High-sensitivity cardiac troponin testing in routine practice: economic and organizational advantages

Troponin testing in routine primary care: observations from a dynamic cohort study in the Amsterdam metropolitan area

OBJECTIVES

Troponin testing is indicated in the diagnostic work-up of acute coronary syndrome (ACS) and incorporated in risk stratification pathways. This study aims to gain insights on the use, outcomes, and diagnostic accuracy of troponin testing in routine primary care; a setting that is understudied.

METHODS

Routine data were used from the academic primary care network in the Amsterdam metropolitan area (968,433 patient records). The study population included adult patients who underwent high-sensitivity troponin I or T (hs-TnI/T) testing between 2011 and 2021. The primary outcome was the reported diagnosis and the secondary outcome was the diagnostic accuracy measured by death or ACS at 30 days.

RESULTS

3,184 patients underwent hs-troponin testing, either with hsTNT (n=2,333) or hsTNI (n=851). Median patients' age was 55 (44-65) years, and 62.3 % were female. Predominant symptoms were chest pain and dyspnea (56.7 %). Additional diagnostic laboratory tests were commonly performed (CRP: 47.7 %, natriuretic peptides: 25.6 %, d-dimer: 21.5 %). Most common diagnoses were musculoskeletal symptoms (21.6 %) and coronary heart disease (7.1 %; 1.1 % ACS). Troponin testing showed sensitivity and specificity of 77.8 % (60.9-89.9) and 94.3 % (93.5-95.1), respectively. Negative and positive predictive values were 99.7 (99.5-99.9) and 13.5 (11.1-16.4), and positive and negative likelihood ratios were 13.7 (10.9-17.1) and 0.24 (0.13-0.43).

CONCLUSIONS

GPs occasionally use troponin testing in very low-risk patients, often as part of a multi-marker rule-out strategy. The diagnostic characteristics of troponin tests, while promising, warrant prospective validation and implementation to facilitate appropriate use.

How Do Cardiovascular Biomarkers Behave in Patients with Severe Aortic Valve Stenosis with and without Echocardiographically Proven Pulmonary Hypertension?—A Retrospective Study of Biomarker Trends before and after Transcatheter Aortic Valve Replacement

Background: Since right heart catheterization is rarely performed in patients with severe aortic valve stenosis (AS), echocardiography is currently the tool of choice to determine the presence or absence of pulmonary hypertension (PH). The systolic pulmonary artery pressure (sPAP) has established itself as a reliable measurement value for this purpose. The aim of our study was to evaluate the behavior of plasma-level concentrations of novel cardiovascular biomarkers (sST2, GDF-15, H-FABP, IGF-BP2, and suPAR) in patients with severe AS and an sPAP < 40 mmHg in comparison to patients with an sPAP ≥ 40 mmHg before transcatheter aortic valve replacement (TAVR) and after TAVR (24 h, 96 h, 3 months, and 12 months). Methods: We retrospectively separated 85 patients with echocardiographic evidence of severe AS before TAVR procedure into two groups based on sPAP level. An sPAP of 40 mmHg was considered the cut-off value, with the absence of PH defined by an sPAP < 40 mmH (n = 32) and the presence of PH defined by an sPAP ≥ 40 mmHg (n = 53). Blood samples were drawn from each patient one day before TAVR and 24 h, 96 h, 3 months, and 12 months after TAVR. Plasma concentrations of the cardiovascular biomarkers sST2, GDF-15, H-FABP, IGF-BP2, and suPAR were determined and analyzed with univariate and multivariate binary logistic regression and AUROC curves. Results: Patients with severe AS and an sPAP ≥ 40 mmHg had significantly higher plasma concentrations of H-FABP (baseline: p = 0.022; 24 h: p = 0.012; 96 h: p = 0.037; 3 months: p = 0.006; 12 months: p = 0.030) and IGF-BP2 (baseline: p = 0.029; 24 h: p = 0.012; 96 h: p = 0.001; 3 months: p = 0.015; 12 months: p = 0.022) before and continuously up to 12 months after TAVR than did patients with an sPAP < 40 mmHg sST2, with the exception of the 12-month follow-up. We also consistently found significantly higher plasma concentrations in the sPAP ≥ 40 mmHg group (baseline: p = 0.007; 24 h: p = 0.006; 96 h: p = 0.014; 3 months: p ≤ 0.001; 12 months: p = 0.092), whereas suPAR had significantly elevated values at baseline and after 24 h in patients with echocardiographic evidence of PH and significantly decreased values after 3 months (baseline: p = 0.003; 24 h p = 0.041; 96 h: p = 0.127; 3 months: p = 0.006; 12 months: p = 0.477). Plasma concentrations of GDF-15 were only significantly different after 24 h (baseline: p = 0.075; 24 h: p = 0.016; 96 h: p = 0.101; 3 months: p = 0.244; 12 months: p = 0.090). In a multivariate binary logistic regression, atrial fibrillation, tricuspid annular plane systolic excursion (TAPSE), and sST2 at baseline were found to have a significant p-value < 0.050. Conclusion: In this descriptive study, sST2, H-FABP, and IGF-BP2 emerged as the cardiovascular biomarkers with the greatest potential with respect to echocardiographically PH detection in long-term follow-up after TAVR, as patients with an sPAP ≥ 40 mmHg had significantly continuously higher plasma biomarker concentrations than the corresponding cohort did, with an sPAP < 40 mmHg.

A new digital single-axis fluxgate magnetometer according to the cobalt-based amorphous effects

Fluxgate sensors are currently widely used for weak magnetic field measurement because of their relatively great performance, such as resolution, power consumption, and measurement of vector magnetic fields directly. Since the analog fluxgate sensor has some drawbacks, e.g., it would be influenced by the noise of the analog circuit. Hence, in recent years, the analog circuit is gradually inclined to be realized by digital processing in which the software parameter adjustment is employed to replace the analog components, which can greatly improve the flexibility of the design. This paper proposes a digital single-axis fluxgate sensor according to the cobalt-based amorphous effect. To be specific, the analog signal output by the fluxgate is sampled directly by an analog-to-digital converter to obtain the signal waveform in digital form after amplification. The demodulation, filtering, and integration of the signal are all solved by mathematical algorithms. Based on the working principle of the fluxgate sensor, the selection of the magnetic core material and coil winding method of the fluxgate sensor probe is introduced in detail. The design and function of the excitation circuit and preamplifier circuit, as well as the specific realization of digital signal processing, are described. Finally, the performance test of the digital fluxgate sensor was performed under laboratory conditions, and the magnetic anomaly detection comparison experiment was performed outdoors with commercial fluxgate sensors. To sum up, the linearity of the digital single-axis fluxgate sensor is better than 1 × 10^-5, and the root mean square noise value is below 0.1 nT. At the same time, it has good magnetic field tracking performance and is extremely sensitive to the magnetic field of the measurement area.

Immobilization of Molecularly Imprinted Polymer Nanoparticles onto Surfaces Using Different Strategies: Evaluating the Influence of the Functionalized Interface on the Performance of a Thermal Assay for the Detection of the Cardiac Biomarker Troponin I

We demonstrate that a novel functionalized interface, where molecularly imprinted polymer nanoparticles (nanoMIPs) are attached to screen-printed graphite electrodes (SPEs), can be utilized for the thermal detection of the cardiac biomarker troponin I (cTnI). The ultrasensitive detection of the unique protein cTnI can be utilized for the early diagnosis of myocardial infraction (i.e., heart attacks), resulting in considerably lower patient mortality and morbidity. Our developed platform presents an innovative route to develop accurate, low-cost, and disposable sensors for the diagnosis of cardiovascular diseases, specifically myocardial infraction. A reproducible and advantageous solid-phase approach was utilized to synthesize high-affinity nanoMIPs (average size = 71 nm) for cTnI, which served as synthetic receptors in a thermal sensing platform. To assess the performance and commercial potential of the sensor platform, various approaches were used to immobilize nanoMIPs onto thermocouples or SPEs: dip coating, drop casting, and a covalent approach relying on electrografting with an organic coupling reaction. Characterization of the nanoMIP-functionalized surfaces was performed with electrochemical impedance spectroscopy, atomic force microscopy, and scanning electron microscopy. Measurements from an in-house designed thermal setup revealed that covalent functionalization of nanoMIPs onto SPEs led to the most reproducible sensing capabilities. The proof of application was provided by measuring buffered solutions spiked with cTnI, which demonstrated that through monitoring changes in heat transfer at the solid-liquid interface, we can measure concentrations as low as 10 pg L^-1, resulting in the most sensitive test of this type. Furthermore, preliminary data are presented for a prototype platform, which can detect cTnI with shorter measurement times and smaller sample volumes. The excellent sensor performance, versatility of the nanoMIPs, and reproducible and low-cost nature of the SPEs demonstrate that this sensor platform technology has a clear commercial route with high potential to contribute to sustainable healthcare.

Exploring the association between extra-cardiac troponin elevations and risk of future mortality

Although the measurement of cardiac troponin I (cTnI) and T (cTnT) has now become the cornerstone for diagnosing cardiac injury, both ischemic and non-ischemic, recent evidence has become available that many patients display extra-cardiac causes of cTn elevations and carry a considerably enhanced risk of future mortality. The current literature data suggests that cTn elevations may be equally common in patients with cardiac and extra-cardiac diseases. Among the latter cohort of patients, the leading extra-cardiac diseases which may be responsible for either cTnI or cTnT elevations include infectious diseases/sepsis, pulmonary disorders, renal failure, malignancy, as well as gastrointestinal, neurological and musculoskeletal diseases. What also emerges rather clearly from the current literature data, is that the risk of dying for extra-cardiac diseases is higher (i.e., between two to three-fold) in patients with extra-cardiac cTn elevations than in those with cardiac pathologies, and that the most frequent cause of death would then be infections/sepsis, followed by malignancy, respiratory disorders, myocardial infarction, gastrointestinal and neurological diseases, heart failure, stroke, cardiac arrhythmias, renal failure, psychiatric, metabolic, urogenital and musculoskeletal disorders. These figures would lead to conclude that there is a considerable risk that the underlying pathology causing cardiac injury and cTn elevation would then become the cause of death in these patients. This important evidence shall lead the way to defining appropriate and effective strategies for managing patients with extra-cardiac cTn elevations, so that their risk of future death could be prevented or limited.

"Ultra-sensitive" cardiac troponins: Requirements for effective implementation in clinical practice

The measurement of cardiac troponins, either cardiac troponin I or T, has become the culprit of clinical decision making in patients with suspected acute coronary syndrome (ACS), especially in those with non-ST elevation myocardial infarction (NSTEMI). The leading analytical mainstays of cardiac troponin immunoassays include the limit of blank (LoB), limit of detection (LoD), functional sensitivity, the 99th percentile of a healthy reference population, along with the percentage of "ostensibly healthy" subjects displaying measurable values < 99th percentile. The latest generation of cardiac troponin immunoassays, conventionally defined as "high-sensitive" (HS), is characterized by a LoD over 100-fold lower compared to the first commercialized techniques and a percentage of measurable values consistently > 50% in the general healthy population. The very recent commercialization of methods with further improved analytical sensitivity (i.e., "ultra-sensitive" assays), which allow to measure cardiac troponin values in the vast majority of healthy subjects, is now challenging the diagnostic paradigm based on early rule-out of subjects with cardiac troponin values comprised between the 99th percentile and LoD. New diagnostic strategies, entailing assay-specific cut-offs, must hence be developed and validated in large multicenter studies. The aim of this article is to provide an update on commercially available HS and "ultra"-sensitive techniques for measuring cardiac troponins, along with possible implications of increasingly enhanced analytical sensitivity on diagnostic algorithms for evaluating patients with suspected ACS.