The relationship between workload and exercise-induced cardiac troponin elevations is influenced by non-obstructive coronary atherosclerosis

The relationship between exercise-induced troponin elevation and non-obstructive coronary artery disease (CAD) is unclear. This observational study assessed non-obstructive CAD's impact on exercise-induced cardiac Troponin I (cTnI) elevation in middle-aged recreational athletes. cTnI levels of 40 well-trained recreational athletes (73% males, 50 ± 9 years old) were assessed by a high-sensitive cTnI assay 24 h before, and at 3 and 24 h following two high-intensity exercises of different durations; a cardiopulmonary exercise test (CPET), and a 91-km mountain bike race. Workload was measured with power meters. Coronary computed tomography angiography was used to determine the presence or absence of non-obstructive (<50% obstruction) CAD. A total of 15 individuals had non-obstructive CAD (Atherosclerotic group), whereas 25 had no atherosclerosis (normal). There were higher post-exercise cTnI levels following the race compared with CPET, both at 3 h (77.0 (35.3-112.4) ng/L vs. 11.6 (6.4-22.5) ng/L, p < 0.001) and at 24 h (14.7 (6.7-16.3) vs. 5.0 (2.6-8.9) ng/L, p < 0.001). Absolute cTnI values did not differ among groups. Still, the association of cTnI response to power output was significantly stronger in the CAD versus Normal group both at 3 h post-exercise (Rho = 0.80, p < 0.001 vs. Rho = -0.20, p = 0.33) and 24-h post-exercise (Rho = 0.87, p < 0.001 vs. Rho = -0.13, p = 0.55). Exercise-induced cTnI elevation was strongly correlated with exercise workload in middle-aged athletes with non-obstructive CAD but not in individuals without CAD. This finding suggests that CAD influences the relationship between exercise workload and the cTnI response even without coronary artery obstruction.

Reference intervals of circulating secretoneurin concentrations determined in a large cohort of community dwellers: the HUNT study

OBJECTIVES

Secretoneurin (SN) is a novel cardiac biomarker that associates with the risk of mortality and dysfunctional cardiomyocyte Ca2+ handling in heart failure patients. Reference intervals for SN are unknown.

METHODS

SN was measured with a CE-marked ELISA in healthy community dwellers from the fourth wave of the Trøndelag Health Study (HUNT4) conducted in 2017-2019. The common, sex and age specific 90th, 95th, 97.5th and 99th percentiles were calculated using the non-parametric method and outlier exclusion according to the Reed test. The applicability of sex and age specific reference intervals were investigated using Harris and Boyd test. We also estimated the percentiles in a subset with normal findings on echocardiographic screening.

RESULTS

The total cohort included 887 persons (56.4 % women). After echocardiographic screening 122 persons were excluded, leaving a total of 765 persons (57.8 % women). The 97.5th percentile (95 % CI in brackets) of SN was 59.7 (57.5-62.1) pmol/L in the total population and 58.6 (57.1-62.1) pmol/L after echocardiography screening. In general, slightly higher percentiles were found in women and elderly participants, but less than 4 % in these subgroups had concentrations deviating from the common 97.5th percentile. Low BMI or eGFR was also associated with higher concentrations of SN.

CONCLUSIONS

Upper reference limits for SN were similar amongst healthy adult community dwellers regardless of prescreening including cardiac echocardiography or not. Women and elderly showed higher concentrations of SN, but the differences were not sufficiently large to justify age and sex stratified upper reference limits.

Prognostic significance of chronic myocardial injury diagnosed by three different cardiac troponin assays in patients admitted with suspected acute coronary syndrome

OBJECTIVES

Chronic myocardial injury (CMI) is defined as stable concentrations of cardiac troponin T or I (cTnT or cTnI) above the assay-specific 99th percentile upper reference limit (URL) and signals poor outcome. The clinical implications of diagnosing CMI are unclear. We aimed to assess prevalence and association of CMI with long-term prognosis using three different high-sensitivity cTn (hs-cTn) assays.

METHODS

A total of 1,292 hospitalized patients without acute myocardial injury had cTn concentrations quantified by hs-cTn assays by Roche Diagnostics, Abbott Diagnostics and Siemens Healthineers. The median follow-up time was 4.1 years. The prevalence of CMI and hazard ratios for mortality and cardiovascular (CV) events were calculated based on the URL provided by the manufacturers and compared to the prognostic accuracy when lower percentiles of cTn (97.5, 95 or 90), limit of detection or the estimated bioequivalent concentrations between assays were used as cutoff values.

RESULTS

There was no major difference in prognostic accuracy between cTnT and cTnI analyzed as continuous variables. The correlation between cTnT and cTnI was high (r=0.724-0.785), but the cTnT assay diagnosed 3.9-4.5 times more patients with having CMI based on the sex-specific URLs (TnT, n=207; TnI Abbott, n=46, TnI Siemens, n=53) and had higher clinical sensitivity and AUC at the URL.

CONCLUSIONS

The prevalence of CMI is highly assay-dependent. cTnT and cTnI have similar prognostic accuracy for mortality or CV events when measured as continuous variables. However, a CMI diagnosis according to cTnT has higher prognostic accuracy compared to a CMI diagnosis according to cTnI.

Lower Limits for Reporting High-Sensitivity Cardiac Troponin Assays and Impact of Analytical Performance on Patient Misclassification

BACKGROUND

Cardiac troponin measurements are indispensable for the diagnosis of myocardial infarction and provide useful information for long-term risk prediction of cardiovascular disease. Accelerated diagnostic pathways prevent unnecessary hospital admission, but require reporting cardiac troponin concentrations at low concentrations that are sometimes below the limit of quantification. Whether analytical imprecision at these concentrations contributes to misclassification of patients is debated.

CONTENT

The International Federation of Clinical Chemistry Committee on Clinical Application of Cardiac Bio-Markers (IFCC C-CB) provides evidence-based educational statements on analytical and clinical aspects of cardiac biomarkers. This mini-review discusses how the reporting of low concentrations of cardiac troponins impacts on whether or not assays are classified as high-sensitivity and how analytical performance at low concentrations influences the utility of troponins in accelerated diagnostic pathways. Practical suggestions are made for laboratories regarding analytical quality assessment of cardiac troponin results at low cutoffs, with a particular focus on accelerated diagnostic pathways. The review also discusses how future use of cardiac troponins for long-term prediction or management of cardiovascular disease may require improvements in analytical quality.

SUMMARY

Clinical guidelines recommend using cardiac troponin concentrations as low as the limit of detection of the assay to guide patient care. Laboratories, manufacturers, researchers, and external quality assessment providers should extend analytical performance monitoring of cardiac troponin assays to include the concentration ranges applicable in these pathways.

Imprecision of high-sensitivity cardiac troponin assays at the female 99th-percentile

BACKGROUND

An analytical benchmark for high-sensitivity cardiac troponin (hs-cTn) assays is to achieve a coefficient of variation (CV) of ≤ 10.0 % at the 99th percentile upper reference limit (URL) used for the diagnosis of myocardial infarction. Few prospective multicenter studies have evaluated assay imprecision and none have determined precision at the female URL which is lower than the male URL for all cardiac troponin assays.

METHODS

Human serum and plasma matrix samples were constructed to yield hs-cTn concentrations near the female URLs for the Abbott, Beckman, Roche, and Siemens hs-cTn assays. These materials were sent (on dry ice) to 35 Canadian hospital laboratories (n = 64 instruments evaluated) participating in a larger clinical trial, with instructions for storage, handling, and monthly testing over one year. The mean concentration, standard deviation, and CV for each instrument type and an overall pooled CV for each manufacturer were calculated.

RESULTS

The CVs for all individual instruments and overall were ≤ 10.0 % for two manufacturers (Abbott CVpooled = 6.3 % and Beckman CVpooled = 7.0 %). One of four Siemens Atellica instruments yielded a CV > 10.0 % (CVpooled = 7.7 %), whereas 15 of 41 Roche instruments yielded CVs > 10.0 % at the female URL of 9 ng/L used worldwide (6 cobas e411, 1 cobas e601, 4 cobas e602, and 4 cobas e801) (CVpooled = 11.7 %). Four Roche instruments also yielded CVs > 10.0 % near the female URL of 14 ng/L used in the United States (CVpooled = 8.5 %).

CONCLUSIONS

The number of instruments achieving a CV ≤ 10.0 % at the female 99th-percentile URL varies by manufacturer and by instrument. Monitoring assay precision at the female URL is necessary for some assays to ensure optimal use of this threshold in clinical practice.

The liver-heart axis in patients with severe obesity: The association between liver fibrosis and chronic myocardial injury may be explained by shared risk factors of cardiovascular disease

BACKGROUND

Severe obesity is associated with increased risk of non-alcoholic fatty liver disease and cardiovascular disease. We hypothesized that liver fibrosis as quantified by the Enhanced Liver Fibrosis (ELF) test would be predictive of myocardial injury and fibrosis, expressed by higher concentrations of cardiac troponin T and I measured by high-sensitivity assays (hs-cTnT and hs-cTnI, respectively).

MATERIAL AND METHODS

We performed cross-sectional analyses of baseline data from 136 patients (mean age 45 years, 38 % male) with severe obesity participating in the non-randomized clinical trial Prevention of Coronary Heart Disease in Morbidly Obese Patients (ClinicalTrials.gov NCT00626964). Associations between ELF scores, hs-cTnT, and hs-cTnI concentrations were assessed using linear regression analysis.

RESULTS

ELF scores were associated with hs-cTnT in the unadjusted model (B 0.381, 95 % Confidence Interval [CI] 0.247, 0.514), but the association was attenuated upon adjustment for potential confounders (B -0.031, 95 % CI -0.155, 0.093). Similarly, for hs-cTnI, an observed association with ELF scores in the unadjusted model was attenuated upon adjustment for potential confounders ((B 0.432, 95 % CI 0.179, 0.685) and (B 0.069, 95 % CI -0.230, 0.367), respectively). Age, sex, hypertension, and estimated glomerular filtration rate were amongst the shared predictors of ELF score, hs-cTnT, and hs-cTnI that provided the univariable models with the highest R-squared and lowest Akaike Information Criterion values.

CONCLUSIONS

Contrary to our hypothesis, ELF score did not predict myocardial injury and fibrosis, but we rather demonstrated an association between liver fibrosis and myocardial injury and fibrosis may be explained by shared risk factors of cardiovascular disease.

Antibody-mediated interferences affecting cardiac troponin assays: recommendations from the IFCC Committee on Clinical Applications of Cardiac Biomarkers

The International Federation of Clinical Chemistry Committee on Clinical Applications of Cardiac Biomarkers (IFCC C-CB) provides educational documents to facilitate the interpretation and use of cardiac biomarkers in clinical laboratories and practice. Our aim is to improve the understanding of certain key analytical and clinical aspects of cardiac biomarkers and how these may interplay. Measurements of cardiac troponin (cTn) have a prominent place in the clinical work-up of patients with suspected acute coronary syndrome. It is therefore important that clinical laboratories know how to recognize and assess analytical issues. Two emerging analytical issues resulting in falsely high cTn concentrations, often several fold higher than the upper reference limit (URL), are antibody-mediated assay interference due to long-lived cTn-antibody complexes, called macrotroponin, and crosslinking antibodies that are frequently referred to as heterophilic antibodies. We provide an overview of antibody-mediated cTn assay interference and provide recommendations on how to confirm the interference and interpret the results.

Single Troponin Measurement to Rule Out Myocardial Infarction: JACC Review Topic of the Week

The term "single-sample rule-out" refers to the ability of very low concentrations of high-sensitivity cardiac troponin (hs-cTn) on presentation to exclude acute myocardial infarction with high clinical sensitivity and negative predictive value. Observational and randomized studies have confirmed this ability. Some guidelines endorse use of a concentration of hs-cTn at the assay's limit of detection, while other studies have validated the use of higher concentrations, allowing this approach to identify a greater proportion of patients at low risk. In most studies, at least 30% of patients can be triaged with this approach. The concentration of hs-cTn varies according to the assay used and sometimes how regulations permit reporting. It is clear that patients need to be at least 2 hours from the onset of symptoms being evaluated. Caution is warranted, particularly with older patients, women, and patients with underlying cardiac comorbidities.

Growth Differentiation Factor 15: A Prognostic Marker in Patients with Acute Chest Pain without Acute Myocardial Infarction

BACKGROUND

Acute chest pain is associated with an increased risk of death and cardiovascular events even when acute myocardial infarction (AMI) has been excluded. Growth differentiation factor-15 (GDF-15) is a strong prognostic marker in patients with acute chest pain and AMI, but the prognostic value in patients without AMI is uncertain. This study sought to investigate the ability of GDF-15 to predict long-term prognosis in patients presenting with acute chest pain without AMI.

METHODS

In total, 1320 patients admitted with acute chest pain without AMI were followed for a median of 1523 days (range: 4 to 2208 days). The primary end point was all-cause mortality. Secondary end points included cardiovascular (CV) death, future AMI, heart failure hospitalization, and new-onset atrial fibrillation (AF).

RESULTS

Higher concentrations of GDF-15 were associated with increased risk of death from all causes (median concentration in non-survivors vs survivors: 2124 pg/mL vs 852 pg/mL, P < 0.001), and all secondary end points. By multivariable Cox regression, GDF-15 concentration ≥4th quartile (compared to <4th quartile) remained an independent predictor of all-cause death (adjusted hazard ratio (HR): 2.75; 95% CI, 1.69-4.45, P < 0.001), CV death (adjusted HR: 3.74; 95% CI, 1.31-10.63, P = 0.013), and heart failure hospitalization (adjusted HR: 2.60; 95% CI, 1.11-6.06, P = 0.027). Adding GDF-15 to a model consisting of established risk factors and high-sensitivity cardiac troponin T (hs-cTnT) led to a significant increase in C-statistics for prediction of all-cause mortality.

CONCLUSIONS

Higher concentrations of GDF-15 were associated with increased risk of mortality from all causes and risk of future CV events.

Cardiac troponin measurement at the point of care: educational recommendations on analytical and clinical aspects by the IFCC Committee on Clinical Applications of Cardiac Bio-Markers (IFCC C-CB)

The International Federation of Clinical Chemistry and Laboarator Medicine (IFCC) Committee on Clinical Applications of Cardiac Bio-Markers (C-CB) has provided evidence-based educational resources to aid and improve the understanding of important analytical and clinical aspects of cardiac biomarkers. The present IFCC C-CB educational report focuses on recommendations for appropriate use, analytical performance, and gaps in clinical studies related to the use of cardiac troponin (cTn) by point of care (POC) measurement, often referred to as a point of care testing (POCT). The use of high-sensitivity (hs)-cTn POC devices in accelerated diagnostic protocols used in emergency departments or outpatient clinics investigating acute coronary syndrome has the potential for improved efficacy, reduction of length of stay and reduced costs in the health care system. POCT workflow integration includes location of the instrument, assignment of collection and testing responsibility to (non-lab) staff, instrument maintenance, in-service and recurrent training, quality control, proficiency assessments, discrepant result trapping, and troubleshooting and inventory management.

Growth differentiation factor 15 at 3 months after an acute chest pain admission is associated with increased risk of death and cardiovascular events

Background

Growth differentiation factor 15 (GDF-15) is related to increased risk of death and cardiovascular events when measured at initial presentation in patients with acute chest pain. Whether follow-up measurements at 3 months provide prognostic information is unknown.

Purpose

This study sought to investigate the ability of GDF-15 to predict long-term prognosis when measured 3 months after an acute chest pain admission.

Methods

GDF-15 was measured at baseline and 3 months after admission in 760 patients admitted with suspected NSTEMI-ACS. NSTEMI-ACS was diagnosed in 228 (30%) patients. Patients were followed for a median of 1480 (17–2118) days. GDF-15 concentration on admission and at 3-months was skewed and therefore compared using the related samples Wilcoxon signed ranked test. A baseline GDF-15 concentration of 1200pg/ml (previously defined as the 90th percentile in a healthy population) was used to divide patients into high and low concentration groups. Kaplan-Meier plots were generated and adjusted hazard ratios were estimated using multiple Cox proportional hazard regression analysis (adjusting for age, sex, hypercholesterolemia, current smoking, diabetes, hypertension, previous myocardial infarction, eGFR &lt;60 ml/min/1.73 m2 and cardiac troponin T). The primary endpoint was all-cause mortality following the 3-month visit and a secondary endpoint included all-cause mortality, future AMI and heart failure hospitalization.

Results

Median GDF-15 concentration on admission was 940 pg/ml (IQR: 678–1464) and similar to the concentration at 3 months: 927 pg/ml (IQR: 652–1431), p=0.183.

In the high-concentration group (n=249) 45 (18%) patients died, and 62 (25%) met the secondary endpoint. In the low-concentration group (n=511) 9 (1.7%) patients died (negative predictive value: 98.2%) and 22 (4%) met the secondary endpoint (negative predictive value: 95.6%).

Patients with persistently elevated GDF-15 at the 3 months follow-up visit carried the highest risk for death and cardiovascular events, followed by patients who developed high concentrations during the 3-month follow-up period. Patients with elevated levels at baseline who return to normal concentrations had similar risk as patients with low levels in both measurements (Figure 1).

The Kaplan-Meier curves demonstrated an increased risk of the primary and secondary endpoint in the high concentration group (Figure 2). GDF-15 concentration &gt;1200 pg/ml at 3 months was an independent predictor of all-cause mortality with an adjusted HR for death of 4.0 (1.7–9.5, p=0.001) and for the secondary endpoint (adjusted HR 2.9, 95% CI: 1.6–5.4, p=0.001).

Conclusion

Elevated GDF-15 three months after admission due to suspected NSTEMI-ACS independently predicts long-term mortality and cardiovascular events, irrespective of GDF-15 values during admission.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Western Norway Regional Health Authority

Validation of a novel high-sensitivity cardiac troponin assay

Background

The accuracy for early identification of non-ST-elevation myocardial infarction (NSTEMI) in the emergency department must be determined for all novel high-sensitivity cardiac troponin assays (hs-cTn). In this prospective, multi-centre study we developed rule-out algorithms for a high-sensitivity cardiac troponin I (hs-cTnI) assay and compared it to established algorithms for hs-cTnT and hs-cTnI.

Methods

Two rule-out algorithms for NSTEMI were developed from a derivation cohort of 977 patients assessed by the Siemens Atellica IM hs-cTnI assay. Diagnostic performance was compared with hs-cTnT (Roche) and hs-cTnI (Abbott) algorithms. The derived algorithms were tested in two different validation cohorts (n=518 and n=405, respectively).

Results

An admission sample algorithm (hs-cTnI (Siemens)) for rule-out of NSTEMI with cutoff &lt;5 ng/L had negative predictive value (NPV) 99.4–100.0%, sensitivity 98.3–100% and specificity 46.7–56.5% in the two validation cohorts. Sensitivity and NPV was similar, specificity trended towards improvement over the comparator algorithms (Figure 1).

A 0–1 hour algorithm (hs-cTnI (Siemens)) with cutoff &lt;10 ng/L and Δ change &lt;3 ng/L achieved sensitivity and NPV 100% with specificity &gt;70% in both validation cohorts, similar to the comparator algorithms (Table 1).

Conclusions

Rule-out algorithms from the Siemens Atellica hs-cTnI assay has comparable diagnostic accuracy to established hs-cTn rule-out algorithms.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Public grant: Western Norway Regional Health Authority.Private company funding: Siemens Healthineers AG

Analytical Considerations in Deriving 99th Percentile Upper Reference Limits for High-Sensitivity Cardiac Troponin Assays: Educational Recommendations from the IFCC Committee on Clinical Application of Cardiac Bio-Markers

The International Federation of Clinical Chemistry Committee on Clinical Application of Cardiac Bio-Markers provides evidence-based educational documents to facilitate uniform interpretation and utilization of cardiac biomarkers in clinical laboratories and practice. The committee's goals are to improve the understanding of certain key analytical and clinical aspects of cardiac biomarkers and how these may interplay in clinical practice. Measurement of high-sensitivity cardiac troponin (hs-cTn) assays is a cornerstone in the clinical evaluation of patients with symptoms and/or signs of acute cardiac ischemia. To define myocardial infarction, the Universal Definition of Myocardial Infarction requires patients who manifest with features suggestive of acute myocardial ischemia to have at least one cTn concentration above the sex-specific 99th percentile upper reference limit (URL) for hs-cTn assays and a dynamic pattern of cTn concentrations to fulfill the diagnostic criteria for MI. This special report provides an overview of how hs-cTn 99th percentile URLs should be established, including recommendations about prescreening and the number of individuals required in the reference cohort, how statistical analysis should be conducted, optimal preanalytical and analytical protocols, and analytical/biological interferences or confounds that can affect accurate determination of the 99th percentile URLs. This document also provides guidance and solutions to many of the issues posed.

Biological variation of cardiac myosin-binding protein C in healthy individuals

OBJECTIVES

Cardiac myosin-binding protein C (cMyC) is a novel biomarker of myocardial injury, with a promising role in the triage and risk stratification of patients presenting with acute cardiac disease. In this study, we assess the weekly biological variation of cMyC, to examine its potential in monitoring chronic myocardial injury, and to suggest analytical quality specification for routine use of the test in clinical practice.

METHODS

Thirty healthy volunteers were included. Non-fasting samples were obtained once a week for ten consecutive weeks. Samples were tested in duplicate on the Erenna® platform by EMD Millipore Corporation. Outlying measurements and subjects were identified and excluded systematically, and homogeneity of analytical and within-subject variances was achieved before calculating the biological variability (CVI and CVG), reference change values (RCV) and index of individuality (II).

RESULTS

Mean age was 38 (range, 21-64) years, and 16 participants were women (53%). The biological variation, RCV and II with 95% confidence interval (CI) were: CVA (%) 19.5 (17.8-21.6), CVI (%) 17.8 (14.8-21.0), CVG (%) 66.9 (50.4-109.9), RCV (%) 106.7 (96.6-120.1)/-51.6 (-54.6 to -49.1) and II 0.42 (0.29-0.56). There was a trend for women to have lower CVG. The calculated RCVs were comparable between genders.

CONCLUSIONS

cMyC exhibits acceptable RCV and low II suggesting that it could be suitable for disease monitoring, risk stratification and prognostication if measured serially. Analytical quality specifications based on biological variation are similar to those for cardiac troponin and should be achievable at clinically relevant concentrations.

Adding stress biomarkers to high-sensitivity cardiac troponin for rapid non-ST-elevation myocardial infarction rule-out protocols

AIMS

This study tested the hypothesis that combining stress-induced biomarkers (copeptin or glucose) with high-sensitivity cardiac troponin (hs-cTn) increases diagnostic accuracy for non-ST-elevation myocardial infarction (NSTEMI) in patients presenting to the emergency department.

METHODS AND RESULTS

The ability to rule-out NSTEMI for combinations of baseline hs-cTnT or hs-cTnI with copeptin or glucose was compared with the European Society of Cardiology (ESC) hs-cTnT/I-only rule-out algorithms in two independent (one Norwegian and one international multicentre) diagnostic studies. Among 959 patients (median age 64 years, 60.5% male) with suspected NSTEMI in the Norwegian cohort, 13% had NSTEMI. Adding copeptin or glucose to hs-cTnT/I as a continuous variable did not improve discrimination as quantified by the area under the curve {e.g. hs-cTnT/copeptin 0.91 [95% confidence interval (CI) 0.89-0.93] vs. hs-cTnT alone 0.91 (95% CI 0.89-0.93); hs-cTnI/copeptin 0.85 (95% CI 0.82-0.87) vs. hs-cTnI alone 0.93 (95% CI 0.91-0.95)}, nor did adding copeptin <9 mmol/L or glucose <5.6 mmol/L increase the sensitivity of the rule-out provided by hs-cTnT <5 ng/L or hs-cTnI <4 ng/L in patients presenting more than 3 h after chest pain onset (target population in the ESC-0 h-algorithm). The combination decreased rule-out efficacy significantly (both P < 0.01). These findings were confirmed among 1272 patients (median age 62 years, 69.3% male) with suspected NSTEMI in the international validation cohort, of which 20.7% had NSTEMI. A trend towards increased sensitivity for the hs-cTnT/I/copeptin combinations (97-100% vs. 91-97% for the ESC-0 h-rule-out cut-offs) was observed in the Norwegian cohort.

CONCLUSION

Adding copeptin or glucose to hs-cTnT/I did not increase diagnostic performance when compared with current ESC guideline hs-cTnT/I-only 0 h-algorithms.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

Biological variation of secretoneurin; a novel cardiovascular biomarker implicated in arrhythmogenesis

BACKGROUND

Secretoneurin is a novel prognostic biomarker that may predict mortality in heart failure and the occurrence of ventricular arrhythmias. This study reports the within subject variation (CVI), between subject variation (CVG), reference change values (RCV) and index of individuality (II) of secretoneurin.

METHODS

Thirty healthy volunteers were included. Non-fasting samples were obtained between 8 and 10 am once a week for ten weeks. Secretoneurin was analyzed in duplicate using ELISA. No outliers were present according to Burnett and Reeds' criteria. Simple linear regression did not identify significant trends. Variance homogeneity in the analytical variance and CVI were tested using Cochrane's and Bartlett's tests and four participants were excluded. Calculation of CVI, CVG and RCV were done on ln transformed data as described by Fokkema, the II was calculated using retransformed data.

RESULTS

The median age of the participants was 36 years and 53% were female. Non-fasting glucose, eGFR(CKD-EPI), cTnT and NT-proBNP concentrations were within the normal range. Median secretoneurin concentrations were 38 pmol/L (women) and 33 pmol/L (men), p-value < 0.001. CVI and CVG were 9.8% (CI 8.7% to 11.0%) and 20.0 (CI 15.4% to 28.0%), respectively. RCV were 38.7% (CI 35.5% to 42.7%) and -27.9 (CI -29.9 to -26.2) and the II were 0.60 (CI 0.42-0.78). No gender differences were present.

CONCLUSION

Secretoneurin has a fairly low CVI, CVG, RCV and II, indicating that it could be suitable as a diagnostic or prognostic biomarker and that delta values in serial samplings may be preferable for identifying clinical changes.

Growth differentiation factor 15 – a strong prognostic marker in patients presenting with acute chest pain without acute myocardial infarction

Background

Patients who present with acute chest pain who are not diagnosed with acute myocardial infarction (AMI) may still carry an increased cardiovascular risk. Growth differentiation factor-15 (GDF-15) has earlier been shown to be a strong prognostic marker in the general population and after AMI. However, the prognostic value in the chest pain population without AMI is unknown.

Purpose

The objective of this study was to investigate the prognostic power of GDF-15 in patients presenting with acute chest pain without myocardial infarction.

Methods

A total of 984 patients admitted with suspected NSTE-ACS were included. After excluding patients with AMI the remaining 849 patients were followed for median 722 days (range 1 to 1112 days). The primary endpoint was all-cause mortality. The secondary endpoint was all-cause mortality or AMI. GDF-15 was measured in biobanked admission samples, and patients were divided into two groups based on GDF-15 levels (1: ≤1800 pg/ml, 2: &gt;1800 pg/ml). Kaplan-Meier survival curves according to GDF-15 concentrations ≤1800 pg/ml or &gt;1800 pg/ml were generated. Cox proportional hazards regression analysis was used to estimate unadjusted and adjusted hazard ratios, the latter using age, sex, hypercholesterolemia, current smoking, diabetes, hypertension, BMI, previous myocardial infarction and eGFR &lt;60ml/min/1.73m2 as covariates. The incremental prognostic value of adding GDF-15 to cardiac troponin T was estimated.

Results

GDF-15 concentrations were strongly associated with outcome. GDF-15 concentration were higher in non-survivors than survivors (median 2572 pg/ml vs. 910 pg/ml, p&lt;0,001). In the category with GDF-15 &gt;1800 pg/ml, 28 (17.9%) died, and 49 (31.4%) patients met the secondary endpoint, whereas in the category with GDF-15 levels &lt;1800 pg/ml, only 12/693 (1.7%) died and 25 (3.6%) reached the secondary endpoint, respectively. GDF-15 &gt;1800 pg/ml was associated with an increased risk of death with an unadjusted hazard ratio (HR) of 10.9 (95% CI: 5.6 – 21.5, p: 0.001) and an adjusted HR of 5.2 (95% CI: 1.4 – 19.4, p: 0.014). The risk of death or AMI in patients with GDF-15 &gt;1800 pg/ml was also increased with an unadjusted HR of 9.5 (95% CI 5.9 – 17.7 p: 0.001) and an adjusted hazard ratio of 4.6 (95% CI: 1.7–12.27, p: 0.002). Adding GDF-15 to troponin T led to an increase in C-statistic from: 0.80 (95% CI: 0.73- 0.88) to 0.86 (95% CI 0.79 – 0.91) in predicting all-cause mortality. The optimal cut-off value for predicting the primary endpoint was estimated to be 1818 pg/ml, resulting in a Youden Index of 0.55 with a specificity of 85% and sensitivity of 70%.

Conclusion

GDF-15 is a strong prognostic marker in patients presenting with acute chest pain without AMI and may aid identifying those patients with high cardiovascular risk who require further diagnostics and treatment.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Western Norway Regional Health Authority

Associations of circulating polyunsaturated fatty acids with coronary artery calcium score in hospitalized patients with suspected coronary artery disease

Background

Inadequate intake of polyunsaturated fatty acids (PUFAs) is recognized as a modifiable risk factor for atherosclerotic cardiovascular disease (CVD) (1,2). The n-6 PUFA linoleic acid (LA) constitutes the predominant portion of total dietary PUFAs (3). However, whereas cardiometabolic effects of PUFAs belonging to the n-3 series have been studied for decades, less attention has been payed to potential health effects from n-6 PUFAs (4). Further, there has been concern regarding possible proinflammatory properties of several n-6 PUFA related metabolites.

Purpose

We explored correlations of serum total PUFAs, LA and the n-3 PUFA docosahexaenoic acid (DHA) with the inflammation marker GlycA. Further, we evaluated associations of total PUFAs, LA and DHA with the extension of atherosclerosis, as determined by the Agatston coronary artery calcium (CAC) score (5).

Methods

The study includes 250 patients who were hospitalized due to acute chest pain and referred to coronary CT angiography (CCTA) during in hospital stay. Exclusion criteria included diagnosis of acute myocardial infarction and/or revascularization within 24 hours after admittance. Serum levels of total PUFAs, LA, DHA and GlycA were analyzed by NMR technology in samples that had been frozen and stored at −80°C. After logarithmic transformation, relations of total PUFA, LA, and DHA with GlycA were evaluated by Pearson correlation analyses. The associations with CAC score were visualized in generalized additive regression plots and further evaluated in linear regression models including age, gender, body mass index, diabetes, hypertension and smoking status as independent covariables.

Results

Mean (SD) age was 57.6 (12.0) years, and 91 (36.4%) of the patients were women. Median (25th-75th percentiles) serum levels (in mmol/L) were for total PUFA 6.36 (5.76–7.06), LA 5.00 (4.51–5.55), DHA 0.36 (0.31–0.43) and GlycA 1.04 (0.94–1.13). Interestingly, GlycA was strongly, positively correlated with total PUFA (r=0.54). LA (r=0.53) and DHA (r=0.27), all P&lt;0.001. In contrast, total PUFA and LA were inversely associated with CAC score both providing standardized betas of −0.17, P=0.03 after multivariable adjustments. No significant associations were found between CAC score and DHA or GlycA (P≥0.22). Further, the addition of GlycA to the multivariable model did not materially affect the relationship between CAC score and total PUFA or LA, which remained statistically significant (P=0.04).

Conclusion

In patients undergoing CCTA due to acute chest pain, serum levels of total PUFA and LA were strongly positively correlated with the pro-inflammatory marker GlycA. Still, total PUFA and LA were both inversely associated with the CAC score and the associations remained statistically significant after adjustments for CVD risk factors and GlycA levels. Future studies should further address the diverse effects of n-6 PUFAs on inflammatory pathways, atherogenesis and coronary calcification.

Funding Acknowledgement

Type of funding sources: Public hospital(s). Main funding source(s): Western Norway Regional Health Authority

Patients with NSTEMI have fewer symptoms and higher quality of life three months after admission for acute chest pain

Background

A substantial proportion of patients admitted for possible non-ST elevation acute coronary syndrome (NSTE-ACS) who are not diagnosed with non-ST elevation myocardial infarction (NSTEMI) suffer from conditions (e.g. chronic myocardial injury [CMI]) that may imply serious cardiac risk and impaired quality of life. It is unknown what predicts quality of life and recurrence of symptoms in chest pain patients.

Purpose

To investigate which demographic and clinical characteristics, including discharge diagnosis, that predict recurrent symptoms and quality of life three months after hospitalization for acute chest pain.

Methods

A total of 1506 patients ≥18 years admitted with suspected NSTE-ACS at Haukeland University Hospital, Bergen, Norway, were included in the WESTCOR study. The final diagnosis was adjudicated by two independent cardiologists based on all clinical data including routine cTnT (5th gen, Roche Diagnostics). Three months after discharge patients received questionnaires assessing general health (SF-12v1), angina-related health (SAQ-7) and dyspnea (Rose Dyspnea Scale). In all, 774 (51.3%) patients responded and were included in the analyses. Univariable and multivariable regression models were applied to identify predictors of symptoms and quality of life scores after adjusting for a subset of candidate predictors. A subgroup analysis was undertaken in patients with stable troponin concentrations (N=658).

Results

Based on the discharge diagnosis the patients were grouped as NSTEMI (14.2%), unstable angina pectoris (UAP) (16.9%), non-coronary cardiac disease (6.6%), non-cardiac disease (6.3%) and non-cardiac chest pain (NCCP) (56.0%). After three months the NSTEMI patients had the highest quality of life scores and the lowest prevalence of symptoms (angina and dyspnea), while the inverse was true for the UAP patients (Fig 1). Revascularized patients had a better quality of life compared to those treated conservatively (P&lt;0.001). Adjusted multivariable analysis also demonstrated that revascularization (β=0.19, P=0.002) and a diagnosis of UAP (β=−0.18, P=0.007) succeeded to predict angina frequency. Additionally, current smoking and hypertension were also associated with worse quality of life outcomes (Table 1). NCCP patients had high median prevalence of symptoms after three months, with 50% of the group reporting chest pain in the last four weeks, and 33% reporting dyspnea. In the subgroup analysis, current smoking predicted worse quality of life in all domains (all P&lt;0.05) except SAQ7-Angina frequency.

Conclusions

Three months after hospitalization for chest pain revascularized patients had better quality of life and less symptoms compared to other patient groups. A diagnosis of UAP predicted recurrent symptoms and impaired quality of life in patients, suggesting that closer monitoring should be considered in order to minimize re-hospitalization.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The study is funded by grants from the Western Norway Regional Health Authority, Haukeland and Stavanger University hospitals. Figure 1Table 1

Regular consumption of cod liver oil is associated with reduced basal and exercise-induced C-reactive protein levels; a prospective observational trial : A NEEDED (The North Sea Race Endurance Exercise Study) 2014 sub-study

Background

Dietary supplement use among recreational athletes is common, with the intention of reducing inflammation and improving recovery. We aimed to describe the relationship between omega-3 fatty acid supplement use and inflammation induced by strenuous exercise.

Methods

C-reactive protein (CRP) concentrations were measured in 1002 healthy recreational athletes before and 24 h after a 91-km bicycle race. The use of omega-3 fatty acid supplements was reported in 856 out of 1002 recreational athletes, and the association between supplement use and the exercise-induced CRP response was assessed.

Results

Two hundred seventy-four subjects reported regular use of omega-3 fatty acid supplements. One hundred seventy-three of these used cod liver oil (CLO). Regular users of omega-3 fatty acid supplements had significantly lower basal and exercise-induced CRP levels as compared to non-users (n = 348, p < 0.001). Compared to non-users, regular users had a 27% (95% confidence interval (CI): 14–40) reduction in Ln CRP response (unadjusted model, p < 0.001) and 16% (95% CI: 5–28, p = 0.006) reduction after adjusting for age, sex, race duration, body mass index, delta creatine kinase, MET hours per week, resting heart rate and higher education. CLO was the primary driver of this response with a 34% (95% CI: 19–49) reduction (unadjusted model, p < 0.001) compared to non-users. Corresponding numbers in the adjusted model were 24% (95% CI: 11–38, p < 0.001).

Conclusion

Basal CRP levels were reduced, and the exercise-induced CRP response was attenuated in healthy recreational cyclists who used omega-3 fatty acid supplements regularly. This effect was only present in regular users of CLO.

Trial registration

NCT02166216, registered June 18, 2014 – Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12970-021-00437-1.

How Well Do Laboratories Adhere to Recommended Guidelines for Cardiac Biomarkers Management in Europe? The CArdiac MARker Guideline Uptake in Europe (CAMARGUE) Study of the European Federation of Laboratory Medicine Task Group on Cardiac Markers

BACKGROUND

The CARdiac MARker Guideline Uptake in Europe (CAMARGUE) program is a multi-country audit of the use of cardiac biomarkers in routine clinical practice.

METHODS

An email link to a web-based questionnaire of 30 multiple-choice questions was distributed via the professional societies in Europe.

RESULTS

374 questionnaires were returned from 39 countries, the majority of which were in northern Europe with a response rate of 8.2%-42.0%. The majority of the respondents were from hospitals with proportionately more responses from central hospitals than district hospitals. Cardiac troponin was the preferred cardiac biomarker, evenly split between cardiac troponin T (cTnT) and cardiac troponin I (cTnI). Aspartate transaminase and lactate dehydrogenase are no longer offered as cardiac biomarkers. Creatine kinase, creatine kinase MB isoenzyme, and myoglobin continue to be offered as part of the cardiac biomarker profile in approximately on 50% of respondents. There is widespread utilization of high sensitivity (hs) troponin assays. The majority of cTnT users measure hs-cTnT. 29.5% of laboratories measure cTnI by a non-hs method but there has been substantial conversion to hs-cTnI. The majority of respondents used ng/L and use the 99th percentile as the upper reference limit (71.9% of respondents). A range of diagnostic protocols are in use.

CONCLUSIONS

There is widespread utilization of hs troponin methods. A significant minority do not use the 99th percentile as recommended and there is, as yet, little uptake of very rapid diagnostic strategies. Education of laboratory professionals and clinicians remains a priority.

Quantifying atherogenic lipoproteins for lipid-lowering strategies: consensus-based recommendations from EAS and EFLM

The joint consensus panel of the European Atherosclerosis Society (EAS) and the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) recently addressed present and future challenges in the laboratory diagnostics of atherogenic lipoproteins. Total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDLC), LDL cholesterol (LDLC), and calculated non-HDLC (=total - HDLC) constitute the primary lipid panel for estimating risk of atherosclerotic cardiovascular disease (ASCVD) and can be measured in the nonfasting state. LDLC is the primary target of lipid-lowering therapies. For on-treatment follow-up, LDLC shall be measured or calculated by the same method to attenuate errors in treatment decisions due to marked between-method variations. Lipoprotein(a) [Lp(a)]-cholesterol is part of measured or calculated LDLC and should be estimated at least once in all patients at risk of ASCVD, especially in those whose LDLC declines poorly upon statin treatment. Residual risk of ASCVD even under optimal LDL-lowering treatment should be also assessed by non-HDLC or apolipoprotein B (apoB), especially in patients with mild-to-moderate hypertriglyceridemia (2-10 mmol/L). Non-HDLC includes the assessment of remnant lipoprotein cholesterol and shall be reported in all standard lipid panels. Additional apoB measurement can detect elevated LDL particle (LDLP) numbers often unidentified on the basis of LDLC alone. Reference intervals of lipids, lipoproteins, and apolipoproteins are reported for European men and women aged 20-100 years. However, laboratories shall flag abnormal lipid values with reference to therapeutic decision thresholds.

Cardiac Troponin Assays With Improved Analytical Quality: A Trade-Off Between Enhanced Diagnostic Performance and Reduced Long-Term Prognostic Value

Background

Cardiac troponin (cTn) permits early rule‐out/rule‐in of patients admitted with possible non–ST‐segment–elevation myocardial infarction. In this study, we developed an admission and a 0/1 hour rule‐out/rule‐in algorithm for a troponin assay with measurable results in >99% of healthy individuals. We then compared its diagnostic and long‐term prognostic properties with other protocols.

Methods and Results

Blood samples were collected at 0, 1, 3, and 8 to 12 hours from patients admitted with possible non–ST‐segment–elevation myocardial infarction. cTnT (Roche Diagnostics), cTnI_(Abbott) (Abbott Diagnostics), and cTnI_(sgx) (Singulex Clarity System) were measured in 971 admission and 465 1‐hour samples. An admission and a 0/1 hour rule‐out/rule‐in algorithm were developed for the cTnI_(sgx) assay and its diagnostic properties were compared with cTnT_ESC (European Society of Cardiology), cTnI_(Abbott)ESC, and 2 earlier cTnI_(sgx) algorithms. The prognostic composite end point was all‐cause mortality and future nonfatal myocardial infarction during a median follow‐up of 723 days. non–ST‐segment–elevation myocardial infarction prevalence was 13%. The novel cTnI_(sgx) algorithms showed similar performance regardless of time from symptom onset, and area under the curve was significantly better than comparators. The cTnI_{(sgx)0/1 hour} algorithm classified 92% of patients to rule‐in or rule‐out compared with ≤78% of comparators. Patients allocated to rule‐out by the prior published 0/1 hour algorithms had significantly fewer long‐term events compared with the rule‐in and observation groups. The novel cTnI_{(sgx)0/1 hour} algorithm used a higher troponin baseline concentration for rule‐out and did not allow for prognostication.

Conclusions

Increasingly sensitive troponin assays may improve identification of non–ST‐segment–elevation myocardial infarction but could rule‐out patients with subclinical chronic myocardial injury. Separate protocols for diagnosis and risk prediction seem appropriate.

Clinical risk scores identify more patients at risk for cardiovascular events within 30 days as compared to standard ACS risk criteria: the WESTCOR study

AIMS

Troponin-based algorithms are made to identify myocardial infarctions (MIs) but adding either standard acute coronary syndrome (ACS) risk criteria or a clinical risk score may identify more patients eligible for early discharge and patients in need of urgent revascularization.

METHODS AND RESULTS

Post-hoc analysis of the WESTCOR study including 932 patients (mean 63 years, 61% male) with suspected NSTE-ACS. Serum samples were collected at 0, 3, and 8-12 h and high-sensitivity cTnT (Roche Diagnostics) and cTnI (Abbott Diagnostics) were analysed. The primary endpoint was MI, all-cause mortality, and unplanned revascularizations within 30 days. Secondary endpoint was non-ST-elevation myocardial infarction (NSTEMI) during index hospitalization. Two combinations were compared: troponin-based algorithms (ESC 0/3 h and the High-STEACS algorithm) and either ACS risk criteria recommended in the ESC guidelines, or one of eleven clinical risk scores, HEART, mHEART, CARE, GRACE, T-MACS, sT-MACS, TIMI, EDACS, sEDACS, Goldman, and Geleijnse-Sanchis. The prevalence of primary events was 21%. Patients ruled out for NSTEMI and regarded low risk of ACS according to ESC guidelines had 3.8-4.9% risk of an event, primarily unplanned revascularizations. Using HEART score instead of ACS risk criteria reduced the number of events to 2.2-2.7%, with maintained efficacy. The secondary endpoint was met by 13%. The troponin-based algorithms without evaluation of ACS risk missed three-index NSTEMIs with a negative predictive value (NPV) of 99.5% and 99.6%.

CONCLUSION

Combining ESC 0/3 h or the High-STEACS algorithm with standardized clinical risk scores instead of ACS risk criteria halved the prevalence of rule-out patients in need of revascularization, with maintained efficacy.

Gastric bypass surgery is associated with reduced subclinical myocardial injury and greater activation of the cardiac natriuretic peptide system than lifestyle intervention

AIMS

Morbid obesity is a risk factor for cardiovascular disease. The relative effects of Roux-en-Y gastric bypass surgery (GBS) and intensive lifestyle intervention (ILI) on subclinical myocardial injury, the activity of the cardiac natriuretic system, and systemic inflammation remain unclear.

METHODS

In a 59-week non-randomized clinical trial that included 131 patients with morbid obesity, we compared the effects ofGBS and ILI on concentrations of cardiac troponin T (cTnT) and I (cTnI), N-terminal pro-B-type natriuretic peptide (NT-proBNP) and C-reactive protein (CRP).

RESULTS

In the GBS and ILI group, median body mass index (BMI) was reduced by 14.4 kg/m² versus 3.9 kg/m², respectively (p value < 0.001). Cardiac troponins decreased after GBS, p = 0.014 (cTnT) and p = 0.065 (cTnI) and increased significantly in those treated with ILI (p values ≤ 0.021) (between-group differences for deltas: p ≤ 0.003). NT-proBNP increased in both groups, but significantly more in the GBS than in the ILI group (between-group differences for deltas: p = 0.008). CRP decreased significantly within the GBS and the ILI group, with this change significantly greater in the GBS group (between-group differences for deltas p < 0.001). The dominating mediator of the biomarker changes was weight loss. Prior coronary artery disease and diabetes were predictive of the magnitude of the changes in cTnI and NT-proBNP, respectively.

CONCLUSION

Compared to ILI, GBS was associated with reduced subclinical myocardial injury and systemic inflammation, and enhancement of the cardiac natriuretic peptide system. The biomarker changes were predominantly mediated by weight loss.

Analytical performance of cardiac troponin assays - Current status and future needs

Concurrent with the introduction of cardiac troponin measurements into the diagnostic definition of myocardial infarction (MI), clinicians and laboratory professionals signaled a clear clinical need for improved analytical quality. This was an important precipitant for developing high-sensitivity cardiac troponin (hs-cTn) assays, currently used in rapid algorithms guiding investigations of patients presenting to the emergency department with possible MI. The hs-cTn assays were also important for the detection and monitoring of low-grade chronic myocardial injury, a condition that has been linked to increased long-term risk of cardiovascular morbidity and mortality. This review summarizes the general recommendations for defining analytical performance specifications while providing relevant clinical situations related to analytical performance. Importantly, outcome studies suggest analytical quality performance for hs-cTn is sufficient for early discharge of patients investigated for possible MI. However, bias due to change in calibrators or reagents may significantly affect the percentage of patients discharged. Biological variation data is suitable for defining performance specifications when hs-cTn measurements are used for diagnosing and monitoring chronic myocardial injury. Further improvement in analytical performance for hs-cTn testing may result in even faster decision making in the emergency setting; while also identifying those with chronic injury at risk for an adverse cardiac event.

Endurance exercise training volume is not associated with progression of coronary artery calcification

BACKGROUND

Recent cross-sectional studies have suggested a dose-dependent relationship between lifelong exposure to physical activity and the burden of calcified coronary artery disease (CAD). No longitudinal studies have addressed this concern.

HYPOTHESIS

Exercise volume is associated with progression of coronary artery calcium (CAC), defined as ≥10 units increase in CAC score.

METHODS

Sixty-one recreational athletes who were assessed by coronary computed tomography angiography (CCTA) as part of the NEEDED 2013/14 study were re-assessed 4-5 years later, in 2018.

RESULTS

Subjects were 45.9 ± 9.6 years old at inclusion, and 46 (74%) were male. Between 2013 and 2018, the participants reported median 5 (range: 0-20, 25th-75th percentile: 4-6) hours of high-intensity exercise per week. None of the included subjects smoked during follow-up. At inclusion, 21 (33%) participants had coronary artery calcifications. On follow-up CCTA in 2018, 15 (25%) subjects had progressive coronary calcification (≥10 Agatston units increase in CAC). These subjects were older (53 ± 9 vs 44 ± 9 years old, P = .002) and had higher levels of low-density lipoprotein at baseline (3.5 (2.9-4.3) vs 2.9 (2.3-3.5) mmol/L, P = .031) as compared to subjects with stable condition. No relationship was found between hours of endurance training per week and progression of coronary artery calcification. In multiple regression analysis, age and baseline CAC were the only significant predictors of progressive CAC.

CONCLUSION

No relationship between exercise training volume and the progression of coronary artery calcification was found in this longitudinal study of middle-aged recreational athletes.

P2500The high-sensitivity cardiac troponin I and T response following strenuous activity is attenuated by smokeless tobacco:The North Sea Race Endurance Exercise Study (NEEDED) 2014

Background

Use of snus, a smokeless oral tobacco product, is increasing among athletes and recreational exercisers in Scandinavia. Strenuous physical activity is associated with an acute increase in high-sensitivity cardiac troponins (hs-cTn) in healthy individuals. Current smoking is associated with lower baseline hs-cTn concentrations in current smokers in the general population, but whether tobacco affects the hs-cTn response to exercise remains unknown.

Methods

We measured serial cTnI and cTnT concentrations in 1002 healthy recreational athletes before, 3 and 24 h after a 91 km bicycle race. Self-reported snus habits were reported as: non-current (n=794) and current (n=118). The association between snus use and change in log hs-cTnI and hs-cTnT (differences between concentrations at baseline and 3 h (Δ3 h) and 24 h (Δ24 h)) were assessed by multivariable linear regression analysis.

Results

Current snus use was associated with lower cTnI (current users of snus vs non-current: median, 1.7 ng/l; interquartile range (IQR), 1.6–2.3 vs 2.0 ng/L; IQR 1.6–3.2; p=0.020) and cTnT (current users of snus vs non-current: median, 3.0 ng/L, IQR, 3.0–3.5 vs 3.0 ng/L, IQR 3.0–4.3; p=0.021) concentrations at baseline. Both in unadjusted and fully adjusted linear regression models, users of snus had significantly lower Δ3 h and Δ24 h cTnI and cTnT concentrations (Table).

Association between snus use and change in concentrations of hs-cTnI and hs-cTnT (95% CI) Model 1 Model 2 Model 3 Model 4 ΔcTnI 3 h   Current snus −28% (−46% to −10%), p=0.003 −33% (−51% to −14%), p=0.001 −31% (−49% to −13%), p=0.001 −29% (−47% to −11%), p=0.002 ΔcTnI 24 h   Current snus −38% (−62% to −15%), p=0.002 −36% (−59% to −12%), p=0.003 −32% (−56% to −9%), p=0.007 −30% (−54% to −7%), p=0.010 ΔcTnT 3 h   Current snus −28% (−10% to −46%), p=0.003 −33% (−51% to −14%), p=0.001 −31% (−49% to −13%), p=0.001 −29% (−47% to −11%), p=0.002 ΔcTnT 24 h   Current snus −20% (−4% to −36%), p=0.015 −23% (−39% to −8%), p=0.004 −21% (−36% to −5%), p=0.009 −19% (−34% to −14%), p=0.013 Model 1 unadjusted; Model 2 adjusted for sex and age; Model 3 adjusted for Model 2 and systolic blood pressure, body mass index, low-density lipoprotein and estimated glomerular filtration rate; Model 4 adjusted for the same variables as in Model 3 but also race duration and resting heart rate.

Conclusion

The exercise-induced cTn response in healthy recreational cyclist is attenuated in users of smokeless tobacco compared to never users. These findings extend observations of lower hs-cTn concentrations in tobacco smokers in the general population.

Acknowledgement/Funding

Operating grant from North Sea Race, Abbot Diagnostics, Lærdal Foundation. PhD fellowship from South-Eastern Norway Regional Health Authority.

P4425The exercise-induced troponin I elevation is highly correlated with power output during exercise in recreational cyclists with coronary atherosclerosis

Background

Following strenuous exercise there is an increase cardiac Troponins (cTn) elevation considered being a physiological response. During prolonged strenuous physical activity, high work-loads may induce demand myocardial ischemia due to an oxygen demand/supply mismatch in susceptible subjects, causing an excessive cTn elevation.

Purpose

This study aimed to assess the relationship between exercise-induced cTnI elevation and direct measurement of work performed during prolonged strenuous exercise in subjects with and without atherosclerotic CAD.

Methods

Work during a 91 km mountain bike race was quantified by Stages™ power meters. Power (Watt) and heart rate data were stored in Garmin™ Forerunner 935 monitors. Coronary computed tomography angiography was performed after the race. Blood pressure was measured 4 times during the race. Blood samples (hs-cTnI from Abbot Diagnostics) were obtained one day prior to the race and at 3 and 24 h after the race. Data are presented as mean±SD or median (25th and 75th percentile).

Results

40 subjects (10 women) were included in the final analysis. 15 Participants (4 women) had atherosclerosis, none had obstructive CAD. These participants were significantly older (55±8 years vs. 46±8 years p=0.007) and had higher training volumes (METS: 69 (64–102) hrs/week) compared with normal subjects (METS: 51 (33–88) hrs/week) (p=0.03). Baseline cTnI was higher (p=0.04) in the atherosclerotic group (4.5 (3.4–8.8) ng/L) compared with normals (2.6 (1.6–4.8) ng/L). There were no differences in baseline blood pressure, peak VO2 max, heart rate or BMI. There was no significant difference in race duration between normals (3.9 (3.5–4.5) hrs) and subjects with atherosclerosis (4.1 (3.6–4.5) hrs). During the race there were no differences in peak power or peak Watt/kg. cTnI increased after the race in all participants, but there were no differences between groups: 3h: atherosclerosis: 89 (27–131) ng/L vs. normal 77 (36–104) ng/L, 24h: atherosclerosis: 13 (6.3–23.7) ng/L vs. normal: 17 (12–37) ng/L. There were no significant difference between the groups in average power during the race: atherosclerosis: 167±50 Watt vs. 174 (±50) Watt or ratio: 2.0±0.49 Watt/kg vs 2.2±0.58 Watt/kg during the race. Maximal systolic and diastolic blood pressures during the race were higher (p=0.002) in the atherosclerotic group: SBP: 241±14 mmHg vs. 219±26 mmHg, DBP: 107±8 vs 95±8 mmHg. In atherosclerotic subjects cTnI both at 3h and 24 h were highly correlated (p<0.001) with Watt/kg ratio during the race in contrast to no correlations in the normal group (Figure).

Conclusions

Our findings suggest that the presence of coronary atherosclerosis, even in the absences of significant stenosis, alters the relationship between workload and the troponin response. This indicates different release kinetics in exercise-induced cTn in participants with and without CAD, with prolonged elevation in cTnI in CAD subjects exceeding the highest work-intensities.

Acknowledgement/Funding

Grant Western Norway Health service, Grant ConocoPhillips, Grant Simon Fougner Hartmanns Familyfund

Occult obstructive coronary artery disease is associated with prolonged cardiac troponin elevation following strenuous exercise

Background

Sudden cardiac death among middle-aged recreational athletes is predominantly due to myocardial ischaemia. This study examined whether measuring cardiac troponin I and T (cTnI and cTnT) after strenuous exercise could identify occult obstructive coronary artery disease.

Design

Prospective observational study.

Methods

Subjects were recruited from 1002 asymptomatic recreational cyclists completing a 91-km mountain bike race (North Sea Race Endurance Exercise Study). No subject had known cardiovascular disease or took cardiovascular medication. Blood samples were collected within 24 h before and 3 h and 24 h after the race. Coronary computed tomography angiography was performed in 80 participants with the highest post-exercise cTnI and in 40 reference subjects with moderately elevated cTnI values.

Results

Study subjects ( N = 120) were 45 (36–52) years old and 74% were male. There were similar demographics in the High-cTnI group and the Reference group. The cTn concentrations were highest at 3 h post-race: cTnI, 224 (125–304) ng/L; cTnT, 89 (55–124) ng/L. Nine subjects had obstructive coronary artery disease on coronary computed tomography angiography, eight of whom were High-cTnI responders. Two subjects had myocardial bridging, both High-cTnI responders. Troponin concentrations at 24 h post-race were higher in subjects with obstructive coronary artery disease than in the rest of the cohort ( n = 109): cTnI, 151 (72–233) ng/L vs. 24 (19–82) ng/L, p = 0.005; cTnT, 39 (25–55) ng/L vs. 20 (14–31) ng/L, p = 0.002. The areas under the receiver operating characteristic curves for predicting obstructive coronary artery disease were 0.79, p = 0.005 (cTnI) and 0.82, p = 0.002 (cTnT).

Conclusion

In subjects with occult obstructive coronary artery disease there was a prolonged elevation of cTn following strenuous exercise.

The copeptin response after physical activity is not associated with cardiac biomarkers or asymptomatic coronary artery disease: The North Sea Race Endurance Exercise Study (NEEDED) 2013

BACKGROUND

Copeptin concentrations increase both during acute coronary syndrome and following physical exercise. The relationship between copeptin increase following physical exercise and coronary artery disease (CAD) is uncertain. The aim of this study was to 1) describe the copeptin response following strenuous physical exercise, and 2) investigate the determinants of exercise induced copeptin concentrations, particularly in relation to cardiac biomarkers and CAD.

METHODS

Serum samples were collected from 97 recreational cyclists 24h before, and immediately, 3 and 24h after a 91-km bike race. Three subjects were subsequently diagnosed with significant asymptomatic CAD. Delta copeptin concentrations were correlated to patient characteristics and to biomarker concentrations.

RESULTS

Participants were 42.8±9.6years, and 76.3% were male. Copeptin concentrations increased to maximal levels immediately after the race and were normalized in >90% after 3h. A total of 53% and 39% exceeded the 95th and 99th percentile of the assay (10 and 19pmol/L) respectively. In multivariate models, race time, serum sodium, creatinine and cortisol were significant predictors of copeptin levels. There was no correlation between changes in copeptin and changes in cardiac biomarkers (hs-cTnI, hs-cTnT and BNP). Copeptin concentrations were normal in the subjects with asymptomatic CAD.

CONCLUSIONS

The moderate, short-term, exercise induced copeptin increase observed in the present study was not related to hs-cTn or BNP levels. Copeptin was normal in three asymptomatic recreational athletes with significant CAD.

A survey of patients' views from eight European countries of interpretive support from Specialists in Laboratory Medicine

BACKGROUND

There is increasing interest in direct patient engagement including receiving their laboratory medicine results. We previously established an appetite for Specialists in Laboratory Medicine to support patients in understanding results. The aim of this study was to establish whether patients agreed with such an approach, determined through surveying views in eight European countries.

METHODS

A standardized five-question survey was administered across eight European countries to a total of 1084 individuals attending medical outpatient clinics, with 100 patients each in Poland, Serbia, Netherlands, Turkey and Czech Republic, 101 in Estonia, 116 in Denmark and 367 in Norway. The responses across countries were compared using the chi-square test (p<0.05).

RESULTS

Patients wanting their results ranged from 50% to 94% (mean 65%) of those responding positively, a mean of 72% wanted additional information with their results; direct receipt was preferred over referral to a website. Specialists in Laboratory Medicine providing such information were acceptable to a mean of 62% of those respondents wishing their results; in countries where payment was possible, there was little interest in making additional payment for such a service.

CONCLUSIONS

A clear proportion of patients are interested in receiving their laboratory medicine results, the majority with explanatory notes; a role for Specialists in Laboratory Medicine is acceptable and raises the potential for direct engagement by such specialists with patients offering a new paradigm for the provision of laboratory medicine activities.

Within-day biological variation and hour-to-hour reference change values for hematological parameters

BACKGROUND

Middle- and long-term biological variation data for hematological parameters have been reported in the literature. Within-day 24-h variability profiles for hematological parameters are currently lacking. However, comprehensive hour-to-hour variability data are critical to detect diurnal cyclical rhythms, and to take into account the 'time of sample collection' as a possible determinant of natural fluctuation. In this study, we assessed 24-h variation profiles for 20 hematological parameters.

METHODS

Blood samples were collected under standardized conditions from 24 subjects every hour for 24 h. At each measurement, 20 hematological parameters were determined in duplicate. Analytical variation (CVA), within-subject biological variation (CVI), between-subject biological variation (CVG), index of individuality (II), and reference change values (RCVs) were calculated. For the parameters with a diurnal rhythm, hour-to-hour RCVs were determined.

RESULTS

All parameters showed higher CVG than CVI. Highest CVG was found for eosinophils (46.6%; 95% CI, 34.9%-70.1%) and the lowest value was mean corpuscular hemoglobin concentration (MCHC) (3.2%; 95% CI, 2.4%-4.8%). CVI varied from 0.4% (95% CI, 0.32%-0.42%) to 20.9% (95% CI, 19.4%-22.6%) for red cell distribution width (RDW) and eosinophils, respectively. Six hematological parameters showed a diurnal rhythm.

CONCLUSIONS

We present complete 24-h variability profiles for 20 hematological parameters. Hour-to-hour reference changes values may help to better discriminate between random fluctuations and true changes in parameters with rhythmic diurnal oscillations.

How Well Do Laboratories Adhere to Recommended Clinical Guidelines for the Management of Myocardial Infarction: The CARdiac MArker Guidelines Uptake in Europe Study (CARMAGUE)

BACKGROUND

We undertook an assessment of current use of evidence-based guidelines for the use of cardiac biomarkers in Europe (EU) and North America (NA).

METHODS

In 2013–2014 a web-based questionnaire was distributed via NA and EU biochemical societies. Questions covered cardiac biomarkers measured, analytical methods used, decision thresholds, and use of decision-making protocols. Results were collated using a central database and analyzed using comparative and descriptive nonparametric statistics.

RESULTS

In EU, returns were obtained from 442 hospitals, 50% central or university hospitals, and 39% from local hospitals from 35 countries with 395/442 (89%) provided an acute service. In NA there were 91 responses (63.7% central or university hospitals, 19.8% community hospitals) with 76/91 (83.5%) providing an acute service. Cardiac troponin was the preferred cardiac biomarker in 99.5% (EU) and 98.7% (NA), and the first line marker in 97.7% (EU) and 97.4% (NA). There were important differences in the choice of decision limits and their derivations. The origin of the information was also significantly different, with EU vs NA as follows: package insert, 61.9% vs 40%; publications, 17.1% vs 15.0%; local clinical or analytical validation choice, 21.0% vs 45.0%; P = 0.0003.

CONCLUSIONS

There are significant differences between EU and NA use of cardiac biomarkers. This probably relates to different availability of assays between EU and NA (such as high-sensitivity troponin assays) and different laboratory practices on assay introduction (greater local evaluation of assay performance occurred in NA).

Analytical Bias Exceeding Desirable Quality Goal in 4 out of 5 Common Immunoassays: Results of a Native Single Serum Sample External Quality Assessment Program for Cobalamin, Folate, Ferritin, Thyroid-Stimulating Hormone, and Free T4 Analyses

BACKGROUND

We undertook this study to evaluate method differences for 5 components analyzed by immunoassays, to explore whether the use of method-dependent reference intervals may compensate for method differences, and to investigate commutability of external quality assessment (EQA) materials.

METHODS

Twenty fresh native single serum samples, a fresh native serum pool, Nordic Federation of Clinical Chemistry Reference Serum X (serum X) (serum pool), and 2 EQA materials were sent to 38 laboratories for measurement of cobalamin, folate, ferritin, free T4, and thyroid-stimulating hormone (TSH) by 5 different measurement procedures [Roche Cobas (n = 15), Roche Modular (n = 4), Abbott Architect (n = 8), Beckman Coulter Unicel (n = 2), and Siemens ADVIA Centaur (n = 9)]. The target value for each component was calculated based on the mean of method means or measured by a reference measurement procedure (free T4). Quality specifications were based on biological variation. Local reference intervals were reported from all laboratories.

RESULTS

Method differences that exceeded acceptable bias were found for all components except folate. Free T4 differences from the uncommonly used reference measurement procedure were large. Reference intervals differed between measurement procedures but also within 1 measurement procedure. The serum X material was commutable for all components and measurement procedures, whereas the EQA materials were noncommutable in 13 of 50 occasions (5 components, 5 methods, 2 EQA materials).

CONCLUSIONS

The bias between the measurement procedures was unacceptably large in 4/5 tested components. Traceability to reference materials as claimed by the manufacturers did not lead to acceptable harmonization. Adjustment of reference intervals in accordance with method differences and use of commutable EQA samples are not implemented commonly.

Critical review of laboratory investigations in clinical practice guidelines: proposals for the description of investigation

BACKGROUND

Correct information provided by guidelines may reduce laboratory test related errors during the pre-analytical, analytical and post-analytical phase and increase the quality of laboratory results.

METHODS

Twelve clinical practice guidelines were reviewed regarding inclusion of important laboratory investigations. Based on the results and the authors' experience, two checklists were developed: one comprehensive list including topics that authors of guidelines may consider and one consisting of minimal standards that should be covered for all laboratory tests recommended in clinical practice guidelines. The number of topics addressed by the guidelines was related to involvement of laboratory medicine specialists in the guideline development process.

RESULTS

The comprehensive list suggests 33 pre- analytical, 37 analytical and 10 post-analytical items. The mean percentage of topics dealt with by the guidelines was 33% (median 30%, range 17%-55%) and inclusion of a laboratory medicine specialist in the guideline committee significantly increased the number of topics addressed. Information about patient status, biological and analytical interferences and sample handling were scarce in most guidelines even if the inclusion of a laboratory medicine specialist in the development process seemingly led to increased focus on, e.g., sample type, sample handling and analytical variation. Examples underlining the importance of including laboratory items are given.

CONCLUSIONS

Inclusion of laboratory medicine specialist in the guideline development process may increase the focus on important laboratory related items even if this information is usually limited. Two checklists are suggested to help guideline developers to cover all important topics related to laboratory testing.

Weekly and 90-minute biological variations in cardiac troponin T and cardiac troponin I in hemodialysis patients and healthy controls

BACKGROUND

Myocardial infarction (MI) is diagnosed by the finding of a single cardiac troponin value above the 99th percentile and a significant time-dependent change in cardiac troponin concentration. The aim of this study was to determine the 90-min and weekly biological variations, the reference change value (RCV), and the index of individuality (II) of high-sensitivity cardiac troponin T (hs-cTnT) (Roche Diagnostics) and hs-cTnI (Abbott Diagnostics) in patients receiving hemodialysis (HD) and in healthy individuals.

METHOD

Blood samples were collected from 19 HD patients (on an HD-free day) and 20 healthy individuals at 90-min intervals over a 6-h period (between 08:30 and 14:30) and before the midweek HD treatment for 10 weeks. The within-person variation (CVi), between-person variation, RCV, and II were calculated.

RESULTS

During the 6-h sampling period, the concentrations of hs-cTnT (both groups) and hs-cTnI (HD patients only) decreased on average by 0.8% to 1.7% per hour, respectively. These declining trends were included in the calculation of a 90-min asymmetric RCV: -8%/+5% in HD patients (hs-cTnT), -18%/+21% in HD patients (hs-cTnI), -27%/+29% in healthy individuals (hs-cTnT), and -39%/+64% in healthy individuals (hs-cTnI). The II was low in both groups for both assays. The weekly CVi values were approximately 8% (hs-cTnT) and 15% (hs-cTnI) in both groups.

CONCLUSIONS

When using a cardiac troponin change of 20%-50% to diagnose an MI, the false-positive rate is likely to be lower for the hs-cTnT assay than for the hs-cTnI assay. The low II suggests that use of a diagnostic cutoff value can be omitted.