Some Minor Differences Exist Between Two hs-Troponin Pathways for NSTEMI

For patients presenting to the emergency department (ED) for acute chest discomfort, both the European Society of Cardiology (ESC) 0/1-hour algorithm and the High-STEACS 0/2- or 0/3-hour pathways, which are based on high-sensitivity cardiac troponin (hs-cTn) testing, perform well for diagnosing NSTEMI, according to prospective data from Europe. However, the study also found some key differences that could play into a center’s choice of test.

When using assays measuring troponin I, the ESC algorithm had higher sensitivity for diagnosing NSTEMI compared with the High-STEACS pathways, but reduced efficacy indicated by a lower proportion of patients placed in the rule-out group, researchers led by Jonas Glaeser, MD, and Pedro Lopez-Ayala, MD (both from University Hospital Basel, Switzerland), report.

Sensitivity and efficacy were similar with either strategy in the context of testing with a high-sensitivity troponin T assay. On the other hand, regardless of the type of hs-cTn assay used, the ESC 0/1-hour algorithm had higher specificity and positive predictive value compared with the High-STEACS 0/2- and 0/3-hour pathways.

The findings were published online recently in JACC.

“The main message is that there are a lot of similarities in the performance of these two pathways. But to some extent, related to differences in how they were derived, it’s clear that performance is also different, so that sites now have, for the first time, solid data to consider whether the benefit of option one or possibly the benefit of option two might be more attractive to them,” senior author Christian Mueller, MD (University Hospital Basel), told TCTMD.

Centers that prioritize high sensitivity and not missing any NSTEMIs—due to a high risk of litigation in case of medical errors, for example—may prefer the ESC 0/1-hour algorithm, Mueller said. But for those hospitals that are operating under economic pressure or have an extremely high number of patients to manage, the simpler and more effective High-STEACS approach may be the better option, said Mueller.

Additional research is needed to look into whether choice of diagnostic strategy influences ED workflow, crowding, and clinical outcomes, the investigators note, adding that “in the interim, institutions already using either approach should continue their current practice, as both algorithms show excellent and largely comparable diagnostic performance and remain fully aligned with current guideline recommendations.”

A Tale of Two Pathways

International guidelines differ as to what accelerated pathway based on hs-cTn testing should be used to diagnose NSTEMI in patients with acute chest pain after a 12-lead ECG has ruled out STEMI. The ESC 0/1-hour algorithm is recommended in the ESC’s latest guideline on the management of patients with acute coronary syndromes, whereas the High-STEACS approach is preferred in 2020 guidance from the National Institute for Health and Care Excellence in the United Kingdom. US guidelines do not favor a specific hs-cTn pathway for diagnosing NSTEMI.

This analysis—“the first methodologically solid, direct comparison of the two most extensively validated patient pathways,” according to Mueller—used data from the prospective APACE study conducted at 13 sites in Switzerland, Spain, Czechia, Italy, and Poland. It included 4,663 adult patients (median age 61 years; 32% women) who presented to the ED with acute chest discomfort, had STEMI excluded, and had hs-cTn test results that allowed both the ESC and High-STEACS algorithms to be applied. Three well-validated hs-cTn assays were used in the study: Architect Stat (Abbott) and Advia Centaur/Atellica IM (Siemens Healthineers) measuring troponin I and Elecsys (Roche) measuring troponin T.

Overall, 14.2% of patients had NSTEMI type 1, with the final diagnosis adjudicated by two independent cardiologists.

There were some differences in performance between the two pathways depending on the type of troponin assay used.

For instance, the ESC 0/1-hour algorithm had higher sensitivity than the High-STEACS 0/2-hour pathway when using the Architect Stat assay (100% vs 98.1%), although the proportion of patients placed in the rule-out group was lower (52.1% vs 72.5%; P <0.001 for both comparisons). The results were similar when using the other troponin I assay, but there were no significant differences in safety or efficacy between algorithms when the Elecsys troponin T assay was used.

Specificity and positive predictive value tended to be higher with the ESC 0/1-hour algorithm than with the High-STEACS 0/2- or 0/3-hour pathways when any of the three assays were used.

The increased specificity with the ESC algorithm is consistent with how these algorithms were initially derived, Mueller said. “The ESC algorithm really was designed in a way to identify NSTEMI, whereas the High-STEACS pathway was a bit more designed to identify patients that need hospitalization in general. It’s not really a diagnostic rule-in pathway.”

The researchers showed similar findings across assays when comparing the ESC 0/1-hour and High-STEACS 0/3-hour strategies in a separate prospective study called BACC, which included 2,485 patients (median age 64 years; 37% women); 8.9% were diagnosed with NSTEMI type 1 in the ED.

Choosing Between the Two

Commenting for TCTMD, Cian McCarthy, MBBCh (Massachusetts General Hospital, Boston, MA), said the results are important because there are very few data directly comparing the two diagnostic pathways.

“Collectively, the data suggests that if you’re using a high-sensitivity cardiac troponin T assay, there’s not much difference at all in terms of safety or efficiency in terms of the proportion of patients being ruled out with either pathway. I think either option’s very reasonable,” McCarthy said.

A potential advantage of the ESC 0/1-hour pathway, if using a troponin T assay, “is that you can rule patients out with two troponins spaced 1 hour apart, rather than waiting 2 to 3 hours for that second troponin,” he said. “That could save a little bit of time.”

As for centers that use a troponin I assay, the ESC 0/1-hour algorithm appears to have slightly better safety, McCarthy said. “But the difference is small in terms of sensitivity and negative predictive value, so if you really wanted more of a focus on efficiency and ruling out a larger number of patients with still quite good safety data, then High-STEACS might be a better option for you.” Ruling out NSTEMI in more patients initially could translate into less resource use, shorter ED stays, and lower costs, although that wasn’t explored in the current study, he added.

It remains unclear, too, whether these results would be generalizable to the United States, where troponin testing in the ED is much more common than it is in Europe, McCarthy said.

In an accompanying editorial, Christopher Baugh, MD (Brigham and Women’s Hospital, Boston, MA), and colleagues note that the application of accelerated diagnostic protocols (ADPs) for acute chest pain in EDs involves multiple different specialists, including emergency physicians, cardiologists, laboratorians, and informaticists, with “overlapping but distinct priorities.”

“The optimal ADP strikes a careful balance among sensitivity, specificity, safety, and efficacy. It must be designed collaboratively, adapted pragmatically, and continuously refined to reflect the best available evidence and evolving technologies,” they write. “Glaeser et al contribute important insights toward achieving this balance. Their study underscores the ongoing need to align assay capabilities, patient presentation patterns, and system logistics to create actionable, high-performing ADPs for patients with chest pain.”