title: Outcomes of cardiac resynchronization therapy in patients with versus those without atrial fibrillation: a systematic review and meta-analysis.
abstract: BACKGROUND
  Whether the benefits observed with cardiac resynchronization therapy (CRT) are similar in patients with versus those without atrial fibrillation (AF) is unclear. Furthermore, whether patients with AF receiving CRT should undergo atrioventricular nodal (AVN) ablation remains uncertain.
  
  
  OBJECTIVE
  The purpose of this study was to compare outcomes in patients with and those without AF receiving CRT and to evaluate the influence of AVN ablation on outcomes in patients with AF.
  
  
  METHODS
  A systematic review and meta-analysis was performed. Outcomes included death, CRT nonresponse, and changes in left ventricular (LV) remodeling, quality of life (QoL), and 6-minute hall walk distance (6MWD).
  
  
  RESULTS
  Twenty-three observational studies were included and followed a total of 7,495 CRT recipients, 25.5% with AF, for a mean of 33 months. AF was associated with an increased risk of nonresponse to CRT (34.5% vs 26.7%; pooled relative risk [RR] 1.32; 95% confidence interval [CI] 1.12, 1.55; P = .001)) and all-cause mortality (10.8% vs 7.1% per year, pooled RR 1.50, 95% CI 1.08, 2.09; P = .015). The presence of AF was also associated with less improvement in QoL, 6-minute hall walk distance, and LV end-systolic volume but not LV ejection fraction. Among patients with AF, AVN ablation appeared favorable with a lower risk of clinical nonresponse (RR 0.40; 95% CI 0.28, 0.58; P <.001) and a reduced risk of death.
  
  
  CONCLUSIONS
  The benefits of CRT appear to be attenuated in patients with AF. The presence of AF is associated with an increased risk of clinical nonresponse and death than in patients without AF. AVN ablation may improve CRT outcomes in patients with AF.
authors.affiliation: Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada. sbwilton@ucalgary.ca
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Wilton
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Leung
authors.forename: William A
authors.initials: WA
authors.lastname: Ghali
authors.forename: Peter
authors.initials: P
authors.lastname: Faris
authors.forename: Derek V
authors.initials: DV
authors.lastname: Exner
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D001283:Atrioventricular Node / Q000503:physiopathology*; D058406:Cardiac Resynchronization Therapy / Q000379:methods*; D006801:Humans; D016896:Treatment Outcome