Utility of T-wave alternans during night time as a predictor for ventricular fibrillation in patients with Brugada syndrome.

The prognostic value of T-wave alternans (TWA) during the night time in patients with Brugada syndrome (Br-S) remains unknown. We assessed TWA for risk stratification using 24-h multichannel Holter electrocardiogram (24-M-ECG) in Br-S. We enrolled 129 patients with Br-S [grouped according to histories of ventricular fibrillation (VF), n = 16; syncope, n = 10; or no symptoms (asymptomatic), n = 103] and 11 controls. Precordial electrodes were attached to the third (3L-V1, 3L-V2) and fourth (4L-V1, 4L-V2 and 4L-V5) intercostal spaces. We measured the values of maximum TWA (max-TWA) during the night time (12 a.m.-6 a.m.) and the day time (12 p.m.-6 p.m.) and calculated parameters of heart rate variability. Compared to the asymptomatic and control groups, the VF and syncope groups showed significantly greater 3L-V2 max-TWA during the night time. The cutoff value for the 3L-V2 max-TWA during the night time was determined as 20 µV (sensitivity 94 % and specificity 48 %; p = 0.01). Multivariate analysis revealed that 3L-V2 max-TWA during the night time ≥20 µV and previous VF episodes were independent predictors of future VF episodes. During a mean follow-up period of 68 ± 37 months, 16 patients experienced VF episodes. The incidence of VF episodes was the highest during the night time (p < 0.001). The 3L-V2 max-TWA during the night time may be a useful predictor for VF episodes in patients with Br-S.