title: Electrocardiographic predictors of Brugada type response during Na channel blockade challenge.
abstract: OBJECTIVE
  To identify ECG predictors of Brugada type response during Na channel blockade challenge.
  
  
  METHODS
  We studied prospectively 103 patients (M = 76, 45 +/- 13 years) in whom ECGs were collected during ajmaline challenge. ECG recordings included the high right precordial leads (-2V(1) and -2V(2)). A positive response was defined by a >0.2 mV J point or ST segment elevation and a down-sloping pattern of the ST segment in at least one right precordial lead.
  
  
  RESULTS
  Ajmaline challenge was positive in 48 (47%) of the 103 cases. Baseline J wave elevation was greater in -2V(1) (0.077 +/- 0.078 mV vs. 0.038 +/- 0.046 mV, P = 0.003) and -2V(2) (0.149 +/- 0.103 mV vs. 0.043 +/- 0.088 mV, P < 0.001) in cases with a subsequent positive response. In contrast, ST segment elevation and T wave amplitudes were reduced in V(1), V(2) and V(3). Logistic regression showed that J wave elevation in -2V(2) and decreased T wave amplitude in V(3) at baseline were independent predictors of a positive response. Baseline J wave elevation >0.16 mV in -2V(2) had a specificity of 100%, a sensitivity of 40%, a positive predictive value of 100% and a negative predictive value of 28%.
  
  
  CONCLUSIONS
  J wave elevation >0.16 mV in -2V(2) was the strongest predictor of a Brugada type response to Na channel blockade challenge when Brugada syndrome was suspected on a baseline ECG.
authors.affiliation: Amiens-Picardie University Hospital, Hôpital Sud, France. hermida.jean-sylvain@chu-amiens.fr
authors.forename: Jean-Sylvain
authors.initials: JS
authors.lastname: Hermida
authors.forename: Isabelle
authors.initials: I
authors.lastname: Denjoy
authors.forename: Geneviève
authors.initials: G
authors.lastname: Jarry
authors.forename: Serge
authors.initials: S
authors.lastname: Jandaud
authors.forename: Cathy
authors.initials: C
authors.lastname: Bertrand
authors.forename: Jean
authors.initials: J
authors.lastname: Delonca
mesh_terms: D000404:Ajmaline; D000704:Analysis of Variance; D000889:Anti-Arrhythmia Agents; D002037:Bundle-Branch Block / Q000175:diagnosis*; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D015222:Sodium Channels / Q000187:drug effects
chemical_list: D000889:Anti-Arrhythmia Agents; D015222:Sodium Channels; D000404:Ajmaline