title: A novel electrocardiographic criterion for differentiating a left from right ventricular outflow tract tachycardia origin: the V2S/V3R index.
abstract: BACKGROUND
  Although several ECG criteria have been proposed for differentiating between left and right origins of idiopathic ventricular arrhythmias (VA) originating from the outflow tract (OT-VA), their accuracy and usefulness remain limited. This study was undertaken to develop a more accurate and useful ECG criterion for differentiating between left and right OT-VA origins.
  
  
  RESULTS
  We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 207 patients who underwent successful catheter ablation in the right (RVOT; n = 154) or left ventricular outflow tract (LVOT; n = 53). The surface ECGs during the OT-VAs and during sinus beats were analyzed with an electronic caliper. The V2S/V3R index was defined as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT-VA. The V2S/V3R index was significantly smaller for LVOT origins than RVOT origins (P < 0.001). The area under the curve (AUC) for the V2S/V3R index by a receiver operating characteristic analysis was 0.964, with a cut-off value of ≤1.5 predicting an LVOT origin with an 89% sensitivity and 94% specificity. In the AUC and accuracy, the V2S/V3R index was superior to any previously proposed ECG criteria in an analysis of all OT-VAs. This advantage of the V2S/V3R index over the V2 transition ratio and other indices also held true for a subanalysis of 77 OT-VAs with a lead V3 precordial transition.
  
  
  CONCLUSIONS
  The V2S/V3R index outperformed other ECG criteria to differentiate left from right OT-VA origins independent of the site of the precordial transition.
authors.affiliation: Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, Alabama, USA.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshida
authors.forename: Takumi
authors.initials: T
authors.lastname: Yamada
authors.forename: H Thomas
authors.initials: HT
authors.lastname: McElderry
authors.forename: Yasuya
authors.initials: Y
authors.lastname: Inden
authors.forename: Masayuki
authors.initials: M
authors.lastname: Shimano
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Murohara
authors.forename: Vineet
authors.initials: V
authors.lastname: Kumar
authors.forename: Harish
authors.initials: H
authors.lastname: Doppalapudi
authors.forename: Vance J
authors.initials: VJ
authors.lastname: Plumb
authors.forename: G Neal
authors.initials: GN
authors.lastname: Kay
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D017115:Catheter Ablation; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D016278:Ventricular Function, Right; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*
keywords: catheter ablation; electrocardiogram; premature ventricular contraction; ventricular outflow tract; ventricular tachycardia