🫀 San Francisco Syncope Rule
Identify high-risk syncope with the San Francisco Syncope Rule (CHESS).
Clinical takeaway
Any positive factor flags higher risk.
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When to use
Predict serious 7-day outcomes after syncope.
How it works
Any of CHF history, Haematocrit < 30%, abnormal ECG, Shortness of breath, SBP < 90 mmHg → high risk.
Key points
- Any positive factor flags higher risk.
- Sensitive but limited specificity.
- Use with clinical judgement and other risk tools.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| History of congestive heart failure | No |
|---|---|
| Haematocrit < 30% | No |
| Abnormal ECG (new changes / non-sinus) | No |
| Shortness of breath | No |
| Systolic BP < 90 mmHg at triage | No |
→Low riskNo CHESS factor
- CHESS：CHF, Haematocrit < 30%, ECG abnormal, Shortness of breath, SBP < 90.
- Note：Low risk of serious 7-day outcome.
| History of congestive heart failure | Yes |
|---|---|
| Haematocrit < 30% | Yes |
| Abnormal ECG (new changes / non-sinus) | Yes |
| Shortness of breath | Yes |
| Systolic BP < 90 mmHg at triage | Yes |
→High risk≥ 1 CHESS factor
- CHESS：CHF, Haematocrit < 30%, ECG abnormal, Shortness of breath, SBP < 90.
- Note：Consider admission/further evaluation.
Frequently asked questions
- What is San Francisco Syncope Rule?
- Identify high-risk syncope with the San Francisco Syncope Rule (CHESS).
- How is San Francisco Syncope Rule calculated? What is the core formula?
- Any of CHF history, Haematocrit < 30%, abnormal ECG, Shortness of breath, SBP < 90 mmHg → high risk.
- When is San Francisco Syncope Rule used?
- Predict serious 7-day outcomes after syncope.
- What are the key clinical points for San Francisco Syncope Rule?
- Any positive factor flags higher risk. Sensitive but limited specificity. Use with clinical judgement and other risk tools.
- What are the limits and cautions when using San Francisco Syncope Rule?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is San Francisco Syncope Rule calculated in practice? Can you show a worked example?
- Inputs: History of congestive heart failure No, Haematocrit < 30% No, Abnormal ECG (new changes / non-sinus) No, Shortness of breath No, Systolic BP < 90 mmHg at triage No → Result: Low risk No CHESS factor（CHESS: CHF, Haematocrit < 30%, ECG abnormal, Shortness of breath, SBP < 90., Note: Low risk of serious 7-day outcome.） Inputs: History of congestive heart failure Yes, Haematocrit < 30% Yes, Abnormal ECG (new changes / non-sinus) Yes, Shortness of breath Yes, Systolic BP < 90 mmHg at triage Yes → Result: High risk ≥ 1 CHESS factor（CHESS: CHF, Haematocrit < 30%, ECG abnormal, Shortness of breath, SBP < 90., Note: Consider admission/further evaluation.）