title: System survival of nontransvenous implantable cardioverter-defibrillators compared to transvenous implantable cardioverter-defibrillators in pediatric and congenital heart disease patients.
abstract: BACKGROUND
  Nontransvenous (NTV) implantable cardioverter-defibrillator (ICD) systems with pericardial and/or subcutaneous coils are used in select pediatric and congenital heart disease patients who are not candidates for transvenous ICD leads. Outcomes with these hybrid configurations are not well understood.
  
  
  OBJECTIVE
  The purpose of this study was to compare survival of NTV ICD systems to standard transvenous (TV) ICD systems.
  
  
  METHODS
  We conducted a retrospective single-center study in which the TV group was matched to the NTV group 2:1 by type of cardiac disease and implant date.
  
  
  RESULTS
  There were 39 patients in the NTV group and 78 matched in the TV group. Compared to the TV group, the NTV group was younger (median 7 vs 20 years) with a smaller body surface area at implant (0.9 vs 1.8 m(2); both P <.001). Median follow-up in the NTV group was 17 months. System survival at 12, 24, and 36 months was 73%, 55%, and 49% in the NTV group versus 91%, 83%, and 76% in the TV group (P = .003). A multivariable Cox proportional hazards model including group, body surface area, and age at implant revealed the NTV group to be an independent predictor of system failure (hazard ratio 2.9, P = .04). Rate of total unanticipated interventions in the NTV group was 18 versus 6 per 1,000 person-months in the TV group. In patients with NTV systems, 23% received appropriate shocks and 18% received inappropriate shocks.
  
  
  CONCLUSIONS
  Survival of ICD systems using NTV defibrillation coils is significantly shorter than with TV ICD systems. Although NTV systems provide protection for this unique subset of patients, more durable options are needed.
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Radbill
authors.forename: John K
authors.initials: JK
authors.lastname: Triedman
authors.forename: Charles I
authors.initials: CI
authors.lastname: Berul
authors.forename: Francis
authors.initials: F
authors.lastname: Fynn-Thompson
authors.forename: Joseph
authors.initials: J
authors.lastname: Atallah
authors.forename: Mark E
authors.initials: ME
authors.lastname: Alexander
authors.forename: Edward P
authors.initials: EP
authors.lastname: Walsh
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D017147:Defibrillators, Implantable; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000628:therapy*; D006331:Heart Diseases / Q000000981:diagnostic imaging / Q000628:therapy*; D006801:Humans; D008297:Male; D016016:Proportional Hazards Models; D011859:Radiography; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D055815:Young Adult