ECG Cases 33 Brugada Syndrome: 3-Step Approach to Diagnosis and Management

Brugada pattern, phenocopy and syndrome

Brugada syndrome was described in 1992 in 8 previously healthy patients aged 2 to 53, who presented with syncope without prodrome, and then developed polymorphic ventricular tachycardia—which either self terminated or led to sudden cardiac death. Two patients were siblings and two had family members with sudden cardiac death. Further episodes were provoked by febrile illnesses and prevented by ICD. They were on no medications or drugs, had normal labs and a normal echo, and had a distinctive electrocardiogram: “The ECG during sinus rhythm showed right bundle branch block, normal QT interval and persistent ST segment elevation in precordial leads V1 to V2-V3 not explainable by electrolyte disturbances, ischemia or structural heart disease.” [1].

The family history, febrile provocation and ECG findings have been linked to an inherited, temperature-sensitive, right ventricular sodium channelopathy. Sometimes the ECG pattern can be concealed and other times provoked—by fever, medications, or vagal stimulation—and provocative testing with sodium channel blockers can be used to confirm the diagnosis.[2]

It’s important to know Brugada pattern as a differential for ST elevation, and to consider Brugada syndrome in patients with syncope, “seizures” and nocturnal agonal breathing. But there are other situations that can mimic, from lead misplacement to hyperkalemia. Here are three steps towards the diagnosis:

Step 1. ECG interpretation to identify Brugada pattern

This first step is ECG interpretation: is there Brugada pattern in lead V1-V2? There are two Brugada patterns[2]: type 1 (coved) is an rS complex followed by at least 2mm of concave ST elevation which descends into an inverted and symmetric T wave, while type 2 (saddle-back) is an rSr’ complex where the r’ is at least 2mm elevated and followed by saddle back ST elevation and positive T wave. Type 1 is pathognomonic but type 2 has a variety of mimics—from lead misplacement to normal variants.

The differential for rSr’ in V1-2 is a two-step process[3]. First look at the P wave: if it is fully negative in V1 and not fully upright in V2 then then the leads are too high, which can produce an RsR’ pattern, and the lead misplacement should be corrected. if lead placement is correct, then look at the triangle created by the r’ and measure it 5mm from the peak: if the base of the triangle is 4mm or greater (i.e broad based), this identifies type 2 Brugada pattern. RsR’ patterns with a narrow triangle base can be caused by incomplete RBBB or present in healthy athletes, and does not indicate Brugada pattern.

In other words:

1. V1-2 coved ST elevation and symmetric T wave inversion = Brugada pattern type 1
2. V1-2 saddle back ST elevation and upright T wave
   1. P wave fully inverted in V1 or biphasic in V1 = high lead placement
   2. Normal P wave with narrow base of triangle = normal variant
   3. Normal P wave with wide base of triangle = Brugada type 1 pattern

Step 2. treat reversible causes of Brugada phenocopy

If there is Brugada pattern on ECG, the next step to put it in clinical context: are there any reversible causes of Brugada phenocopy? These are clinical conditions that can mimic Brugada pattern but are reversible. These causes include metabolic conditions that alter condution (severe hyper/hypokalemia, hyponatremia, hypocalcemia, hypothyroid, or hypothermia), mechanical compression of the right ventricle (mediastinal mass, tension pneumothorax), V1-3 ischemia (anterior or RV infarct, pulmonary embolism), and myo/pericarditis.

Brugada phenocopies can be suspected when there is a) Brugada pattern on ECG, but b) a secondary cause is found, and c) the pattern resolves with treatment, and d) the patient has a low pre-test of Brugada syndrome (i.e no history of syncope, seizure or nocturnal agonal breathing, and no family history of sudden cardiac death). This can be further confirmed by referral to electrophysiologist for provocative or genetic testing, both of which are negative in Brugada phenocopies.[4]

Step 3. diagnosis, management and risk stratification of Brugada syndrome

If there is Brugada pattern on ECG but no secondary causes to suggest Brugada phenocopy, then does the patient have Brugada syndrome? The diagnosis requires a type 1 pattern, either spontaneously or provoked by sodium channel blockers. Risk stratification is based on symptoms: symptomatic patients (rescuscitated arrest, nonvagal syncope, seizure, or nocturnal agonal breathing) require an ICD, while asymptomatic patients can be referred to electrophysiologists for further testing.[5] All patients should treat fevers and avoid Brugada drugs (especially those with sodium channel blocking properties—including procainamide, tricyclic antidepressants, and cocaine) that provoke the type 1 pattern.

Back to the cases

Case 1: saddle-back ST elevation from high lead placement

• Heart rate/rhythm: normal sinus rhythm
• Electrical conduction: normal intervals
• Axis: normal
• R-wave progression: normal
• Tall/small voltages: normal voltages
• ST/T changes: saddle-back STE in V2 preceded by biphasic P wave, and with narrow triangle

Impression: V2 too high. Repeat with correct lead placement: saddle-back STE resolved

Case 2: Brugada phenocopy from hyperkalemia

• H: sinus tach
• E: nonspecific intraventricular conduction delay
• A: normal axis
• R: normal R wave
• T: normal voltages
• S: diffuse peaked T waves and Brugada pattern in V1 (coved) and V2 (saddle-back)

Impression: severe hyperkalemia with Brugada phenocopy. Treated and ECG normalized (copy not available)

Case 3: Brugada phenocopy from LAD occlusion

• H: borderline sinus tach
• E: borderline long QT
• A: left axis from LAFB (old)
• R: delayed R wave progression (old) with new loss of anterior R waves
• T: normal voltages
• S: coved ST elevation anterolaterally, with reciprocal ST depression inferiorly

Impression: proximal LAD occlusion with Brugada phenocopy. Cath lab activated: 99% proximal LAD occlusion, first trop 50,000. Discharge ECG had typical reperfusion T wave inversion: