Validation of the San Francisco Syncope Rule

Summary and Comment |
July 21, 2006

Validation of the San Francisco Syncope Rule

  1. Richard D. Zane, MD, FAAEM

The rule looks promising for identifying patients at risk for serious outcomes.

  1. Richard D. Zane, MD, FAAEM

The causes of syncope range from potentially fatal to inconsequential. As a result, many patients are hospitalized for observation and work-up who might safely have been discharged home with follow-up. Admitted patients rarely have any work-up beyond 24 hours of cardiac monitoring and simple blood testing. These authors previously derived a syncope risk-stratification tool, dubbed the San Francisco Syncope Rule, and in this study they sought to prospectively validate it.

The rule categorizes patients as at high risk for serious outcomes if they have a history of congestive heart failure, hematocrit <30%, electrocardiogram abnormality, shortness of breath, or systolic blood pressure <90 mm Hg (the criteria can be remembered by the mnemonic, CHESS). Serious outcomes were defined broadly as death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or anemia requiring transfusion, a procedural intervention to treat a related cause of syncope or any condition causing or likely to cause a return emergency department visit, and hospitalization for a related event.

The authors applied the rule to 791 ED patients who presented with syncope, defined as any transient loss of consciousness not due to trauma, intoxication, or seizure. Patients were followed up at 30 days. Overall, 411 patients (52%) were categorized as high risk. At follow-up, 53 patients (6.7%) had serious outcomes that were not clinically apparent at ED presentation. The rule was 98% sensitive and 56% specific for predicting these events.


Syncope often presents a conundrum, as patients often look remarkably well after the syncopal episode, yet discharging a patient who has a significant cause of syncope may have dire consequences. The San Francisco Syncope Rule might make discharge decisions easier, but before we can adopt it, larger, multicenter studies are needed.


Reader Comments (2)

Mark T Abell

Was looking to define " triage systolic blood pressure". Does it refer to:

1) Patients' historical blood pressure.

2) Patients' blood pressure at the start of the test.

3) Patients' blood pressure at the time of syncope.

Competing interests: None declared

Mark T Abell

I have learned that the "triage systolic blood pressure" refers only to those patients that were "triaged" to the emergency room.

It has no bearing in a tilt test that was scheduled.

Competing interests: None declared

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