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Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.

Ambulatory ECG and implantable loop monitoring

Cardiology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

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Admit or urgently assess syncope with an abnormal ECG, structural heart disease, exertional or supine occurrence, injury, heart failure, family history of young sudden death, or ongoing unstable arrhythmia; ambulatory monitoring must not replace acute telemetry.

Synopsis

Match ECG-monitor duration and technology to symptom frequency so clinically important intermittent arrhythmias are captured and correlated with events.

  • Choose the monitor from event frequency: short continuous recording for daily events, longer external recording for less frequent events and an implantable recorder for infrequent unexplained syncope.
  • NICE recommends 24-hour ambulatory ECG when suspected paroxysmal AF episodes are less than 24 hours apart or asymptomatic episodes are suspected.
  • For suspected paroxysmal AF with episodes more than 24 hours apart, use longer ambulatory ECG, event recording or another appropriate ECG technology.
  • In suspected arrhythmic syncope, ambulatory ECG is first-line; do not put tilt testing ahead of rhythm monitoring.
  • A symptom diary with exact clock time, activity and symptoms materially improves interpretation.
  • Patient-triggered devices miss asymptomatic events and events causing immediate loss of consciousness; auto-trigger capability matters.
  • A negative short recording is non-diagnostic when the target event did not occur.

Key red flags

High-risk bradyarrhythmia

Symptomatic pauses, high-grade AV block or profound bradycardia require prompt specialist assessment and may lead to pacing.

Sustained ventricular tachycardia

A broad-complex sustained tachycardia, especially with syncope or structural heart disease, needs emergency assessment rather than routine report follow-up.

Investigation priorities

01
24–48-hour continuous ECGFirst step

Capture daily palpitations, frequent presyncope or suspected frequent/asymptomatic AF.

Management branches

Preferred routeIntermittent palpitations

No diagnostic rhythm on a resting ECG

  1. Clarify frequency, duration, regularity, triggers and associated syncope or chest pain; obtain baseline ECG and relevant blood tests.
  2. Select continuous 24-hour monitoring for daily or very frequent episodes and longer patch or event recording for less frequent episodes.
  3. Require raw ECG confirmation of algorithm-detected AF or tachycardia.
  4. Escalate sustained arrhythmia, pre-excitation, high-grade conduction disease or symptoms with haemodynamic compromise.
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Apply principles in context and verify current guidance when a decision affects care. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE CG109: Transient loss of consciousness in over 16s
  • NICE NG196: Atrial fibrillation diagnosis and management
  • ESC 2018 Guidelines for syncope
  • ESC 2022 Guidelines for ventricular arrhythmias and sudden cardiac death

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateRapid draftClinical stateAwaiting reviewJurisdictionUnited Kingdom