Unexplained syncope is one of the least satisfying emergency department dispositions. The patient is well, the arrhythmia is presumed but unproven, and prolonged monitoring is the obvious next step. ASPIRED tested whether it helps.
This open-label randomised trial at 45 UK hospitals enrolled 2,234 adults whose syncope remained unexplained after emergency department evaluation and assigned them to 14-day ambulatory ECG monitoring or to whatever standard care each site provided. Mean age was 58.3 and 52.1% were male. After excluding those with no follow-up, 1,970 patients entered the primary analysis.
The mean number of patient-reported syncope episodes at one year was 1.37 in the monitoring group and 1.58 with standard care, incidence rate ratio 0.89 (95% CI 0.68 to 1.18, p=0.42). Adverse events numbered 49 in the monitoring arm against 8 in standard care, with one serious event in each.
The choice of primary outcome is what makes this trial useful and also what limits it. Recurrent syncope is what the patient cares about, and monitoring did not reduce it. But monitoring is a diagnostic intervention, and a diagnostic test only changes outcomes if a treatable diagnosis follows and is treated. This trial tells you the whole pathway did not deliver, not that the monitor failed to detect anything.
For practice, the honest position is that routine 14-day monitoring for undifferentiated unexplained syncope is not supported, while targeted monitoring for a patient with a specific arrhythmic suspicion — structural heart disease, exertional syncope, abnormal ECG, family history of sudden death — is a different question this trial did not ask.
- Do not order 14-day ambulatory monitoring routinely for syncope that is unexplained after emergency department assessment
- Do risk-stratify first: exertional syncope, structural heart disease, abnormal ECG or a family history of sudden death still warrant investigation
- Note the adverse event imbalance — 49 versus 8 — mostly reflecting skin reactions and the burden of wearing a device
- Spend the consultation on the vasovagal explanation and safety advice, which is what most of these patients need
- Arrange follow-up for recurrence rather than for the monitor result
The statistics, in plain English
An incidence rate ratio of 0.89 with an interval of 0.68 to 1.18 crosses 1.0, so no benefit can be claimed, though a 32% reduction remains within the interval. Look at the standard deviations reported alongside the means — 5.10 and 8.56 against means of 1.37 and 1.58 — which tell you the distribution is extremely skewed. Most patients had no further syncope and a few had a great many, so the mean is a poor summary and the comparison is dominated by a small number of high-frequency patients. That skew, not the sample size, is the main reason the interval is wide.
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