Design and rationale of the RISC-trial: multicentre

Aims: Syncope is responsible for 1-3% of emergency department presentations. The European Society of Cardiology guidelines on syncope recommend a structured initial evaluation to diagnose syncope patients. If the cause of the syncopal event remains unexplained, risk-stratification is applied to distinguish between patients at high risk of serious cardiovascular events and low-risk patients, who can be safely discharged. However, there is a group of patients in whom this risk can currently not be adequately determined, hereafter called intermediate risk. In clinical practice, these patients are either immediately discharged or admitted for 24 h in-hospital cardiac rhythm monitoring. Due to the high cost of admission, immediate discharge could lower healthcare costs, hospital bed utilization, and patient burden. To our knowledge, there is no sufficient scientific basis for the superiority of either. The RISC trial aims to resolve this knowledge gap. Study Design: The RISC trial is an investigator-initiated multicentre prospective randomized controlled trial. A total of 640 predefined low- and intermediate-risk syncope patients are randomized to either immediate discharge or discharge after 24 h in-hospital rhythm monitoring (1:1). The trial is powered to claim non-inferiority of immediate discharge with respect to (non-)fatal composite safety endpoints, which entail arrhythmic disorders, syncope recurrence, and (cardiovascular)death. Furthermore, healthcare costs and quality of life will be evaluated. Conclusion: The RISC trial is a multicentre RCT that aims to gather scientific evidence for immediate discharge of the ESC guideline-based pre-defined low- and intermediate-risk syncope patients in the emergency department. Primary endpoints entail cardiovascular events such as arrhythmias, syncope, and death. This trial is registered at ClinicalTrials.gov with trial-ID: NCT06472375.