Analytical evaluation of a new point of care system for measuring cardiac Troponin I

Microfluidic-based blood immunoassays

Microfluidics enables the integration of whole protocols performed in a laboratory, including sample loading, reaction, extraction, and measurement steps on a single system, which offers significant advantages thanks to small-scale operation combined with precise fluid control. These include providing efficient transportation mechanisms and immobilization, reduced sample and reagent volumes, fast analysis and response times, lower power requirements, lower cost and disposability, improved portability and sensitivity, and greater integration and automation capability. Immunoassay is a specific bioanalytical method based on the interaction of antigens and antibodies, which is utilized to detect bacteria, viruses, proteins, and small molecules in several areas such as biopharmaceutical analysis, environmental analysis, food safety, and clinical diagnostics. Because of the advantages of both techniques, the combination of immunoassays and microfluidic technology is considered one of the most potential biosensor systems for blood samples. This review presents the current progress and important developments in microfluidic-based blood immunoassays. After providing several basic information about blood analysis, immunoassays, and microfluidics, the review points out in-depth information about microfluidic platforms, detection techniques, and commercial microfluidic blood immunoassay platforms. In conclusion, some thoughts and future perspectives are provided.

The "Bloodless" Blood Test: Intradermal Prick Nanoelectronics for the Blood Extraction-Free Multiplex Detection of Protein Biomarkers

Protein biomarkers' detection is of utmost importance for preventive medicine and early detection of illnesses. Today, their detection relies entirely on clinical tests consisting of painful, invasive extraction of large volumes of venous blood; time-consuming postextraction sample manipulation procedures; and mostly label-based complex detection approaches. Here, we report on a point-of-care (POC) diagnosis paradigm based on the application of intradermal finger prick-based electronic nanosensors arrays for protein biomarkers' direct detection and quantification down to the sub-pM range, without the need for blood extraction and sample manipulation steps. The nanobioelectronic array performs biomarker sensing by a rapid intradermal prick-based sampling of proteins biomarkers directly from the capillary blood pool accumulating at the site of the microneedle puncture, requiring only 2 min and less than one microliter of a blood sample for a complete analysis. A 1 mm long microneedle element was optimal in allowing for pain-free dermal sampling with a 100% success rate of reaching and rupturing dermis capillaries. Current common micromachining processes and top-down fabrication techniques allow the nanobioelectronic sensor arrays to provide accurate and reliable clinical diagnostic results using multiple sensing elements in each microneedle and all-in-one direct and label-free multiplex biomarkers detection. Preliminary successful clinical studies performed on human volunteers demonstrated the ability of our intradermal, in-skin, blood extraction-free detection platform to accurately detect protein biomarkers as a plausible POC detection for future replacement of today's invasive clinical blood tests. This approach can be readily extended in the future to detect other clinically relevant circulating biomarkers, such as miRNAs, free-DNAs, exosomes, and small metabolites.

A versatile and automated microfluidic platform for a quantitative magnetic bead based protocol: application to gluten detection

A microfluidic platform for the integration of multi-step biological assays has been developed. The presented system is a unique instrument compatible with microfluidic chips for various applications based on bead manipulation. Two examples of microfluidic cartridges are presented here. The first one contains two rows of eight chambers (40 and 80 μL), six reagent inlets, eight testing solution (calibrators and samples) inlets and eight outlets to reproduce precisely each step of a biological assay. This configuration is versatile enough to integrate many different biological assays and save a lot of development time. The second architecture is dedicated to one specific protocol and is completely automated from the standard and sample dilutions to the optical detection. Linear dilutions have been integrated to prepare automatically a range of standard concentrations and outlets have been modified for integrated colorimetric detection. The technology uses pneumatically collapsible chambers to perform all the fluidic operations for a fully automated protocol such as volume calibrations, fluid transport, mixing, and washing steps. A programmable instrument with a software interface has been developed to adapt rapidly a protocol to this cartridge. As an example, these new microfluidic cartridges have been used to successfully perform an immunoassay for gluten detection in the dynamic range of 10-30 ppm with good sensitivity (2 ppm) and specificity.

Prehospital troponin as a predictor of early clinical deterioration

BACKGROUND AND OBJECTIVES

Elevated troponin T (cTnT) values are associated with comorbidities and early mortality, in both cardiovascular and noncardiovascular diseases. The objective of this study is to evaluate the prognostic accuracy of the sole utilization of prehospital point-of-care cardiac troponin T to identify the risk of early in-hospital deterioration, including mortality within 28 days.

METHODS

We conducted a prospective, multicentric, controlled, ambulance-based, observational study in adults with acute diseases transferred with high priority by ambulance to emergency departments, between 1 January and 30 September 2020. Patients with hospital diagnosis of acute coronary syndrome were excluded. The discriminative power of the predictive cTnT was assessed through a discrimination model trained using a derivation cohort and evaluated by the area under the curve of the receiver operating characteristic on a validation cohort.

RESULTS

A total of 848 patients were included in our study. The median age was 68 years (25th-75th percentiles: 50-81 years), and 385 (45.4%) were women. The mortality rate within 28 days was 12.4% (156 cases). The predictive ability of cTnT to predict mortality presented an area under the curve of 0.903 (95% CI: 0.85-0.954; P < .001). Risk stratification was performed, resulting in three categories with the following optimal cTnT cut-off points: high risk greater than or equal to 100, intermediate risk 40-100 and low risk less than 40 ng/L. In the high-risk group, the mortality rate was 61.7%, and on the contrary, the low-risk group presented a mortality of 2.3%.

CONCLUSIONS

The implementation of a routine determination of cTnT on the ambulance in patients transferred with high priority to the emergency department can help to stratify the risk of these patients and to detect unknown early clinical deterioration.

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.

Recent advances in cardiac biomarkers detection: From commercial devices to emerging technologies

Although cardiac pathologies are the major cause of death in the world, it remains difficult to provide a reliable diagnosis to prevent heart attacks. Rapid patient care and management in emergencies are critical to prevent dramatic consequences. Thus, relevant biomarkers such as cardiac troponin and natriuretic peptides are currently targeted by commercialized Point-Of-Care immunoassays. Key points still to be addressed concern cost, lack of standardization, and poor specificity, which could limit the reliability of the assays. Consequently, alternatives are emerging to address these issues. New probe molecules such as aptamers or molecularly imprinted polymers should allow a reduction in cost of the assays and an increase in reproducibility. In addition, the assay specificity and reliability could be improved by enabling multiplexing through the detection of several molecular targets in a single device.

Aptamer-based surface-enhanced resonance Raman scattering assay on a paper fluidic platform for detection of cardiac troponin I

SIGNIFICANCE

Cardiac troponin I (cTnI) is a primary biomarker for diagnosis of myocardial infarction (MI). In contrast to central laboratory tests for cTnI, point-of-care (POC) testing has the advantage of providing results when the patient is first encountered, which helps high-risk patients to be treated more rapidly and low-risk patients to be released in a timely fashion. A paper fluidic platform is good for POC testing because the paper is abundant, low cost, and disposable. However, current cTnI assays on paper platforms use antibodies as the recognition element, which has limitations due to the high cost of production and antibody stability issues at the POC.

AIM

To develop an aptamer-based assay on a paper strip using surface-enhanced resonance Raman spectroscopy (SERRS) for detection of cTnI in the clinically relevant range at the POC.

APPROACH

Gold nanoparticles (AuNPs) were functionalized with a Raman reporter molecule, malachite green isothiocyanate. The functionalized AuNPs were encapsulated in a silica shell and provided a SERRS signal using a handheld Raman system with a 638-nm excitation wavelength. A primary aptamer and a secondary aptamer of cTnI were used in a sandwich assay format to bind the cTnI on a test line of a paper fluidic platform. By measuring the SERRS signal from the test line, the concentration of cTnI was quantitatively determined.

RESULTS

The aptamer-based SERRS assay on a paper strip had a detection range of 0.016 to 0.1  ng  /  ml for cTnI, had good selectivity for cTnI compared to three other markers, had good stability over 10 days, and had good performance in the more complex serum sample matrix.

CONCLUSIONS

The aptamer-based SERRS assay on a paper strip has the potential to provide a sensitive, selective, stable, repeatable, and cost-effective platform for the detection of cTnI toward eventual use in diagnosis of MI at the POC.

Cardiac biomarker measurement by point of care testing - Development, rationale, current state and future developments

Cardiac biomarker measurements are integral to the diagnosis and management of patients presenting with breathlessness and chest pain. Measurement of B type natriuretic peptide either directly or of the N-terminal portion of the prohormone although possible by point of care testing (POCT) has largely become a laboratory test. Measurement of the cardiac troponins cardiac troponin T (cTnT) and cardiac troponin I (cTnI) can easily and accurately be performed by POCT. The situation has been complicated by the development of high sensitivity assays for cTnT and cTnI and the subsequent development of rapid rule out algorithms allowing patient categorisation and discharge on admission and 1 to 2 h following admission. This article reviews the development of POCT for cardiac biomarkers, the evidence base comparing POCT with central laboratory testing, its strengths and limitations, and how POCT fits into the world of high sensitivity troponin assays. It also discusses what evidence there is that POCT can form part of rapid decision-making strategies and how this applies in an era of algorithms based on and is derived from measurement of high sensitivity troponin in the central laboratory.

Cardiac biomarkers by point-of-care testing – back to the future?

The measurement of the cardiac troponins (cTn), cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are integral to the management of patients with suspected acute coronary syndromes (ACS). Patients without clear electrocardiographic evidence of myocardial infarction require measurement of cTnT or cTnI. It therefore follows that a rapid turnaround time (TAT) combined with the immediacy of results return which is achieved by point-of-care testing (POCT) offers a substantial clinical benefit. Rapid results return plus immediate decision-making should translate into improved patient flow and improved therapeutic decision-making. The development of high sensitivity troponin assays offer significant clinical advantages. Diagnostic algorithms have been devised utilising very low cut-offs at first presentation and rapid sequential measurements based on admission and 3 h sampling, most recently with admission and 1 h sampling. Such troponin algorithms would be even more ideally suited to point-of-care testing as the TAT achieved by the diagnostic laboratory of typically 60 min corresponds to the sampling interval required by the clinician using the algorithm. However, the limits of detection and analytical imprecision required to utilise these algorithms is not yet met by any easy-to-use POCT systems.

How to choose a point-of-care testing for troponin

BACKGROUND

Point-of-care (POC) cTn assays are needed when the central laboratory is unable to provide timely results to the emergency department. Many POC devices are available. The prospect of choosing them is daunting. In order to provide a quick decision-making reference for POC cTn device selection comparing them to the central laboratory, seven POC devices commonly employed by emergency department were evaluated.

METHODS

Firstly, we reviewed all devices package inserts. Secondly, we evaluated several POC cTn assays for imprecision, linearity, and correlation with central laboratory assays according to CLSI EP protocols. The linear regression analyses were performed only for the detectable concentrations. Five cTnI devices (Alere Triage, BioMerieux Vidas, Mitsubishi Pathfast, ReLIA TZ-301, and Radiometer AQT90) were evaluated against a contemporary cTnI assay (Beckman Access II Accu TnI). Two cTnT assays (Radiometer AQT90 and Roche Cobas h232) were compared to a high-sensitivity (hs) cTnT method (Roche Cobas e601).

RESULTS

For cTn levels around the 99th percentile upper reference limits (URLs) of the comparator assays, imprecision could not be assessed for the Alere, BioMerieux, and Cobas h232 as they gave undetectable readings due to a lack of assay sensitivity. Imprecision (CV) was unacceptably high for the ReLIA (33.3%). On account of this precision metric, these four assays were deemed unsuitable. Regression analyses showed acceptable linearity for all the POC devices. The correlation coefficients for ReLIA, BioMerieux, Cobas h232, and Radiometer cTnT were >0.95. Unlike the cTnT devices, the cTnI assays employ different capture and detection antibodies leading to non-commutable results. The POC cTn results were concordant with their comparator-Radiometer cTnT 90%, Pathfast cTnI 85%, and Radiometer cTnI 75%.

CONCLUSION

Our study provides the procedure and essential data to guide selection of a POC cTn device. Of the point-of-care devices, methods evaluated Radiometer AQT90 (cTnI and cTnT) and Pathfast might be considered.

Sensitivity Enhancement of Point-of-Care for Cardiac Markers Detection using Micro-Impedimetric Immunosensor Arrays

This paper describes the development and characterisation of a novel, electrical impedance spectroscopy-based (EIS) immunosensor array for point-of-care applications. EIS is a highly sensitive, label-free, real time technique suitable for single use, point-of-care cardiac marker detection devices. However, the underlying source of the observed change in EIS immunoassay response has not been well characterised or understood. A full understanding of the relationship between target binding and impedance response would significantly advance biosensor design and most probably increase detection limit sensitivity. The development of micro-/nano- structured electrodes for multi-frequency EIS procedure propose substantial benefits over classical macro-structured systems.Countless manipulations of electrode features and inter-electrode spacing will enhance the electrode surface area, increase the charge-transfer resistance and reduce the double-layer capacitance. These in turn give rise to improved signal-to-noise ratios, therefore affording greater sensitivity, lower detection limits and faster detection times.The sensor sensitivity range was within that required for human myoglobin determination, following acute myocardial infarction (heart attack). Real-time MyAb-MyAg interaction monitoring, permitted the determination of the binding events in less than one minute.

Evaluation of Molecularly Imprinted Polymers for Point-of-Care Testing for Cardiovascular Disease

Molecular imprinting is a rapidly growing area of interest involving the synthesis of artificial recognition elements that enable the separation of analyte from a sample matrix and its determination. Traditionally, this approach can be successfully applied to small analyte (<1.5 kDa) separation/ extraction, but, more recently it is finding utility in biomimetic sensors. These sensors consist of a recognition element and a transducer similar to their biosensor counterparts, however, the fundamental distinction is that biomimetic sensors employ an artificial recognition element. Molecularly imprinted polymers (MIPs) employed as the recognition elements in biomimetic sensors contain binding sites complementary in shape and functionality to their target analyte. Despite the growing interest in molecularly imprinting techniques, the commercial adoption of this technology is yet to be widely realised for blood sample analysis. This review aims to assess the applicability of this technology for the point-of-care testing (POCT) of cardiovascular disease-related biomarkers. More specifically, molecular imprinting is critically evaluated with respect to the detection of cardiac biomarkers indicative of acute coronary syndrome (ACS), such as the cardiac troponins (cTns). The challenges associated with the synthesis of MIPs for protein detection are outlined, in addition to enhancement techniques that ultimately improve the analytical performance of biomimetic sensors. The mechanism of detection employed to convert the analyte concentration into a measurable signal in biomimetic sensors will be discussed. Furthermore, the analytical performance of these sensors will be compared with biosensors and their potential implementation within clinical settings will be considered. In addition, the most suitable application of these sensors for cardiovascular assessment will be presented.

Clinical performance of a new point-of-care cardiac troponin I test

BACKGROUND

We evaluated the clinical performance of the Minicare cardiac troponin-I (cTnI), a new point-of-care (POC) cTnI test for the diagnosis of acute myocardial infarction (AMI) in a prospective, multicentre study (ISRCTN77371338).

METHODS

Of 474 patients (≥18 years) admitted to an emergency department (ED) or chest pain unit (CPU) with symptoms suggestive of acute coronary syndrome (ACS; ≤12 h from symptom onset), 465 were eligible. Minicare cTnI was tested immediately, 3 h and 6 h after presentation. AMI diagnoses were adjudicated independently based on current guidelines.

RESULTS

The diagnostic performance of the Minicare cTnI test at 3 h was similar for whole blood and in plasma: sensitivity 0.92 vs. 0.90; specificity 0.91 vs. 0.90; positive predictive value (PPV) 0.68 vs. 0.66; negative predictive value (NPV) 0.98 vs. 0.98; positive likelihood ratio (LR+) 10.18 vs. 9.41; negative likelihood ratio (LR-) 0.09 vs. 0.11. The optimal diagnostic performance was obtained at 3 h using cut-offs cTnI >43 ng/L plus cTnI change from admission ≥18.5 ng/L: sensitivity 0.90, specificity 0.96, PPV 0.81, NPV 0.98, and LR+ 21.54. The area under the receiver operating characteristics (ROC) curve for cTnI whole blood baseline value and absolute change after 3 h curve was 0.93.

CONCLUSIONS

These data support the clinical usefulness of Minicare cTnI within a 0 h/3 h-blood sampling protocol supported by current guidelines for the evaluation of suspected ACS.

Analytical performance of a single epitope B-type natriuretic peptide sandwich immunoassay on the Minicare platform for point-of-care diagnostics

Point-of-care B-type natriuretic peptide (BNP) testing with adequate analytical performance has the potential to improve patient flow and provide primary care givers with easy-to-use advanced diagnostic tools in the management of heart failure. We present the analytical evaluation of the Minicare BNP immunoassay under development on the Minicare I-20 platform for point-of-care testing. Analytical performance was evaluated using EDTA venous whole blood, EDTA plasma and capillary whole blood. Method comparison with a lab-testing system was performed using samples from 187 patients. Normal values were determined based on 160 healthy adults, aging from 19 to 70 years. Limit of blank (LoB), limit of detection (LoD) were determined to be 3.3 ng/L, 5.8 ng/L. Limit of quantitation (LoQ) in whole blood at 20% and 10% coefficient of variation (CV) was found < 9 ng/L and <30 ng/L respectively without significant differences between EDTA whole blood and EDTA plasma. Total CV was found to be from 6.7% to 9.7% for BNP concentrations between 92.6 and 3984 ng/L. The sample type comparison study demonstrated correlation coefficients between 0.97 and 0.99 with slopes between 1.03 and 1.09 between the different samples. Method comparison between Minicare BNP and Siemens ADVIA Centaur BNP demonstrated a correlation coefficient of 0.92 with a slope of 1.06. The 97.5% URL of a healthy population was calculated to be 72.6 ng/L. The Minicare BNP assay is a robust, easy-to-use and sensitive test for rapid determination of BNP concentrations that can be used in a near-patient setting.

Rapid and Sensitive Detection of Cardiac Troponin I for Point-of-Care Tests Based on Red Fluorescent Microspheres

A reliable lateral flow immunoassay (LFIA) based on a facile one-step synthesis of single microspheres in combining with immunochromatography technique was developed to establish a new point-of-care test (POCT) for the rapid and early detection of cardiac troponin I (cTnI), a kind of cardiac specific biomarker for acute myocardial infarction (AMI). The double layered microspheres with clear core-shell structures were produced using soap-free emulsion polymerization method with inexpensive compounds (styrene and acrylic acid). The synthetic process was simple, rapid and easy to control due to one-step synthesis without any complicated procedures. The microspheres are nanostructure with high surface area, which have numerous carboxyl groups on the out layer, resulting in high-efficiency coupling between the carrier and antibody via amide bond. Meanwhile, the red fluorescent dye, Nile-red (NR), was wrapped inside the microspheres to improve its stability, as well to reduce the background noise, because of its higher emission wavelength than interference from real plasma samples. The core-shell structures provided different functional areas to separate antibody and dyes, so the immunoassay has highly sensitive, wide working curves in the range of 0–40 ng/mL, low limits of detection (LOD) at 0.016 ng/mL, and limits of quantification (LOQ) at 0.087 ng/mL with coefficient of variations (CV) of 10%. This strategy suggested an outstanding platform for LFIA, with good reproducibility and stability to straightforwardly analyze the plasma samples without washing steps, thereby reducing the operating procedures for non-professionals and promoting detection efficiency. The whole detection process can be completed in less than 15 min. This novel immunoassay offers a reliable and favorable analytical result by detecting the real samples, indicating that it holds great potential as a new alternative for biomolecule detection in complex samples, for the early detection of cardiac specific biomarkers.

Nanoswitch-linked immunosorbent assay (NLISA) for fast, sensitive, and specific protein detection

Protein detection and quantification play critical roles in both basic research and clinical practice. Current detection platforms range from the widely used ELISA to more sophisticated, and more expensive, approaches such as digital ELISA. Despite advances, there remains a need for a method that combines the simplicity and cost-effectiveness of ELISA with the sensitivity and speed of modern approaches in a format suitable for both laboratory and rapid, point-of-care applications. Building on recent developments in DNA structural nanotechnology, we introduce the nanoswitch-linked immunosorbent assay (NLISA), a detection platform based on easily constructed DNA nanodevices that change conformation upon binding to a target protein with the results read out by gel electrophoresis. NLISA is surface-free and includes a kinetic-proofreading step for purification, enabling both enhanced sensitivity and reduced cross-reactivity. We demonstrate femtomolar-level detection of prostate-specific antigen in biological fluids, as well as reduced cross-reactivity between different serotypes of dengue and also between a single-mutation and wild-type protein. NLISA is less expensive, uses less sample volume, is more rapid, and, with no washes, includes fewer hands-on steps than ELISA, while also achieving superior sensitivity. Our approach also has the potential to enable rapid point-of-care assays, as we demonstrate by performing NLISA with an iPad/iPhone camera for imaging.

Inkjet-printed point-of-care immunoassay on a nanoscale polymer brush enables subpicomolar detection of analytes in blood

The ELISA is the mainstay for sensitive and quantitative detection of protein analytes. Despite its utility, ELISA is time-consuming, resource-intensive, and infrastructure-dependent, limiting its availability in resource-limited regions. Here, we describe a self-contained immunoassay platform (the "D4 assay") that converts the sandwich immunoassay into a point-of-care test (POCT). The D4 assay is fabricated by inkjet printing assay reagents as microarrays on nanoscale polymer brushes on glass chips, so that all reagents are "on-chip," and these chips show durable storage stability without cold storage. The D4 assay can interrogate multiple analytes from a drop of blood, is compatible with a smartphone detector, and displays analytical figures of merit that are comparable to standard laboratory-based ELISA in whole blood. These attributes of the D4 POCT have the potential to democratize access to high-performance immunoassays in resource-limited settings without sacrificing their performance.

Metabolomics and Cardiology: Toward the Path of Perinatal Programming and Personalized Medicine

Heart diseases are one of the leading causes of death in Western Countries and tend to become chronic, lowering the quality of life of the patients and ending up in a massive cost for the Health Systems and the society. Thus, there is a growing interest in finding new technologies that would allow the physician to effectively treat and prevent cardiac illnesses. Metabolomics is one of the new "omics" sciences enabling creation of a photograph of the metabolic state of an individual exposed to different environmental factors and pathologies. This review analyzed the most recent literature about this technology and its application in cardiology in order to understand the metabolic shifts that occur even before the manifestation of these pathologies to find possible early predictive biomarkers. In this way, it could be possible to find better treatments, ameliorate the patient's quality of life, and lower the death rate. This technology seems to be so promising that several industries are trying to set up kits to immediately assess the metabolites variations in order to provide a faster diagnosis and the best treatment specific for that patient, offering a further step toward the path of the development of a tailored medicine.

Equal clinical performance of a novel point-of-care cardiac troponin I (cTnI) assay with a commonly used high-sensitivity cTnI assay

BACKGROUND

Efficient rule-out of acute myocardial infarction (MI) facilitates early disposition of chest pain patients in emergency departments (ED). Point-of-care (POC) cardiac troponin (cTn) may improve patient throughput. We compared the diagnostic accuracy of a novel cTnI test (Minicare cTnI, Philips), with current POC cTnI (I-Stat, Abbott) and high-sensitivity central laboratory cTnI (hs-cTnI; Architect, Abbott) assays.

METHODS

The clinical performance of the assays were compared in samples from 450 patients from a previous clinical evaluation of Minicare cTnI.

RESULTS

Minicare cTnI correlated with Architect hs-cTnI (r²=0.85, p<0.0001) and I-Stat cTnI (r²=0.93, p<0.0001). Areas under the receiver operating characteristics curves were 0.87-0.91 at admission (p=ns) and 0.96-0.97 3h after admission (p=ns). The negative predictive values (NPV) at admission were 95% ((92-97%, 95% CI) for Minicare cTnI and increased to 99% (97-100%) at 2-4h, and similar to Architect hs-cTnI (98%, 96-100%), but higher than I-Stat cTnI (95%, 92-97%; p<0.01). Negative likelihood ratios (LR-) after 2-4h were 0.06 (0.02-0.17, 95% CI) for Minicare cTnI, 0.11 (0.05-0.24) for Architect hs-cTnI (p=0.02) and 0.28 (0.18-0.43) for I-Stat cTnI (p<0.0001). The clinical concordances between Minicare cTnI and Architect hs-cTnI were 92% (admission) and 95% (2-4h), with lower concordances between Minicare cTnI and I-Stat cTnI (83% and 78%, respectively; p=0.007).

CONCLUSIONS

The Minicare cTnI POC assay may become useful for prompt and safe ruling-out of AMI in ED patients with suspected AMI using a guideline supported 0/3h sampling protocol.