Elsevier

Heart Rhythm

Volume 5, Issue 11, November 2008, Pages 1523-1527
Heart Rhythm

Original-clinical
Seasonal and circadian distributions of ventricular fibrillation in patients with Brugada syndrome

Presented in part at the 29th annual scientific sessions of the Heart Rhythm Society which was held in San Francisco, on May 14–17, 2008, and published in abstract form.
https://doi.org/10.1016/j.hrthm.2008.08.022Get rights and content

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.

Introduction

Brugada syndrome is an arrhythmogenic disease characterized by a particular electrocardiogram (ECG) pattern with a coved-type ST-segment elevation in the right precordial leads and an increased risk for sudden cardiac death due to ventricular tachyarrhythmias.1, 2, 3, 4, 5, 6 It is well-known that the incidence of ventricular tachyarrhythmias, including ventricular tachycardia (VT) and ventricular fibrillation (VF), is the highest in the winter and during the daytime in patients with structural heart disease.7, 8, 9, 10, 11, 12 In patients with Brugada syndrome, however, the seasonal patterns of the development of malignant ventricular tachyarrhythmias remain unknown, and the circadian patterns have been reported in only a small population.4, 13 Identification of the distribution of VF seems to contribute to a therapy option and the elucidation of the underlying pathophysiology of Brugada syndrome. Therefore, we investigated the seasonal and circadian patterns of VF by analyzing the data stored in an implantable cardioverter-defibrillator (ICD) of patients with Brugada syndrome.

Section snippets

Study population

The study population consisted of 62 consecutive patients with Brugada syndrome (58 men and four women, mean age 48 ± 14 years) who received an ICD between July 1992 and October 2005 at National Cardiovascular Center, Suita, Japan. The following devices were implanted: Medtronic 7217CX, 7221CX, 7223CX, 7227CX, 7228CX, 7229CX, 7230CX, 7036CX, and 7274CX; Guidant 1859, 1860, 1861, and 1790; and CPI 1000, 1600, 1718, and 1742. Brugada syndrome was diagnosed when J-wave amplitude was over 0.2 mV

Patient characteristics and VF episodes

Table 1 shows the clinical characteristics and follow-up data of the 62 patients with Brugada syndrome. Forty-seven (76%) patients had a history of VF/CA/unknown syncope. We could obtain the precise data of the first episodes of VF/CA/unknown syncope before implantation of ICD in 44 patients, and seasonal and circadian distributions of the first episodes of VF/CA/unknown syncope are shown in Figure 1, Figure 2. The seasonal distribution of the first episodes of VF/CA/unknown syncope indicated

Discussion

Our study indicates that there are specific seasonal and circadian variations of the VF episodes in patients with Brugada syndrome, which are quite different from those observed in patients with structural heart disease. There was a significant seasonal peak from spring to early summer and a significant circadian peak from midnight to early morning. The seasonal and circadian variations of electrical storms were similar to those of isolated VF episodes. These findings could be related to the

Conclusion

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.

Acknowledgments

We gratefully acknowledge the expert statistical assistance of Akiko Kada.

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