title: Association of single- vs dual-chamber ICDs with mortality, readmissions, and complications among patients receiving an ICD for primary prevention.
abstract: OBJECTIVE
  Randomized trials of implantable cardioverter-defibrillators (ICDs) for primary prevention predominantly used single-chamber devices. In clinical practice, patients often receive dual-chamber ICDs, even without clear indications for pacing. The outcomes of dual- vs single-chamber devices are uncertain.
  
  
  OBJECTIVE
  To compare outcomes of single- and dual-chamber ICDs for primary prevention of sudden cardiac death.
  
  
  METHODS
  Retrospective cohort study of admissions in the National Cardiovascular Data Registry's (NCDR) ICD registry from 2006-2009 that could be linked to Centers for Medicare & Medicaid Services fee-for-service Medicare claims data. Patients were included if they received an ICD for primary prevention and did not have a documented indication for pacing.
  
  
  METHODS
  Adjusted risks of 1-year mortality, all-cause readmission, heart failure readmission, and device-related complications within 90 days were estimated with propensity-score matching based on patient, clinician, and hospital factors.
  
  
  RESULTS
  Among 32,034 patients, 12,246 (38%) received a single-chamber device and 19,788 (62%) received a dual-chamber device. In a propensity-matched cohort, rates of complications were lower for single-chamber devices (3.51% vs 4.72%; P < .001; risk difference, -1.20 [95% CI, -1.72 to -0.69]), but device type was not significantly associated with 1-year mortality (unadjusted rate, 9.85% vs 9.77%; hazard ratio [HR], 0.99 [95% CI, 0.91 to 1.07]; P = .79), 1-year all-cause hospitalization (unadjusted rate, 43.86% vs 44.83%; HR, 1.00 [95% CI, 0.97-1.04]; P = .82), or hospitalization for heart failure (unadjusted rate, 14.73% vs 15.38%; HR, 1.05 [95% CI, 0.99-1.12]; P = .19).
  
  
  CONCLUSIONS
  Among patients receiving an ICD for primary prevention without indications for pacing, the use of a dual-chamber device compared with a single-chamber device was associated with a higher risk of device-related complications and similar 1-year mortality and hospitalization outcomes. Reasons for preferentially using dual-chamber ICDs in this setting remains unclear.
authors.affiliation: Department of Medicine, Denver Health Medical Center, 777 Bannock St, MC 0960, Denver, CO 80204, USA. Pamela.Peterson@ucdenver.edu
authors.forename: Pamela N
authors.initials: PN
authors.lastname: Peterson
authors.forename: Paul D
authors.initials: PD
authors.lastname: Varosy
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heidenreich
authors.forename: Yongfei
authors.initials: Y
authors.lastname: Wang
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Dewland
authors.forename: Jeptha P
authors.initials: JP
authors.lastname: Curtis
authors.forename: Alan S
authors.initials: AS
authors.lastname: Go
authors.forename: Robert T
authors.initials: RT
authors.lastname: Greenlee
authors.forename: David J
authors.initials: DJ
authors.lastname: Magid
authors.forename: Sharon-Lise T
authors.initials: SL
authors.lastname: Normand
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Masoudi
mesh_terms: D000368:Aged; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000517:prevention & control*; D003657:Decision Making; D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000706:statistics & numerical data; D004867:Equipment Design; D005260:Female; D006333:Heart Failure; D006801:Humans; D008297:Male; D009026:Mortality / Q000639:trends; D010359:Patient Readmission / Q000706:statistics & numerical data*; D011322:Primary Prevention; D012042:Registries / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012306:Risk; D014481:United States