Background: Risk stratification is important in the management of Brugada syndrome (BrS). Late potentials (LPs) and T-wave amplitude variability (TAV) in high-resolution ambulatory electrocardiography (ECG) were retrospectively investigated.
Methods and results: One hundred and twenty-seven patients diagnosed with BrS on 12-lead ECG were classified into 3 groups: documented ventricular fibrillation (VF)/asystole (n=19), episodes of syncope alone (n=30), and asymptomatic (n=78). Healthy volunteers were enrolled as controls (n=25). In the BrS patients, LPs showed appreciable circadian periodicity; filtered QRS duration (fQRS) and duration of the terminal low-amplitude signal <40 μV (LAS40) increased, whereas root mean square voltage of the terminal 40 ms of the fQRS (RMS40) decreased at night compared with the day. TAV did not have such a circadian periodicity. LP-positive incidence (night-time) and peak TAV were as follows: VF/asystole>syncope/asymptomatic>control (P<0.001). VF/asystole was discriminated from control at a ratio of 81-84% by night-time LPs (fQRS >116 ms, LAS40 >35 ms, RMS40 <25 μV) or peak TAV (>54 μV); VF/asystole was discriminated from syncope/asymptomatic at a ratio of 60-69%, by night-time LPs (fQRS >122 ms, LAS40 >42 ms, RMS40 <18μV) or peak TAV (>58 μV). Combined analysis of LPs and peak TAV increased the discriminant ratio up to 93% and 77%, respectively.
Conclusions: Analysis of both LPs and TAV (taking circadian periodicity into account) is useful in identification of high-risk BrS patients.