title: Defibrillation energy requirements in an ICD population receiving cardiac resynchronization therapy.
abstract: OBJECTIVE
  While defibrillation energy requirements (DERs) have been extensively studied in patients receiving conventional defibrillators, the DERs of patients receiving cardiac resynchronization therapy with defibrillation capability (CRT-D) devices have not been well described. The purpose of this analysis was to characterize DERs (defined as true threshold or the presence of appropriate safety margins) in patients undergoing implant of a CRT-D and to determine whether DERs in this population were similar to those reported for patients undergoing implantation of conventional defibrillators.
  
  
  METHODS
  Data were analyzed retrospectively from the VENTAK CHF/CONTAK CD biventricular pacing study. An appropriate safety margin of at least 10 J was verified with at least two successful conversions with 21 J or less. Multivariate logistic regression was performed to determine baseline predictors of failed DER testing.
  
  
  RESULTS
  Of 501 patients enrolled, 444 (89%) had successful DER test outcomes. Of the remaining 57 patients, 34 converted with energies > or = 21J, and 23 had their testing terminated prematurely or were not tested, primarily due to patient condition. Larger left ventricular internal dimension in diastole (P = 0.003) and prolonged procedure time (P = 0.01) were significant predictors of higher energy requirements. Few significant complications arose from DER testing.
  
  
  CONCLUSIONS
  DER testing can be accomplished safely and successfully in the majority of CRT-D patients. However, safety margins cannot be ascertained in a significant number of these patients. Left ventricular inner diameter in diastole (LVIDd) and prolonged procedure time may predict higher DERs, and could be used to anticipate the need for a high-energy device or inclusion of a subcutaneous array.
authors.affiliation: Henry Ford Hospital, Detroit, Michigan, USA. cschuge1@hfhs.org
authors.forename: Claudio
authors.initials: C
authors.lastname: Schuger
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Ellenbogen
authors.forename: Mitchell
authors.initials: M
authors.lastname: Faddis
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
authors.forename: Patrick
authors.initials: P
authors.lastname: Yong
authors.forename: Ross
authors.initials: R
authors.lastname: Sample
mesh_terms: D000368:Aged; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D017147:Defibrillators, Implantable; D004554:Electric Countershock; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012189:Retrospective Studies; D016896:Treatment Outcome