title: Impact of right ventricular pacing sites on exercise capacity during ventricular rate regularization in patients with permanent atrial fibrillation.
abstract: BACKGROUND
  The deleterious effects of right ventricular apical (RVA) pacing may offset the potential benefit of ventricular rate (VR) regularization and rate adaptation during an exercise in patient's atrial fibrillation (AF).
  
  
  METHODS
  We studied 30 patients with permanent AF and symptomatic bradycardia who receive pacemaker implantation with RVA (n = 15) or right ventricular septal (RVS, n = 15) pacing. All the patients underwent an acute cardiopulmonary exercise testing using VVI-mode (VVI-OFF) and VVI-mode with VR regularization (VRR) algorithm on (VVI-ON).
  
  
  RESULTS
  There were no significant differences in the baseline characteristics between the two groups, except pacing QRS duration was significantly shorter during RVS pacing than RVA pacing (138.9 +/- 5 vs 158.4 +/- 6.1 ms, P = 0.035). Overall, VVI-ON mode increased the peak exercise VR, exercise time, metabolic equivalents (METs), and peak oxygen consumption (VO(2)max), and decreased the VR variability compared with VVI-OFF mode during exercise (P < 0.05), suggesting that VRR pacing improved exercise capacity during exercise. However, further analysis on the impact of VRR pacing with different pacing sites revealed that only patients with RVS pacing but not patients with RVA pacing had significant increased exercise time, METs, and VO(2)max during VVI-ON compared with VVI-OFF, despite similar changes in peaked exercise VR and VR variability.
  
  
  CONCLUSIONS
  In patients with permanent AF, VRR pacing at RVS, but not at RVA, improved exercise capacity during exercise.
authors.affiliation: Department of Medicine, Cardiology Division, The University of Hong Kong, Queen Mary Hospital, Hong Kong, China.. hftse@hkucc.hku.hk
authors.forename: Hung-Fat
authors.initials: HF
authors.lastname: Tse
authors.forename: Chung-Wah
authors.initials: CW
authors.lastname: Siu
authors.forename: Chu-Pak
authors.initials: CP
authors.lastname: Lau
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000628:therapy*; D001919:Bradycardia / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006352:Heart Ventricles; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption