High-sensitivity cardiac troponin I testing: A compelling point of care option for the emergency department

The emergency department (ED) plays a pivotal role in providing patients in need of immediate and critical attention with prompt and effective clinical care. However, it’s not just important for patients to be processed quickly due to severity of injury or disease or risk factors such as age or predisposition. The entire system needs to be efficient and well-planned to ensure patient length of stay is kept as short as possible to avoid overcrowding.

With this in mind, clinicians and researchers working in emergency medicine are continuously developing strategies to improve practices such as care transitions, triage, and observational units. In addition to these interventions, access to timely test results will undoubtedly have a marked impact on treatment decisions and, ultimately, length of stay (LOS). The widespread implementation of point of care testing (POCT) has been identified as a method that could have a significant reduction in turnaround time, providing diagnostic results within minutes rather than hours.¹

Approximately 20% of acute hospital admissions can be attributed to presentations with chest pain, which means EDs are under substantial pressure to investigate and manage these patients to prevent further risk of infarction and ensure appropriate treatment is delivered quickly.² With the ability to measure lower values than conventional troponin I testing, in-lab high-sensitivity cardiac troponin I (hs-cTnI) assays are quickly becoming a mainstay in hospitals worldwide as a strategy to identify patients most at risk of acute coronary syndrome and characterize those at low risk and suitable for immediate discharge.³ However, as manufacturers are now able to adapt these high-sensitivity tests to produce compelling point of care platforms, the choice of which technology to incorporate presents itself to clinicians and hospital administrators alike.

Reducing ED length of stay with POCT

The effectiveness of POCT with analytes such as lipids, urine, blood gases, electrolytes, and renal function tests has been well-documented by a number of research groups. For example, following a single-center observational study, Kankaanpää et al., concluded that POCT permitted faster access to results than a centralized lab and shortened the laboratory process overall, allowing patients to be discharged quicker.⁴ Goyder et al., performed a meta-analysis and systematic review of nine ED-based studies to determine the effect of POCT on patient LOS.⁵ They found general panel tests performed at the point of care led to a LOS reduction of 34 minutes, with care decisions being made on average 40 minutes faster than with central laboratory testing. In the context of the ongoing COVID-19 pandemic, POCT continues to play a major part in preventing viral transmission in the community. In a clinical setting, poor patient flow has been associated with delays in centralized laboratory PCR testing, impeding effective prevention of nosocomial transmission.⁶ Therefore, clinicians are now looking to POCT as a means to significantly reduce time to results and improve infection control in preparation for future surges in cases.

In the case of POC standard cardiac troponin I assays, comparable conclusions regarding the impact on ED-LOS have been made. In a 2021 study, Hight et al. reported a median time to results that was 29 minutes quicker than the conventional lab assay.⁷ Similarly, an earlier study by Blick et al., performed at the Oklahoma University Medical Center, demonstrated that the implementation of cTn POCT, along with central laboratory automation, effectively halved the turnaround time for results and significantly reduced ED-LOS. The center subsequently achieved a Six Sigma level of performance.⁸

Despite the advantages of high-sensitivity troponin I testing compared to the standard assay, its value as a POCT platform has not yet been fully described. However, it is thought that comparable, if not superior, efficacy to established POC cTn tests is to be expected, and there are now studies that have begun to explore the potential of this innovative technology. For example, when comparing a 1-hour hs-cTn testing protocol with a standard 3-hour cTn protocol, Chew et al. reported that patients suspected of having acute coronary syndrome were more likely to be discharged from the ED when tested with the hs-cTn protocol, and median ED LOS was shorter.⁹ Using a diagnostic algorithm, Sörensen et al. concluded that the performance of high-sensitivity troponin I POC assays is comparable to the already widely used hs-cTn lab-based assay, indicating the considerable benefits of POCT could be harnessed without a reduction in efficacy.¹⁰

What expectations need to be met prior to the adoption of patient-side technology?

To be a feasible purchase and acceptable to clinicians, a POCT assay must meet certain requirements. It should be compatible with existing diagnostic strategies already in place and show comparable or improved analytical performance compared to the centralized laboratory version of the same assay. Only when in accordance with the above criteria can a POCT solution be suitably integrated into the patient decision-making pathway.¹¹ Conversely, hospital administrators in charge of purchasing decisions must see either a savings on equipment cost or comparable indirect cost-effectiveness when compared to the existing in-lab test.

How Siemens Healthineers aims to meet these demands

Recognizing the stringent requirements of clinicians working in emergency medicine, Siemens Healthineers has launched its Atellica^® VTLi Patient-side Immunoassay Analyzer* along with the Atellica VTLi hs-cTnI Reagent Cartridge*. The system is designed with simplicity at its core, promising accurate, clinically actionable high-sensitivity troponin I results and easy integration with existing diagnostic systems. Using the system, a prospective study with whole-blood samples from 1089 patients presenting to the emergency department with signs and symptoms suggestive of acute myocardial infarction was completed at a large urban hospital.¹² Using the Forth Universal Definition for Myocardial Infarction, an independent panel of two physicians found 91 patients suffered from AMI (8.4% prevalence), and the overall negative predicative value using the 99th URL at the 2-hour timeframe was 98.0%. This study demonstrated laboratory-comparable results using the POC system.

The cost-effectiveness of standard hs-cTnI testing has been demonstrated in a number of settings and can primarily be attributed to the resultant reduction in unnecessary cardiac admissions.^13,14,15 For example, a cost reduction of $490 per patient was reported in a 2017 study by Jülicher et al.¹³ With the emergence of research alluding to similar cost savings with a POC version of the assay,^16,17 and the known reduction in patient LOS provided by POCT, Siemens Healthineers believes its Atellica VTLi system for hs-cTnI POCT will prove to be an added value for hospitals overall, alleviating the need to compromise between speed and accuracy. Regardless, it is promising to see that the direct and indirect costs of hs-cTnI testing are beginning to come down, and with advancements in this technology now starting to address the pain points of laboratory testing, there is a compelling case for hospitals to consider the incorporation of hs-cTnI at the POC, which may reduce patient LOS and in turn diminish overcrowding.

References

Goldstein LN, Wells M, Vincent-Lambers C. Doctors’ perceptions of the impact of upfront point-of-care testing in the emergency department. PLoS ONE. 2018.

Sweeney M, Bleeze G, Storey S, et al. The impact of an acute chest pain pathway on the investigation and management of cardiac chest pain. FHJ. 2018.

Chapman AR, Mills NL. High-sensitivity cardiac troponin and the early rule out of myocardial infarction: time for action. Heart. 2020.

Kankaanpää M, Holma-Eriksson M, Kapanen S, et al. Comparison of the use of comprehensive point-of-care test panel to conventional laboratory process in emergency department. BMC Emergency Medicine; 18(1): 43 (2018). 

Goyder C, Tan PS, Verbakel J, et al. Impact of point-of-care panel tests in ambulatory care: a systematic review and meta-analysis. BMJ Open; 10(2): e032132 (2020).

Brendish NJ, Poole S, Naidu VV, et al. Clinical impact of molecular point-of-care testing for suspected COVID-19 in hospital (COV-19POC): a prospective, interventional, non-randomised, controlled study. Lancet Respiratory Medicine; 8(10): 1192-1200 (2020). 

Hight M, Conklin K, Archer B, et al. Implementing Point-of-Care Troponin Testing in the Emergency Department: Impact on Time to Result. Journal of Emergency Nursing; 47(2): 299-304 (2021).

Blick KE. Providing critical laboratory results on time, every time to help reduce emergency department length of stay: how our laboratory achieved a Six Sigma level of performance. American Journal of Clinical Pathology; 140(2): 193-202 (2013). 

Chew DP, Lambrakis K, Blyth A, et al. A Randomized Trial of a 1-Hour Troponin T Protocol in Suspected Acute Coronary Syndromes: The Rapid Assessment of Possible Acute Coronary Syndrome in the Emergency Department With High-Sensitivity Troponin T Study (RAPID-TnT). Circulation; 140(19): 1543-1556 (2019).

Sörensen NA, Neumann JT, Ojeda F, et al. Diagnostic Evaluation of a High-Sensitivity Troponin I Point-of-Care Assay. Clinical Chemistry; 65(12): 1592-1601 (2019).

Apple FS, Fantz CR, Collinson PO. Implementation of High-Sensitivity and Point-of-Care Cardiac Troponin Assays into Practice: Some Different Thoughts. Clinical Chemistry. 2020.

Atellica^® VTLi system Instructions for use. 11538069 Rev. A, 2021-01. 

Jülicher P, Greenslade JH, Parsonage WA, et al. The organisational value of diagnostic strategies using high-sensitivity troponin for patients with possible acute coronary syndromes: a trial-based cost-effectiveness analysis. BMJ Open; 7(6): e013653 (2017).

Fitzgerald P, Goodacre SW, Cross E, et al. Cost-effectiveness of point-of-care biomarker assessment for suspected myocardial infarction: the randomized assessment of treatment using panel Assay of cardiac markers (RATPAC) trial. Academic Emergency Medicine; 18(5): 488-495 (2011).

Bhatti Y, Stevenson A, Weerasuriya S, et al. Reducing avoidable chest pain admissions and implementing high-sensitivity troponin testing. BMJ Open Quality; 8(4): e000629 (2019). 

Jülicher P, Varounis C. Estimating the cost-effectiveness of screening a general population for cardiovascular risk with high-sensitivity troponin-I. European Heart Journal. 2021. 

Goodacre S, Thokala P, Carroll C, et al. Systematic review, meta-analysis and economic modelling of diagnostic strategies for suspected acute coronary syndrome. Health Technology Assessment; 17(1): 1-188 (2013).

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