title: Randomized controlled trial of fixed rate versus rate responsive pacing after radiofrequency atrioventricular junction ablation: quality of life, ventricular refractoriness, and paced QT dispersion.
abstract: BACKGROUND
  Ablation of the AV junction is a widely accepted treatment of drug-refractory atrial fibrillation. Long-term pacing of the right ventricular (RV) apex following AV junction ablation can result in adverse cardiac remodeling. However, anecdotal studies report that pacing too slowly following AV junction ablation was associated with propensity to sudden cardiac death. The aim of this study was to provide information about the balance between measures of quality of life versus measures of electrical remodeling achieved by pacing with different rate modalities in a randomized pilot clinical trial.
  
  
  RESULTS
  Patients with permanent atrial fibrillation were randomized to VVI (80 beats/min) versus VVIR (minimum rate 80 beats/min), whereas patients with paroxysmal atrial fibrillation were randomized to DDI versus DDDR pacing at discharge from hospital. Serially, measurements of exercise capacity, quality of life, cycle length dependence of QT dispersion (QTdisp), RV refractoriness, and the incidence of nonsustained ventricular tachycardia were made in 28 patients over a 6-month follow-up period. Time-dependent increases in QTdisp were observed in patients randomized to the rate responsive mode (RR-ON) but only when paced at 40 beats/min. This was paralleled by time-dependent increases in RV refractoriness (270 +/- 11 ms at baseline to 302 +/- 5 ms at 6 months) in patients with RR-ON. RR-ON also was associated with trends to an increasing incidence of episodes of nonsustained ventricular tachycardia and worsening of some measures of quality of life. Exercise capacity was not substantially different in the randomized groups.
  
  
  CONCLUSIONS
  Rate responsive pacing results in electrical remodeling of the ventricle following AV junction ablation, but exercise capacity was similar in groups with RR-ON or RR-OFF.
authors.affiliation: Cardiovascular Disease Research Group, University of Calgary Health Sciences Centre, HSC 1632, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1. hduff@ucalgary.ca
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Duff
authors.forename: Satish R
authors.initials: SR
authors.lastname: Raj
authors.forename: Derek V
authors.initials: DV
authors.lastname: Exner
authors.forename: Robert S
authors.initials: RS
authors.lastname: Sheldon
authors.forename: Dan
authors.initials: D
authors.lastname: Roach
authors.forename: L Brent
authors.initials: LB
authors.lastname: Mitchell
authors.forename: D George
authors.initials: DG
authors.lastname: Wyse
authors.forename: Margaret
authors.initials: M
authors.lastname: Morck
authors.forename: Anne M
authors.initials: AM
authors.lastname: Gillis
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000517:prevention & control / Q000601:surgery / Q000628:therapy*; D001283:Atrioventricular Node / Q000601:surgery*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D017115:Catheter Ablation / Q000379:methods*; D003131:Combined Modality Therapy / Q000379:methods; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011182:Postoperative Care / Q000379:methods*; D011788:Quality of Life; D016896:Treatment Outcome