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    San Francisco Syncope Rule

    Predicts risk for serious outcomes at 7 days in patients presenting with syncope or near-syncope.
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    INSTRUCTIONS

    Use in adult patients presenting with syncope or near-syncope who are back to their neurologic baseline. Do not use in patients with persistent or new neurologic deficits, alcohol or drug-related loss of consciousness, definite seizure, or transient loss of consciousness from head trauma.

    When to Use
    Pearls/Pitfalls
    Why Use

    • Adult patients presenting to the emergency department with syncope or near syncope of unknown etiology who are back to their neurologic baseline.

    • Do not use if any of the following:

      • Persistent altered mental status or new neurologic deficits.

      • Alcohol or drug-related loss of consciousness.

      • Definite seizure.

      • Transient loss of consciousness due to head trauma.

    • The most common serious outcome in the studies was cardiac dysrhythmia. Most were bradydysrhythmia or sick sinus syndrome, the remainder were supraventricular or ventricular dysrhythmias.

    • Other common serious outcomes misclassified as low risk were stroke and intracranial hemorrhage (see Evidence for details).

    • Note that validation studies were not able to replicate the high sensitivity found in the original studies published by the creators of the rule.

    • A commonly used mnemonic to recall the five variables is “CHESS”:

      • Congestive heart failure (history of).

      • Hematocrit under 30%.

      • EKG abnormal.

      • Shortness of breath.

      • Systolic blood pressure less than 90 mmHg.

    • Syncope may be relatively benign or a manifestation of serious underlying pathology.

    • ED physician gestalt is highly sensitive but poorly specific for predicting high risk patients. The creators designed the rule to improve specificity while maintaining high levels of sensitivity.

    • The tool can be utilized to predict low risk syncope patients who would not likely benefit from aggressive work-up and hospitalization, thus reducing unnecessary testing, healthcare costs, and potential harms associated with hospitalization.

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    Result:

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    Next Steps
    Evidence
    Creator Insights

    Advice

    Emergency physician gestalt has been found to be 100% sensitive and 30% specific for identifying high-risk syncope (Sun 2007). Even at best, the SF Syncope Rule is not 100% sensitive, so if there is any concern for serious underlying disease, the patient should undergo further workup. While no serious clinical outcomes were missed, many low-risk patients were unnecessarily admitted to the hospital (the goal of the study was to decrease unnecessary admissions while retaining high sensitivity). Validation studies were not able to replicate the high sensitivity found in the original studies published by the creators of the rule.

    Management

    Critical Actions

    Clinician judgment should prevail, even if patients are deemed low risk by the San Francisco Syncope Rule. If there is significant concern for a serious underlying cause of the patient’s syncope, workup should be expanded.

    Content Contributors
    Reviewed By
    • Marc Probst, MD, MS
    About the Creator
    Dr. James V. Quinn
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    Dr. Ian Stiell
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    Content Contributors
    Reviewed By
    • Marc Probst, MD, MS