Evaluation of first-draw whole blood, point-of-care cardiac markers in the context of the universal definition of myocardial infarction: a comparison of a multimarker panel to troponin alone and to testing in the central laboratory

Advances in point-of-care testing for cardiovascular diseases

Point-of-care testing (POCT) is a specific format of diagnostic testing that is conducted without accompanying infrastructure or sophisticated instrumentation. Traditionally, such rapid sample-to-answer assays provide inferior analytical performances to their laboratory counterparts when measuring cardiac biomarkers. Hence, their potentially broad applicability is somewhat bound by their inability to detect clinically relevant concentrations of cardiac troponin (cTn) in the early stages of myocardial injury. However, the continuous refinement of biorecognition elements, the optimization of detection techniques, and the fabrication of tailored fluid handling systems to manage the sensing process has stimulated the production of commercial assays that can support accelerated diagnostic pathways. This review will present the latest commercial POC assays and examine their impact on clinical decision-making. The individual elements that constitute POC assays will be explored, with an emphasis on aspects that contribute to economically feasible and highly sensitive assays. Furthermore, the prospect of POCT imparting a greater influence on early interventions for medium to high-risk individuals and the potential to re-shape the paradigm of cardiovascular risk assessments will be discussed.

Diagnostic Performance of Point-of-Care Troponin I and Laboratory Troponin T in Patients Presenting to the ED with Chest Pain: A Comparative Study

Background

Chest pain is a common symptom in patients visiting the emergency department (ED). Diagnosing acute coronary syndrome is a challenging task for emergency physicians. Evaluation of chest pain depends on clinical symptoms and signs, ECG, and cardiac enzymes. Here, we aimed to compare the diagnostic performance of the point-of-care troponin I assay with laboratory HsTnT assay in patients presenting to the ED with chest pain.

Methods

A prospective study was done at the ED of Alkhor Hospital, Hamad Medical Corporation, between March 2016 and December 2016. Patients more than 18 years old who presented to the ED with chest pain were enrolled. Patients with renal failure, initial ECG showing ST-elevation MI, or arrhythmias, and hemodynamically unstable patients were excluded. A blood sample was collected at 0 and 3 hours post-admission for POC TnI and laboratory HsTnT assay. The sensitivity, specificity, PPV, NPV, and AUC were determined and compared.

Results

Out of 313 patients enrolled, ten were excluded. At 0 hour, the POC TnI assay had a lower sensitivity (72.5% versus 97.5%) and had almost equal specificity (99.24% versus 93.2%) when compared to lab HsTnT assay. At 3 hours post-admission, the sensitivity increased to 95% versus 100%, and specificity was 100% versus 94.3% when compared to lab HsTnT. The POC TnI assay had a higher PPV than HsTnT, whereas both assays showed a high NPV at 0 and 3 hours.

Conclusion

Although the diagnostic performance of POC TnI was lower than that of Lab HsTnT at 0 hour, at 3 hours post-admission, the diagnostic performance was almost equal to that of HsTnT. Hence we conclude that chest pain in patients with a negative POC TnI at 3 hours post-admission is unlikely to be due to NSTEMI.

A paper microfluidics-based fluorescent lateral flow immunoassay for point-of-care diagnostics of non-communicable diseases

In the emergency diagnosis of patients, acute myocardial infarction (AMI) is always time-consuming to diagnose, and the process requires multiple laboratory procedures, expensive equipment and skilled workers. Herein, we developed an easy-to-use, low-cost and portable fluorescent lateral flow immunoassay based on paper microfluidics for the point-of-care diagnostics of non-communicable diseases. The fluorescent lateral flow immunoassay can produce results in less than 10 minutes, and the limit of detection (LOD) is 0.019 ng ml^-1. The slope was linear from 0 to 100 ng ml^-1; the equation is y = 0.0342e^2.1181x and R² = 0.9618, which are distinctive features that ensure maximum amplification of the signal and recording of quantitative values by an analyser. The detection sensitivity showed an exceptional increase to 0.01 ng ml^-1. Compared with conventional bioassay readers, our analyser shows some advantages to easily, clearly and effectively read data. The present point-of-care test for cardiac troponin I decreases the turnaround time and has a high coefficient of variation even at lower concentrations of troponin. So, the development of lateral flow assay-based point-of-care assays with higher analytical performance for real world samples can decrease the rule-out time for AMI in emergency departments and other fields.

A systematic evaluation of immunoassay point-of-care testing to define impact on patients' outcomes

Background Point-of-care testing has been developed to provide rapid test results. Most published studies focus on analytical performance, neglecting its impact on patient outcomes. Objective To review the analytical performance and accuracy of point-of-care testing specifically planned for immunoassay and to evaluate the impact of faster results on patient management. Methods A search of electronic databases for studies reporting immunoassay results obtained in both point-of-care testing and central laboratory scenarios was performed. Data were extracted concerning the study details, and the methodological quality was assessed. The analytical characteristics and diagnostic accuracy of six points-of-care testing: troponin, procalcitonin, parathyroid hormone, brain natriuretic peptide, C-reactive protein and neutrophil gelatinase-associated lipocalin were evaluated. Results A total of 116 scientific papers were analysed. Studies measuring procalcitonin, parathyroid hormone and neutrophil gelatinase-associated lipocalin reported a limited impact on diagnostic decisions. Seven studies measuring C-reactive protein claimed a significant reduction of antibiotic prescription. Several authors evaluated brain natriuretic peptide or troponin reporting faster decision-making without any improvement in clinical outcome. Forty-four per cent of studies reported analytical data, showing satisfactory correlations between results obtained through point-of-care testing and central laboratory setting. Half of studies defined the diagnostic accuracy of point-of-care testing as acceptable for troponin (median sensitivity and specificity: 74% and 94%, respectively), brain natriuretic peptide (median sensitivity and specificity: 82% and 88%, respectively) and C-reactive protein (median sensitivity and specificity 85%). Conclusions Point-of-care testing immunoassay results seem to be reliable and accurate for troponin, brain natriuretic peptide and C-reactive protein. The satisfactory analytical performance, together with an excellent practicability, suggests that it could be a consistent tool in clinical practice, but data are lacking regarding the patient outcomes.

ANMCO/ELAS/SIBioC Consensus Document: biomarkers in heart failure

Biomarkers have dramatically impacted the way heart failure (HF) patients are evaluated and managed. A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biological or pathogenic processes, or pharmacological responses to a therapeutic intervention. Natriuretic peptides [B-type natriuretic peptide (BNP) and N-terminal proBNP] are the gold standard biomarkers in determining the diagnosis and prognosis of HF, and a natriuretic peptide-guided HF management looks promising. In the last few years, an array of additional biomarkers has emerged, each reflecting different pathophysiological processes in the development and progression of HF: myocardial insult, inflammation, fibrosis, and remodelling, but their role in the clinical care of the patient is still partially defined and more studies are needed before to be well validated. Moreover, several new biomarkers have the potential to identify patients with early renal dysfunction and appear to have promise to help the management cardio-renal syndrome. With different biomarkers reflecting HF presence, the various pathways involved in its progression, as well as identifying unique treatment options for HF management, a closer cardiologist-laboratory link, with a multi-biomarker approach to the HF patient, is not far ahead, allowing the unique opportunity for specifically tailoring care to the individual pathological phenotype.

Highly Sensitive and Quick Detection of Acute Myocardial Infarction Biomarkers Using In2O3 Nanoribbon Biosensors Fabricated Using Shadow Masks

We demonstrate a scalable and facile lithography-free method for fabricating highly uniform and sensitive In₂O₃ nanoribbon biosensor arrays. Fabrication with shadow masks as the patterning method instead of conventional lithography provides low-cost, time-efficient, and high-throughput In₂O₃ nanoribbon biosensors without photoresist contamination. Combined with electronic enzyme-linked immunosorbent assay for signal amplification, the In₂O₃ nanoribbon biosensor arrays are optimized for early, quick, and quantitative detection of cardiac biomarkers in diagnosis of acute myocardial infarction (AMI). Cardiac troponin I (cTnI), creatine kinase MB (CK-MB), and B-type natriuretic peptide (BNP) are commonly associated with heart attack and heart failure and have been selected as the target biomarkers here. Our approach can detect label-free biomarkers for concentrations down to 1 pg/mL (cTnI), 0.1 ng/mL (CK-MB), and 10 pg/mL (BNP), all of which are much lower than clinically relevant cutoff concentrations. The sample collection to result time is only 45 min, and we have further demonstrated the reusability of the sensors. With the demonstrated sensitivity, quick turnaround time, and reusability, the In₂O₃ nanoribbon biosensors have shown great potential toward clinical tests for early and quick diagnosis of AMI.

Point-of-Care Testing of Troponin Levels Compared With Automated Laboratory Evaluation: A Reliability Study

Traditionally, troponin levels are measured in the blood using an automated laboratory protocol, but the use of a faster technology, the point-of-care (POC) testing of troponin levels, has shown promise in the effective differential diagnosis of cardiac injury. The purpose of this study was to compare the 2 methods. A total of 1567 patients were seen in the emergency department who were tested with both the POC iSTAT troponin and laboratory troponin from a secondary analysis of retrospective data collected between June 2012 and December 2012. The values for laboratory troponin varied between 0 and 30 with a mean and standard deviation of 0.060 ± 0.842 and the values for POC testing varied between 0 and 17.2 with a mean and standard deviation of 0.042 ± 0.492. The Bland-Altman analysis showed a systematic negative bias for the POC values compared with the laboratory troponin values. Lowering the POC cut-off value for troponin to 0.035 yielded 3 out of 4 better validity coefficients compared with those with the suggested manufacturer's cut-off value of 0.08 when predicting the gold standard. The POC troponin can be used to measure troponin level and similar diagnosis if the cut-off value for the POC troponin is lowered to 0.035 instead of the 0.08 suggested manufacturer's cut-off.

Effectiveness of practices for improving the diagnostic accuracy of Non ST Elevation Myocardial Infarction in the Emergency Department: A Laboratory Medicine Best Practices™ systematic review

OBJECTIVES

This article is a systematic review of the effectiveness of four practices (assay selection, decision point cardiac troponin (cTn) threshold selection, serial testing, and point of care testing) for improving the diagnostic accuracy Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) in the Emergency Department.

DESIGN AND METHODS

The CDC-funded Laboratory Medicine Best Practices (LMBP) Initiative systematic review method for quality improvement practices was used.

RESULTS

The current ACC/AHA guidelines recommend using cardiac troponin assays with a 99th percentile upper reference limit (URL) diagnostic threshold to diagnose NSTEMI. The evidence in this systematic review indicates that contemporary sensitive cTn assays meet the assay profile requirements (sensitivity, specificity, PPV, and NPV) to more accurately diagnose NSTEMI than alternate tests. Additional biomarkers did not increase diagnostic effectiveness of cTn assays. Sensitivity, specificity, and NPV were consistently high and low PPV improved with serial sampling. Evidence for use of point of care cTn testing was insufficient to make recommendation, though some evidence suggests that use may result in reduction to patient length of stay and costs.

CONCLUSIONS

Based on the review of and the LMBP(TM) A-6 Method criteria, we recommend the use of cardiac troponin assays without additional biomarkers using the 99th percentile URL as the clinical diagnostic threshold for the diagnosis of NSTEMI. We recommend serial sampling with one sample at presentation and at least one additional second sample taken at least 6h later to identify a rise or fall in the troponin level. No recommendation is made either for or against the use of point of care tests.

DISCLAIMER

The findings and conclusions in this article are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry (CDC/ATSDR).

Cardiac troponins I and T: molecular markers for early diagnosis, prognosis, and accurate triaging of patients with acute myocardial infarction

Acute myocardial infarction (AMI) is the leading cause of death worldwide, with early diagnosis still being difficult. Promising new cardiac biomarkers such as troponins and creatine kinase (CK) isoforms are being studied and integrated into clinical practice for early diagnosis of AMI. The cardiac-specific troponins I and T (cTnI and cTnT) have good sensitivity and specificity as indicators of myocardial necrosis and are superior to CK and its MB isoenzyme (CK-MB) in this regard. Besides being potential biologic markers, cardiac troponins also provide significant prognostic information. The introduction of novel high-sensitivity troponin assays has enabled more sensitive and timely diagnosis or exclusion of acute coronary syndromes. This review summarizes the available information on the potential of troponins and other cardiac markers in early diagnosis and prognosis of AMI, and provides perspectives on future diagnostic approaches to AMI.