Seasonal, weekly, and circadian distribution of ventricular fibrillation in patients with J‐wave syndrome from the J‐PREVENT registry

BACKGROUND: Ventricular fibrillation (VF) in Brugada syndrome (BrS) is known to occur more frequently during nighttime and from spring to early summer. In this study, we investigated whether early repolarization syndrome (ERS) has the same seasonal, weekly, and circadian distribution of VF events as BrS using data from the "J-wave associated with prior cardiac event" (J-PREVENT) registry. METHODS: The study included 90 consecutive patients with BrS and 31 patients with ERS during a mean follow-up of 49±37 months. Follow-up data from implantable cardioverter-defibrillators were evaluated in all cases. RESULTS: In patients with ERS, the circadian distribution of VF episodes differed among the four 6-h periods, with a significant peak from midnight to 6:00 am (p<0.01) similar to that observed in BrS patients. However, VF occurred more frequently on weekends in patients with ERS, whereas on weekdays in patients with BrS (p<0.01). The months of peak VF occurrence also differed between the groups, with the frequency of VF episodes at peak between December and March in ERS patients and between March and June in BrS patients. In ERS patients, VF events had an inverse correlation with air temperature (r=-0.726, p<0.01). CONCLUSIONS: ERS and BrS patients show similar nighttime increases in the occurrence of VF, but different seasonal and weekly distributions, suggesting a pathophysiological difference between the two syndromes.