title: Value of high-density endocardial and epicardial mapping for catheter ablation of hemodynamically unstable ventricular tachycardia.
abstract: BACKGROUND
  Percutaneous epicardial mapping has been used for ablation of recurrent ventricular tachycardia (VT).
  
  
  OBJECTIVE
  The purpose of this study was to use a combined epicardial and endocardial mapping strategy to delineate the myocardial substrate for recurrent VT in both ischemic (n = 12) and nonischemic cardiomyopathy (n = 8), and to define the role of epicardial ablation.
  
  
  METHODS
  Electroanatomic mapping was performed in 20 patients. High-density voltage maps were obtained by acquiring both endocardial and epicardial electrograms. Electrograms derived from six patients with structurally normal hearts were used as controls. A total of 26 VTs were targeted in the 20 patients.
  
  
  RESULTS
  Most VTs (23/26 [88.5%]) were hemodynamically unstable. In patients with ischemic cardiomyopathy, the extent of endocardial scar was greater than epicardial scar. A definable pattern of scar could not be demonstrated in nonischemic cardiomyopathy. Pathologic examination of explanted hearts in two patients with nonischemic cardiomyopathy demonstrated that low-voltage areas were not always predictive of scarred myocardium. A substrate-based approach was used for catheter ablation. Catheter ablation was performed on the endocardium in all patients; additional epicardial delivery of radiofrequency energy was required in 8 (40%) of 20 patients for successful ablation. During follow-up (12 +/- 4 months), 15 (75%) of 20 patients have been arrhythmia-free.
  
  
  CONCLUSIONS
  Patients with ischemic cardiomyopathy tend to have a larger endocardial than epicardial scar. Use of epicardial and endocardial electroanatomic mapping to define the full extent of myocardial scars allows successful catheter ablation in patients with hemodynamically unstable VTs.
authors.affiliation: UCLA Cardiac Arrhythmia Center, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Cesario
authors.forename: Marmar
authors.initials: M
authors.lastname: Vaseghi
authors.forename: Noel G
authors.initials: NG
authors.lastname: Boyle
authors.forename: Michael C
authors.initials: MC
authors.lastname: Fishbein
authors.forename: Miguel
authors.initials: M
authors.lastname: Valderrábano
authors.forename: Calambur
authors.initials: C
authors.lastname: Narasimhan
authors.forename: Isaac
authors.initials: I
authors.lastname: Wiener
authors.forename: Kalyanam
authors.initials: K
authors.lastname: Shivkumar
mesh_terms: D000328:Adult; D000368:Aged; D009202:Cardiomyopathies / Q000503:physiopathology; D016022:Case-Control Studies; D017115:Catheter Ablation; D002921:Cicatrix / Q000473:pathology / Q000503:physiopathology; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D004699:Endocardium / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000503:physiopathology; D010496:Pericardium / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D013610:Tachycardia / Q000503:physiopathology / Q000601:surgery*