title: QRS characteristics fail to reliably identify ventricular tachycardias that require epicardial ablation in ischemic heart disease.
abstract: OBJECTIVE
  We tested proposed algorithms for idiopathic and nonischemic tachycardias for their ability to identify epicardial LV-VT origins.
  
  
  BACKGROUND
  Several ECG features have been reported to identify epicardial origins for left ventricular tachycardias (LV-VTs) in the absence of myocardial infarction. Only limited data exist in postinfarction patients.
  
  
  METHODS
  The QRS features of 24 VTs that were ablated from the epicardium and 39 left ventricular VTs ablated from the endocardium were retrospectively analyzed for various 12-lead ECG features previously reported.
  
  
  RESULTS
  No ECG feature consistently predicted an epicardial LV-VT origin in infarct-related tachycardias, with epicardial VTs showing slightly longer QRS durations (189 ± 32 ms in epicardial vs 179 ± 37 ms in endocardial, P = 0.28). Pseudo-delta duration was 38 ± 27 versus 47 ± 27 ms (P = 0.2), intrinsicoid deflection time 93 ± 35 versus 86 ± 32 ms (P = 0.4), shortest RS 97 ± 38 versus 99 ± 32 ms (P = 0.77), and median deflection index 0.82 ± 0.25 versus 0.87 ± 0.22 (P = 0.43). The finding of a Q wave in lead I and the absence of a Q wave in the inferior leads failed to predict an epicardial origin in superior LV-VT sites. Q waves in any inferior lead and aVR/aVL-ratio<1 were not specific for an epicardial origin in inferior sites (all P = ns). Furthermore, all inferior LV-VTs showed a Q wave in the inferior leads which correlated with pre-existing Q-waves in sinus rhythm (P = 0.045).
  
  
  CONCLUSIONS
  Proposed 12-lead ECG features for differentiation of epicardial versus endocardial sites for nonischemic LV-VTs do not reliably identify VTs that require ablation from the epicardium. Endocardial mapping should be the first approach to catheter ablation for VTs in patients with ischemic heart disease.
authors.affiliation: Cardiac Arrhythmia Division, Brigham and Women's Hospital, Boston, Massachusetts, USA. martin.martinek@elisabethinen.or.at
authors.forename: Martin
authors.initials: M
authors.lastname: Martinek
authors.forename: William G
authors.initials: WG
authors.lastname: Stevenson
authors.forename: Keiichi
authors.initials: K
authors.lastname: Inada
authors.forename: Michifumi
authors.initials: M
authors.lastname: Tokuda
authors.forename: Usha B
authors.initials: UB
authors.lastname: Tedrow
mesh_terms: D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology / Q000627:therapeutic use; D017115:Catheter Ablation / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D010496:Pericardium / Q000187:drug effects / Q000503:physiopathology* / Q000601:surgery; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy
chemical_list: D000889:Anti-Arrhythmia Agents