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

Exploring strategies to rapidly identify false positives in high-sensitivity cardiac troponin I assay: A prospective study

BACKGROUND

Cardiac troponin is the pivotal biomarker of myocardial injury, playing a central role in the diagnosis of acute coronary syndrome and various clinical situations. Nevertheless, challenges arise when patients exhibit elevated cardiac troponin levels in the absence of evident cardiac origin, as evidenced by extensive cardiac exploration, which suggests the presence of an interfering factor. Despite the high performance of high-sensitive cardiac troponin immunoassays, these tests remain susceptible to interferences that may lead to false-positives.

METHODS

In the period between July 2021 and July 2024, 8129 patients were hospitalized in the cardiology departments of Bordeaux University Hospital with positive results for high-sensitivity cardiac troponin I. Among them, 15 patients were suspected of having false-positive results, based on clinical and biological observations.

RESULTS

In this subpopulation, we evaluated prospectively various techniques, including serial dilutions, antibody-binding tubes, and alternative immunoassays (for cardiac troponin I and T) with the objective of identifying any potential analytical interference in their high-sensitive cardiac troponin I measurements. Our investigations revealed that 12 out of 15 suspected cases exhibited an interference on the high-sensitive cardiac troponin I assay.

CONCLUSION

In conclusion, we propose an original algorithm designed to identify high-sensitive cardiac troponin I false-positives. This algorithm can help clinicians to make prompt and informed decisions about patient care, and to avoid erroneous clinical interventions that may result from such interferences.

Fouling-Free electrochemical strategy based on vertically-aligned peptide layer for cardiac troponin I sensitive detection in human serum

BACKGROUND

Cardiac troponin I (CTnI) is demonstrated as one of the most promising disease biomarkers for early diagnosing acute myocardial infarction (AMI). To date, electrochemical immunosensors have been extensively studied in the field of cTnI determination. But highly accurate and sensitive cTnI detection by this method is still a challenge due to non-specific adsorption on electrode interfaces in complex human serum. As a result, it is necessary to develop an antifouling electrochemical immunosensor with high sensitivity for the detection of cTnI.

RESULTS

In this work, an antifouling electrochemical immunosensor was constructed based on vertically-aligned peptide layer consisting of Au nanoparticles (AuNPs) and amphiphilic CEAK16 peptide (CEAK16@AuNPs) for sensitive and accurate detection of cTnI in human serum. The vertically-aligned CEAK16@AuNPs interface provided a stable hydration layer originated from attraction of water molecules by amino acids on the hydrophilic side of the CEAK16, which effectively reduced non-specific adsorption and enhanced electron transfer rate. The cTnI immunosensor possessed great analytical performance with a wide range from 1 fg mL-1 to 1 μg mL-1 and a low detection limit of 0.28 fg mL-1 (S/N = 3). Additionally, the proposed CEAK16@AuNPs sensing interface showed excellent long-term antifouling performance and electrochemical activity that preserved 80 % of the initial signal after 20-days exposure in human serum samples. Consequently, the cTnI immunosensor displayed excellent detection accuracy compared to clinical methods and owned good selectivity, stability and reproducibility.

SIGNIFICANCE

The development of this strategy provides a versatile tool for accurate quantitative cTnI analysis in real human serum, thus helping to achieve early AMI diagnosis effectively and holding the promising potentials for other immunosensor in disease diagnosis.

The Role of Artificial Intelligence for Providing Scientific Content for Laboratory Medicine

BACKGROUND

Artificial intelligence (AI) promises to become an important tool in the practice of laboratory medicine. AI programs are available online that can provide concise medical and laboratory information within seconds after a question is submitted.

METHODS

We posed the following contemporary and relevant question for clinical chemists using an AI program: "Should labs eliminate CK-MB testing?" The results of this inquiry were critically reviewed by a cardiologist, emergency department physician, and clinical laboratorians for accuracy and appropriateness.

RESULTS

An AI report answering this question was generated within 15 s. The experts felt that the information was inaccurate with the statements that CK-MB results are released earlier than cardiac troponin (cTn), and are more useful for detection of myocardial injury in patients with renal insufficiencies. The summary omitted discussion on the ongoing debate for periprocedural detection of acute myocardial infarction (MI), the perceived value for detection of reinfarction, the value in risk stratification compared to cTn, the economic justification for testing both CK-MB and cTn, and medicolegal aspects of testing when results are discordant.

CONCLUSIONS

At this time, AI does not appear to be ready to be used by clinical laboratories for answering important practice questions.

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.

Methods for analyzing positive cardiac troponin assay interference

OBJECTIVES

The cardiac damage biomarkers cardiac troponin T (cTnT) and troponin I (cTnI) are used to identify patients with myocardial infarction (MI). To make the correct clinical decisions it is important to identify false positive results due to troponin assay interference. Often interferences are caused by high-molecular weight immunocomplexes called macrotroponin that may result in false troponin elevations because of delayed troponin clearance, or heterophilic antibodies that crosslink troponin assay antibodies and generate troponin-independent signals.

DESIGN & METHODS

We describe and compare four methods for cTnI assay interference analysis using a protein G spin column method, gel filtration chromatography and two versions of a sucrose gradient ultracentrifugation for cTnI assay interference analysis on five patients with confirmed cTnI interference and one MI patient without cTnI interference from our troponin interference referral center.

RESULTS

The protein G spin column method had a high between run variability but was still able to identify all five patients with cTnI interference. The sucrose gradient ultracentrifugation methods and the gel filtration method had simlar performancec and correctly identified the immunocomplexes that caused the cTnI interference.

CONCLUSIONS

Our experience is that these methods are sufficient to safely confirm or exclude positive cTnI assay interference.

High-Sensitivity Cardiac Troponin Publications during the COVID-19 Pandemic (2020-2022)

The first publications detailing the clinical utility of high-sensitivity cardiac troponin (hs-cTn) in patients with possible acute coronary syndrome (ACS) are traceable to 2009 [...].