Differences in 12-Lead Electrocardiogram for Brugada Syndrome Patients

Abstract and Introduction

Abstract

Introduction: Brugada syndrome (BrS) is an inherited disorder that predisposes some subjects to sudden cardiac death (SCD). It is not well established which BrS patients are at risk of severe arrhythmias. Our aim was to study whether standard 12-lead electrocardiogram (ECG) would give useful information for this purpose.
Methods: This study included 200 BrS probands (142 male, 62%; mean age 42 ± 16 years). Symptoms related to BrS were defined as syncope, documented ventricular tachyarrhythmia, or SCD. We determined PR, QRS, QTc, T_peak, and T_end interval from leads II and V₂ and QRS from lead V₅, R’/S ratio from lead aVR (aVR sign), QRS axis, and J-point elevation amplitude from right precordial leads from the baseline ECGs.
Results: Sixty-six subjects (33%) had experienced symptoms related to BrS. The only significant difference between the symptomatic and asymptomatic BrS subjects was the QRS duration measured from lead II or lead V₂, for example, the mean QRS in V₂ was 115 ± 26 ms in symptomatic versus 104 ± 19 ms in asymptomatic patients (P < 0.001). The optimized cut-off point of V₂ QRS ≥120 ms gave an odds ratio (OR) of 2.5 (95% CI: 1.4-4.6, P = 0.003) for being symptomatic. In a multivariate analysis adjusted with gender, age, and SCN5A mutation, the OR was 2.6 (95% CI: 1.4-4.8, P = 0.004).
Conclusion: Prolonged QRS duration, measured from standard 12-lead ECG, is associated with symptoms and could serve as a simple noninvasive risk marker of vulnerability to life-threatening ventricular arrhythmias in BrS.

Introduction

Brugada syndrome (BrS) is an inherited cardiac channelopathy that predisposes to life-threatening ventricular arrhythmias and manifests itself as syncope episodes, ventricular tachyarrhythmias, and sudden cardiac death (SCD). BrS is characterized by a coved type J-point and ST-segment in more than one right precordial lead (V_1-3) in 12-lead electrocardiogram (ECG). This ECG abnormality is also known as the “Brugada sign” or type 1 Brugada ECG.

The vulnerability of individual subjects with the “Brugada sign” to SCD or life-threatening ventricular tachyarrhythmias is not well established. So far, prior symptoms (syncope or aborted SCD), spontaneous type 1 Brugada ECG, male gender, inducibility to ventricular tachycardia (VT), or ventricular fibrillation (VF) in electrophysiological (EP) study have been linked to a higher risk of life-threatening events, but also controversial results have been reported. In several studies, spontaneous type 1 ECG and prior symptoms have shown to be the best predictors of symptom recurrence. Noninvasive ECG risk markers have also been recently studied. For example, fluctuation of ST-segment elevation in the “Brugada sign” and measurement of T_peak-T_end interval have been suggested to be useful in risk assessment. Also late potentials on signal average ECG have been shown to be more common in symptomatic than asymptomatic patients. However, the utility of standard 12-lead ECG has not been systematically studied in a large BrS patient population in respect to risk assessment. Therefore, we set out to study whether various 12-lead ECG measurements could differentiate subjects with prior symptoms (syncope, SCD, or documented ventricular arrhythmias) from those without symptoms in a large existing BrS cohort.