHC™-11 scores compared to those on monotherapy. With treatment, hypertensive patients can reach SBP and cholesterol goals; however, population-wide improvement in treatment goal adherence continues to be a challenge for physicians. The COSEHC™ GVRM Study shows, however, that continuous monitoring and feedback to physicians of accurate longitudinal data is an effective tool in achieving better control rates of cardiovascular risk factors.

Highly-sensitive troponin I is increased in patients with gynecological cancers

OBJECTIVES

To investigate troponin I (TnI) in patients with gynecological cancers.

METHODS

Highly-sensitive (HS) and conventional TnI were measured in 25 patients with untreated ovarian cancer, 25 with endometriosis and 25 with benign masses.

RESULTS

Both HS and conventional TnI were increase in cancer patients. Values above the cut-off were found in 44% and 16% cancer patients using HS and conventional TnI methods, respectively.

CONCLUSIONS

Cardiac involvement is frequent in patients with gynecological cancers and should be preferably assessed using HS troponin immunoassays.