PRESC1SE-MI: One-hour troponin pathway is safe but does not shorten emergency department stay

The PRESC1SE-MI trial found that a 0/1-hour pathway for assessing patients with suspected myocardial infarction was non-inferior to a more conservative 0/3-hour pathway for safety, but did not reduce the time patients spent in the emergency department.

Rapid assessment of patients presenting to the emergency department (ED) with suspected myocardial infarction (MI) is important both to identify those requiring urgent treatment and to safely rule out MI in the large proportion of patients whose symptoms have another cause. Serial measurement of high-sensitivity cardiac troponin (hs-cTn) plays a central role in this process, with European Society of Cardiology (ESC) guidelines recommending rapid 0/1-hour or 0/2-hour algorithms for patients with suspected non-ST-elevation acute coronary syndrome.¹

The 0/1-hour pathway has been extensively validated in diagnostic and implementation studies, but randomized evidence directly comparing its safety and effectiveness with a 0/3-hour strategy has remained limited.^1-3 The international PRESC1SE-MI trial was designed to address this evidence gap. The pragmatic, stepped-wedge, cluster-randomized controlled trial included consecutive adults presenting with acute non-traumatic chest discomfort and suspected MI at 19 hospitals across 10 countries, comparing implementation of the ESC 0/1-hour pathway with continued use of a 0/3-hour pathway.²,³

Presented during a Hot Line session at ESC Congress 2026 and published simultaneously in The Lancet, PRESC1SE-MI included 67,624 ED presentations.²,⁴ The 0/1-hour pathway was non-inferior for the co-primary safety outcome of all-cause death or new type 1 MI within 30 days, which occurred in 1.1% of presentations managed using the 0/1-hour pathway and 1.2% using the 0/3-hour pathway.² However, the more rapid testing strategy did not improve the co-primary efficacy outcome. Median ED length of stay was 309 minutes in both groups, indicating that earlier repeat troponin testing alone did not translate into faster discharge from the ED.²

At ESC 2026, touchCARDIO spoke with Prof. Jasper Boeddinghaus, University Hospital Basel, Switzerland, and University Hospital Bonn, Germany, about why the trial was needed, the factors that may explain its findings, and what they mean for clinical practice.

Why was the PRESC1SE-MI trial needed?

There are millions of people who present to the emergency department every year with chest pain because they have suspected myocardial infarction. It is very important to have an early assessment of these patients because only around one in 10 patients is finally diagnosed with a heart attack. In around 90%, a heart attack can be ruled out, and many of these patients can be sent home quite early.

To accelerate this process, the 0/1-hour pathway was developed around 13 or 14 years ago. It was recommended by the European guidelines with a Class I recommendation for the first time in the 2015 iteration of the guidelines. What we observed, however, was that despite this recommendation, clinical adoption of the 1-hour pathway was quite slow. I think one reason was that the evidence mainly came from diagnostic studies, and there was only one randomized controlled trial, which enrolled patients between 2015 and 2019 in Australia.

There was therefore very limited randomized evidence showing whether the 1-hour pathway was similarly safe compared with the 3-hour pathway and whether it was more effective by shortening the time patients spend in the emergency department. We felt there was a real need for a large, international randomized controlled trial assessing the safety and efficacy of the 1-hour pathway compared with the more conservative 0/3-hour pathway. That is why we initiated PRESC1SE-MI.

We started planning the study in 2018 and began enrollment in December 2020. We enrolled patients over 4 years at 19 sites in 10 countries to provide solid evidence on whether the 1-hour pathway was non-inferior in terms of safety and whether it was more effective than the 3-hour pathway.

What were the topline findings?

The study confirms that the safety of the 1-hour pathway was non-inferior in terms of new type 1 myocardial infarction or all-cause death within 30 days compared with the 3-hour pathway.

However, we were not able to show superiority in terms of efficacy, meaning that emergency department length of stay was not reduced. It therefore seems that the 1-hour pathway is similarly safe, but it does not reduce the time patients spend in the emergency department.

Why do you think the 1-hour pathway failed to reduce emergency department length of stay?

I think this is the most important question because the result was surprising. The guidelines recommend this pathway partly on the premise that it reduces time in the emergency department.

I think the answer is that simply retesting cardiac troponin at an earlier time point, at 1 hour rather than 3 hours, does not necessarily translate into a shorter emergency department stay. Emergency departments, particularly at large centers, are extremely busy places. There can be hundreds of patients at the same time, all with different conditions and all needing attention.

Even if the cardiac troponin result is available at an earlier time point, it still has to be reviewed by a nurse or physician so they can act on the result. That might mean discharging the patient because it is very unlikely that they have had a heart attack, looking for an alternative diagnosis, admitting the patient to hospital or even sending the patient to the catheterization laboratory for an invasive angiogram. There are therefore so many factors involved, including understaffing, crowding in the emergency department and when the physician actually sees the second cardiac troponin result. I think it is multifactorial, and earlier retesting alone does not necessarily change anything.

Could the impact of the 1-hour pathway differ between hospitals or healthcare systems?

Absolutely. I think Basel, where I worked previously and where the 1-hour pathway was developed, is a good example. We introduced it into clinical practice in 2015 and really trained the nurses, laboratory staff and cardiologists on an almost daily basis that we were using a new pathway and that it was very important to take the second blood sample exactly 1 hour after presentation to the emergency department. When a patient comes in and triage identifies suspected myocardial infarction, the nurse immediately makes a note that troponin should be taken at baseline and then again after 1 hour.

That is quite different from what happened within the trial, where we told centers to implement the 1-hour pathway. We provided educational material, there were presentations from local principal investigators and we tried to monitor how well the second blood draw was performed, for example. But ultimately, implementation was left to the individual centers and they implemented the pathway in the way that was feasible for them.

Basel also has a relatively small emergency department. There is not the same degree of understaffing, and there are sufficient nurses to take care of a limited number of patients. In other hospitals and healthcare systems, there may be staff shortages and it can be very difficult to make sure that the second blood draw is taken on time.

What should clinicians and hospitals take away from the findings?

I think the information we get from the study is very important.

The first message is that the 1-hour pathway is non-inferior in terms of safety to the 3-hour pathway. That is an important message for hospitals worldwide that have already implemented the 1-hour pathway because there is no safety signal. There is no need to consider turning back to the 3-hour pathway.

The second message, particularly for hospitals that are still using a 3-hour pathway, is that they should not expect that simply implementing the 1-hour pathway will shorten the time patients spend in the emergency department.

If hospitals are really keen to implement it, they have to think about the organization and structure of the entire emergency department. What is the bed capacity for patients who need to be admitted? What is the discharge pathway once a heart attack has been ruled out? What is the turnaround time between taking the blood sample and reporting the troponin result? In some hospitals that can be quite long depending on availability within the central laboratory. These are all factors that hospitals need to be aware of and take into account when considering implementation of the pathway.

References

1. Byrne RA, Rossello X, Coughlan JJ, et al. 2023 ESC Guidelines for the management of acute coronary syndromes. Eur Heart J. 2023;44:3720–3826.
2. Boeddinghaus J, Bima P, Crisanti L, et al. Safety and efficacy of the 0/1 h pathway for myocardial infarction in the emergency department: an international, pragmatic, stepped-wedge, cluster-randomised, controlled trial. Lancet. Published online August 29, 2026. doi:10.1016/S0140-6736(26)01654-5.
3. Boeddinghaus J, Bima P, Crisanti L, et al. PRospective evaluation of the European Society of Cardiology 0/1h-algorithm’s safety and efficacy for triage of patients with suspected myocardial infarction (PRESC1SE-MI): rationale and design of a prospective international multicenter stepped-wedge cluster randomized controlled trial. Am Heart J. 2026;292:107299.
4. Mueller CE. PRESC1SE-MI: Safety and efficacy of the ESC 0/1-hour algorithm. Presented during Hot Line 4, ESC Congress 2026; August 29, 2026; Munich, Germany.