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Frequency of Inappropriate Therapy in Patients Implanted with Dual- Versus Single-Chamber ICD Devices in the ICD Arm of MADIT-CRT


  • Clinical identifier: NCT00180271.

  • The MADIT-CRT study was supported by a research grant from Boston Scientific to the University of Rochester, with funds distributed to the coordination and data center, enrolling centers, core laboratories, committees, and boards under subcontracts from the University of Rochester.

  • This research was performed while Dr. Anne-Christine Ruwald was a Mirowski-Moss Awardee. Dr. Anne-Christine Ruwald has received unrestricted grants from Falck Denmark and The Lundbeck-Foundation. Dr. Zareba reports receiving grant support from Boston Scientific. Dr. Moss reports receiving grant support from Boston Scientific and lecture fees from Boston Scientific, Medtronic, and St. Jude Medical. Dr. Clyne reports receiving grant support from Boston Scientific, Biotronic, and St. Jude Medical as well as honoraria relevant to this topic from Boston Scientific and St. Jude Medical. Dr. Wang reports receiving grant support from Boston Scientific and Medtronic as well as honoraria relevant to this topic from Boston Scientific, Medtronic, St. Jude Medical, and Sorin. Other authors: No disclosures.

Address for correspondence: Anne-Christine H. Ruwald, M.D., Heart Research Follow-Up Program, University of Rochester Medical Center, 265 Crittenden Boulevard, CU 420653 Rochester, NY 14642, USA.

Fax: +1 585 273 5283; E-mail:

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.