Does One Negative Troponin Measurement Rule Out Acute Coronary Syndrome?

This is a summarized version of the full in-depth article on Relias Media.

By Michael H. Crawford, MD, Editor. Professor of Medicine, Lucy Stern Chair in Cardiology, University of California, San Francisco

Overview

Acute coronary syndrome (ACS) is a common concern among patients presenting with chest pain, but only a small percentage of these patients are diagnosed with ACS. The advent of point-of-care (POC) rapid troponin testing has introduced the potential to identify low-risk patients for ACS in a prehospital setting, possibly avoiding unnecessary emergency department (ED) visits. However, this strategy had not been tested in a randomized trial prior to the ARTICA trial, conducted by Camaro et al in the Netherlands. The study aimed to assess the safety and cost-effectiveness of a prehospital rule-out strategy for ACS using POC troponin measurements and the HEAR score (History, ECG, Age, and Risk factors).

Study Design and Population

The ARTICA trial involved 112 ambulances and 552 paramedics across five regions in the Netherlands. The study population included 866 low-risk chest pain patients, randomized between 2019 and 2022, with a mean age of 54 years and a predominance of women (57%). These patients were identified using the HEAR score, which was automatically calculated by paramedics based on patient history, ECG findings, age, and risk factors for coronary disease. Inclusion criteria required patients to have a HEAR score of 3 or lower, with symptom onset at least two hours before ambulance arrival. Paramedics were trained to perform POC troponin tests, and if troponin levels were elevated, patients were transferred to the ED. Otherwise, they were referred to their primary care physician.

Patients were randomized into two groups:

• Prehospital strategy: Patients underwent a POC troponin test in the ambulance, and if the result was normal, they were not transported to the ED.

• Standard ED strategy: Patients were transported to the ED for further evaluation, including traditional troponin testing.

Outcomes

The primary outcome was healthcare costs at 30 days, while the secondary outcome was the incidence of major adverse cardiac events (MACE), which includes death, myocardial infarction, and revascularization. Follow-up included phone calls, emails, and review of hospital data.

Key Results:

• Healthcare costs: Patients in the prehospital group had significantly lower costs compared to the ED group (€1,349 vs. €1,960, P < 0.001).

• MACE rates: MACE within 30 days occurred in 3.9% of prehospital patients and 3.7% of ED patients—a statistically insignificant difference.

• Among patients who were ruled out for ACS, MACE occurred in 0.5% of prehospital patients and 1% of ED patients.

• In the prehospital group, 15 patients were ruled in for ACS, compared to 12 in the ED group.

Commentary on Findings

The ARTICA trial provides evidence that prehospital POC troponin testing is a cost-effective strategy for ruling out ACS in low-risk patients without increasing the risk of MACE. The cost savings are primarily driven by the reduction in unnecessary ED visits and testing, as 92% of patients in the prehospital group did not require transport to the ED. This suggests that, for a subset of patients, early assessment in the ambulance can streamline care and reduce healthcare resource utilization.

Considerations and Limitations

While the trial's findings are promising, several considerations must be taken into account when interpreting the results and their potential applicability in other healthcare systems:

1. Safety of the prehospital strategy: The study was not powered to detect differences in safety outcomes, such as MACE, between the two groups. However, among patients ruled out for ACS, the MACE rate was low (0.5% in the prehospital group vs. 1% in the ED group), suggesting the prehospital strategy is likely safe for low-risk patients.

1. Applicability to other health systems: The study was conducted in the Netherlands, where the ambulance system is highly developed, and paramedics receive extensive training. In other countries, including the United States, where paramedic training and healthcare infrastructure vary significantly, this strategy may not be as easily implemented. In urban areas with dense populations and well-trained paramedics, however, the prehospital POC strategy could be feasible and cost-effective.

1. Limitations of POC troponin testing: The POC troponin tests used in the study were less sensitive than the high-sensitivity troponin assays typically used in hospitals. This limitation was addressed by excluding patients with chest pain lasting less than two hours, a period during which troponin may not yet be elevated. This exclusion criterion may reduce the risk of false-negative results but also limits the generalizability of the findings to all chest pain patients.

1. Time and Resource Use in Ambulances: One potential downside of the prehospital strategy is the increased time paramedics spend at the scene conducting POC tests and assessments. However, the study found that ambulance availability was actually improved, as the prehospital group reduced the need for transport to the ED, freeing up ambulances more quickly.

1. Potential for broader implementation: The authors suggest that low-risk patients could be referred to primary care urgent clinics rather than EDs. In some healthcare systems, this may reduce the burden on emergency services and offer an alternative pathway for managing low-risk chest pain.

Summary

The ARTICA trial demonstrates that prehospital POC troponin testing combined with the HEAR score can safely reduce healthcare costs in patients with low-risk chest pain without increasing the risk of major adverse cardiac events. While this strategy may not be suitable for all healthcare settings, it holds promise in systems with well-trained paramedics and efficient ambulance services. Further studies are needed to evaluate its broader applicability, particularly in healthcare environments with different infrastructure and resources.

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