Differences in 12-lead electrocardiogram between symptomatic and asymptomatic Brugada syndrome patients

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.