Syncope (fainting) is a common, challenging presentation in the emergency department. While most cases are benign (e.g., vasovagal syncope), a subset of patients have life-threatening underlying causes such as arrhythmias, pulmonary embolism, or internal bleeding. The San Francisco Syncope Rule (SFSR) was developed to help identify these high-risk patients.
The CHESS Criteria
The rule uses the mnemonic CHESS to evaluate the risk of serious outcomes (like death, myocardial infarction, arrhythmia, pulmonary embolism, or significant hemorrhage) within 7 days:
- Congestive Heart Failure (history of)
- Hematocrit < 30%
- ECG abnormality (any non-sinus rhythm or new changes)
- Shortness of breath (as a symptom associated with the syncope)
- Systolic Blood Pressure < 90 mmHg at ED triage
CHESS Criteria: High risk if any one of: CHF history, Hematocrit <30%, ECG abnormal, Shortness of breath, Systolic BP <90.
Interpretation
If a patient has any one of the CHESS criteria, they are considered high risk and typically warrant admission or prolonged observation with cardiac monitoring. If they have none, they are lower risk and may be candidates for outpatient follow-up. Note: Subsequent external validation studies of the SFSR have yielded varying sensitivities, leading many clinicians to use it alongside other risk stratification tools (like the OESIL score or clinical gestalt).