Role of Syncope Scores in Patient Evaluation
Syncope risk stratification scores may be reasonable in the management of patients with syncope, but they have important limitations and have not performed better than unstructured clinical judgment. 1
Clinical Value and Limitations of Syncope Scores
Evidence-Based Assessment
The 2017 ACC/AHA/HRS Syncope Guidelines provide a Class IIb recommendation (Level of Evidence: B-NR) for the use of risk stratification scores in syncope management 1. This moderate recommendation reflects both the potential utility and significant limitations of these tools.
San Francisco Syncope Rule (SFSR)
The SFSR was developed to identify patients at risk for short-term serious outcomes and includes five predictors:
- Abnormal ECG
- Shortness of breath
- Hematocrit <30%
- Systolic blood pressure <90 mmHg
- History of congestive heart failure
While the original derivation study reported 96% sensitivity 2, subsequent validation studies have shown variable performance:
- A 2006 validation found 98% sensitivity and 56% specificity 3
- A 2008 independent validation found significantly lower sensitivity (74%) 4
- A Canadian validation study showed 90% sensitivity but only 33% specificity 5
Important Limitations
Risk stratification tools for syncope have several documented limitations:
- Inconsistent definitions of syncope across studies
- Variable outcome definitions and timeframes
- Inclusion of patients with serious outcomes already identified in the ED
- Use of composite outcomes that combine events with different pathophysiologies
- Small sample sizes limiting model reliability
- Limited external validation 1
Practical Application in Clinical Decision-Making
When to Consider Using Syncope Scores
- When the cause of syncope is not evident after initial evaluation
- To supplement (not replace) clinical judgment in risk stratification
- To help identify patients who may need admission vs. outpatient management
Risk Factors to Consider Beyond Formal Scores
Short-term risk factors include:
- Abnormal ECG
- History of heart failure
- Dyspnea
- Hypotension
- Advanced age
Long-term risk factors include:
- Male sex
- Older age
- Absence of nausea/vomiting preceding syncope
- Ventricular arrhythmias
- Cancer
- Structural heart disease
- Heart failure
- Cerebrovascular disease
- Diabetes mellitus
- High CHADS-2 score
- Abnormal ECG
- Lower GFR 1
Pitfalls to Avoid
Common Errors in Using Syncope Scores
- Relying solely on risk scores without clinical judgment
- Applying scores to patients with obvious serious causes of syncope
- Failing to consider that outcomes vary widely based on underlying conditions
- Not recognizing that short-term prognosis relates to the cause of syncope, while long-term prognosis relates to underlying disease severity 1
Specific Concerns with the SFSR
- A systematic review found substantial between-study heterogeneity in SFSR performance 6
- The most common cause of false-negative classification was cardiac arrhythmia 6
- Implementation of the SFSR in some settings could significantly increase admission rates 5
Recommended Approach
- Perform thorough evaluation to identify the cause of syncope
- Assess for short and long-term morbidity and mortality risk (Class I recommendation) 1
- Consider using risk stratification scores as a supplement to clinical judgment
- Recognize that risk scores have not performed better than unstructured clinical judgment 1
- Pay particular attention to cardiac risk factors, as they strongly influence both short and long-term outcomes
Risk stratification should focus primarily on identifying underlying cardiac disease and arrhythmias, as these are the most common causes of serious outcomes in syncope patients.