Unexplained syncope after an emergency department workup is a common and unsatisfying situation, and prolonged ambulatory monitoring has become the reflex next step. ASPIRED tested it properly. At 45 UK hospitals, 2,234 adults whose syncope remained unexplained after emergency department evaluation were randomised to 14 days of ambulatory ECG monitoring or to whatever that site normally did. Mean age was 58.3 years and just over half were male. The primary outcome was the number of patient-reported syncope episodes over the following year.
There was no difference. The mean number of episodes at one year was 1.37 with monitoring and 1.58 with standard care (incidence rate ratio 0.89, 95% CI 0.68 to 1.18, p=0.42). Adverse events were reported in 49 patients in the monitoring group against 8 in the standard-care group, with one serious event in each — mostly the minor skin and device problems that come with wearing a monitor for a fortnight.
The result is worth sitting with, because the intervention is popular and intuitive. Fourteen days of monitoring undoubtedly finds some arrhythmias. What it did not do is reduce how often patients fainted over the next year. The gap between those two statements is the whole problem with diagnostic tests judged on yield: finding something is only useful if what follows changes the outcome, and for most unexplained syncope the arrhythmia either is not there or is not caught in a two-week window.
This does not abolish the test. A patient with structural heart disease, an abnormal ECG, syncope on exertion or without prodrome is a different proposition, and this trial was not designed to isolate them. For the large undifferentiated group who faint, get investigated and are sent home with no answer, a monitor is more likely to reassure the clinician than to help the patient. Spend the effort on orthostatic measurement, medication review and driving advice instead.
- Do not order 14-day monitoring routinely for undifferentiated unexplained syncope.
- Reserve prolonged monitoring for red flags: structural heart disease, abnormal ECG, exertional syncope, no prodrome, family history of sudden death.
- Do the cheap things properly — lying and standing blood pressure, full medication review, especially antihypertensives and alpha blockers.
- Give explicit driving and occupational advice; that changes more than a monitor does.
- Set the expectation with the patient that a normal monitor does not mean it will not happen again.
The statistics, in plain English
The incidence rate ratio of 0.89 with an interval of 0.68 to 1.18 spans no difference, so this is a null result. It is not, however, proof that monitoring is useless: the interval leaves room for up to a 32% reduction. Note also what the endpoint was — patient-reported faints, not arrhythmias detected. Monitoring almost certainly increased diagnoses; the trial asked whether that translated into fewer episodes, and it did not. Note too that 264 of the 2,234 randomised patients contributed no follow-up at all and were left out of the analysis.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for top clinical updates, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free