title: Predictors of pacemaker dependence and pacemaker dependence as a predictor of mortality in patients with implantable cardioverter defibrillator.
abstract: BACKGROUND
  The prevalence, predictors, and survival for the development of pacemaker dependence (PD) in patients implanted with an implantable cardioverter defibrillator (ICD) are unknown.
  
  
  METHODS
  This was a retrospective analysis of 1,550 consecutive patients with ICD implantation at a single center from 1996 to 2008 with a mean of 4.2 ± 3.4 years. Patients with implant intrinsic heart rates less than 40 beats/min (n = 48) and cardiac resynchronization therapy (n = 444) were excluded leaving 1,058 patients in this study. PD was defined as an intrinsic rhythm <40 beats/min after inhibiting the pacemaker, <50 beats/min with transient symptoms of dizziness relieved by resumption of pacing and right ventricle pacing despite algorithms to promote intrinsic conduction at the 3 monthly follow-up ICD clinic visits. Multivariate regression and Cox proportional hazard models were used for analysis.
  
  
  RESULTS
  The mean age was 64 ± 13 years; 79% were male with a primary indication for the ICD in 57%. PD occurred in 142 (13.4%) of patients, with a mean time to PD of 2.6 ± 1.9 years. PD was associated with a 48% increased odds for mortality versus non-PD ICD patients during the mean follow-up time of 4.2 ± 3.4 years (adjusted odds ratio = 1.48 [95% confidence interval 1.080-2.042]; P = 0.015). Older age, a history of atrial fibrillation, amiodarone use, and secondary prevention were the strongest predictors for the development of PD.
  
  
  CONCLUSIONS
  In this single-center ICD cohort, the development of PD was not uncommon and was associated with decreased survival.
authors.affiliation: Division of Cardiology, Lahey Clinic, Burlington, Massachusetts, USA.
authors.forename: Nitesh
authors.initials: N
authors.lastname: Sood
authors.forename: Eric
authors.initials: E
authors.lastname: Crespo
authors.forename: Meir
authors.initials: M
authors.lastname: Friedman
authors.forename: Danette
authors.initials: D
authors.lastname: Guertin
authors.forename: Steven
authors.initials: S
authors.lastname: Zweibel
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kluger
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Clyne
mesh_terms: D001145:Arrhythmias, Cardiac / Q000401:mortality* / Q000517:prevention & control*; D001900:Boston / Q000453:epidemiology; D002304:Cardiac Pacing, Artificial / Q000401:mortality* / Q000706:statistics & numerical data; D003131:Combined Modality Therapy; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D004554:Electric Countershock / Q000401:mortality* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis
keywords: defibrillation - ICD; electrophysiology - clinical