The San Francisco Syncope Rule


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Clinical Use

Predict 7-day adverse outcomes in patients presenting with syncope

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The San Francisco Syncope Rule is a rule for predicting the risk of adverse outcomes in patients presenting with syncope.1
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
If any of these criteria are present, patient cannot be considered “low risk” of 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.
The San Francisco Syncope Rule was retrospectively found to have 98% sensitivity and specificity of 56% for serious causes of syncope.2 However, external prospective validation of the criteria found sensitivity to be 74%, substantially lower than the initial study.3

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1. Quinn JV, Stiell IG, McDermott DA, Sellers KL, Kohn MA, Wells GA. Derivation of the San Francisco Syncope Rule to Predict Patients With Short-Term Serious Outcomes. Annals of Emergency Medicine. 2004;43(2):224-232. Full text
2. Quinn J; McDermott D; Stiell I; Kohn M; Wells G (May 2006). Prospective validation of the San Francisco Syncope Rule to predict patients with serious outcomes. Ann Emerg Med. 47 (5): 448–54. Full text
3. Birnbaum A; Esses D; Bijur P; Wollowitz A; Gallagher EJ (February 2008). Failure to Validate the San Francisco Syncope Rule in an Independent Emergency Department Population. Ann Emerg Med. 52 (2): 151–9. Full text


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