Brugada Syndrome

Updated May 11, 2014
Author: VerLee, with credits to UpToDate®

Description: Brief Synopsis of Brugada Syndrome

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Definition of Brugada Syndrome and Brugada Pattern:

  1. Brugada syndrome is an autosomal dominant genetic disorder, with variable expression, characterized by:
    1. abnormal findings on the electrocardiogram (ECG) in conjunction with an
    2. increased risk of ventricular tachyarrhythmias and sudden cardiac arrest (SCA)
  2. Patients with typical ECG features who are asymptomatic and have no other clinical criteria are said to have the Brugada Pattern,
    while those with typical ECG features who have one or more of the associated clinical criteria (see below: Clinical Presentation) are said to have the Brugada Syndrome

Prevalence:

  1. The prevalence of the typical ECG changes of the Brugada pattern
    1. ranges from 0.1 to 1 percent of the general population, with
    2. males > females, by 9:1
  2. Among those with the Brugada ECG pattern, the prevalence of symptoms or other clinical features which would result in the diagnosis of Brugada syndrome, is not known.

Clinical Presentation:

  1. Most clinical manifestations of the Brugada syndrome are related to life-threatening ventricular arrhythmias.
  2. SCA (sudden cardiac arrest) may be the initial presentation of Brugada syndrome in as many as one-third of patients.
  3. Patients may also present with an episode of syncope with features suggestive of a tachyarrhythmic cause of the syncope.
  4. Nocturnal agonal respiration is also described and is part of the diagnostic criteria.

ECG Findings and Confirmational Testing:

  1. Brugada pattern findings on ECG have some form of a pseudo-right bundle branch block, and persistent ST segment elevation in leads V1 to V3
    1. In the classic Brugada type 1 ECG ("A", below), the elevated ST segment (≥2 mm) descends with an upward convexity to an inverted T wave. This is referred to as the "coved type" Brugada pattern.brugada1
    2. Brugada type 2 ("B", below) patterns have a "saddle back" ST-T wave configuration, in which the elevated ST segment descends toward the baseline and then rises again to an upright or biphasic T wave.
      brugada2
  2. Legend:
    (A) This typical Coved Pattern present in V1-V2 shows the following:
    • At the end of QRS, an ascending and quick slope with a high take-off ?2 mm followed by concave or rectilinear downsloping ST. There are few cases of coved pattern with a high take-off between 1 and 2 mm.
    • There is no clear r' wave.
    • The high take-off often does not correspond with the J point.
    • At 40 ms of high take-off, the decrease in amplitude of ST is ?4 mm. In RBBB and athletes, it is much higher.
    • ST at high take-off N ST at 40 ms N ST at 80 ms.
    • ST is followed by negative and symmetric T wave.
    • The duration of QRS is longer than in RBBB, and there is a mismatch between V1 and V6.
    (B) This typical Saddle-Back Pattern present in V1-V2 shows the following:
    • High take-off of r' (that often does not coincide with J point) ?2 mm.
    • Descending arm of r' coincides with beginning of ST (often is not well seen).
    • Minimum ST ascent ?0.5 mm.
    • ST is followed by positive T wave in V2 (T peak N ST minimum N 0) and of variable morphology in V1.
    • The characteristics of triangle formed by r' allow to define different criteria useful for diagnosis.
      • ? angle.
      • Duration of the base of the triangle of r' at 5 mm from the high take-off greater than 3.5 mm.
    • The duration of QRS is longer in BrP type 2 than in other cases with r' in V1, and there is a mismatch between V1 and V6.
  3. Confirmational Testing: Once the diagnosis of Brugada syndrome is suspected based on the clinical presentation and ECG findings, additional testing may be considered to further confirm the diagnosis of Brugada syndrome, and to provide an estimate of risk of ventricular arrhythmias and SCA in the individual patient.
    1. a drug challenge (flecanide, procainamide)
    2. signal-average ECG
    3. invasive electrophysiology testing
    4. genetic testing

Diagnosis & Prognosis:

  1. The diagnosis of Brugada syndrome is most commonly made following a clinically significant event (ie, syncope, SCA) in which the patient has the typical ECG findings associated with this entity.
  2. The most important prognostic risk factor for patients with the Brugada ECG pattern or Brugada syndrome appears to be a history of ventricular tachyarrhythmias leading to SCA or syncope.
  3. Other less powerful predictors of future events may include atrial fibrillation, male gender, and a family history of SCA

Drug Interactions & Drugs to Avoid / Use with caution

  1. Some drugs and therapies may provoke or unmask characteristic Brugada ECG changes:
    1. sodium channel blockers, such as flecainide, ajmaline, or procainamide
      1. flecainide can also induce QT prolongation that is primarily seen in the right precordial leads (V1 and V2)
    2. beta blockers
    3. tricyclic or tetracyclic antidepressants
    4. lithium
    5. local anesthetics: bupivicaine, lidocaine
    6. propofol
    7. hypokalemia, hyperkalemia, hypercalcemia
    8. cocaine
  2. Pacing, vagal maneuvers, and increased alpha-adrenergic tone also may provoke the typical ECG changes of BS
  3. A website (brugadadrugs.org) is established that lists drugs to avoid, and drugs to use with caution.
  4. Anesthetic Management: In a series of 8 patients with BS, undergoing 17 anesthetics, (7 GA, 9 Local/MAC, 1 spinal/epidural), all patients tolerated anesthesia without adverse events; 4 patients had 20 occurences of ST elevation but no tachyarrhthymia. For complete journal article click here.

Treatment:

  1. Treatment for patients diagnosed with the Brugada syndrome is primarily focused around termination of any ventricular arrhythmias with an implantable cardioverter-defibrillator (ICD).
    1. In patients who refuse ICD implantation or are not considered a candidate for ICD implantation due to reduced life expectancy or significant comorbidities, initial therapy with either quinidine or amiodarone is suggested.
    2. In patients with an ICD who have recurrent arrhythmias resulting in ICD shocks, therapy with amiodarone or quinidine.
  2. For patients with the Brugada ECG pattern who are otherwise asymptomatic, and have none of the criteria which would suggest Brugada syndrome (ie, family history of sudden cardiac death or type 1 Brugada ECG pattern), no treatment recommended.
  3. Since Brugada syndrome follows an autosomal dominant genetic pattern with variable penetrance, all first-degree relatives of patients with confirmed Brugada syndrome should undergo screening with a clinical history and 12-lead electrocardiogram (ECG).