Ambulatory ECG Monitor Improves Arrhythmia Detection in Syncope

Syncope, also called fainting or blackout, sends large numbers of patients to emergency departments (EDs) and accounts for around 650,000 ED visits in the UK each year. Determining an arrhythmic cause at presentation is difficult because rhythm disturbances are often intermittent, delaying diagnosis and treatment. Delays matter clinically because high-risk patients may deteriorate while awaiting outpatient investigations. A new randomized trial shows that immediate ambulatory electrocardiographic (ECG) monitoring started in the ED can address this gap in care.

Investigators from The Usher Institute at the University of Edinburgh evaluated a 14‑day ambulatory ECG monitor initiated immediately after ED assessment in the ASPIRED trial, which was presented in a Hot Line session at ESC Congress 2026 and published simultaneously in the New England Journal of Medicine. The device was small, waterproof, leadless, and noninvasive, and it recorded cardiac rhythm continuously. Participants were instructed to press a button on the device if another syncopal event occurred.

Across 45 hospitals in the UK, adults with syncope that remained unexplained after ED evaluation were randomized 1:1 to immediate 14-day monitoring or standard management. In both groups, patients recorded syncopal episodes in a paper diary. The analysis included 2,233 patients with a mean age of 58.3 years, 48% of whom were female, making this the largest randomized trial to evaluate immediate ambulatory monitoring for unexplained syncope.

The primary endpoint showed no significant difference in the mean number of self-reported syncope episodes at one year between monitoring and standard care, with 1.37 versus 1.58 events, respectively (incidence rate ratio 0.89; 95% confidence interval 0.68 to 1.18; p=0.43). However, early monitoring more than doubled detection of clinically significant cardiac arrhythmias, at 22% versus 9%, and shortened time to diagnosis, with a median of 22 days compared with 55 days.

Early monitoring also increased use of targeted therapies. Pacemaker implantation occurred in 6.8% of monitored patients compared with 4.6% receiving standard care, while antiarrhythmic therapy was used in 10.8% versus 7.3%. All-cause mortality at one year was 1.5% with monitoring and 2.9% with standard care, corresponding to a 50% relative reduction.

Patient-reported acceptability of the wearable was very high. Overall, the findings support consideration of early ambulatory monitoring as part of routine ED care for unexplained syncope, while further research is warranted to explore the observed survival benefit.

"Although immediate ECG monitoring did not reduce recurrent fainting, it enabled earlier identification of serious cardiac rhythm disorders, allowing patients to receive treatment much sooner, reducing uncertainty and anxiety and potentially preventing avoidable deaths,"  said principal investigator Matthew Reed of The Usher Institute, Edinburgh, UK. "These findings suggest that early monitoring should be considered as part of routine ED care for patients with unexplained syncope, while further research explores the observed survival benefit."

Related Links
The Usher Institute
European Society of Cardiology (ESC)