Transient loss of consciousness in an adult
Suspected syncope or presyncope. Assess presyncope the same way: it carries the same prognosis.
All Pathways
CardiologyDiagnostic
Syncope Evaluation (ESC 2018)
Syncope Evaluation (ESC 2018): Transient loss of consciousness in an adult → Initial evaluation: history, exam, lying and standing BP, 12-lead ECG → Red...
Pathway Overview
18 steps
Algorithm Steps
18 total
01Start 02Action Initial evaluation: history, exam, lying and standing BP, 12-lead ECG
Do this for every patient.
- History from patient and witness: trigger, posture, prodrome, exertion, palpitations, drugs
- Examination, including heart murmur and injury from the fall
- Lying and standing BP. OH: SBP fall of 20 mmHg or more, DBP fall of 10 mmHg or more, or SBP <90 mmHg
- 12-lead ECG. Pacemaker or ICD: interrogate the device promptly
- Capillary blood glucose. Other blood tests only if indicated: Hb (bleeding), troponin (ischaemia), D-dimer (PE), SpO2 or blood gas (hypoxia)
03Warning Red flags: exclude an acute life-threatening cause
Syncope can be the first sign of PE, aortic dissection, ruptured AAA or ectopic pregnancy, haemorrhage, SAH or ACS.
- New chest pain, breathlessness, abdominal pain or headache
- Unexplained SBP <90 mmHg, signs of bleeding, or ECG signs of acute ischaemia
- Pregnancy possible: do a pregnancy test (ruptured ectopic pregnancy)
04Decision Acute serious illness causing the syncope?
Suspected or confirmed PE, aortic dissection, ruptured AAA or ectopic pregnancy, haemorrhage, SAH or ACS.
- If Yes
05Outcome Acute serious illness: resuscitate and follow that condition's pathway
Syncope is a symptom of the principal disease. Treat that disease first.
If No06Decision No acute illness: is the loss of consciousness syncope?
Exclude epileptic seizure, psychogenic TLOC, falls without TLOC, hypoglycaemia or other metabolic cause, intoxication and TIA.
- If Yes
07Decision Syncope: is the cause certain or highly likely?
Reflex: pain, fear or standing with typical prodrome. Situational: cough, micturition, defaecation, meal. OH: syncope on standing with OH. Cardiac: diagnostic ECG, acute ischaemia, severe aortic stenosis.
- If Yes
08Outcome Cause certain or highly likely: treat the cause
Cardiac cause: admit with ECG monitoring where resuscitation is available; urgent cardiology review. Reflex or situational: explain and avoid triggers. OH: review BP-lowering drugs. Give driving advice (AU: Austroads).
If No09Action Cause uncertain: check ESC high-risk features
Any major feature is high risk. Do not use risk scores alone.
- Event: new chest pain, breathlessness, abdominal pain or headache; syncope on exertion or when supine; sudden palpitations then syncope
- History: severe structural or coronary heart disease (heart failure, low LVEF, previous MI)
- Exam: unexplained SBP <90 mmHg; suspected GI bleed; persistent HR <40/min awake and not athletic; undiagnosed systolic murmur
- ECG: acute ischaemia; Mobitz II or 3rd-degree AV block; slow AF <40/min; persistent sinus bradycardia <40/min, repeated sinoatrial block or pauses >3 s (awake, not athletic); BBB, IVCD, LVH or Q waves; sustained or non-sustained VT; pacemaker or ICD dysfunction; type 1 Brugada; QTc >460 ms on repeated ECGs
- High risk only with structural heart disease or abnormal ECG: no or short (<10 s) prodrome; family history of sudden death at young age; syncope when sitting
- High risk only if history suggests arrhythmia: Mobitz I or 1st-degree AV block with long PR; mild sinus bradycardia or slow AF 40-50/min; SVT or paroxysmal AF; pre-excitation; QTc 340 ms or less; atypical Brugada; negative T waves in right precordial leads or epsilon waves
10Decision Any high-risk feature present?
Yes if any major feature, or a conditional feature whose condition is met (see list above).
- If Yes
11Action High risk: early intensive evaluation with ECG monitoring
ED observation unit, syncope unit or admission. Monitor where resuscitation is available: up to 6 h in ED, up to 24 h in hospital.
- Admit if severe coexisting disease, injury, or urgent tests or treatment not possible otherwise
- Echocardiography if structural heart disease is suspected
- Pacemaker or ICD: interrogate the device promptly
- Still unexplained: EP study (previous MI or scar) or implantable loop recorder, per cardiology
- Driving (AU, Austroads): no driving until assessed. Syncope other than clear-trigger vasovagal: at least 4 weeks (private), 3 months (commercial). Blackout not confirmed as syncope: 6 months (private), 5 years (commercial)
12Outcome Observed or admitted: treat the cause found
Cardiology review. If cause still unknown and no ICD or pacemaker indication: implantable loop recorder.
If No13Decision No high-risk feature: only low-risk features?
Typical reflex prodrome or trigger, syncope on standing up, years of similar episodes, no structural heart disease, normal exam and normal ECG.
- If Yes
14Action Low risk: discharge from ED (adults)
Likely reflex, situational or OH syncope. No further ED tests. Admit only for injury, other illness or welfare reasons. Head strike on an anticoagulant or antiplatelet (not aspirin alone): consider CT head before discharge.
- Explain the diagnosis and the good prognosis
- Avoid triggers; teach physical counterpressure manoeuvres
- Review BP-lowering drugs
- Recurrent episodes: refer to a syncope clinic
- Driving (AU, Austroads): vasovagal with a clear trigger unlikely while driving: can drive after 24 h. Other cardiovascular cause (for example OH): at least 4 weeks (private), 3 months (commercial)
15Outcome Discharged: GP or syncope clinic follow-up if recurrent
Return if syncope on exertion, chest pain, palpitations or injury.
If No16Action Neither high nor low risk: observe in ED or syncope unit
Do not routinely admit. Arrange expert syncope assessment, usually as an outpatient.
- ED observation unit or fast-track to a syncope unit
- Echocardiography if structural heart disease is suspected
- ECG monitoring by symptom frequency: Holter if 1 or more episodes a week; external loop recorder if 4 weeks or less between episodes
- Carotid sinus massage if over 40 years and reflex mechanism possible; caution after TIA, stroke or carotid stenosis >70%
- Driving (AU, Austroads): syncope other than clear-trigger vasovagal: at least 4 weeks (private), 3 months (commercial). Blackout not confirmed as syncope: 6 months (private), 5 years (commercial)
17Outcome Syncope unit follow-up; loop recorder if recurrent and unexplained
Implantable loop recorder early if recurrent syncope of uncertain cause, no high-risk features, and recurrence likely within battery life.
If No18Outcome Not syncope: assess for seizure, psychogenic TLOC or other cause
Use the pathway for that condition.
Guideline Source
2018 ESC Guidelines for the Diagnosis and Management of Syncope
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Risk stratification relies on clinical judgement; ESC 2018 advises against using risk scores alone.
- Adults only. Treatment of specific causes (pacing, ICD, ablation, drugs) is not covered.
- ESC 2018 is the current ESC syncope guideline; an ESC update on syncope and autonomic disorders is planned for 2027.
Contraindicated Populations
pediatric
Applicable Regions
EUUSAU
AU: Driving (Austroads Assessing Fitness to Drive 2022): vasovagal syncope with a clear trigger unlikely while driving: may drive again within 24 h. Other cardiovascular cause: no driving for at least 4 weeks (private) or 3 months (commercial), then reassess. Single blackout of undetermined nature: no driving for 6 months (private) or 5 years (commercial).
EU: ESC 2018: syncope risk scores perform no better than clinical judgement; do not use them alone.
US: The 2017 ACC/AHA/HRS syncope guideline uses a similar risk-based approach; decision rules such as the San Francisco Syncope Rule should not be used alone.
Version 2Next review: 2027-09-30
Next steps
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Related Resources
Frequently Asked Questions
What is the Syncope Evaluation (ESC 2018)?
The Syncope Evaluation (ESC 2018) is a diagnostic clinical algorithm for Cardiology. It provides a structured decision tree to guide clinical decision-making, based on 2018 ESC Guidelines for the Diagnosis and Management of Syncope.
What guideline is the Syncope Evaluation (ESC 2018) based on?
This algorithm is based on 2018 ESC Guidelines for the Diagnosis and Management of Syncope (DOI: 10.1093/eurheartj/ehy037).
What are the limitations of the Syncope Evaluation (ESC 2018)?
Known limitations include: Risk stratification relies on clinical judgement; ESC 2018 advises against using risk scores alone.; Adults only. Treatment of specific causes (pacing, ICD, ablation, drugs) is not covered.; ESC 2018 is the current ESC syncope guideline; an ESC update on syncope and autonomic disorders is planned for 2027.. Individual patient factors may require deviation from these recommendations.
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