title: Long-term follow-up of patients supplied with single-chamber or dual-chamber cardioverter defibrillators.
abstract: BACKGROUND
  In patients who have an indication for an implantable cardioverter defibrillator (ICD) a dual-chamber device is indicated in the case of concomitant significant sinus node disease or atrioventricular block. It is a matter of debate whether dual-chamber ICD may be beneficial for patients with preserved sinus and atrioventricular nodal function as data from prospective randomized trials are limited. Mid- or long-term follow-up data are unavailable.
  
  
  RESULTS
  One hundred patients (age 60+/-12 years, 11 women) with the indication for the implantation of an ICD and without antibradycardia pacing indication were randomly assigned to either receive a dual-chamber ICD (n=52) or a single-chamber ICD (n=48). Patients were followed-up for a mean of 52+/-14 months. Mortality and arrhythmogenic morbidity were assessed. All-cause mortality was 21% for single-chamber and 31% for dual-chamber ICD recipients, respectively (P=0.26). Cardiovascular mortality was 13% for single-chamber ICD recipients versus 21% in the dual-chamber group (P=0.25). Subgroup analysis using 35% of ventricular paced beats as cutoff value in the dual-chamber ICD group revealed a 42% mortality rate for the patients with frequent ventricular pacing compared to 10% of patients with a low rate of ventricular pacing (P=0.05, relative risk 4.21, 95% confidence interval: 0.9-19.8). As for arrhythmogenic morbidity, the difference in the ventricular tachyarrhythmia load was not different in both groups (single chamber: 23+/-74 VT episodes, dual chamber: 54+/-134 VT episodes, P=0.17).
  
  
  CONCLUSIONS
  In ICD recipients without conventional indication for dual-chamber pacing, dual chamber compared to single-chamber ICD has no advantage concerning mortality and arrhythmogenic morbidity in a long-term follow-up. In these patients the implantation of a single-chamber device is sufficient.
authors.affiliation: Deutsches Herzzentrum München & 1. Med. Klinik, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany. kolb@dhm.mhn.de
authors.forename: Christof
authors.initials: C
authors.lastname: Kolb
authors.forename: Isabel
authors.initials: I
authors.lastname: Deisenhofer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schmieder
authors.forename: Petra
authors.initials: P
authors.lastname: Barthel
authors.forename: Bernhard
authors.initials: B
authors.lastname: Zrenner
authors.forename: Martin R
authors.initials: MR
authors.lastname: Karch
authors.forename: Claus
authors.initials: C
authors.lastname: Schmitt
mesh_terms: D001145:Arrhythmias, Cardiac / Q000401:mortality* / Q000517:prevention & control*; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D004554:Electric Countershock / Q000295:instrumentation* / Q000379:methods / Q000401:mortality*; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D015996:Survival Rate; D016896:Treatment Outcome