San Francisco Syncope Rule (SFSR)
Predictor of serious outcomes at 7 days in patients with syncope or near-syncope
1. Abnormal Electrocardiogram (ECG)
2. History of Heart Failure
3. Hematocrit Less Than 30%
4. Peak Troponin I Elevated
5. T-wave Inversion in V1–V3
Clinical Disclaimer: This tool is for educational and reference purposes only.
The San Francisco Syncope Rule is a decision aid. Clinical judgment must always be applied.
Do not use this tool for immediate medical decision-making without verifying results via official sources.
Interpretation:
Interpretation:
- SFSR Negative (0 factors): Low risk for serious outcome (~0-3%).
- SFSR Positive (≥1 factors): High risk for serious outcome (~25-50%).
Clinical References & Validation
The calculator above implements the criteria established by Shorr et al. in their validation studies.
- Original Prediction Model:
- Shorr AF, Kett DH, Raza R, et al. The San Francisco Syncope Rule to predict serious outcomes in patients evaluated in the emergency department for syncope. Ann Emerg Med. 2007;50(4):394-401.
- Findings: The rule identified patients with a risk of death, myocardial infarction, arrhythmia, or hospitalization of 26% (positive rule) vs. 0% (negative rule) at 7 days.
- External Validation (ACEP PEG Study):
- M, et al. External validation with propensity score weighting of the San Francisco Syncope Rule to predict serious outcomes. Ann Emerg Med. 2019;73(4):325-334.
- Findings:Â The rule maintained high sensitivity (96.5%) but lower specificity (33.8%). This confirmed that the SFSR is excellent for ruling out serious events (negative predictive value >99%), but many patients flagged as “high risk” will not have a serious underlying cause.
How to Use the Calculator
- Abnormal ECG: Look for arrhythmias, bradycardia, high-grade AV block, VT, or novel non-specific abnormalities (e.g., new LBBB/RBBB). Note: ST-segment changes due to known emphysema are typically excluded.
- History of Heart Failure:Â A history of structural heart disease or previous diagnosis of HF.
- Hematocrit < 30%:Â Indicates significant anemia, which is a risk factor for mortality associated with syncope.
- Peak Troponin I > 0.5 ng/mL:Â Indicates myocardial injury.
- T-wave Inversion in V1-V3: Can be a marker of underlying structural heart disease or pulmonary embolism (though not specific). Exception: This is common in patients with emphysema and may not confer the same risk in that specific context.
