title: Is dual-chamber programming inferior to single-chamber programming in an implantable cardioverter-defibrillator? Results of the INTRINSIC RV (Inhibition of Unnecessary RV Pacing With AVSH in ICDs) study.
abstract: BACKGROUND
  The INTRINSIC RV (Inhibition of Unnecessary RV Pacing with AVSH in ICDs) study tested the hypothesis that dual-chamber rate-responsive (DDDR) with atrioventricular search hysteresis (AVSH) 60-130 programming is not inferior to single-chamber (VVI)-40 programming in an implantable cardioverter defibrillator with respect to all-cause mortality and heart failure hospitalizations using an equivalence margin of 5%.
  
  
  RESULTS
  At 108 centers, 1530 patients with an implantable cardioverter defibrillator indication received a VITALITY AVT (Guidant Corporation, St. Paul, Minn) implantable cardioverter defibrillator programmed consistently to DDDR AVSH 60-130 for the first week. Of those, 988 patients with <20% right ventricular pacing at 1 week were randomized to DDDR AVSH 60-130 or to VVI-40 programming. Among those randomized, 502 were assigned to DDDR AVSH and 486 to VVI. Groups were similar with regard to coronary disease (68%), gender (21% female), and New York Heart Association functional class >I (79%). A total of 32 patients (6.4%) in the DDDR AVSH arm and 46 patients (9.5%) in the VVI arm died or were hospitalized for heart failure during a mean follow-up of 10.4 months (relative risk=0.67, P=0.072 in favor of DDDR AVSH). DDDR AVSH was not inferior to VVI programming (P<0.001). All-cause mortality was not significantly different between the DDDR AVSH arm (3.6%) and the VVI arm (5.1%; P=0.23). The mean percent right ventricular pacing in the DDDR AVSH arm was 10% (median 4%) versus 3% (median 0%) in the VVI arm.
  
  
  CONCLUSIONS
  In the INTRINSIC RV trial, among those randomized, DDDR AVSH was associated with similar outcomes as with VVI backup pacing.
authors.affiliation: University of Iowa Hospitals, 200 Hawkins Dr, Iowa City, IA 52242, USA. brian-olshansky@uiowa.edu
authors.forename: Brian
authors.initials: B
authors.lastname: Olshansky
authors.forename: John D
authors.initials: JD
authors.lastname: Day
authors.forename: Stephen
authors.initials: S
authors.lastname: Moore
authors.forename: Lawrence
authors.initials: L
authors.lastname: Gering
authors.forename: Murray
authors.initials: M
authors.lastname: Rosenbaum
authors.forename: Maureen
authors.initials: M
authors.lastname: McGuire
authors.forename: Scott
authors.initials: S
authors.lastname: Brown
authors.forename: Darin R
authors.initials: DR
authors.lastname: Lerew
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D002318:Cardiovascular Diseases / Q000401:mortality / Q000628:therapy; D017147:Defibrillators, Implantable / Q000592:standards; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged