title: Anterior-posterior versus anterior-lateral electrode positions for external cardioversion of atrial fibrillation: a randomised trial.
abstract: BACKGROUND
  External cardioversion is a readily available treatment for persistent atrial fibrillation. Although anatomical and electrophysiological considerations suggest that an anterior-posterior electrode position should create a more homogeneous shock-field gradient throughout the atria than an anterior-lateral position, both electrode positions are equally recommended for external cardioversion in current guidelines. We undertook a randomised trial comparing the two positions with the endpoint of successful cardioversion.
  
  
  METHODS
  108 consecutive patients (mean age 60 years [SD 16]) with persistent atrial fibrillation (median duration 5 months, range 0.1-120) underwent elective external cardioversion by a standardised step-up protocol with increasing shock strengths (50-360 J). Electrode positions were randomly assigned as anterior-lateral or anterior-posterior. If sinus rhythm was not achieved with 360 J energy, a single cross-over shock (360 J) was applied with the other electrode configuration. A planned interim analysis was done after these patients had been recruited; it was by intention to treat.
  
  
  RESULTS
  Cardioversion was successful in a higher proportion of the anterior-posterior than the anterior-lateral group (50 of 52 [96%] vs 44 of 56 [78%], difference 23.7% (95% CI 9.1-37.8, p=0.009). Cross-over from the anterior-lateral to the anterior-posterior electrode position was successful in eight of 12 patients, whereas cross-over in the other direction was not successful (two patients). After cross-over, cardioversion was successful in 102 of 108 randomised patients (94%).
  
  
  CONCLUSIONS
  An anterior-posterior electrode position is more effective than the anterior-lateral position for external cardioversion of persistent atrial fibrillation. These results should be considered in clinical practice, for the design of defibrillation electrode pads, and when guidelines for cardioversion of atrial fibrillation are updated.
authors.affiliation: Department of Cardiology and Angiology and Institute for Arteriosclerosis Research, University of Münster, Münster, Germany. kirchhp@uni-muenster.de
authors.forename: Paulus
authors.initials: P
authors.lastname: Kirchhof
authors.forename: Lars
authors.initials: L
authors.lastname: Eckardt
authors.forename: Peter
authors.initials: P
authors.lastname: Loh
authors.forename: Karoline
authors.initials: K
authors.lastname: Weber
authors.forename: Rudolf-Josef
authors.initials: RJ
authors.lastname: Fischer
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Seidl
authors.forename: Dirk
authors.initials: D
authors.lastname: Böcker
authors.forename: Günter
authors.initials: G
authors.lastname: Breithardt
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Haverkamp
authors.forename: Martin
authors.initials: M
authors.lastname: Borggrefe
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000628:therapy*; D018592:Cross-Over Studies; D004554:Electric Countershock / Q000379:methods*; D004566:Electrodes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged