Brugada syndrome classification

There are three electrocardiographic patterns associated with Brugada syndrome: Type I, Type II and Type III. The diagnosis of Brugada syndrome is based upon the presence of Type I EKG changes. Patients with Type II or Type III Brugada patterns can convert to a Type I Brugada pattern following the administration of sodium channel blockers such as ajmaline and flecainide. To be classified as having Brugada syndrome (not just the pattern), one or more of the following criteria must also be met:

• Family history of sudden cardiac death (SCD) (<45 years old)
• Documented ventricular fibrillation (VF)
• Polymorphic ventricular tachycardia
• Coved-type ECG changes in family members
• Inducibility of ventricular tachycardia (VT) with programmed electrical stimulation (PES)

The patient is also diagnosed as having Brugada syndrome when a Type 2 (saddleback pattern) or Type 3 ST-segment elevation is observed in more than one right precordial lead under baseline conditions that can be converted to the diagnostic Type 1 Brugada pattern following administration of a sodium channel blocker and the clinical criteria listed above are met as well.

• There are three types of electrocardiogram patterns that are seen in Brugada syndrome; Type I, Type II, and Type III. Type I Brugada syndrome may always be present on the EKG, or it may be elicited by the administration of particular drugs (e.g., Class IC antiarrythmic drugs that blocks sodium channels such as ajmaline, flecainide) or it may be unmasked by various triggers or risk factors.^[1]

• Type I Brugada pattern is characterized by ST elevations in leads V₁-V₃ with a right bundle branch block (RBBB). A prolongation of the PR interval is also frequently seen. The EKG changes of Brugada syndrome can vary over time, depending on the autonomic balance and the administration of antiarrhythmic drugs. Adrenergic stimulation decreases the ST segment elevation, while vagal stimulation worsens it. The administration of class Ia, Ic and III drugs increases the ST segment elevation, as does fever.^[2][3]
• Exercise decreases ST segment elevation in some patients but increases it in others (after exercise when the body temperature has risen). The changes in heart rate induced by atrial pacing are accompanied by changes in the degree of ST segment elevation. When the heart rate decreases, the ST segment elevation increases and when the heart rate increases the ST segment elevation decreases.^[4]

• The three patterns of Brugada syndrome (Type I,II,III) are shown below:

The table below is from ECG pedia and is adapted from Wilde et al.^[5]

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