A Three-Site Immunoassay for High-Sensitivity Cardiac Troponin I with Low Immunoreactivity for Macrocomplexes

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

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

Disagreement between Cardiac Troponin Tests Yielding a Higher Incidence of Myocardial Injury in the Emergency Setting

Differences in patient classification of myocardial injury between high-sensitivity cardiac troponin (hs-cTn) assays have largely been attributed to assay design and analytical sensitivity aspects. Our objective was to compare Ortho Clinical Diagnostics' (OCD) hs-cTnI assay to OCD's contemporary/conventional assay (cTnI ES) and another hs-cTnI assay (Abbott hs-cTnI) in samples obtained from different emergency departments (EDs). Two different sample types were evaluated (lithium heparin and ethylenediaminetetraacetic acid (EDTA) plasma) in a non-selected ED population (study 1, n = 469 samples) and in patients for which ED physicians ordered cardiac troponin testing (study 2, n = 1147 samples), from five different EDs. The incidence of injury in study 1 was higher with the OCD hs-cTnI assay (30.9%; 95% CI: 26.9 to 35.2) compared to that of the Abbott hs-cTnI (17.3%; 95% CI: 14.1 to 21.0) and the OCD cTnI ES (15.4%; 95% CI: 12.4 to 18.9) assays, with repeat testing identifying 4.8% (95% CI: 3.0 to 7.5) of the OCD hs-cTnI results with poor reproducibility. In study 2, 4.6% (95% CI: 3.5 to 6.0) of the results were not reported for the OCD hs-cTnI assay (i.e., poor reproducibility) with 12.7% (95%CI: 8.7 to 17.8) of the OCD hs-cTnI results positive for injury being negative for injury with the Abbott hs-cTnI assay. In summary, the OCD hs-cTnI assay yields higher rates of biochemical injury with a higher rate of poor reproducible results in different ED populations.

Neurohumoral, cardiac and inflammatory markers in the evaluation of heart failure severity and progression

Heart failure is common in adult population, accounting for substantial morbidity and mortality worldwide. The main risk factors for heart failure are coronary artery disease, hypertension, obesity, diabetes mellitus, chronic pulmonary diseases, family history of cardiovascular diseases, cardiotoxic therapy. The main factor associated with poor outcome of these patients is constant progression of heart failure. In the current review we present evidence on the role of established and candidate neurohumoral biomarkers for heart failure progression management and diagnostics. A growing number of biomarkers have been proposed as potentially useful in heart failure patients, but not one of them still resembles the characteristics of the “ideal biomarker.” A single marker will hardly perform well for screening, diagnostic, prognostic, and therapeutic management purposes. Moreover, the pathophysiological and clinical significance of biomarkers may depend on the presentation, stage, and severity of the disease. The authors cover main classification of heart failure phenotypes, based on the measurement of left ventricular ejection fraction, including heart failure with preserved ejection fraction, heart failure with reduced ejection fraction, and the recently proposed category heart failure with mid-range ejection fraction. One could envisage specific sets of biomarker with different performances in heart failure progression with different left ventricular ejection fraction especially as concerns prediction of the future course of the disease and of left ventricular adverse/reverse remodeling. This article is intended to provide an overview of basic and additional mechanisms of heart failure progression will contribute to a more comprehensive knowledge of the disease pathogenesis.

Prussian blue-doped PAMAM dendrimer nanospheres for electrochemical immunoassay of human plasma cardiac troponin I without enzymatic amplification

Rapid and accurate identification of cardiac troponin I (cTnl) in biological fluids is very essential for judging acute myocardial infarction (AMI).

Analytical assessment of ortho clinical diagnostics high-sensitivity cardiac troponin I assay

Objectives

To analytically evaluate Ortho Clinical Diagnostics VITROS high-sensitivity cardiac troponin I (hs-cTnI) assay in specific matrices with comparison to other hs-cTn assays.

Methods

The limit of detection (LoD), imprecision, interference and stability testing for both serum and lithium heparin (Li-Hep) plasma for the VITROS hs-cTnI assay was determined. We performed Passing-Bablok regression analyses between sample types for the VITROS hs-cTnI assay and compared them to the Abbott ARCHITECT, Beckman Access and the Siemens ADVIA Centaur hs-cTnI assays. We also performed Receiver-operating characteristic curve analyses with the area under the curve (AUC) determined in an emergency department (ED)-study population (n=131) for myocardial infarction (MI).

Results

The VITROS hs-cTnI LoD was 0.73 ng/L (serum) and 1.4 ng/L (Li-Hep). Stability up to five freeze-thaws was observed for the Ortho hs-cTnI assay, with the analyte stability at room temperature in serum superior to Li-Hep with gross hemolysis also affecting Li-Hep plasma hs-cTnI results. Comparison of Li-Hep to serum concentrations (n=202), yielded proportionally lower concentrations in plasma with the VITROS hs-cTnI assay (slope=0.85; 95% confidence interval [CI]:0.83-0.88). In serum, the VITROS hs-cTnI concentrations were proportionally lower compared to other hs-cTnI assays, with similar slopes observed between assays in samples frozen <-70 °C for 17 years (ED-study) or in 2020. In the ED-study, the VITROS hs-cTnI assay had an AUC of 0.974 (95%CI:0.929-0.994) for MI, similar to the AUCs of other hs-cTn assays.

Conclusions

Lack of standardization of hs-cTnI assays across manufacturers is evident. The VITROS hs-cTnI assay yields lower concentrations compared to other hs-cTnI assays. Important differences exist between Li-Hep plasma and serum, with evidence of stability and excellent clinical performance comparable to other hs-cTn assays.

Using the clinical chemistry score in the emergency department to detect adverse cardiac events: a diagnostic accuracy study

BACKGROUND

The ability to rule out or in a major adverse cardiac event (MACE) in patients with suspected acute coronary syndrome at emergency department (ED) presentation would be beneficial to patient care and the health care system. The clinical chemistry score (CCS) was evaluated in this context.

METHODS

This diagnostic accuracy study evaluated 2 different ED cohorts with suspected acute coronary syndrome. For patients in cohort 1, who presented to the ED of 3 hospitals in Hamilton, Ontario, between May and August 2013, retrospective measurements were taken using the Ortho Clinical Diagnostics high-sensitivity cardiac troponin I (hs-cTnI) assay; for patients in cohort 2, who presented to the ED of the same 3 hospitals in Hamilton between November 2012 and February 2013, an ED cardiac presentation blood test panel was performed with the Abbott Diagnostics hs-cTnI assay. The sensitivity and specificity of the CCS (cut-offs of ≥ 1 and 5) and hs-cTnI alone (published cut-offs) were compared for MACE (composite of death, myocardial infarction, unstable angina, revascularization) at 30 days for both cohorts and at 90 days for cohort 2.

RESULTS

The incidence of MACE at 30 days was higher in cohort 1 (n = 1058) (19.4%, 95% confidence interval [CI] 16.8%-22.2%) than in cohort 2 (n = 5974) (14.6%, 95% CI 13.6%-15.6%). In cohort 1, a CCS of 1 or above yielded a sensitivity of 99.5% (95% CI 97.3%-99.9%). The sensitivity with an Ortho hs-cTnI cut-off of 1 ng/L or above was 91.2% (95% CI 86.5%-95.7%). The specificity of a CCS of 5 (97.8%, 95% CI 96.5%-98.7%) was higher than when the overall 99th-percentile cut-off for the Ortho hs-cTnI assay (> 11 ng/L; 90.1%, 95% CI 87.9%-92.0%) was used. A similar pattern was observed in cohort 2 at 30 days and persisted at 90 days with the Abbott hs-cTnI assay.

INTERPRETATION

The CCS derived with 2 different hs-cTnI assays and ED populations yielded higher sensitivity and specificity estimates for MACE than hs-cTnI alone. An intervention study is needed to evaluate the impact of the CCS at both the patient and hospital levels.

TRIAL REGISTRATION

ClinicalTrials.gov, no. NCT01994577.