Original Articles
The Prevalence and Prognosis of a Brugada-type Electrocardiogram in a Population of Middle-aged Japanese-American Men with Follow-up of Three Decades

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ABSTRACT

Background

The Brugada syndrome is an inherited arrhythmogenic and nonstructural heart disease associated with an increased risk of sudden cardiac death from ventricular fibrillation. There are conflicting data about its prevalence and prognosis. Particularly, population-based studies are lacking in the United States and other countries.

Methods

A total of 8006 Japanese-American men aged 45 to 68 years participated in the initial examination of the Honolulu Heart Program during the period of 1965 through 1968. After excluding prevalent cases with coronary heart disease, 864 electrocardiograms coded as right bundle branch block were reviewed using the specified criteria for Brugada-type electrocardiogram. Baseline characteristics and the prognosis of Brugada-type electrocardiogram were compared with 5983 control subjects who had electrocardiograms coded as normal at the initial examination.

Results

There were 12 typical cases and 11 atypical cases of Brugada-type electrocardiogram at the initial examination (prevalence, 0.15% and 0.14%, respectively). Analysis of baseline characteristics revealed no difference between control cases and either typical or atypical Brugada-type electrocardiogram cases except significantly lower body mass index in subjects with Brugada-type electrocardiogram. During the 30-year follow-up period, none of the subjects died suddenly within 24 hours after the onset of symptoms. Survival analysis revealed no significant difference between case and control groups.

Conclusions

Brugada-type electrocardiograms among middle-aged or elderly Japanese-American men are uncommon and are not associated with increased risk of either sudden death or total mortality.

Section snippets

Methods

The Honolulu Heart Program is a prospective cohort study of coronary heart disease and stroke among Japanese-American men born between 1900 and 1919 who were living on Oahu, Hawaii in 1965. A total of 8006 men aged 45 to 68 years participated in the initial examination carried out from 1965 to 1968. Details of the procedures of recruiting cohort and the initial examination have been reported elsewhere.12., 13. Continuous surveillance of cardiovascular and cancer morbidity and all mortality

Prevalence

After reviewing 864 ECGs coded as RBBB from patients without history or clinical evidence of coronary heart disease, 12 cases with typical B-ECG and 11 cases with atypical B-ECG were identified. The prevalence rates of typical and atypical B-ECG in our study population was 0.15% and 0.14%, respectively. The prevalence rates by 5-year age group did not show a significant trend, although it was lowest in the oldest age group (Table 1).

Baseline Characteristics

Baseline characteristics are shown in Table 2. Although body

Discussion

Our population study showed a low prevalence rate and excellent prognosis in subjects with B-ECG. Although our study population is limited to older Japanese-American men, this is the first population-based study of B-ECG in the United States.

Conclusion

Our study suggests that middle-aged or elderly Japanese American males with B-ECG found incidentally did not have increased risk of either sudden death or total mortality. Our study further suggests that this ECG pattern is uncommonly observed in middle-aged or elderly community-dwelling men at routine or screening examinations. These results are consistent with the previously reported data by Japanese population-based studies.10., 11. Thus, primary prophylactic use of an automatic implantable

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Sources of support: the National Heart, Lung, and Blood Institute contract N01-HC-05102 and grant U01HL-56274

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