UK trial finds hidden heart risks after unexplained fainting

demoduck.co.uk editorial team 2026-08-31 19:03 4 min read

An older woman wearing a small medical heart monitor attached to her upper chest.

A wearable heart monitor used for 14 days after unexplained fainting detected heart rhythm problems in 22 per cent of patients within a year, compared with nine per cent among those receiving standard care. The University of Edinburgh-led study involved 2,234 people treated at UK A&E departments.

The findings suggest that starting longer monitoring soon after a collapse can reveal intermittent arrhythmias that routine hospital tests or shorter monitoring periods may miss. Researchers also reported a lower one-year death rate in the monitored group, although that comparison does not establish by itself exactly how monitoring affected every outcome.

By the demoduck.co.uk Health Desk | Published 31 August 2026

Detection more than doubled with 14-day monitoring

Half of the study participants received a small chest-worn monitor that recorded their heart rhythm continuously for two weeks. The remaining participants received standard care, which can include referral to a cardiology clinic and use of a Holter monitor, usually worn for 48 hours.

The longer-monitoring group could begin recording within 72 hours of arriving at A&E. After one year, arrhythmias had been identified in 22 per cent of this group, against nine per cent under standard care.

Measure	Study finding
Arrhythmia detected within one year	22% with the 14-day monitor; 9% with standard care
Average time to detection	22 days with the monitor; 54.5 days with standard care
Anti-arrhythmic medication started	10.8% with the monitor; 7.3% with standard care
Pacemaker implanted	6.8% with the monitor; 4.6% with standard care
Death within one year	1.5% with the monitor; 2.9% with standard care

Researchers identified serious conditions including complete heart block and pauses in the heartbeat lasting more than six seconds. When a monitor recorded a serious arrhythmia, the patient’s clinician was alerted within 24 working hours.

A normal A&E test may miss an intermittent arrhythmia

Fainting can have a harmless cause, but it can also result from an abnormal heart rhythm. The diagnostic difficulty is timing: patients have often recovered before reaching A&E, and their heart rhythm may have returned to normal by the time an electrocardiogram or other assessment is performed.

A 48-hour Holter monitor offers another opportunity to capture an irregular rhythm, but only during that limited period. The source also reports that outpatient monitoring may not begin until between six weeks and two years after the original A&E attendance. A continuous two-week recording started soon after the event creates a wider and earlier observation window.

UK trial finds hidden heart risks after unexplained fainting

Around 650,000 people attend A&E with unexplained fainting each year in the UK, according to the University of Edinburgh report. The trial focused specifically on people whose collapse remained unexplained after their emergency assessment, rather than every patient who faints.

How the UK study followed 2,234 patients

The research team divided the study volunteers between the new monitoring strategy and current standard monitoring. Data from the wearable heart monitors were sent to clinicians after the two-week recording period so they could assess whether an arrhythmia was present and whether treatment was required.

Participants were then followed for one year. The study compared the number and timing of arrhythmia diagnoses, subsequent treatment and deaths in the two groups. It was funded by the British Heart Foundation, published in the New England Journal of Medicine and presented at the European Society of Cardiology Congress in Munich.

Earlier findings led to faster treatment

The monitored group received an arrhythmia diagnosis after an average of 22 days, compared with 54.5 days under standard care. More participants in that group subsequently received anti-arrhythmic medication or had a pacemaker implanted.

The one-year death rate was 1.5 per cent with 14-day monitoring and 2.9 per cent with standard care. Study lead Professor Matthew Reed said the reduction provided strong evidence that the strategy could save lives and called for hospitals across the country to adopt it.

The reported mortality difference is clinically significant, but the supplied study summary does not provide detailed subgroup results or establish which diagnoses and treatments accounted for the full difference. Professor Bryan Williams, chief scientific and medical officer at the British Heart Foundation, said the findings should help inform future clinical practice for patients with sudden, unexplained collapse.

Source: University of Edinburgh News

Context & actions About this article

Source check Source trail

The figures and clinical context were checked against the University of Edinburgh’s report of the UK trial.

Checks

Confirmed that the study included 2,234 patients attending UK A&E departments with unexpla...
Compared the reported one-year arrhythmia detection rates of 22 per cent and nine per cent...
Retained the reported treatment, diagnosis-time and mortality figures without extending th...
Distinguished the study findings from claims of proven cause and effect.

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