Immediate Ambulatory Electrocardiographic Monitoring in Syncope

In patients with syncope who present to the emergency department for evaluation, diagnosing an underlying cardiac arrhythmia remains difficult.

We conducted an open-label, randomized, controlled trial at 45 hospitals in the United Kingdom 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 emergency department were assigned in a 1:1 ratio to undergo 14-day ambulatory electrocardiographic (ECG) monitoring (the intervention group) or to receive the standard care provided for patients with unexplained syncope at each participating site (the standard-care group). The primary outcome was the mean number of patient-reported episodes of syncope at 1 year.

A total of 2234 patients underwent randomization: 1123 were assigned to the intervention group and 1111 to the standard-care group. The mean age of the patients was 58.3 years, and 52.1% were male. After the exclusion of patients who did not complete any follow-up, a total of 1970 patients (1004 in the intervention group and 966 in the standard-care group) were included in the primary analysis. The mean (±SD) number of patient-reported syncope episodes at 1 year was 1.37±5.10 in the intervention group and 1.58±8.56 in the standard-care group (incidence rate ratio, 0.89; 95% confidence interval, 0.68 to 1.18; P = 0.42). A total of 49 adverse events were reported in the intervention group, and 8 adverse events were reported in the standard-care group, with 1 serious adverse event in each group.

Among patients with syncope that remained unexplained after evaluation in the emergency department, the use of 14-day ambulatory ECG monitoring did not result in significantly fewer patient-reported syncope episodes at 1 year than standard care. (Funded by the British Heart Foundation and National Health Service Research Scotland; ASPIRED ISRCTN Registry number, ISRCTN10278811.).