San Francisco Syncope Rule

History of Congestive Heart Failure

Hematocrit <30%

Abnormal EKG (new changes or non-sinus rhythm)

Shortness of Breath

Systolic BP <90 at Triage

Criteria Positive: 0

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

Why Use

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.

When to 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.

Formula

Series of Yes/No Questions; if any answered “Yes” patient cannot be considered “Low Risk.”

Pearls / Pitfalls

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.

Management

From Quinn et al, 2005 .

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.

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.

More Information

This rule has a 96% sensitivity and 62% specificity for serious outcome - negative predictive value: 99.2%; positive predictive value 24.8%. However, an external validation at the Albert Einstein College of Medicine showed a lower sensitivity of 74%. Serious outcome in this study is defined as "death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage, or any condition causing a return ED visit and hospitalization for a related event."