• complications;
  • dual-chamber;
  • heart failure;
  • implantable cardioverter defibrillator;
  • inappropriate therapy;
  • single-chamber

Inappropriate Therapy in Single Versus Dual Chamber


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.


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.


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).


No significant difference was found in inappropriate therapy or complications in patients treated with single- versus dual-chamber ICD devices.