title: New electrocardiographic criteria for discriminating between Brugada types 2 and 3 patterns and incomplete right bundle branch block.
abstract: OBJECTIVE
  The aim of this study was to evaluate new electrocardiographic (ECG) criteria for discriminating between incomplete right bundle branch block (RBBB) and the Brugada types 2 and 3 ECG patterns.
  
  
  BACKGROUND
  Brugada syndrome can manifest as either type 2 or type 3 pattern. The latter should be distinguished from incomplete RBBB, present in 3% of the population.
  
  
  METHODS
  Thirty-eight patients with either type 2 or type 3 Brugada pattern that were referred for an antiarrhythmic drug challenge (AAD) were included. Before AAD, 2 angles were measured from ECG leads V(1) and/or V(2) showing incomplete RBBB: 1) α, the angle between a vertical line and the downslope of the r'-wave, and 2) β, the angle between the upslope of the S-wave and the downslope of the r'-wave. Baseline angle values, alone or combined with QRS duration, were compared between patients with negative and positive results on AAD. Receiver-operating characteristic curves were constructed to identify optimal discriminative cutoff values.
  
  
  RESULTS
  The mean β angle was significantly smaller in the 14 patients with negative results on AAD compared to the 24 patients with positive results on AAD (36 ± 20° vs. 62 ± 20°, p < 0.01). Its optimal cutoff value was 58°, which yielded a positive predictive value of 73% and a negative predictive value of 87% for conversion to type 1 pattern on AAD; α was slightly less sensitive and specific compared with β. When the angles were combined with QRS duration, it tended to improve discrimination.
  
  
  CONCLUSIONS
  In patients with suspected Brugada syndrome, simple ECG criteria can enable discrimination between incomplete RBBB and types 2 and 3 Brugada patterns.
authors.affiliation: Arrhythmia Unit, Department of Cardiology, Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 46, Lausanne, Switzerland.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Chevallier
authors.forename: Andrei
authors.initials: A
authors.lastname: Forclaz
authors.forename: Joanna
authors.initials: J
authors.lastname: Tenkorang
authors.forename: Yannis
authors.initials: Y
authors.lastname: Ahmad
authors.forename: Mohamed
authors.initials: M
authors.lastname: Faouzi
authors.forename: Denis
authors.initials: D
authors.lastname: Graf
authors.forename: Juerg
authors.initials: J
authors.lastname: Schlaepfer
authors.forename: Etienne
authors.initials: E
authors.lastname: Pruvot
mesh_terms: D000328:Adult; D000404:Ajmaline; D000889:Anti-Arrhythmia Agents; D053840:Brugada Syndrome / Q000145:classification* / Q000175:diagnosis*; D002037:Bundle-Branch Block / Q000175:diagnosis*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D015203:Reproducibility of Results
chemical_list: D000889:Anti-Arrhythmia Agents; D000404:Ajmaline