title: Importance of Ventricular Tachycardia Induction and Mapping for Patients Referred for Epicardial Ablation.
abstract: BACKGROUND
  Many nonischemic cardiomyopathy (NICMP) patients referred for catheter ablation of ventricular tachycardia (VT) undergo an initial epicardial approach under general anesthesia (GA). However, GA may suppress inducibility and decrease tolerance of induced VT, leaving substrate modification as the sole ablation method.
  
  
  OBJECTIVE
  Determine the utility of a strategy of initial programmed electrical stimulation (PES) under light sedation in patients referred for epicardial ablation of VT.
  
  
  METHODS
  Of 68 NICMP patients referred for VT ablation, 25 were referred specifically for epicardial ablation. All patients underwent PES under conscious sedation, with conversion to GA and epicardial access only if VT morphology and/or endocardial mapping suggested an epicardial substrate.
  
  
  RESULTS
  VT was induced with PES in 24 of 25 patients (mean age 52 years; 76% male; ejection fraction 38 ± 18%). VT was hemodynamically tolerated in 63% and unstable in 38% of patients. The noninducible/unstable VT patients underwent substrate modification based on voltage and pace mapping. Of the patients with stable VT, 73% were mapped and ablated endocardially (six right ventricle, three left ventricle, one left coronary cusp, one middle cardiac vein), and 33% were successfully ablated in areas of normal endocardial voltage. After ablation, the clinical VT was noninducible in all patients. After mean follow-up of 10 months, 80% were free of implantable cardioverter defibrillator shocks or sustained VT.
  
  
  CONCLUSIONS
  An initial approach of PES and entrainment mapping under conscious sedation is critically important for patients with NICMP referred for epicardial ablation. Empiric ablation of endocardial/epicardial scar would have missed the clinical VT in 20% of patients.
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Babak
authors.initials: B
authors.lastname: Nazer
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Christopher
authors.initials: C
authors.lastname: Woods
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dewland
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Brian
authors.initials: B
authors.lastname: Moyers
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Nitish
authors.initials: N
authors.lastname: Badhwar
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California San Francisco, San Francisco, California.
authors.forename: Edward P
authors.initials: EP
authors.lastname: Gerstenfeld
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation; D056149:Epicardial Mapping; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000601:surgery*; D055815:Young Adult
keywords: epicardial ablation; nonischemic cardiomyopathy; ventricular tachycardia