General MedicineTier 1Approach to a presentation

Undifferentiated presentations - syncope or pre-syncope

Red flags

Syncope during exertion - structural cardiac cause (aortic stenosis, HCM) until excluded
Syncope with no/minimal prodrome, esp. supine or seated
Syncope + chest pain/palpitations preceding it
Family history of sudden cardiac death, known structural heart disease, abnormal ECG
Syncope + focal neurological signs post-event (beyond brief post-ictal confusion)
Older age with syncope and injury from the fall

Reflex (vasovagal/situational) - commonest overall

Vasovagal - prodrome (nausea, diaphoresis, visual greying), triggers (prolonged standing, pain, emotion, venepuncture)
Situational - cough, micturition, defecation

Orthostatic

Volume depletion, autonomic failure (diabetic, Parkinson's, multiple system atrophy), drug-induced (antihypertensives, diuretics, alpha-blockers)

Cardiac (highest mortality risk category)

Arrhythmic: bradyarrhythmia (sick sinus, AV block), tachyarrhythmia (VT, SVT with rapid rate), long QT
Structural: aortic stenosis, HCM, pulmonary embolism, cardiac tamponade, PE

Neurological mimics (not true syncope)

Seizure (post-ictal confusion, tongue biting, longer recovery), TIA (rarely causes isolated LOC without focal signs), cataplexy

Position at onset, prodrome (present/absent, duration, character), triggers, duration of LOC, recovery speed
Associated palpitations/chest pain, injury sustained
Full medication list, cardiac history, family history of sudden death
Eyewitness account - convulsive movements (brief jerks common even in vasovagal syncope, don't over-call seizure)

Postural BP (lying/standing at 1 and 3 minutes) - orthostatic hypotension
Cardiovascular exam - murmurs (AS, HCM), irregular pulse
Carotid sinus massage if carotid sinus hypersensitivity suspected (elderly, syncope with head-turning/tight collar) - specialist setting

ECG in every case - arrhythmia, QTc, conduction abnormality, LVH/HCM pattern, Brugada pattern, delta wave
Bloods - FBE (anaemia), UEC, glucose, troponin if cardiac cause suspected
Echocardiogram if structural heart disease suspected/abnormal ECG/exertional syncope
Ambulatory ECG monitoring (Holter, event monitor, implantable loop recorder) if arrhythmia suspected but not captured
Tilt-table testing for recurrent unexplained syncope with suspected reflex/orthostatic mechanism

Risk-stratify to determine admission vs safe outpatient workup - high-risk features (abnormal ECG, structural heart disease, exertional syncope, family history of sudden death, heart failure) warrant admission and urgent cardiology review
Reflex syncope: reassurance, trigger avoidance, adequate hydration/salt intake, counter-pressure manoeuvres at prodrome onset; permanent pacing rarely for severe cardioinhibitory carotid sinus syncope
Orthostatic: review/stop causative drugs, compression stockings, fludrocortisone/midodrine if refractory
Cardiac: treat the specific cause - pacemaker for bradyarrhythmia, ICD for high-risk ventricular arrhythmia, valve intervention for severe AS
Driving restrictions apply and must be discussed - jurisdiction-specific

Brief myoclonic jerks occur in a substantial proportion of vasovagal syncope and are commonly over-interpreted as epileptic seizure
Syncope during exertion is a red flag that is easily dismissed as "just vasovagal" without an ECG/echo
A single normal ECG does not exclude a paroxysmal arrhythmia - prolonged monitoring may be needed for recurrent unexplained syncope
Elderly patients with polypharmacy and orthostatic hypotension are often mislabelled as having "unexplained falls" rather than syncope

"Position and prodrome do most of the diagnostic work; the ECG confirms or refutes a cardiac cause in everyone."
"Exertional syncope doesn't go home without an echo."

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