We report a case of a 43 year old man who was diagnosed with Brugada syndrome after propafenone administration for chemical cardioversion of new onset atrial fibrillation. Brugada syndrome has been described in the medical literature and is thought to be responsible for the majority of sudden cardiac deaths in patients without ischaemic heart disease. This syndrome has not yet been extensively discussed in the emergency medicine literature despite its importance. Emergency physicians should consider Brugada syndrome in patients who present to the emergency department with right bundle branch block and ST segment elevation in the right precordial leads, which is the classic electrocardiographic pattern of this syndrome.
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- BS, Brugada syndrome
- ED, emergency department
- ICD, implantable cardioverter defibrillator
- RBBB, right bundle brunch block
- SCD, sudden cardiac death
- VF, ventricular fibrillation
- VT, ventricular tachycardia
Ventricular fibrillation (VF) is the main cause of sudden cardiac death (SCD). Most SCDs are associated with acute coronary ischaemia near the time of death. However, 10–20% of SCD patients have no evidence of structural or ischaemic heart disease, and these patients have been referred to as having “idiopathic VF”.1,2 Brugada syndrome (BS) is now suspected to be responsible for 40–60% of cases of idiopathic VF.3
A 43 year old man presented to the emergency department (ED) complaining of palpitations, which hadstarted 1 hour prior to presentation. He denied syncope or chest pain. Blood pressure was 135/76 mmHg, pulse 138 beats/min, O2 saturation 98%, respiratory rate 14 breaths/min, and temperature 36.0°C. Past medical history included a negative treadmill stress test for atypical chest pain 1.5 years previously, as his mother had died of sudden cardiac death (SCD) at 44 years of age. The patient was placed on a monitor and an intravenous catheter was inserted. The initial ECG demonstrated atrial fibrillation with rapid ventricular response (134 beats/min) and incomplete right bundle brunch block (RBBB) without ST segment elevation (fig 1A). A prior ECG, which was obtained for comparison, showed sinus rhythm with RBBB and 1 mm ST elevation in leads V1–2. Intravenous diltiazem (40 mg) was administered, which achieved rate control. Complete blood count, serum electrolytes, and initial cardiac markers were normal.
Because atrial fibrillation was considered as new onset, 600 mg of propafenone was administered orally to achieve chemical cardioversion. After 6 hours, a repeat ECG showed 1–3 mm ST segment elevation in leads V1–3, and T wave inversion in leads V1 and V2 (fig 1B). The patient denied any chest pain or angina equivalent during the observation period. Cardiology consultation was obtained because of suspected silent acute myocardial infarction, and repeat cardiac markers were ordered. Subsequently, ST segment elevation was persistent for 6 hours and then progressively declined to baseline. Additionally, atrial fibrillation converted to sinus rhythm, and the RBBB resolved (fig 1C). At 12 hours, cardiac markers were not elevated. The patient was admitted to the coronary care unit with a diagnosis of suspected BS.
The following day, echocardiography and coronary angiography were performed, which revealed no evidence of structural heart disease. Programmed ventricular stimulation was also performed but it failed to induce ventricular tachycardia (VT) or VF. The patient was discharged on the third day of admission with the diagnosis of BS.
BS was first described by Pedro and Josep Brugada in 1992. The syndrome is characterised by SCD or episodes of syncope resulting from polymorphic VT or VF in previously healthy people, with the classic ECG finding of RBBB and ST segment elevation in the right precordial leads.4 Patients with BS may be completely asymptomatic, and are often recognised by chance because of ECG screening for insurance, sport licensing, atypical complaint, or investigation of other family members with known BS. Therefore, BS should be considered and investigated in patients with the characteristic ECG pattern, even if they are asymptomatic.5
BS is a primary electrical disorder resulting in abnormal electropyhsiological activity, and is typically seen in the fourth or fifth decade of life in men.5,6 Although the syndrome has autosomal dominant transmission, sporadic cases have been reported.3 Mutation of the SCN5A gene, which encodes for cardiac sodium channels, causes loss of cardiac sodium channel function,7 resulting in a shortening of the action potential duration in the right ventricular epicardium, which causes a transmural voltage gradient, seen as ST elevation and re-excitation on the ECG. This voltage gradient creates a vulnerable window for extrasystoles or premature impulses to initiate phase 2 re-entry, triggering VF.8,9 Class IA (for example, ajmaline, procainamide) and class IC (for example, propafenone, flecainide) antiarrhythmic agents and heightened parasympathetic tone increase ST segment elevation and may precipitate VF. Sympathetic activation, stress testing, isoproterenol, and dobutamine may decrease ST segment elevation and result in transient normalisation of the ECG.10,11 The VF frequently seen during sleep in patients with BS is probably due to a decrease in sympathetic tone.12
The typical presentation of BS is syncope or SCD, depending on the duration of VT. If VT is persistent, it eventually degenerates into VF and results in SCD. If VT is self terminating in a short period, it results in syncope or near-syncope.13 In addition, it has been suggested that there is a higher than normal incidence of supraventricular tachyarrhythmias in Brugada patients.14 Nearly 10% of patients with BS have concomitant atrial fibrillation.10 Therefore, BS should not be only considered in SCD victims or syncope patients, but also in patients who present to the ED with new onset atrial fibrillation with ST segment elevation in the right precordial leads.
Half of patients with BS have non-diagnostic resting ECG, and in 42% of cases, the ECG can normalise transiently.11,15 Because of the intermittent and concealed nature of the ECG signs, diagnosis of BS may be difficult. A consensus report of the diagnostic criteria for BS is outlined in table 1.16
Patients with suspected BS should undergo a pharmacological challenge test with class IA antiarrhythmic drugs in the electrophysiology laboratory.5 It has been reported that propafenone has an unmasking effect and can reveal a concealed BS, 17,18 as occurred in our patient. False positive pharmacological challenge tests have not been reported so far.5
Electrophysiological testing is useful for both further confirmation of the diagnosis and determination of treatment strategies. In the largest series yet reported in the literature, 30% of symptomatic Brugada patients developed a recurrent arrhythmic event (VF, SCD, or syncope due to ventricular arrhythmias) at a mean (SD) of 31 (41) months’ follow up. In the same study, while 12% of asymptomatic patients who were induced by programmed ventricular stimulation developed their first arrhythmic event, only 1.1% of non-inducible asymptomatic patients developed arrhythmias.19 Treatment criteria for BS are shown in table 2.5,19 Because of the autosomal dominant inheritance, other family members should be referred to a cardiologist for diagnostic testing.5
The mortality of BS is approximately 30% at 2 years following the diagnosis.6 An implantable cardioverter defibrillator (ICD) implant is the only effective treatment option for prevention of SCD in patients with BS. In one study, with use of an ICD, the mortality at 10 year follow up was 0%.20 Antiarrhythmic drugs, including amiodarone and beta blockers have not been shown to reduce mortality or recurrence of ventricular arrhythmias.21
BS is a preventable cause of SCD. Failure to diagnose the syndrome results in a high mortality rate. Early recognition of this syndrome may contribute to a decrease in the frequency of idiopathic VF and may improve prognosis of patients with BS. Therefore, emergency physicians should be familiar with the ECG findings of BS, and patients with suspected BS should be referred to a cardiologist. For all patients with new onset atrial fibrillation with RBBB, if chemical cardioversion is planned with propafenone in the ED, they should be also observed for ST segment elevation, which would be indicative of BS.
Competing interests: none declared
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