Sunday, 6 April 2014


Syncope is common, and difficult to investigate because by definition, the patient has recovered from the event! It is summarised here. There are five main causes to consider:

1. Neurocardiogenic or vasovagal (emotional, situational or orthostatic triggers)
2. Cardiac
3. Orthostatic
4. Neurological / psychiatric (5%). Neurological causes of syncope include basilar artery migraine, vestibular dysfunction and vertebrobasilar ischaemia. Psychiatric syncope is a recognised syndrome consisting of syncopal episodes found in anxiety, depression and conversion disorder that resolve with treatment of the psychiatric disorder.
5. Essential (no cause found -35-50%).

These will all be covered in turn, and separately. There are scoring systems used to help risk-stratify syncope (very important).  I do like EM Basic's quick approach:

Syncope + headache= subarachnoid or intracranial hemorrhage
Syncope + neuro deficit= stroke/TIA or intracranial bleed
Syncope + confusion= seizure
Syncope + chest pain= MI, PE, or aortic dissection
Syncope + back/abdominal pain in older patient= abdominal aortic aneurysm (AAA)
Syncope + positive HCG= ectopic pregnancy

OESIL (Osservatorio Epidemiologico della Sincope nel Lazio) Score
  • age over 65 years;
  • previous history of cardiovascular disease;
  • syncope without prodrome and
  • abnormal ECG
The score predicts 12 month mortality which rises from under 1% for patients with no risk factors to over 50% in patients with all 4 risk factors. I've never seen this used in clinical practice, or heard of it.

The San Francisco Rule
The San Francisco rule identifies high risk patients based on the presence of the following factors:
  • History of congestive cardiac failure
  • Haematocrit < 30%
  • Abnormal ECG
  • Complaint of shortness of breath
  • Systolic Blood Pressure < 90 mm Hg
The presence of any factor is considered sufficient for the patient to be high risk.The rule is 98% sensitive and 56% specific to predict adverse events.

The EGSYS (derived from patients enrolled in the Evaluation of Guidelines in SYncope Study 2 trial) Score

Predictor Score
Palpitations preceding syncope 4
Syncope during effort 3
Heart disease/ abnormal ECG 3
Syncope while supine 2
Precipitating/ predisposing factors -1
Autonomic prodromes -1
This specifically identified cardiac syncope with a score of 3 or more being 99% sensitive and 65% specific for identifying cardiac syncope (positive and negative predictive values 33% and 99%). Again, I've never seen this used in clinical practice.

A completely normal ECG makes a cardiac cause of syncope other than transient arrhythmia unlikely.

Echocardiography should be performed in any patient with a cardiac murmur and to diagnose and quantify suspected heart failure. If aortic stenosis is suspected, echocardiography should be performed urgently.
Carotid sinus massage for 5 to 10 seconds with continuous ECG and blood pressure monitoring can be used to diagnose carotid sinus syndrome. It is considered positive if it produces a drop in systolic blood pressure of 50 mm Hg or a period of asystole of 3 seconds.
Ambulatory 24 hour ECG recording may be considered in patients with a high pre-test probability of arrhythmia.
Tilt table testing is not used much any more

Think about all causes - 18% of patients with syncope in one study had more than one cause.

Driving - consider whether the patient should refrain from driving

Other guidelines can be found here.

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