Evaluating Syncope
Risk-stratifies syncope presentations using validated clinical decision rules to determine disposition, identify high-risk cardiac etiologies, and document medical decision-making that supports admission or discharge decisions.
Why This Skill Exists
Syncope accounts for 1-3% of all emergency department visits and 1-6% of hospital admissions. The challenge is separating the 85% of patients with benign vasovagal or orthostatic syncope from the 10-15% with potentially life-threatening cardiac etiologies. Missed cardiac syncope carries a 6-month mortality rate of 10-30%. Conversely, unnecessary hospital admission for low-risk syncope wastes $2.4 billion annually in the United States alone.
Risk stratification tools exist to guide this decision, but their application requires understanding each tool's derivation population, validated endpoints, sensitivity, and specificity. No single rule is perfect—the San Francisco Syncope Rule (SFSR), Canadian Syncope Risk Score (CSRS), OESIL score, EGSYS score, and Boston Syncope Rule each have distinct strengths and limitations. This skill ensures systematic application and documentation.
Checkpoint A: Pre-Draft Intake (Mandatory)
- What were the exact circumstances of the syncopal event (position, activity, prodromal symptoms, witnesses)?
- Was there true loss of consciousness with spontaneous recovery, or was this pre-syncope, seizure, or mechanical fall?
- What are the patient's vital signs including orthostatic measurements (lying, sitting, standing at 1 and 3 minutes)?
- Is there any history of structural heart disease, arrhythmia, heart failure, or family history of sudden cardiac death?
- What medications is the patient taking (QT-prolonging drugs, antihypertensives, diuretics, antiarrhythmics)?
- Was there any witnessed seizure activity, tongue biting, incontinence, or prolonged post-event confusion?
- What does the ECG show (rhythm, intervals including QTc, axis, morphology, comparison with prior)?
- Has hemoglobin, troponin, and BNP/NT-proBNP been obtained?
Documents to Request
- 12-lead ECG (current and any prior for comparison)
- Orthostatic vital sign measurements with times
- Complete medication list with dosages
- Prior cardiac history and testing (echocardiogram, stress test, Holter/event monitor)
- Witness statements if available
- EMS documentation of on-scene findings and rhythm
- Previous syncope evaluations
- Family history documentation (especially sudden death age <50)
Step 1: Differentiate True Syncope from Mimics
Before applying risk stratification, confirm the event is true syncope (transient loss of consciousness due to cerebral hypoperfusion with rapid spontaneous recovery):
| Diagnosis |
Key Distinguishing Features |
Action |
| True syncope |
Brief LOC, spontaneous recovery, no post-ictal state |
Continue with risk stratification |
| Seizure |
Witnessed tonic-clonic activity, lateral tongue bite, prolonged post-ictal confusion >5 min, elevated prolactin |
Neurology pathway |
| Mechanical fall |
No LOC, trip/slip mechanism, focal injury |
Trauma evaluation |
| Vertigo/presyncope |
Near-faint without LOC, room-spinning sensation |
Separate evaluation pathway |
| Psychogenic |
Prolonged "unresponsiveness" with normal vitals, eyes held closed |
Psychiatric assessment |
| Hypoglycemia |
Low glucose, diabetes history, recovery with dextrose |
Endocrine/metabolic |
| TIA/stroke |
Focal neurologic deficits, LOC atypical for posterior circulation only |
Stroke pathway |
Step 2: Apply Validated Risk Stratification Tools
San Francisco Syncope Rule (SFSR)
Predicts 7-day serious outcomes. Any positive criterion = high risk:
- Congestive heart failure history
- Hematocrit <30%
- ECG abnormal (non-sinus rhythm or new changes)
- Shortness of breath
- Systolic BP <90 mmHg at triage
Sensitivity 96%, specificity 62%. Note: Validated only for ED disposition; does not risk-stratify among high-risk patients.
Canadian Syncope Risk Score (CSRS)
30-day serious adverse event prediction (score range -3 to +11):
| Feature |
Points |
| Predisposition to vasovagal (warm environment, prolonged standing, fear/pain/emotion) |
-1 |
| Heart disease history (CAD, atrial fibrillation, CHF, valvular disease) |
+1 |
| Any ED systolic BP <90 or >180 mmHg |
+2 |
| Elevated troponin (>99th percentile URL) |
+2 |
| Abnormal QRS axis (<-30 or >100 degrees) |
+1 |
| QRS duration >130 ms |
+1 |
| QTc >480 ms |
+2 |
| ED diagnosis of cardiac syncope |
+2 |
Risk categories: Very low (-3 to -2): 0.4%; Low (-1 to 0): 1.2%; Medium (1 to 3): 3.1%; High (4 to 5): 9.4%; Very high (6+): 28.9%.
OESIL Score
1-year mortality predictor (1 point each):
- Age >65 years
- History of cardiovascular disease
- Syncope without prodrome
- Abnormal ECG
Score 0: 0% mortality; Score 1: 0.6%; Score 2: 14%; Score 3-4: 29%.
Step 3: ECG Interpretation for Syncope-Specific Findings
The ECG is the single highest-yield test in syncope evaluation. Systematically assess:
- Rate and rhythm: Bradycardia <40, pauses >3 sec, high-grade AV block, tachyarrhythmias
- PR interval: First-degree block >200 ms, Mobitz I vs II, third-degree block
- QRS duration: Bundle branch block (new LBBB is high risk), fascicular blocks
- QT interval: QTc >480 ms (long QT syndrome), QTc <340 ms (short QT)
- ST-T wave: Brugada pattern (coved ST in V1-V3), ARVC (epsilon waves, T-wave inversion V1-V3), early repolarization in inferior/lateral leads
- Hypertrophy: LVH suggesting HCM or aortic stenosis
- Pre-excitation: Delta waves (WPW syndrome)
High-risk ECG findings requiring admission: Any of the above abnormalities warrant cardiac monitoring, even with otherwise low-risk score.
Step 4: Disposition Decision Framework
| Risk Level |
Criteria Met |
Disposition |
Monitoring |
| Low risk |
SFSR negative, CSRS ≤0, normal ECG, no cardiac history, classic vasovagal features |
Discharge with PCP follow-up 1-2 weeks |
None required |
| Intermediate risk |
CSRS 1-3, isolated ECG abnormality, age >60 without cardiac history |
Observation unit 12-24 hours with telemetry |
Continuous cardiac monitoring |
| High risk |
CSRS ≥4, OESIL ≥2, abnormal ECG with structural heart disease, exertional syncope, syncope causing injury |
Hospital admission with telemetry |
Cardiology consultation, echocardiogram, consider EP study |
| Critical |
Syncope with sustained arrhythmia, hemodynamic instability, acute coronary syndrome |
ICU admission |
Continuous monitoring, emergent cardiology |
Step 5: Discharge Planning for Low-Risk Patients
For patients deemed safe for discharge, document:
- Risk score applied and result
- Normal ECG interpretation with comparison to prior if available
- Orthostatic vitals negative
- No high-risk features (exertional syncope, family sudden death, structural heart disease)
- Clear return precautions: recurrent syncope, chest pain, palpitations, exertional symptoms
- Driving restrictions counseled per state law (many states require 3-6 month event-free period)
- Follow-up plan: PCP within 1-2 weeks, cardiology referral if indicated
- Activity modifications if orthostatic (hydration, compression stockings, slow position changes)
Checkpoint B: Post-Draft Alignment (Mandatory)
- Is true syncope confirmed and differentiated from seizure, presyncope, and mechanical fall?
- Are at least two validated risk stratification tools applied and documented with scores?
- Does the ECG interpretation address all syncope-specific high-risk patterns?
- Is the disposition decision clearly supported by the risk stratification results?
- For discharges, are return precautions and driving counseling documented?
Quality Audit
| # |
Criterion |
Pass/Fail |
| 1 |
True syncope vs. mimic differentiation documented |
|
| 2 |
Orthostatic vital signs measured and recorded at 1 and 3 minutes |
|
| 3 |
12-lead ECG obtained and systematically interpreted |
|
| 4 |
At least one validated risk score calculated and documented |
|
| 5 |
Cardiac history specifically queried (CAD, CHF, arrhythmia, valvular) |
|
| 6 |
Family history of sudden cardiac death under age 50 assessed |
|
| 7 |
Medication review for QT-prolonging and hypotensive agents completed |
|
| 8 |
Exertional syncope specifically asked about and documented |
|
| 9 |
Troponin obtained for intermediate/high-risk patients |
|
| 10 |
Disposition supported by documented clinical reasoning |
|
| 11 |
Driving counseling documented for discharged patients |
|
| 12 |
Return precautions specific to syncope provided |
|
| 13 |
Follow-up arranged with timeline specified |
|
| 14 |
ECG compared to prior if available in system |
|
Guidelines
- Syncope in patients under 35 with exertion must prompt evaluation for HCM, ARVC, long QT, Brugada, and anomalous coronary arteries—these are leading causes of sudden cardiac death in young athletes
- No single risk rule is sufficient—apply SFSR for 7-day events and CSRS for 30-day events, and reconcile conflicting results conservatively
- Orthostatic vitals require 3 minutes of standing—measurements taken at 1 minute alone miss 25% of orthostatic hypotension cases
- QTc must be calculated using Bazett correction and verified manually if heart rate is <50 or >100 (automated calculations are unreliable at extremes)
- First-time syncope over age 60 warrants higher suspicion for cardiac etiology even with a normal initial workup—consider outpatient event monitor
- Vasovagal syncope diagnosis is one of exclusion—document the positive features (prodrome, trigger, position) AND the absence of high-risk features
- Recurrent syncope with negative workup may warrant tilt-table testing or implantable loop recorder discussion—document this in the discharge plan
1---2name: evaluating-syncope3description: Risk-stratifies syncope presentations using San Francisco, Canadian, and OESIL rules. Use when evaluating syncope, determining admission criteria, or risk-stratifying fainting episodes.4---5
6# Evaluating Syncope
7
8Risk-stratifies syncope presentations using validated clinical decision rules to determine disposition, identify high-risk cardiac etiologies, and document medical decision-making that supports admission or discharge decisions.
9
10## Why This Skill Exists
11
12Syncope accounts for 1-3% of all emergency department visits and 1-6% of hospital admissions. The challenge is separating the 85% of patients with benign vasovagal or orthostatic syncope from the 10-15% with potentially life-threatening cardiac etiologies. Missed cardiac syncope carries a 6-month mortality rate of 10-30%. Conversely, unnecessary hospital admission for low-risk syncope wastes $2.4 billion annually in the United States alone.
13
14Risk stratification tools exist to guide this decision, but their application requires understanding each tool's derivation population, validated endpoints, sensitivity, and specificity. No single rule is perfect—the San Francisco Syncope Rule (SFSR), Canadian Syncope Risk Score (CSRS), OESIL score, EGSYS score, and Boston Syncope Rule each have distinct strengths and limitations. This skill ensures systematic application and documentation.
15
16---
17
18## Checkpoint A: Pre-Draft Intake (Mandatory)
19
201. What were the exact circumstances of the syncopal event (position, activity, prodromal symptoms, witnesses)?
212. Was there true loss of consciousness with spontaneous recovery, or was this pre-syncope, seizure, or mechanical fall?
223. What are the patient's vital signs including orthostatic measurements (lying, sitting, standing at 1 and 3 minutes)?
234. Is there any history of structural heart disease, arrhythmia, heart failure, or family history of sudden cardiac death?
245. What medications is the patient taking (QT-prolonging drugs, antihypertensives, diuretics, antiarrhythmics)?
256. Was there any witnessed seizure activity, tongue biting, incontinence, or prolonged post-event confusion?
267. What does the ECG show (rhythm, intervals including QTc, axis, morphology, comparison with prior)?
278. Has hemoglobin, troponin, and BNP/NT-proBNP been obtained?
28
29### Documents to Request
30
31- 12-lead ECG (current and any prior for comparison)
32- Orthostatic vital sign measurements with times
33- Complete medication list with dosages
34- Prior cardiac history and testing (echocardiogram, stress test, Holter/event monitor)
35- Witness statements if available
36- EMS documentation of on-scene findings and rhythm
37- Previous syncope evaluations
38- Family history documentation (especially sudden death age <50)
39
40---
41
42## Step 1: Differentiate True Syncope from Mimics
43
44Before applying risk stratification, confirm the event is true syncope (transient loss of consciousness due to cerebral hypoperfusion with rapid spontaneous recovery):
45
46| Diagnosis | Key Distinguishing Features | Action |
47|---|---|---|
48| True syncope | Brief LOC, spontaneous recovery, no post-ictal state | Continue with risk stratification |
49| Seizure | Witnessed tonic-clonic activity, lateral tongue bite, prolonged post-ictal confusion >5 min, elevated prolactin | Neurology pathway |
50| Mechanical fall | No LOC, trip/slip mechanism, focal injury | Trauma evaluation |
51| Vertigo/presyncope | Near-faint without LOC, room-spinning sensation | Separate evaluation pathway |
52| Psychogenic | Prolonged "unresponsiveness" with normal vitals, eyes held closed | Psychiatric assessment |
53| Hypoglycemia | Low glucose, diabetes history, recovery with dextrose | Endocrine/metabolic |
54| TIA/stroke | Focal neurologic deficits, LOC atypical for posterior circulation only | Stroke pathway |
55
56---
57
58## Step 2: Apply Validated Risk Stratification Tools
59
60### San Francisco Syncope Rule (SFSR)
61
62Predicts 7-day serious outcomes. Any positive criterion = high risk:
63
64- **C**ongestive heart failure history
65- **H**ematocrit <30%
66- **E**CG abnormal (non-sinus rhythm or new changes)
67- **S**hortness of breath
68- **S**ystolic BP <90 mmHg at triage
69
70Sensitivity 96%, specificity 62%. Note: Validated only for ED disposition; does not risk-stratify among high-risk patients.
71
72### Canadian Syncope Risk Score (CSRS)
73
7430-day serious adverse event prediction (score range -3 to +11):
75
76| Feature | Points |
77|---|---|
78| Predisposition to vasovagal (warm environment, prolonged standing, fear/pain/emotion) | -1 |
79| Heart disease history (CAD, atrial fibrillation, CHF, valvular disease) | +1 |
80| Any ED systolic BP <90 or >180 mmHg | +2 |
81| Elevated troponin (>99th percentile URL) | +2 |
82| Abnormal QRS axis (<-30 or >100 degrees) | +1 |
83| QRS duration >130 ms | +1 |
84| QTc >480 ms | +2 |
85| ED diagnosis of cardiac syncope | +2 |
86
87Risk categories: Very low (-3 to -2): 0.4%; Low (-1 to 0): 1.2%; Medium (1 to 3): 3.1%; High (4 to 5): 9.4%; Very high (6+): 28.9%.
88
89### OESIL Score
90
911-year mortality predictor (1 point each):
92
93- Age >65 years
94- History of cardiovascular disease
95- Syncope without prodrome
96- Abnormal ECG
97
98Score 0: 0% mortality; Score 1: 0.6%; Score 2: 14%; Score 3-4: 29%.
99
100---
101
102## Step 3: ECG Interpretation for Syncope-Specific Findings
103
104The ECG is the single highest-yield test in syncope evaluation. Systematically assess:
105
1061. **Rate and rhythm**: Bradycardia <40, pauses >3 sec, high-grade AV block, tachyarrhythmias
1072. **PR interval**: First-degree block >200 ms, Mobitz I vs II, third-degree block
1083. **QRS duration**: Bundle branch block (new LBBB is high risk), fascicular blocks
1094. **QT interval**: QTc >480 ms (long QT syndrome), QTc <340 ms (short QT)
1105. **ST-T wave**: Brugada pattern (coved ST in V1-V3), ARVC (epsilon waves, T-wave inversion V1-V3), early repolarization in inferior/lateral leads
1116. **Hypertrophy**: LVH suggesting HCM or aortic stenosis
1127. **Pre-excitation**: Delta waves (WPW syndrome)
113
114**High-risk ECG findings requiring admission**: Any of the above abnormalities warrant cardiac monitoring, even with otherwise low-risk score.
115
116---
117
118## Step 4: Disposition Decision Framework
119
120| Risk Level | Criteria Met | Disposition | Monitoring |
121|---|---|---|---|
122| Low risk | SFSR negative, CSRS ≤0, normal ECG, no cardiac history, classic vasovagal features | Discharge with PCP follow-up 1-2 weeks | None required |
123| Intermediate risk | CSRS 1-3, isolated ECG abnormality, age >60 without cardiac history | Observation unit 12-24 hours with telemetry | Continuous cardiac monitoring |
124| High risk | CSRS ≥4, OESIL ≥2, abnormal ECG with structural heart disease, exertional syncope, syncope causing injury | Hospital admission with telemetry | Cardiology consultation, echocardiogram, consider EP study |
125| Critical | Syncope with sustained arrhythmia, hemodynamic instability, acute coronary syndrome | ICU admission | Continuous monitoring, emergent cardiology |
126
127---
128
129## Step 5: Discharge Planning for Low-Risk Patients
130
131For patients deemed safe for discharge, document:
132
1331. Risk score applied and result
1342. Normal ECG interpretation with comparison to prior if available
1353. Orthostatic vitals negative
1364. No high-risk features (exertional syncope, family sudden death, structural heart disease)
1375. Clear return precautions: recurrent syncope, chest pain, palpitations, exertional symptoms
1386. Driving restrictions counseled per state law (many states require 3-6 month event-free period)
1397. Follow-up plan: PCP within 1-2 weeks, cardiology referral if indicated
1408. Activity modifications if orthostatic (hydration, compression stockings, slow position changes)
141
142---
143
144## Checkpoint B: Post-Draft Alignment (Mandatory)
145
1461. Is true syncope confirmed and differentiated from seizure, presyncope, and mechanical fall?
1472. Are at least two validated risk stratification tools applied and documented with scores?
1483. Does the ECG interpretation address all syncope-specific high-risk patterns?
1494. Is the disposition decision clearly supported by the risk stratification results?
1505. For discharges, are return precautions and driving counseling documented?
151
152---
153
154## Quality Audit
155
156| # | Criterion | Pass/Fail |
157|---|---|---|
158| 1 | True syncope vs. mimic differentiation documented | |
159| 2 | Orthostatic vital signs measured and recorded at 1 and 3 minutes | |
160| 3 | 12-lead ECG obtained and systematically interpreted | |
161| 4 | At least one validated risk score calculated and documented | |
162| 5 | Cardiac history specifically queried (CAD, CHF, arrhythmia, valvular) | |
163| 6 | Family history of sudden cardiac death under age 50 assessed | |
164| 7 | Medication review for QT-prolonging and hypotensive agents completed | |
165| 8 | Exertional syncope specifically asked about and documented | |
166| 9 | Troponin obtained for intermediate/high-risk patients | |
167| 10 | Disposition supported by documented clinical reasoning | |
168| 11 | Driving counseling documented for discharged patients | |
169| 12 | Return precautions specific to syncope provided | |
170| 13 | Follow-up arranged with timeline specified | |
171| 14 | ECG compared to prior if available in system | |
172
173---
174
175## Guidelines
176
1771. **Syncope in patients under 35 with exertion** must prompt evaluation for HCM, ARVC, long QT, Brugada, and anomalous coronary arteries—these are leading causes of sudden cardiac death in young athletes
1782. **No single risk rule is sufficient**—apply SFSR for 7-day events and CSRS for 30-day events, and reconcile conflicting results conservatively
1793. **Orthostatic vitals require 3 minutes of standing**—measurements taken at 1 minute alone miss 25% of orthostatic hypotension cases
1804. **QTc must be calculated using Bazett correction** and verified manually if heart rate is <50 or >100 (automated calculations are unreliable at extremes)
1815. **First-time syncope over age 60** warrants higher suspicion for cardiac etiology even with a normal initial workup—consider outpatient event monitor
1826. **Vasovagal syncope diagnosis is one of exclusion**—document the positive features (prodrome, trigger, position) AND the absence of high-risk features
1837. **Recurrent syncope with negative workup** may warrant tilt-table testing or implantable loop recorder discussion—document this in the discharge plan
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