title: Frequency and Outcomes of Postrandomization Atrial Tachyarrhythmias in the Resynchronization/Defibrillation in Ambulatory Heart Failure Trial.
abstract: BACKGROUND
  Whether adding cardiac resynchronization therapy (CRT-D) to an implanted cardioverter-defibrillator alters the risk of atrial fibrillation or other atrial tachyarrhythmias (AF/AT), or if postimplantation AF/AT modulate the benefits of CRT-D, remain unknown.
  
  
  RESULTS
  We studied 972 Resynchronization/Defibrillation in Ambulatory Heart Failure Trial (RAFT) participants without permanent AF, who were randomized to CRT-D (n=495) versus nonresynchronization defibrillator (implanted cardioverter-defibrillator; n=477) within the predefined stratum eligible for an atrial lead. Occurrence of postrandomization AF/AT was prospectively assessed, and Cox models were used to test the independent association between the postrandomization AF/AT and the RAFT primary composite outcome of all-cause mortality or hospitalization for heart failure. Over 41 (±19) months, postrandomization AF/AT occurred in 216 (45.3%) patients randomized to implanted cardioverter-defibrillator and 249 (50.3%) randomized to CRT-D. After adjusting for competing risk of death, randomization to CRT-D increased risk of postrandomization AF/AT (hazard ratio, 1.20; 95% confidence interval, 1.00-1.42; P=0.045). Postrandomization AF/AT, which remained paroxysmal in 69.5%, did not reduce biventricular pacing percentage. In adjusted models, postrandomization AF/AT was not associated with the primary outcome (hazard ratio, 1.04; 95% confidence interval, 0.84-1.30). However, AF/AT was associated with a borderline decreased risk of mortality (hazard ratio, 0.75; 95% confidence interval, 0.58-1.00) but increased risk of heart failure hospitalization (hazard ratio, 1.43; 95% confidence interval, 1.08-1.90).
  
  
  CONCLUSIONS
  In RAFT, nearly half of the patients developed postrandomization AF/AT, and those randomized to CRT-D had borderline significant higher risk. Postrandomization AF/AT was associated with risk of heart failure hospitalization, but not with the primary composite outcome.
  
  
  BACKGROUND
  URL: http://www.clinicaltrials.gov. Unique identifier: NCT00251251.
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.). sbwilton@ucalgary.ca.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Wilton
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: Derek V
authors.initials: DV
authors.lastname: Exner
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: D George
authors.initials: DG
authors.lastname: Wyse
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Yetisir
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: George
authors.initials: G
authors.lastname: Wells
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: Anthony S L
authors.initials: AS
authors.lastname: Tang
authors.affiliation: From the Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada (S.B.W., D.V.E., D.G.W.); University of Ottawa Heart Institute, University of Ottawa, Ottawa, Ontario, Canada (E.Y., G.W.); Department of Medicine, Western University, London, United Kingdom (A.S.L.T.); and Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada (J.S.H.).
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Healey
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D058406:Cardiac Resynchronization Therapy / Q000379:methods; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000503:physiopathology*; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy*; D006801:Humans; D015994:Incidence; D008297:Male; D011379:Prognosis; D012307:Risk Factors; D013612:Tachycardia, Ectopic Atrial / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D013997:Time Factors; D016896:Treatment Outcome
keywords: atrial fibrillation; cardiac resynchronization therapy; heart failure; mortality; randomized controlled trial