Definition:

  • An inherited disorder that predisposes patients to sudden cardiac death by ventricular arrhythmia that is characterized by the following EKG pattern:
    • ST segment elevation with Type 1 Brugada morphology ≥ 2mm in ≥ 1 of the right precordial leads (V1 or V2), spontaneously or after provocative test with intravenous class I anti-arrhythmic medication
    • Type 1 Brugada morphology defined as cove-shaped ST segment elevation ≥ 2mm followed by inverted T wave

Figure 1: Brugada Pattern (Tintinalli 2016)

  • Diagnosis of Brugada syndrome requires characteristic EKG findings and appropriate clinical scenario

Epidemiology: (Sieira J 2016)

  • Estimated to be reported in 5-40% of sudden deaths in patients without structural heart disease
  • Global prevalence between 5-20 cases per 10,000
  • Increased prevalence in Asian countries

Pathophysiology:

  • Pathophysiology not completely understood
  • Many different genes have been implicated in Brugada syndrome, involving mutations in the sodium channels as well as the calcium and potassium channels.
  • 3 different hypotheses exist for mechanism of Brugada syndrome: (Sieira J et al.)
    1. Repolarization: an outward shift in balance of current in right ventricular epicardium results in repolarization abnormalities, leading to closely coupled premature beats which can lead to ventricular arrhythmia.
    2. Depolarization: conduction delay in the right ventricular outflow tract (RVOT) creates abnormal current leading to ventricular arrhythmia.
    3. Neural crest: the RVOT has different embryologic origin than rest of the heart, and abnormal expression of these cells could lead to both a depolarization delay and abnormal repolarization in the RVOT

ECG Criteria:

  • As above, only Type 1 EKG pattern is diagnostic of Brugada syndrome.
  • Type 2 Brugada pattern is characterized by “saddleback” pattern of ST elevation with positive or biphasic T wave. Type 2 is not diagnostic of Brugada Syndrome, but may raise suspicion for Brugada syndrome, and should lead to further testing.
  • Type 3 Brugada pattern is characterized by coved or saddle back with ST elevation between 1-2mm. This pattern was initially thought to be suggestive of Brugada syndrome, but is no longer considered suggestive of Brugada syndrome, but is now thought to be a normal variant.

Figure 2: Brugada Types (Wilde 2002)

  • Patient’s with Brugada syndrome will not always manifest characteristic EKG at all times

Differential:

  • Must consider Brugada Syndrome in all patients presenting with syncope or unexplained cardiac arrest
  • Right bundle branch block (RBBB): different in that normal RBBB does not have ST segment elevation

Figure 3: RBBB

  • Arrhythmogenic right ventricular cardiomyopathy (ARVC): structural heart disease characterized by fatty replacement and fibrosis of the right ventricle, can also lead to ventricular arrhythmias. EKG shows characteristic Epsilon wave, a small positive deflection buried in the end of the QRS complex.

Figure 4: Epsilon wave (LIFTL)

Presentation and Management

  • Presentation can vary from incidentally found Brugada pattern on screening EKG, to found in workup of syncope or cardiac arrest
  • Implantable cardioverter-defibrillator (ICD) is definitive treatment for patients deemed high risk for ventricular arrhythmia
  • Quinidine, a class I antiarrhythmic, has also been used in conjunction with ICD or if unable to place ICD.

Disposition:

  • Disposition is controversial and depends on clinical scenario that led to finding of Brugada pattern or diagnosis of Brugada syndrome
  • All patients who are symptomatic should be admitted for further workup, electrophysiology studies, and likely ICD placement
  • Asymptomatic patients with Type 1 EKG pattern, or patients with Type 2 EKG pattern can be considered for discharge with close cardiology and Electrophysiology follow-up

Special Considerations:

  • Fever has been thought to precipitate arrhythmic events in patients with Brugada syndrome, sometimes referred to as “Fever-induced Brugada”
    • Recommend that these patient’s have their hyperthermia aggressively treated to avoid inducing potential ventricular arrhythmia
    • First EKG below is patient presenting to ED with febrile illness. Second EKG is same patient next day after fever resolved

 

 

Figure 5: Brugada Febrile

Figure 6: Brugada Afebrile

  • Sodium channel blocking drugs should be avoided in these patients for fear of potentiating life threatening ventricular arrhythmias
    • BrugadaDrugs.org is a reference that lists medications that should be absolutely or relatively avoided

Take Home Points:

  • Must think about Brugada syndrome in any patient presenting with syncope or ventricular arrhythmia
  • Only Type 1 Brugada pattern is diagnostic of Brugada syndrome, and only in appropriate clinical context
  • Symptomatic patients with Brugada type 1 should be admitted for further workup
  • ICD placement is definitive therapy

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References:

  • Wilde AA et al. Proposed diagnostic criteria for the Brugada syndrome: a consensus report. Circulation. 2002 Nov 5;106(19):2514-9. PMID 12417552
  • Tintinalli, Judith E., et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. Eighth edition. New York: McGraw-Hill Education, 2016: 133-134
  • Sieira J and Brugada P. The definition of the Brugada Syndrome. Eur Heart J. 2017 Oct 21;38(40); 3029-3034. PMID 292020354
  • Brugada P and Brugada J. Right Bundle branch block, persistent ST segment elevation and sudden cardiac death: a distinct clinical and electrocardiographic syndrome. A multicenter report. J Am Coll Cardiol. 1992 Nov 15;20(6):1391-6. PMID 1309182
  • Brugada P. Brugada syndrome: More than 20 years of scientific excitement. J Cardiol. 2016 Mar’67(3)215-20. PMID 26627541
  • Sieira J et al. Pathogenesis and management of Brugada syndrome. Nat Rev Cardiol. 2016 Dec;13(12):744-756. PMID 27629507
  • Adler A et al. Fever-induced Brugada pattern: how common is it and what does it mean? Heart Rhythm. 2013 Sep;10(9): 1375-82. PMID 23872691

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