title: Electroanatomic substrate and ablation outcome for suspected epicardial ventricular tachycardia in left ventricular nonischemic cardiomyopathy.
abstract: OBJECTIVE
  The aim of the study was to define the epicardial substrate and ablation outcome in patients with left ventricular nonischemic cardiomyopathy (NICM) and suspected epicardial ventricular tachycardia (VT).
  
  
  BACKGROUND
  Ventricular tachycardia in NICM often originates from the epicardium.
  
  
  METHODS
  Twenty-two patients with NICM underwent detailed endocardial and epicardial bipolar voltage maps and VT ablation for suspected epicardial VT. Eight patients with normal hearts and idiopathic VT served to define normal epicardial electrograms. Low-voltage regions were also assessed for wide (>80 ms), split, or late electrograms.
  
  
  RESULTS
  Normal epicardial bipolar voltage was identified as >1.0 mV on the basis of the reference population. Confluent low-voltage areas were present in 18 epicardial (82%) and 12 endocardial (54%) maps and were typically over basal lateral LV. In the 18 patients with epicardial VT on the basis of activation/pacemapping, the mean epicardial area was greater than the endocardial low-voltage area (55.3 +/- 33.5 cm(2) vs. 22.9 +/- 32.4 cm(2), p < 0.01). Epicardial low-voltage areas showed 49.7% wide (>80 ms), split, and/or late electrograms rarely seen in the reference patients (2.3%). During follow-up of 18 +/- 7 months, ablation resulted in VT elimination in 15 of 21 patients (71%) including 14 of 18 patients (78%) with epicardial VT.
  
  
  CONCLUSIONS
  In patients with NICM and VT of epicardial origin, the substrate is characterized by areas of basal LV epicardial > endocardial bipolar low voltage. The electrograms in these areas are not only small (<1.0 mV) but wide (>80 ms), split, and/or late, and help identify the substrate targeted for successful ablation.
authors.affiliation: Electrophysiology Section, Cardiovascular Division, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Oscar
authors.initials: O
authors.lastname: Cano
authors.forename: Mathew
authors.initials: M
authors.lastname: Hutchinson
authors.forename: David
authors.initials: D
authors.lastname: Lin
authors.forename: Fermin
authors.initials: F
authors.lastname: Garcia
authors.forename: Erica
authors.initials: E
authors.lastname: Zado
authors.forename: Rupa
authors.initials: R
authors.lastname: Bala
authors.forename: Michael
authors.initials: M
authors.lastname: Riley
authors.forename: Joshua
authors.initials: J
authors.lastname: Cooper
authors.forename: Sanjay
authors.initials: S
authors.lastname: Dixit
authors.forename: Edward
authors.initials: E
authors.lastname: Gerstenfeld
authors.forename: David
authors.initials: D
authors.lastname: Callans
authors.forename: Francis E
authors.initials: FE
authors.lastname: Marchlinski
mesh_terms: D000328:Adult; D000368:Aged; D018780:Body Surface Potential Mapping; D054849:Cardiac Electrophysiology; D009202:Cardiomyopathies / Q000503:physiopathology* / Q000601:surgery; D017115:Catheter Ablation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010496:Pericardium / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000503:physiopathology* / Q000601:surgery; D016896:Treatment Outcome