The San Francisco Syncope Rule

– share this tool –

Clinical Use

Predict 7-day adverse outcomes in patients presenting with syncope

More Info

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


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


We are doing our best to prepare the content of this website. However, Cardiology Connections, Corp cannot warranty the expressions and suggestions of the contents, as well as its accuracy. In addition, to the extent permitted by the law, Cardiology Connections, Corp shall not be responsible for any losses and/or damages due to the usage of the information on our website. Furthermore, the links contained on our website may lead to external sites, which are provided for convenience only. Any information or statements that appeared in these sites are not sponsored, endorsed, or otherwise approved by Cardiology Connections, Corp. For these external sites, Cardiology Connections, Corp cannot be held liable for the availability of, or the content located on or through it. Plus, any losses or damages occurred from using these contents or the internet generally.

Developer: Sirikarn Napan, MD, FACC