title: Reasons for failed ablation for idiopathic right ventricular outflow tract-like ventricular arrhythmias.
abstract: BACKGROUND
  The right ventricular outflow tract (RVOT) is the most common site of origin of ventricular arrhythmias (VAs) in patients with idiopathic VAs. A left bundle branch block, inferior axis morphology arrhythmia is the hallmark of RVOT arrhythmias. VAs from other sites of origin can mimic RVOT VAs, and ablation in the RVOT typically fails for these VAs.
  
  
  OBJECTIVE
  To analyze reasons for failed ablations of RVOT-like VAs.
  
  
  METHODS
  Among a consecutive series of 197 patients with an RVOT-like electrocardiographic (ECG) morphology who were referred for ablation, 38 patients (13 men; age 46 ± 14 years; left ventricular ejection fraction 47% ± 14%) in whom a prior procedure failed within the RVOT underwent a second ablation procedure. ECG characteristics of the VA were compared to a consecutive series of 50 patients with RVOT VAs.
  
  
  RESULTS
  The origin of the VA was identified in 95% of the patients. In 28 of 38 (74%) patients, the arrhythmia origin was not in the RVOT. The VA originated from intramural sites (n = 8, 21%), the pulmonary arteries (n = 7, 18%), the aortic cusps (n = 6, 16%), and the epicardium (n = 5, 13%). The origin was within the RVOT in 10 (26%) patients. In 2 (5%) patients, the origin could not be identified despite biventricular, aortic, and epicardial mapping. The VA was eliminated in 34 of 38 (89%) patients with repeat procedures. The ECG features of patients with failed RVOT-like arrhythmias were different from the characteristics of RVOT arrhythmias.
  
  
  CONCLUSIONS
  In patients in whom ablation of a VA with an RVOT-like appearance fails, mapping of the pulmonary artery, the aortic cusps, the epicardium, the left ventricular outflow tract, and the aortic cusps will help identify the correct site of origin. The 12-lead ECG is helpful in differentiating these VAs from RVOT VAs.
authors.affiliation: Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan 48109-5853, USA.
authors.forename: Miki
authors.initials: M
authors.lastname: Yokokawa
authors.forename: Eric
authors.initials: E
authors.lastname: Good
authors.forename: Thomas
authors.initials: T
authors.lastname: Crawford
authors.forename: Aman
authors.initials: A
authors.lastname: Chugh
authors.forename: Frank
authors.initials: F
authors.lastname: Pelosi
authors.forename: Rakesh
authors.initials: R
authors.lastname: Latchamsetty
authors.forename: Krit
authors.initials: K
authors.lastname: Jongnarangsin
authors.forename: Hamid
authors.initials: H
authors.lastname: Ghanbari
authors.forename: Hakan
authors.initials: H
authors.lastname: Oral
authors.forename: Fred
authors.initials: F
authors.lastname: Morady
authors.forename: Frank
authors.initials: F
authors.lastname: Bogun
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000601:surgery*; D002037:Bundle-Branch Block / Q000503:physiopathology / Q000601:surgery*; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017211:Treatment Failure; D014694:Ventricular Outflow Obstruction / Q000503:physiopathology / Q000601:surgery*
keywords: ECG; Failed ablation; Idiopathic ventricular arrhythmia; MRI; Mapping; RVOT; Radiofrequency ablation; VA; VT; electrocardiographic; magnetic resonance imaging; right ventricular outflow tract; ventricular arrhythmia; ventricular tachycardia