Brugada Syndrome EKG Patterns
Brugada syndrome displays three distinct EKG patterns in the right precordial leads (V1-V3), but only Type 1 is diagnostic for the syndrome. 1
The Three EKG Pattern Types
Type 1 Pattern (Diagnostic - "Coved" Type)
This is the only pattern that definitively diagnoses Brugada syndrome 1, 2, 3:
- "Coved" ST-segment elevation ≥2 mm (0.2 mV) in leads V1 and/or V2
- Downsloping ST-segment followed by a negative T-wave
- The ST-segment has a characteristic convex morphology that descends into the negative T-wave
- Can appear spontaneously or after sodium channel blocker challenge (flecainide, ajmaline, procainamide) 1, 4
- The STJ/ST80 ratio >1 (measuring ST elevation at J-point vs. 80ms after) helps distinguish this from athlete's heart 1, 2
Type 2 Pattern (Non-diagnostic - "Saddleback" Type)
This pattern requires further evaluation but is NOT diagnostic alone 1:
- "Saddleback" morphology with high takeoff ST-segment elevation ≥2 mm
- ST-segment remains ≥1 mm above baseline
- Followed by a biphasic or positive T-wave
- Requires sodium channel blocker challenge to unmask Type 1 pattern for diagnosis 1
Type 3 Pattern (Non-diagnostic)
This pattern has largely been merged with Type 2 in recent consensus 5:
- Either coved or saddleback morphology
- J-point elevation ≥2 mm BUT terminal ST-segment <1 mm above baseline
- Also requires provocative testing for diagnosis 1
Critical Diagnostic Considerations
Lead Placement Matters
- Patterns appear in right precordial leads V1-V3, typically positioned in the 2nd, 3rd, or 4th intercostal space 2, 4, 3
- Recording V1 and V2 in higher intercostal spaces (2nd-3rd) increases detection sensitivity 2, 4
- The pattern may be visible in only a single lead (V1 or V2) 6
Associated ECG Features
Beyond the ST-segment patterns, look for 1:
- S1, S2, S3 pattern (mimicking left anterior hemiblock) - reflects right ventricular outflow tract conduction defect
- Fragmented QRS complexes - associated with increased arrhythmic risk 6, 7
- Prolonged PR interval (>200 ms) - marker of increased risk 6
- QRS prolongation in V2 (≥120 ms) - risk marker 6
Dynamic Nature - Critical Pitfall
The Brugada pattern is notoriously dynamic and can normalize completely 1:
- May appear transiently then disappear on subsequent ECGs
- Fever, electrolyte disturbances, increased vagal tone can unmask or enhance the pattern 1, 3
- This is why repeated ECGs and 24-hour Holter monitoring are essential when suspicion exists 8
Distinguishing from Mimics
The downsloping ST-segment with STJ/ST80 ratio >1 is key to differentiating true Brugada Type 1 from 1, 2:
- Athlete's heart early repolarization: upsloping ST-segment with STJ/ST80 ratio <1
- Incomplete RBBB: has reciprocal S-waves in leads I and V6, which Brugada lacks 1
- Brugada phenocopies: similar patterns from other causes (hyperkalemia, RV cardiomyopathy, acute MI) that must be excluded 5, 9
Risk Stratification Based on Pattern
Spontaneous Type 1 pattern carries significantly higher risk than drug-induced pattern 3, 8:
- Spontaneous Type 1 + symptoms (syncope/cardiac arrest): highest risk, warrants ICD 4, 3
- Spontaneous Type 1 + asymptomatic: intermediate risk (~1% annual event rate) 3
- Drug-induced only Type 1: very low risk if spontaneous pattern ruled out with repeated monitoring 8
Type 2 and Type 3 patterns alone do not establish diagnosis or indicate treatment - they require sodium channel blocker challenge to unmask Type 1 pattern 1.