title: Frequency of inappropriate therapy in patients implanted with dual- versus single-chamber ICD devices in the ICD arm of MADIT-CRT.
abstract: BACKGROUND
  The majority of implantable cardioverter defibrillators (ICDs) are dual-chamber devices, but studies on the frequency of inappropriate therapy in dual- versus single-chamber devices have shown conflicting results. The aim of this study is to determine whether implantation of dual-chamber ICD devices decrease the incidence of inappropriate therapy without an unacceptable increase in complications.
  
  
  METHODS
  In the ICD arm of the MADIT-CRT study (N = 704), comparisons of single- versus dual-chamber ICD devices were investigated on the endpoints of inappropriate therapy (antitachycardia pacing [ATP] and shocks) and device- and procedure-related complications by use of multivariate Cox proportional hazard regression analysis (hazard ratio dual:single chamber) adjusting for relevant covariates.
  
  
  RESULTS
  The frequency of inappropriate therapies in single- and dual-chamber recipients was 41/294 (14%) and 50/410 (12%), respectively. There was no significant difference in overall inappropriate therapy (hazard ratio [HR] = 0.95 [CI: 0.63-1.45], P = 0.95) or inappropriate ATP (HR = 0.98 [CI: 0.61-1.58], P = 0.94), between single- and dual-chamber devices, using single-chamber as a reference (Dual:Single). However, there was a trend toward a decrease in inappropriate shocks (HR = 0.60 [CI: 0.34-1.08], P = 0.09) in the dual-chamber group. The same was evident when only analyzing inappropriate therapy for atrial tachyarrhythmias (HR = 0.88 [CI: 0.56-1.38], P = 0.58). There was no significant difference between the groups in device- or procedure-related complications (HR = 1.54 [CI: 0.82-2.90], P = 0.18).
  
  
  CONCLUSIONS
  No significant difference was found in inappropriate therapy or complications in patients treated with single- versus dual-chamber ICD devices.
authors: Heart Research Follow-Up Program, University of Rochester Medical Center, Rochester, NY 14642, USA. anne.ruwald@heart.rochester.edu
authors: Anne-Christine H
authors: AC
authors: Ruwald
authors: Nitesh
authors: N
authors: Sood
authors: Martin H
authors: MH
authors: Ruwald
authors: Christian
authors: C
authors: Jons
authors: Christopher A
authors: CA
authors: Clyne
authors: Scott
authors: S
authors: McNitt
authors: Paul
authors: P
authors: Wang
authors: Wojciech
authors: W
authors: Zareba
authors: Arthur J
authors: AJ
authors: Moss
mesh_terms: D000368:Aged; D009202:Cardiomyopathies / Q000628:therapy*; D017147:Defibrillators, Implantable / Q000009:adverse effects; D004867:Equipment Design; D005260:Female; D006333:Heart Failure / Q000628:therapy*; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models