title: Electrocardiographic characteristics of patients with Ebstein's anomaly before and after ablation of an accessory atrioventricular pathway.
abstract: The abnormal development of the tricuspid valve in patients with Ebstein's anomaly results in several activation abnormalities including delayed intraatrial conduction, right bundle branch block (RBBB), and ventricular preexcitation. The aim of the present study was to define the ECG characteristics before and after ablation of an accessory A-V pathway (AP) in patients with Ebstein's anomaly.
  
  
  METHODS
  A series of 226 consecutive patients with Ebstein's anomaly was studied. Sixty-four patients (28%) had documented tachycardia. Thirty-three patients with recurrent tachycardia were found to have a single right-sided AP that was successfully ablated (study group). Thirty patients without tachycardia served as the control group.
  
  
  RESULTS
  Only 21 of 33 patients (62%) had a typical ECG pattern of preexcitation. In addition, none of the patients had an ECG pattern of RBBB during sinus rhythm. In contrast, 28 of 30 (93%) patients in the control group had RBBB (P < 0.001). Radiofrequency catheter ablation resulted in appearance of RBBB in 31 of 33 (94%) patients. The absence of RBBB in patients with Ebstein's anomaly and recurrent tachycardia had a 98% sensitivity and 92% specificity for the diagnosis of an AP. The positive predictive value was 91% (0.77, 0.97 CI 95%) and the negative predictive value was 98% (0.85, 0.99 CI 95%).
  
  
  CONCLUSIONS
  One-third of patients with Ebstein's anomaly and symptomatic tachyarrhythmias have minimal or absent ECG features of ventricular preexcitation. In these patients, the absence of RBBB pattern is a strong predictor of an AP.
authors.affiliation: Electrophysiology Department National Institute of Cardiology Ignacio Chávez, Mexico City, Mexico. pedroi@yahoo.com
authors.forename: Pedro
authors.initials: P
authors.lastname: Iturralde
authors.forename: Santiago
authors.initials: S
authors.lastname: Nava
authors.forename: Gabriel
authors.initials: G
authors.lastname: Sálica
authors.forename: Argelia
authors.initials: A
authors.lastname: Medeiros
authors.forename: Manlio F
authors.initials: MF
authors.lastname: Márquez
authors.forename: Luis
authors.initials: L
authors.lastname: Colin
authors.forename: Diana
authors.initials: D
authors.lastname: Victoria
authors.forename: Alfredo
authors.initials: A
authors.lastname: De Micheli
authors.forename: Mario D
authors.initials: MD
authors.lastname: Gonzalez
mesh_terms: D000328:Adult; D001283:Atrioventricular Node / Q000002:abnormalities* / Q000601:surgery*; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis*; D017115:Catheter Ablation; D004437:Ebstein Anomaly / Q000175:diagnosis* / Q000601:surgery*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011379:Prognosis; D016896:Treatment Outcome; D014261:Tricuspid Valve / Q000002:abnormalities / Q000601:surgery