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 such as 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 in patients with none of the above criteria, 74-98% had no serious outcome and may be considered as suitable candidates for outpatient monitoring. 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.