Executive summary (CG109 in 90 seconds)
- Assume “cardiac until proven otherwise” when the history is unclear, the event was exertional, or there’s no prodrome.
- Do a 12-lead ECG in everyone after TLoC; ECG “red flags” should trigger urgent specialist assessment.
- Common benign causes in primary care: vasovagal syncope and orthostatic hypotension — but only once high-risk features are excluded.
- Safety-net: recurrent episodes, injury, or evolving symptoms should be escalated.
High-risk features that should change your urgency
- Exertional syncope or syncope while supine.
- Family history of sudden cardiac death (especially <50y) or inherited arrhythmia syndromes.
- Structural heart disease (known HF, cardiomyopathy, valve disease) or new cardiac symptoms (chest pain, breathlessness, palpitations).
- No prodrome, sudden collapse, or features suggesting arrhythmia (rapid palpitations immediately before TLoC).
- Persisting neurological deficit post-event (think stroke/TIA/seizure pathway instead of CG109 syncope pathway).
ECG: “don’t sit on this” abnormalities (refer)
- Brady/heart block: Mobitz II, complete heart block, or significant pauses.
- Ventricular pre-excitation (WPW pattern) or broad complex tachyarrhythmia concerns.
- Long QT or other channelopathy patterns (e.g., Brugada-type patterns).
- Ischaemia/infarct patterns (new Q waves/acute ischaemic changes) in the right clinical context.
- Any ECG you cannot confidently “normalise” in a TLoC story: treat as a referral trigger.
Primary-care work-up (when it looks vasovagal/orthostatic)
- Orthostatic BP: lying and standing BP (at 1 and 3 minutes). Consider meds (antihypertensives, diuretics, vasodilators), dehydration, anaemia.
- Vasovagal clues: prodrome (nausea, warmth, sweating), triggers (standing, pain, emotion), quick recovery once supine.
- Management: hydration + salt (if appropriate), counter-pressure manoeuvres, review meds, gradual position changes; address contributing factors (infection, volume depletion).
Frequently asked questions
Do I need an ECG in all syncope/blackout presentations?
Yes—CG109 recommends a 12-lead ECG after transient loss of consciousness because ECG findings can identify patients at risk of serious arrhythmia/structural disease.
When should I consider seizure instead?
Prolonged post-event confusion, lateral tongue biting, witnessed tonic-clonic activity, or a clear focal neurological deficit should prompt a seizure/neurology pathway rather than “simple syncope” management.
Transparency
This page is an educational, clinician-written summary of publicly available NICE guidance intended for trained healthcare professionals. It uses original wording (not copied text) and should be used alongside the full NICE source, local pathways, and clinical judgement. Doses provided are for general reference; always check the BNF/SPC.