Evaluating Syncope

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)

1. What were the exact circumstances of the syncopal event (position, activity, prodromal symptoms, witnesses)?
2. Was there true loss of consciousness with spontaneous recovery, or was this pre-syncope, seizure, or mechanical fall?
3. What are the patient's vital signs including orthostatic measurements (lying, sitting, standing at 1 and 3 minutes)?
4. Is there any history of structural heart disease, arrhythmia, heart failure, or family history of sudden cardiac death?
5. What medications is the patient taking (QT-prolonging drugs, antihypertensives, diuretics, antiarrhythmics)?
6. Was there any witnessed seizure activity, tongue biting, incontinence, or prolonged post-event confusion?
7. What does the ECG show (rhythm, intervals including QTc, axis, morphology, comparison with prior)?
8. 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):

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):

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:

1. Rate and rhythm: Bradycardia <40, pauses >3 sec, high-grade AV block, tachyarrhythmias
2. PR interval: First-degree block >200 ms, Mobitz I vs II, third-degree block
3. QRS duration: Bundle branch block (new LBBB is high risk), fascicular blocks
4. QT interval: QTc >480 ms (long QT syndrome), QTc <340 ms (short QT)
5. ST-T wave: Brugada pattern (coved ST in V1-V3), ARVC (epsilon waves, T-wave inversion V1-V3), early repolarization in inferior/lateral leads
6. Hypertrophy: LVH suggesting HCM or aortic stenosis
7. 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

Step 5: Discharge Planning for Low-Risk Patients

For patients deemed safe for discharge, document:

1. Risk score applied and result
2. Normal ECG interpretation with comparison to prior if available
3. Orthostatic vitals negative
4. No high-risk features (exertional syncope, family sudden death, structural heart disease)
5. Clear return precautions: recurrent syncope, chest pain, palpitations, exertional symptoms
6. Driving restrictions counseled per state law (many states require 3-6 month event-free period)
7. Follow-up plan: PCP within 1-2 weeks, cardiology referral if indicated
8. Activity modifications if orthostatic (hydration, compression stockings, slow position changes)

Checkpoint B: Post-Draft Alignment (Mandatory)

1. Is true syncope confirmed and differentiated from seizure, presyncope, and mechanical fall?
2. Are at least two validated risk stratification tools applied and documented with scores?
3. Does the ECG interpretation address all syncope-specific high-risk patterns?
4. Is the disposition decision clearly supported by the risk stratification results?
5. For discharges, are return precautions and driving counseling documented?

Quality Audit

Guidelines

1. 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
2. No single risk rule is sufficient—apply SFSR for 7-day events and CSRS for 30-day events, and reconcile conflicting results conservatively
3. Orthostatic vitals require 3 minutes of standing—measurements taken at 1 minute alone miss 25% of orthostatic hypotension cases
4. QTc must be calculated using Bazett correction and verified manually if heart rate is <50 or >100 (automated calculations are unreliable at extremes)
5. First-time syncope over age 60 warrants higher suspicion for cardiac etiology even with a normal initial workup—consider outpatient event monitor
6. Vasovagal syncope diagnosis is one of exclusion—document the positive features (prodrome, trigger, position) AND the absence of high-risk features
7. Recurrent syncope with negative workup may warrant tilt-table testing or implantable loop recorder discussion—document this in the discharge plan