Immediate ambulatory electrocardiographic (ECG) monitoring initiated among patients with syncope in the emergency department (ED) falls short of preventing recurrent syncope over 1 year, according to the ASPIRED study presented at ESC Congress 2026.
However, early ECG monitoring in the ED has improved the diagnosis and treatment of arrythmias and is associated with fewer deaths.
“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 lead author Dr Matthew J Reed, The Usher Institute, Edinburgh, UK, in a statement.
A total of 2,233 patients (mean age 58.3 years, 52.1 percent male) were randomized to early ECG monitoring (intervention; n=1,123) or standard care (n=1,111). After excluding those who did not complete any follow-up, 1,970 patients (1,004 in the intervention group and 966 in the standard-care group) remained for the primary analysis. [N Engl J Med 2026;doi:10.1056/NEJMoa2605812]
No significant between-group difference was observed in the mean number of patient-reported syncope episodes at 1 year (1.37 with ECG monitoring vs 1.58 with standard care; incidence rate ratio, 0.89, 95 percent confidence interval, 0.68‒1.18; p=0.43).
However, early ECG monitoring resulted in a more than twofold detection of clinically significant cardiac arrhythmias (22 percent vs 9 percent) and in earlier diagnosis (median 22 vs 55 days). The intervention also increased the proportion of patients receiving appropriate treatments, including pacemaker implantation (6.8 percent vs 4.6 percent) and antiarrhythmic therapy (10.8 percent vs 7.3 percent).
Survival benefit
Furthermore, monitoring contributed to a 50-percent decrease in all-cause mortality (1.5 percent vs 2.9 percent) at 1 year, and patients in the intervention group reported “very high acceptability” of the monitoring device. In terms of safety, 49 adverse events (AEs) occurred in the intervention group and eight in the standard-care group, with one serious AE in each group.
“Early cardiac monitoring was associated with a difference in 1-year mortality between the groups, according to Kaplan–Meier curves that showed sustained separation over the follow-up,” wrote Reed and colleagues. “This finding may reflect higher numbers of therapeutic interventions in the monitored group, including antiarrhythmic therapy and pacemaker implantation.”
Such difference could be potentially explained by the more frequent identification of severe conduction-system disease in the intervention group, according to Reed and colleagues.
Notably, antiarrhythmic drugs did not show any benefit for survival, but the use of a permanent pacemaker improved outcomes in clinically significant conduction disease. Pacemakers are also a class I recommendation for high-grade atrioventricular block. [J Am Coll Cardiol 2013;61:e6-e75; J Am Coll Cardiol 2008;51:e1-e62; J Am Coll Cardiol 2017;69:189-210; Eur Heart J 2021;42:3427-3520]
“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,” Reed said in a statement.
Study details
ASPIRED was an open-label, randomized, controlled trial conducted at 45 hospitals in the UK to assess the effects of 14-day cardiac monitoring on diagnosis, treatment, and outcomes among patients with syncope. Adults with syncope that remained unexplained after an evaluation in the ED were randomized to undergo 14-day ECG monitoring or to receive standard care. The mean number of patient-reported episodes of syncope at 1 year was the primary outcome.
“It can be difficult to determine the cause of syncope in the ED as many rhythm disturbances occur intermittently and are no longer present by the time patients arrive in hospital. Some patients then have to wait weeks or even months for investigations,” said Reed.
“Prior to the trial, preliminary evidence suggested that cardiac monitoring, initiated during the ED visit, was beneficial for detecting arrhythmias. The ASPIRED trial therefore evaluated whether fitting patients with a 14-day ECG monitor immediately after ED assessment could improve their clinical outcomes,” he added.