title: Incidence and Clinical Significance of Brugada Syndrome Masked by Complete Right Bundle-Branch Block.
abstract: BACKGROUND
  Brugada syndrome (BrS)-type electrocardiogram (ECG) is concealed by complete right bundle-branch block (CRBBB) in some cases of BrS. Clinical significance of BrS masked by CRBBB is not well known.
  
  
  RESULTS
  We reviewed an ECG database of 326 BrS patients who had type 1 ECG with or without pilsicainide. "BrS masked by CRBBB" was defined on ECG as <2-mm elevation of the J point at the time of CRBBB in the right precordial leads, and BrS-type J-point elevation ≥2 mm at the time of normalized QRS complex on relieved CRBBB. We identified 25 BrS patients (7.7%) with persistent (n=12) or intermittent CRBBB (n=13). Relief of CRBBB by pacing was performed in patients with persistent CRBBB. The prevalence of BrS masked by CRBBB was 3.1% (10/326 patients). Three patients had type 1 ECG, and 7 patients had type 2 or 3 ECG on relief of CRBBB. Two of these 10 patients had lethal arrhythmic events during the follow-up period (mean, 86.4±57.2 months). There was no prognostic difference between BrS masked by CRBBB and other BrS.
  
  
  CONCLUSIONS
  In a small BrS population, CRBBB can completely mask typical BrS-type ECG. BrS masked by CRBBB is associated with the same risk of fatal ventricular tachyarrhythmia as other BrS.
authors.affiliation: Department of Cardiovascular Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Wada
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nagase
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Morita
authors.forename: Koji
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishii
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Nakamura
authors.forename: Kunihisa
authors.initials: K
authors.lastname: Kohno
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ito
authors.forename: Kengo F
authors.initials: KF
authors.lastname: Kusano
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohe
mesh_terms: D000328:Adult; D053840:Brugada Syndrome / Q000453:epidemiology / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000453:epidemiology / Q000503:physiopathology*; D016208:Databases, Factual; D004562:Electrocardiography; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D017180:Tachycardia, Ventricular / Q000453:epidemiology / Q000503:physiopathology