Elsevier

Heart Rhythm

Volume 12, Issue 2, February 2015, Pages 367-375
Heart Rhythm

Syncope in Brugada syndrome: Prevalence, clinical significance, and clues from history taking to distinguish arrhythmic from nonarrhythmic causes

https://doi.org/10.1016/j.hrthm.2014.10.014Get rights and content

Background

Syncope in Brugada syndrome (BrS) patients is a sign of increased risk for sudden cardiac death and usually is ascribed to cardiac arrhythmias. However, syncope often occurs in the general population, mostly from nonarrhythmic causes (eg, reflex syncope).

Objective

The purpose of this study was to distinguish arrhythmic events from nonarrhythmic syncope in BrS and to establish the clinical relevance of nonarrhythmic syncope.

Methods

We reviewed the patient records of 342 consecutively included BrS patients and conducted systematic interviews in 141 patients with aborted cardiac arrest (ACA) or syncope.

Results

In total, 23 patients (7%) experienced ECG-documented ACA and 118 (34%) syncope; of these 118, 67 (57%) were diagnosed with suspected nonarrhythmic syncope. Compared to suspected nonarrhythmic syncope patients, ACA patients were older at first event (45 vs 20 years), were more likely to be male (relative risk 2.1) and to have urinary incontinence (relative risk 4.6), and were less likely to report prodromes. ACA was never triggered by hot/crowded surroundings, pain or other emotional stress, seeing blood, or prolonged standing. During follow-up (median 54 months), ACA rate was 8.7% per year among ACA patients and 0% per year among suspected nonarrhythmic syncope patients.

Conclusion

Syncope, especially nonarrhythmic syncope, often occurs in BrS. The high incidence of nonarrhythmic syncope must be taken into account during risk stratification. Arrhythmic events and nonarrhythmic syncope may be distinguished by clinical characteristics (absence of prodromes and, particularly, specific triggers), demonstrating the importance of systematic history taking.

Introduction

Brugada syndrome (BrS) is characterized by sudden cardiac death at a relatively young age and signature ST-segment elevation in the right precordial electrocardiogram (ECG) leads (type 1 BrS ECG). The associated life-threatening tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) may manifest as cardiac arrest or syncope.1

Accordingly, syncope is a sign of increased risk for life-threatening arrhythmias (along with type 1 BrS ECG at baseline, ie, in the absence of provoking drugs), as indicated by studies on risk stratification of BrS.2 Yet, syncope in BrS patients constitutes a diagnostic dilemma. Although syncope in (suspected) BrS patients is often ascribed by default to cardiac arrhythmia in this setting, syncope also may stem from other causes. In the general population, reflex syncope is by far the most frequent cause of syncope, especially in the young, with a cumulative incidence of 40% by the age of 21 years.3 It is difficult to establish whether syncope events in BrS patients are caused by arrhythmia or nonarrhythmic syncope.4 The European Society of Cardiology (ESC) guidelines for syncope are inadequate for risk stratification in relatively young patients with a high risk for ventricular arrhythmias.5 Clearly, it is important to distinguish these types of syncope because the updated consensus statement on the diagnosis and management of patients with inherited primary arrhythmia syndromes6 recommends implantable cardioverter-defibrillator (ICD) placement only in BrS patients with syncope judged likely to be caused by ventricular arrhythmias, given the risk of ICD complications7 and costs.

In an effort to distinguish arrhythmic from nonarrhythmic syncope in BrS patients and to establish the clinical relevance of nonarrhythmic syncope in these patients, we asked the following questions: (1) How many BrS patients sustain arrhythmias and/or nonarrhythmic syncope? (2) Can clinical characteristics be identified to distinguish arrhythmic events from nonarrhythmic syncope in BrS? (3) What is the risk of future arrhythmias in BrS patients with nonarrhythmic syncope?

Section snippets

Study population

We conducted a cohort study at the Academic Medical Center, a large tertiary referral center in the Netherlands, of BrS patients consecutively included between January 1, 2001, and April 1, 2011. BrS was diagnosed when a type 1 BrS ECG was observed in >1 right precordial lead in the presence or absence of a sodium channel-blocking drug (flecainide or ajmaline).1 The institutional review board waived the requirement for informed consent.

Study design

All living patients who had experienced syncope or aborted

Patient characteristics

The total cohort comprised 342 patients. The mean age at diagnosis was 44 ± 14 years, and 205 (60%) were male. About half of the patients (n = 182/342 [53%]) were identified during family screening. Twenty patients (5.8%) initially presented with ACA and 11% (39/343) with syncope. The clinical characteristics of all patients are listed in Table 1.

Sudden cardiac arrest and syncope

By the time of diagnosis, 23 of 342 patients (23/123 families) had experienced ACA (7%; Figure 1), including 20 with an

Main findings

As many as 34% of patients with BrS had a history of ≥1 event of syncope at the time of diagnosis, of whom 57% had suspected nonarrhythmic syncope. Features suggesting ACA were male gender, older age, presence of urinary incontinence, absence of typical prodromes, and, most specifically, absence of typical triggers. The ACA rate during follow-up was 8.7% per year in ACA patients and 0%–0.3% per year in asymptomatic or suspected nonarrhythmic syncope patients. The absence of ACA in patients with

Conclusion

As many as 34% of BrS patients have a lifetime history of syncope at initial presentation, of whom 57% have suspected nonarrhythmic syncope. Clinical features, including absence of prodromes and, particularly, absence of specific triggers, are different between nonarrhythmic syncope and ACA and may be used to distinguish arrhythmic from nonarrhythmic syncope. Therefore, history taking of BrS patients with syncope should be particularly directed to the search for such triggers. The high

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    Dr. Tan was supported by Grant ZonMW Vici 918.86.616 from the Netherlands Organization for Scientific Research.

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