With respect to the ST elevation in the
With respect to the ST elevation in the precordial lead, Antzelevitch et al. demonstrated that this can be an cftr of early repolarization or J-wave caused by transient outward current (Ito)-mediated transmural differences in the early phases of the action potential. BS is an inherited disease with a heterogeneous genetic basis . More than 11 genes have been linked to this disease in the last 15 years, although mutations in SCN5A are the most commonly found mutations in 15–30% of Brugada patients.
Prevalence of Brugada syndrome in Japan BS is responsible for 4% of all sudden deaths and for up to 20% of sudden deaths in patients without structural heart disease [2,6]. The estimated prevalence of BS ranges from 4 to 122 per 10,000 inhabitants in Japan. However, many of these reports were published before 2002 when the consensus report for BS was proposed ; thus, the 12-lead electrocardiogram (ECG) definition in many reports included not only the coved ST elevation but also the saddleback ST elevation with a J-wave of amplitude ≥1mm (0.1mV). Furthermore, right bundle branch block (RBBB) was considered to be an essential ECG feature for BS at that time. Miyasaka et al. reported that the coved ST elevation ≥1mm with RBBB was found in 0.12% of 13,929 subjects, with a prevalence of 0.38% in men and 0.03% in women, who were screened during annual health examinations in Moriguchi-city, Osaka . They also indicated that Brugada-pattern ECG was recognized in 0.7% of all subjects but was higher in men (2.14%) when saddleback ST elevation ≥1mm was also included in the Brugada-pattern. In the same study cohort in Moriguchi, Tsuji et al. later reported that 0.26% of subjects demonstrated type 1 Brugada-pattern ECG with or without RBBB . Atarashi et al. evaluated 10,000 ECGs obtained during annual check-ups of working adults in the Tokyo area and found that 16 men (0.16%) showed coved-type ST elevation ≥1mm with RBBB in the right precordial leads . In addition, Matsuo et al. reported that the prevalence of Brugada-pattern ECG with coved or saddleback ST elevation ≥1mm was 0.146% in a survey of ECG records of 4788 atomic-bomb survivors who underwent biennial health examination for 40 years in Nagasaki . Furuhashi et al. also reported that the prevalence of Brugada-pattern ECG was 0.14% in 8612 healthy subjects . A report with an inclusion criterion for Brugada-type ECG of ST elevation >2mm with or without RBBB was published by Sakabe et al. . They evaluated ECGs of 3339 healthy adult subjects who underwent medical examinations annually from 1992 to 2001 and reported that an average 0.28% of subjects showed coved-type ST elevation in the right precordial lead. They also indicated that the majority (97%) of subjects who showed coved-type or saddleback-type ST elevation (1.22%) were men. Oe et al. studied the prevalence of BS in juveniles . They reported that only one (0.005%) of 21,944 first-year elementary school children (6–7 years old) showed a type 1 ECG, and three showed type 2 or type 3 ECGs. Yamakawa et al. investigated the prevalence of Brugada-type ECG (types 1–3) in 20,387 school children between the first grade and tenth grade (from primary school to high school) . They found that only one (0.07%) male student (15 years old) showed a type 1 ECG and one female student (15 years old) showed a type 2 ECG among 1328 high school students. In addition, none of the younger children showed type 1 ECGs, and nine school children had coved or saddleback ST elevation with J-wave amplitude between 1mm and 2mm. They also demonstrated that the prevalence of the Brugada-pattern ECG increased with age (first graders, 0.01%; fourth graders, 0.05%; seventh graders, 0.08%; and tenth graders, 0.23%).
Prevalence of Brugada syndrome in the rest of the world The prevalence of BS is lower in Western countries than in Japan, even when the classification of Brugada-type ECG is required to have a J-wave amplitude ≥2mm and type 1 ECG is required to have an inverted T-wave, because most studies have been conducted after 2002 when the consensus report was published. Data from the Copenhagen City Heart Study, Denmark, in which a total of 42,560 ECGs were registered from 18,974 participants, showed no type 1 Brugada-pattern and 14 type 2 or 3 patterns . In that study, Pecini et al. reported that the prevalence of BS was 0% and that of Brugada-type ECG was 0.07%, although the representative ECG of the type 2 Brugada-pattern clearly showed coved ST elevation with T-wave inversion in lead V2 . Junttila et al. investigated the prevalence of BS in 2479 young subjects and 542 middle-aged subjects in the Finnish population and found no type 1 ECG and 15 (0.61%) type 2 or 3 ECGs . Sinner et al. reported that not a single individual showed a Brugada-type ECG in the investigation of 12-lead resting ECGs of 4149 German subjects . Letsas et al. reported the prevalence of Brugada-type ECG among 11,488 ECGs recorded in a Greek tertiary hospital; 0.02% of subjects demonstrated type 1 ECGs and 0.2% demonstrated type 2 or 3 ECGs . In a report from Italy and the United Kingdom, 0.016% of 12,012 healthy subjects showed type 1 ECGs and 0.26% showed Brugada-type ECGs . Likewise, Brugada-type ECG has infrequently been identified in the United States (0.012%)  and in Canada (0.07%) . The prevalence of Brugada-pattern ECG with J-wave amplitude ≥1mm was reported by Hermida et al. from France . They reported that the typical coved pattern was identified in 0.1% and the saddleback pattern was observed in 6% of 1000 subjects.