title: Novel ECG predictor of difficult cases of outflow tract ventricular tachycardia: peak deflection index on an inferior lead.
abstract: BACKGROUND
  An ECG predictor of ablation success has not been determined for difficult cases of outflow tract ventricular tachycardia/ventricular premature contractions (OT-VT/VPC).
  
  
  RESULTS
  ECG analysis and radiofrequency catheter ablation (RFCA) were performed in 70 patients with OT-VT/VPC. The peak deflection index (PDI) was determined in the inferior lead presenting the tallest R wave by dividing the time from QRS onset to peak QRS deflection by total QRS duration. In 10 (14%) of the 70 patients, RFCA performed at a septal or epicardial site was unsuccessful (group 1), but was successful in the remaining 60 patients (group 2). Neither activation time (35+/-15 ms vs 40+/-12 ms, P=0.3) nor QRS duration (141+/-19 ms vs 137+/-19 ms, P=0.6) were significantly different between groups 1 and 2. However, PDI was significantly higher in group 1 than in group 2 (0.62+/-0.06 vs 0.55+/-0.06, P=0.002). A PDI >0.6 identified unsuccessful OT-VT/VPC with 80% sensitivity and 90% specificity, and may indicate that the origin of the OT-VT/VPC is deep within the ventricular septum or at an epicardial site.
  
  
  CONCLUSIONS
  A PDI >0.6 is more likely to be associated with a higher rate of RFCA failure.
authors.affiliation: Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Tokyo, Japan. hh8814.cvm@tmd.ac.jp
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hachiya
authors.forename: Kenzo
authors.initials: K
authors.lastname: Hirao
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Koji
authors.initials: K
authors.lastname: Higuchi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hayashi
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Mihoko
authors.initials: M
authors.lastname: Kawabata
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Isobe
mesh_terms: D000328:Adult; D017115:Catheter Ablation; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D017211:Treatment Failure; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery