title: Percent right ventricular pacing predicts outcomes in the DAVID trial.
abstract: BACKGROUND
  The Dual-Chamber and VVI Implantable Defibrillator (DAVID) trial demonstrated a worse outcome in patients with implantable cardioverter-defibrillators (ICDs) programmed to DDDR at 70 bpm compared with patients who had ICDs programmed to VVI backup pacing at 40 bpm. Pacing was more frequent in the DDDR group.
  
  
  OBJECTIVE
  The purpose of this study was to determine whether right ventricular pacing (RV) is an independent predictor of outcome in the DAVID trial.
  
  
  METHODS
  We evaluated the relationship of percent RV pacing to the composite endpoint of death or hospitalization for congestive heart failure. Patients who had a 3-month follow-up and who had not yet reached an endpoint were included in the study. Using Cox regression analysis (VVI group N = 195; DDDR group N = 185), we examined multiple factors, including percent RV pacing at 3-month follow-up, that might be associated with adverse outcomes.
  
  
  RESULTS
  Percent RV pacing as a continuous variable was correlated with the primary endpoint. As a dichotomous variable, the best separation for predicting endpoints occurred with DDDR RV pacing > 40% vs DDDR RV pacing < or = 40% (P = .025). Patients with DDDR RV pacing < or = 40% had similar or better outcomes to the VVI backup group (P = .07). Correction for baseline variables predictive of the composite outcome in the (nonpaced) VVI group (use of nitrates, increased heart rate, and increased age) did not change the findings for RV pacing (P = .008). In contrast, atrial pacing was not predictive of worse outcomes.
  
  
  CONCLUSIONS
  These results suggest, but do not prove, a causal relationship between frequent RV pacing and adverse outcomes in patients with left ventricular ejection fraction < or = 40%.
authors.affiliation: Regional Cardiology Associates, Sacramento, California 95819, USA. asharma@rcamd.com
authors.forename: Arjun D
authors.initials: AD
authors.lastname: Sharma
authors.forename: Carlos
authors.initials: C
authors.lastname: Rizo-Patron
authors.forename: Alfred P
authors.initials: AP
authors.lastname: Hallstrom
authors.forename: Gearoid P
authors.initials: GP
authors.lastname: O'Neill
authors.forename: Stephen
authors.initials: S
authors.lastname: Rothbart
authors.forename: James B
authors.initials: JB
authors.lastname: Martins
authors.forename: Marc
authors.initials: M
authors.lastname: Roelke
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Steinberg
authors.forename: H Leon
authors.initials: HL
authors.lastname: Greene
mesh_terms: D002304:Cardiac Pacing, Artificial; D017147:Defibrillators, Implantable; D006333:Heart Failure / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology*; D006760:Hospitalization; D006801:Humans; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D016032:Randomized Controlled Trials as Topic; D013318:Stroke Volume; D013610:Tachycardia / Q000401:mortality / Q000628:therapy*; D013997:Time Factors; D016896:Treatment Outcome