Rapid or Ultra-rapid Diagnosis of Myocardial Infarction Using High-Sensitivity Cardiac Troponin on Hospital Presentation

Each year, approximately 80,000 individuals present to the Danish healthcare system with chest pain. Of these, around 25,000 are admitted to hospital and approximately 8,000 are diagnosed with acute myocardial infarction. High-sensitivity cardiac troponin (hs-cTn) is the cornerstone biomarker for the diagnosis of myocardial infarction and is essential for the rapid rule-in and rule-out of acute coronary syndromes. Because the diagnosis of myocardial infarction relies not only on troponin concentration but also on changes in troponin levels over time, serial blood sampling is required to distinguish acute myocardial injury from chronic elevations.

Advances in hs-cTn assay sensitivity have enabled progressively shorter intervals between serial blood sampling. Traditionally, most emergency departments have used a 0/3-hour algorithm, in which hs-cTn is measured at presentation and again after 3 hours. However, contemporary European guidelines recommend accelerated diagnostic pathways using a 0/1-hour or 0/2-hour algorithm.

The primary purpose of the DanRUSH trial is to determine whether shortening the interval between serial hs-cTn measurements from 3 hours to 1 hour is both safe and effective in adults presenting with suspected acute coronary syndrome.

The primary safety endpoint is defined as the risk of new (missed or recurrent) myocardial infarction or cardiovascular death after dischage from the index hospitalization -of the 0/1-hour algorithm compared with the 0/3-hour algorithm. Efficacy will be assessed as hospital length of stay, defined as the time from presentation to discharge. The study aims to demonstrate that the 0/1-hour algorithm is non-inferior to the 0/3-hour algorithm with respect to safety while improving efficiency through shorter hospital stays.

The study is designed as a nationwide, pragmatic, open-label, stepped-wedge cluster randomized trial. Participating emergency- and cardiology departments in Denmark will sequentially and randomly transition from the conventional 0/3-hour hs-cTn algorithm to the 0/1-hour hs-cTn algorithm until all sites are exposed to the intervention. A study-specific order set in the electronic medical record will ensure the correct timing of serial blood sampling and facilitate identification of study participants. Relevant baseline and outcome information will be obtained from routinely collected data in the electronic medical record and Danish nationwide health registries.

The results of DanRUSH are expected to provide definitive randomized evidence regarding the safety and effectiveness of the 0/1-hour hs-cTn algorithm. If the accelerated diagnostic strategy is shown to be safe, it may support broader implementation and improve patient flow by reducing unnecessary hospital stays. Conversely, if safety cannot be confirmed, the study may prevent widespread adoption of an insufficiently validated diagnostic strategy.

• New myocardial infarction at 12 months [Time frame: From discharge from the index hospitalization until 12 months after discharge.]
• All-cause mortality [Time frame: 30 days and 12 months following discharge]
• Overall myocardial infarction rate [Time frame: 30 days and 12 months following discharge]
• Diagnostic coronary angiography [Time frame: During the index hospitalization, at 30 days, and at 12 months after the index presentation]
• Invasive treatment [Time frame: During the index hospitalization, at 30 days, and at 12 months after the index presentation]
• Re-presentation to hospital [Time frame: 30 days and 12 months following discharge]
• Re-hospitalization [Time frame: 30 days and 12 months following discharge]
• Time to treatment initiation [Time frame: From emergency department presentation until initiation of treatment, assessed during the index hospitalization (up to 7 days)]