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  • With respect to the ST elevation in the

    2019-05-15

    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 [5]. 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 [7]; 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 [8]. 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 [9]. 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 [10]. 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 [11]. Furuhashi et al. also reported that the prevalence of Brugada-pattern ECG was 0.14% in 8612 healthy subjects [12]. A report with an inclusion criterion for Brugada-type ECG of ST elevation >2mm with or without RBBB was published by Sakabe et al. [13]. 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 [14]. 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) [15]. 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 [16]. 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 [16]. 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 [17]. 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 [18]. 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 [19]. 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 [20]. Likewise, Brugada-type ECG has infrequently been identified in the United States (0.012%) [21] and in Canada (0.07%) [22]. The prevalence of Brugada-pattern ECG with J-wave amplitude ≥1mm was reported by Hermida et al. from France [23]. They reported that the typical coved pattern was identified in 0.1% and the saddleback pattern was observed in 6% of 1000 subjects.