THZ2 Atrial fibrillation is the most common atrial
Atrial fibrillation is the most common atrial arrhythmia studied in BrS [3–14]. The prevalence of AF has been reported to be higher in patients with BrS than in the general THZ2 of the same age [15,16]. Earlier studies reported an approximately 10–50% prevalence of spontaneous, clinical AF in patients with BrS. The most recent studies with larger cohorts reported a prevalence of approximately 5–10% [13,14]. The prevalence of concealed BrS after administration of class IC agents administered for the termination of new-onset AF was reported to be 3.2% overall and 5.8% in patients with AF alone . The prevalence of spontaneous, clinical AVNRT, AVRT, and AT among patients with BrS has been reported to be approximately 7%, 2%, and 3%, respectively . The prevalence of drug-induced type 1 Brugada pattern among patients with spontaneous, clinical AVNRT had been studied by our group and was found to be 27.1%  (Fig. 1).
The most common mode of detection of atrial arrhythmias in the majority of studies was 12-lead ECG and/or Holter monitoring. The incidence of atrial arrhythmias detected by ICD monitoring because of inappropriate shocks during long-term follow-up has been reported to be 4–8.5% [7,18].
The clinical presentation of the J wave syndrome is of paramount importance in determining the true prevalence of atrial arrhythmias. The majority of studies have reported on the prevalence of atrial arrhythmias in BrS cohorts. These patients usually present with symptoms (palpitations, syncope, or cardiac arrest) along with manifested type 1 or suspected type 2 or 3 Brugada pattern and develop type 1 Brugada pattern after the drug challenge test. In contrast, in patients with concealed BrS, type 1 Brugada pattern is unmasked for the first time after administration of class IC agents for the termination of AF [10,13,14]. Another group of patients with concealed BrS presenting with clinical, spontaneous AVNRT or AT/AF and without any signs of Brugada pattern on baseline 12-lead ECG, develop type 1 Brugada pattern with the administration of ajmaline for screening purposes (Figs. 2 and 3).
In terms of ERS, the strongest relationship exists among patients with Wolff–Parkinson–White syndrome (WPWS) [19–25]. The prevalence of inferolateral early repolarization (ER) pattern has been reported to be approximately 40–50% in patients with WPWS prior to and after catheter ablation [22,23]. Following catheter ablation, the ER pattern persists in 25% of patients, disappears in 18% of patients, and newly appears in 10–15% of patients. ER was always observed in leads with positive deflection of the initial part of the delta wave . The inferolateral ER pattern in the general population is not associated with increased risk of AF . In contrast, the prevalence of type 2 Brugada pattern has been demonstrated to be significantly higher in patients with lone AF than in control subjects .
The prevalence of AF and/or AFL has been reported to be approximately 11–16% among patients with SQTS [28,29]. The incidence of AF among family members with SQTS ranges from 26 to 70% [2,30]. AF was more common in patients with type 2 SQTS (63% versus 21%, p=0.012) than in those with other types .
The prevalence of AF and/or AFL has been reported to be approximately 1.7% among patients with LQTS . AF was more common in type 1 (2.4%) than in patients with type 2 LQTS (none). The incidence of atrial arrhythmias (AF and/or AT) detected by ICD monitoring in patients with LQTS during long-term follow-up has been reported to be 33% .
There are anecdotal reports of AF in patients with CPVT [33,34]. In the largest cohort of patients with CPVT, the prevalence of clinical AF and/or AFL has been reported to be 38% .
Epidemiologic implications of atrial arrhythmias The prevalence of diagnosed AF in the general population is closer to 2% . This prevalence increases with age, from <0.5% at 40–50 years, to 5–15% at 80 years. In one recent study, the prevalence of concealed BrS among patients presenting with new-onset AF was found to be 5.8% . All patients had lone AF. If these results could be extrapolated to the entire population, we estimate that nearly 20,000 new cases of AF would be found per year among 1,000,000 persons. Lone AF comprises 5–10% of all AF cases. If the reported prevalence of concealed BrS in patients with new-onset lone AF is confirmed by further studies, the prevalence of concealed BrS may reach approximately 1500 new cases per year among 1,000,000 persons.