Biological variation of high sensitive Troponin T in stable heart failure patients with ischemic or dilated cardiomyopathy

Different expression and prognostic value of troponin in ischemic cardiomyopathy and non-ischemic dilated cardiomyopathy

BACKGROUND

Early risk stratification of patients with ischemic cardiomyopathy (ICM) and non-ischemic dilated cardiomyopathy (NIDCM) may be beneficial for therapies.

METHODS

We retrospectively enrolled all patients admitted for acute heart failure (HF) between January 2019 and December 2021 in Zhongshan Hospital Fudan University, dividing them according to etiology (ICM or NIDCM). Cardiac troponin T (TNT) concentration was compared between two groups. Risk factors for positive TNT and in-hospital all-cause mortality were investigated with regression analysis.

RESULTS

A total of 1525 HF patients were enrolled, including 571 ICM and 954 NIDCM. The TNT positive patients were not different between the two groups (41.3% in ICM group vs. 37.8% in NIDCM group, P = 0.215). However, the TNT value in ICM group were significantly higher than that in NIDCM group (0.025 (0.015-0.053) vs. 0.020 (0.014-0.041), P = 0.001). NT-proBNP was independently associated with TNT in both ICM and NIDCM group. Although the in-hospital all-cause mortality did not show much difference between the two groups (1.1% vs. 1.9%, P = 0.204), the NIDCM diagnosis was associated with reduced risk of mortality after multiple adjustments (OR 0.169, 95% CI 0.040-0.718, P = 0.016). Other independent risk factors included the level of NT-proBNP (OR 8.260, 95% CI 3.168-21.533, P < 0.001), TNT (OR 8.118, 95% CI 3.205-20.562, P < 0.001), and anemia (OR 0.954, 95% CI 0.931-0.978, P < 0.001). The predictive value of TNT and NT-proBNP for all-cause mortality was similar. However, the best cutoff values of TNT for mortality were different between ICM and NIDCM groups, which were 0.113 ng/mL and 0.048 ng/mL, respectively.

CONCLUSION

The TNT level was higher in ICM patient than that in NIDCM patients. TNT was an independent risk factor for in-hospital all-cause mortality for both ICM and NIDCM patients, although the best cutoff value was higher in ICM patients.

Elevation Mechanisms and Diagnostic Consideration of Cardiac Troponins under Conditions Not Associated with Myocardial Infarction. Part 2

This article proceeds with a discussion of the causes and mechanisms of an elevation in cardiac troponins in pathological conditions not associated with acute myocardial infarction. The second part of the article discusses the causes and mechanisms of cardiac troponins elevation in diabetes mellitus, arterial hypertension, hereditary cardiomyopathies, cardiac arrhythmias (atrial fibrillation, supraventricular tachycardia), acute aortic dissection, and diseases of the central nervous system (strokes, subarachnoidal hemorrhage). The final chapter of this article discusses in detail the false-positive causes and mechanisms of elevated cardiac troponins.

Short- and long-term biological variation of cardiac troponin I in healthy individuals, and patients with end-stage renal failure requiring haemodialysis or cardiomyopathy

Objectives High-sensitivity (hs) cardiac troponin (cTn) assays can quantitate small fluctuations in cTn concentration. Determining biological variation allows calculation of reference change values (RCV), to define significant changes. We assessed the short- and long-term biological variation of cardiac troponin I (cTnI) in healthy individuals and patients with renal failure requiring haemodialysis or cardiomyopathy. Methods Plasma samples were collected hourly for 4 h and weekly for seven further weeks from 20 healthy individuals, 9 renal failure patients and 20 cardiomyopathy patients. Pre- and post-haemodialysis samples were collected weekly for 7 weeks. Samples were analysed using a hs-cTnI assay (Abbott Alinity ci-series). Within-subject biological variation (CVI), analytical variation (CVA) and between-subject biological variation (CVG) was used to calculate RCVs and index of individuality (II). Results For healthy individuals, CVI, CVA, CVG, RCV and II values were 8.8, 14.0, 43.1, 45.8% and 0.38 respectively for short-term, and 41.4, 14.0, 25.8, 121.0% and 1.69 for long-term. For renal failure patients, these were 2.6, 5.8, 50.5, 17.6% and 0.30 respectively for short-term, and 19.1, 5.8, 11.2, 55.2% and 1.78 for long-term. For cardiomyopathy patients, these were 4.2, 10.0, 65.9, 30.0% and 0.16 respectively for short-term, and 17.5, 10.0, 63.1, 55.8% and 0.32 for long-term. Mean cTnI concentration was lower post-haemodialysis (15.2 vs. 17.8 ng/L, p < 0.0001), with a 16.9% mean relative change. Conclusions The biological variation of cTnI is similar between end-stage renal failure and cardiomyopathy patients, but proportionately greater in well-selected healthy individuals with very low baseline cTnI concentrations.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

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

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

CRP genetic variants are associated with mortality and depressive symptoms in chronic heart failure patients

OBJECTIVE

Heart failure (HF) is a complex medical condition with a multitude of genetic and other factors being involved in the pathogenesis. Emerging evidence points to an involvement of inflammatory mechanisms at least in subgroups of patients. The same is true for depression and depressive symptoms, which have a high prevalence in HF patients and are risk factors for the development and outcomes of cardiovascular disease.

METHODS

In 936 patients of the Interdisciplinary Network Heart Failure (INH) program, CRP and IL-6 protein blood levels were measured and genetic variants (single nucleotide polymorphisms) of the CRP and IL6 gene analyzed regarding their influence on mortality.

RESULTS

Less common recessive genotypes of two single nucleotide polymorphisms in the CRP gene (rs1800947 and rs11265263) were associated with significantly higher mortality risk (p < 0.006), higher CRP levels (p = 0.029, p = 0.006) and increased depressive symptoms in the PHQ-9 (p = 0.005, p = 0.003). Variants in the IL-6 gene were not associated with mortality.

CONCLUSION

Our results hint towards an association of less common CRP genetic variants with increased mortality risk, depressive symptoms and peripheral CRP levels in this population of HF patients thereby suggesting a possible role of the inflammatory system as link between poor prognosis in HF and depressive symptoms.

Troponin elevation in patients without acute coronary syndrome

INTRODUCTION AND OBJECTIVES

Troponins are specific biomarkers of myocardial injury and are implicated in the diagnosis and prognosis of patients with acute coronary syndrome. Our purpose was to determine the clinical characteristics and prognosis of patients with troponin elevation who are not diagnosed with acute coronary syndrome.

METHODS

A total of 1032 patients with an emergency room troponin measurement were studied retrospectively, dividing them into 3 groups: 681 patients with no troponin elevation and without acute coronary syndrome, 139 with acute coronary syndrome, and 212 with troponin elevation and not diagnosed with acute coronary syndrome. The clinical characteristics and in-hospital and 12-month mortality of these 3 groups were compared.

RESULTS

Patients with troponin elevation not diagnosed with acute coronary syndrome were older and had greater comorbidity than patients with acute coronary syndrome or no troponin elevation. The 12-month mortality was 30.2%, compared with 15.1% and 4.7% in the other groups (log rank test, P<.001). In the Cox logistic regression model adjusted for confounding variables, patients with troponin elevation and no diagnosis of acute coronary syndrome had higher mortality compared with patients with negative troponin without acute coronary syndrome (hazard ratio=3.99; 95% confidence interval, 2.36-6.75; P<.001) and similar prognosis as patients with acute coronary syndrome.

CONCLUSIONS

Troponin elevation is an important predictor of mortality, regardless of the patient's final diagnosis.

Biological variation of cardiac troponin T in patients with end-stage renal disease and in healthy individuals

Background

Serum cardiac troponin T concentrations are important predictors of cardiovascular and all-cause mortality in end-stage renal disease. In patients with end-stage renal disease, assessment of serial results is essential to distinguish between a cardiovascular event and chronic elevation. We employed a high-sensitivity serum cardiac troponin T assay to evaluate the long-term biological variation in end-stage renal disease patients and in healthy individuals; these biological variation data were used to define the reference change value and the analytical goals.

Methods

Serum samples were collected from 18 end-stage renal disease patients in steady-state conditions, one per month for 6 months, and from 11 healthy volunteers at weekly intervals over 5 weeks. Biological variation data were derived using analysis of variance.

Results

Baseline serum cardiac troponin T concentrations in end-stage renal disease patients were above the 99th percentile of the healthy population and increased with duration of haemodialysis. For end-stage renal disease patients, within-subject (CVI) and between-subject (CVG) coefficients of variation were 14.7 and 77.8%, respectively, whereas these were 5.9 and 30.4%, respectively, for healthy individuals. The derived two-tailed and one-tailed reference change values were 44.1 and 37.1%, respectively, for end-stage renal disease patients, and 21.6 and 18.2% for healthy subjects.

Conclusions

For appropriate clinical management of end-stage renal disease patients in the context of a cardiovascular event, regular monitoring of serum cardiac troponin T concentrations could be important in order to allow future comparison through reference change value. Biological variation data in end-stage renal disease patients were significantly higher than for healthy individuals; therefore, the use of proper reference change value data is recommended. Moreover, the observed CVI values provide demanding imprecision goals for current technology.

High-sensitivity cardiac troponins in everyday clinical practice

High-sensitivity cardiac troponin (hs-cTn) assays are increasingly being used in many countries worldwide, however, a generally accepted definition of high-sensitivity is still pending. These assays enable cTn measurement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays (coefficient of variation of < 10% at the 99^th percentile upper reference limit). One of the most important advantages of these new assays is that they allow novel, more rapid approaches to rule in or rule out acute coronary syndromes (ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide. hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia. Therefore, the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity, because more patients with other causes of acute or chronic myocardial injury without overt myocardial ischemia are detected than with previous cTn assays. As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed, this review attempts to synthesize the available clinical data to make recommendations for their everyday clinical routine use.

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.

Biomarkers in outpatient heart failure management; Are they correlated to and do they influence clinical judgment?

AIMS

Heart failure (HF) management is complicated by difficulties in clinical assessment. Biomarkers may help guide HF management, but the correspondence between clinical evaluation and biomarker serum levels has hardly been studied. We investigated the correlation between biomarkers and clinical signs and symptoms, the influence of patient characteristics and comorbidities on New York Heart Association (NYHA) classification and the effect of using biomarkers on clinical evaluation.

METHODS AND RESULTS

This post-hoc analysis comprised 622 patients (77 ± 8 years, 76 % NYHA class ≥3, 80 % LVEF ≤45 %) participating in TIME-CHF, randomising patients to either NT-proBNP-guided or symptom-guided therapy. Biomarker measurements and clinical evaluation were performed at baseline and after 1, 3, 6, 12 and 18 months. NT-proBNP, GDF-15, hs-TnT and to a lesser extent hs-CRP and cystatin-C were weakly correlated to NYHA, oedema, jugular vein distension and orthopnoea (ρ-range: 0.12-0.33; p < 0.01). NT-proBNP correlated more strongly to NYHA class in the NT-proBNP-guided group compared with the symptom-guided group. NYHA class was significantly influenced by age, body mass index, anaemia, and the presence of two or more comorbidities.

CONCLUSION

In HF, biomarkers correlate only weakly with clinical signs and symptoms. NYHA classification is influenced by several comorbidities and patient characteristics. Clinical judgement seems to be influenced by a clinician's awareness of NT-proBNP concentrations.

Association of high-sensitivity assayed troponin I with cardiovascular phenotypes in the general population: the population-based Gutenberg health study

BACKGROUND

Aim of the study was to analyze the correlation of high-sensitivity assayed troponin I with cardiac and vascular structure and function in a large population-based cohort.

METHODS

In a sample of 4,139 subjects (2,099 men, 2,040 women, age 35-74 years) from the population-based Gutenberg Health Study, troponin I was measured with a high-sensitivity assay that had a limit of detection of 1.9 pg/mL.

RESULTS

In the study cohort, 3,405 subjects had detectable troponin I concentrations [82.3% overall, 89.9% men (N = 1,888), 74.4% women (N = 1,517)]. All analyses were adjusted for age. The strongest correlate between detectable troponin I and measures of cardiac phenotypes was observed for left ventricular mass (p < 0.001) and left ventricular end-diastolic diameter (p < 0.001) for both, women and men. Left ventricular ejection fraction was inversely correlated with troponin I (p value <0.001 in men and 0.0013 in women), also measures of diastolic dysfunction as represented by Tei index and E/E' correlated with detectable troponin I concentrations (p < 0.001 for both gender). With respect to vascular structure and function, troponin I correlated with mean intima-media thickness of the carotid artery (p < 0.001 in men and p = 0.013 in women) but showed only borderline correlation with measures of vascular function represented by flow-mediated dilation (p = 0.05 in women and p = 0.018 in men) and arterial stiffness.

CONCLUSIONS

Troponin I assessed by a high-sensitivity assay correlated with measures of left ventricular hypertrophy and systolic and diastolic function, whereas its correlation with vascular phenotypes was only of weak magnitude.

Variation of cardiac troponin I and T measured with sensitive assays in emergency department patients with noncardiac chest pain

BACKGROUND

New-generation high-sensitivity assays for cardiac troponin have lower detection limits and less imprecision than earlier assays. Reference 99th-percentile cutoff values for these new assays are also lower, leading to higher frequencies of positive test results. When cardiac troponin concentrations are minimally increased, serial testing allows discrimination of myocardial infarction from other causes of increased cardiac troponin. We assessed various measures of short-term variation, including absolute concentration changes, reference change values (RCVs), and indices of individuality (II) for 2 cardiac troponin assays in emergency department (ED) patients.

METHODS

We collected blood from patients presenting with cardiac chest pain upon arrival in the ED and 2, 6, and 12 h later. Cardiac troponin was measured with the high-sensitivity cardiac troponin T (hs-cTnT) assay (Roche Diagnostics) and a sensitive cTnI assay (Siemens Diagnostics). Cardiac troponin results from 67 patients without acute coronary syndrome or stable angina were used in calculating absolute changes in cardiac troponin, RCVs, and II.

RESULTS

The 95th percentiles for absolute change in cardiac troponin were 8.3 ng/L for hs-cTnT and 28 ng/L for cTnI. Within-individual and total CVs were 11% and 14% for hs-cTnT and 18% and 21% for cTnI, respectively. RCVs were 38% (hs-cTnT) and 57% (cTnI). The corresponding log-normal RCVs were +46%/-32% for hs-cTnT and +76%/-43% for cTnI. II values were 0.31 (cTnI) and 0.12 (hs-cTnT).

CONCLUSIONS

The short-term variations and IIs of cardiac troponin were low in ED patients free of ischemic myocardial necrosis. The detection of cardiac troponin variation exceeding reference thresholds can help to identify ED patients with acute myocardial necrosis whereas variation within these limits renders acute coronary syndrome unlikely.