Seasonal and circadian distributions of ventricular fibrillation in patients with Brugada syndrome.

Background: It is well-known that the incidence of ventricular tachyarrhythmias is the highest in winter and during the daytime in patients with structural heart disease. However, little is known about the seasonal and circadian distributions of ventricular fibrillation (VF) in patients with Brugada syndrome.

Objective: The aim of this study was to investigate seasonal and circadian distributions of VF in patients with Brugada syndrome.

Methods: We analyzed the data of appropriate shock episodes for VF recorded by an implantable cardioverter-defibrillator (ICD) in patients with Brugada syndrome.

Results: Among 62 consecutive Brugada syndrome patients with an ICD (48 +/- 14 years, 58 males), 19 patients had at least one episode of an appropriate ICD shock due to VF during a mean follow-up of 70 +/- 36 months, and 98 episodes were evaluated as isolated VF. There was a significant peak between March and June (P = .03). As for the circadian variation, significantly more VF occurred from midnight to 6:00 (P <.0001). Electrical storms of VF occurred in seven patients. The seasonal and circadian variations of electrical storms were similar to those of the isolated VF episodes.

Conclusions: In patients with Brugada syndrome, there was a significant seasonal peak from spring to early summer and a significant circadian peak from midnight to early morning in terms of the occurrences of VF.