San Francisco Syncope Rule

The San Francisco Syncope Rule (SFSR) is a simple rule for evaluating the risk of adverse outcomes in patient who present with fainting or syncope.

The mnemonic for features of the rule is CHESS:

•	C - History of congestive heart failure

•	H - Hematocrit < 30%

•	E - Abnormal ECG

•	S - Shortness of breath

•	S - Triage systolic blood pressure < 90

A patient with any of the above measures is considered at high risk for a serious outcome (death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage, or any condition causing a return Emergency Department visit and hospitalization for a related event.

SFSR has a sensitivity of 74-98% and specificity of 56%. This means that 74-98% of patients who had a serious outcome had a positive test. Syncope accounts for 1-2% emergency department visits. Half are hospitalized and of these, 50% have unclear diagnosis and 85% will be simply monitored. Given these statistics, the SFSR will help reduce inefficient admissions.