title: Prevalence of externalized conductors in Riata and Riata ST silicone leads: results from the prospective, multicenter Riata Lead Evaluation Study.
abstract: OBJECTIVE
  Following a class I recall of St. Jude Medical Riata/Riata ST silicone implantable cardioverter-defibrillator leads, we report on the phase I results of the Riata Lead Evaluation Study, a prospective, multicenter investigation to assess the prevalence of externalized conductors (ECs) and the electrical dysfunction in these leads.
  
  
  METHODS
  We enrolled patients previously implanted with Riata/Riata ST leads and performed cinefluoroscopy using multiple views. A physician panel adjudicated the images for the presence of EC. The prevalence of EC was stratified and compared by lead model and patient characteristics. Upon occurrence of a lead revision, another physician panel determined whether electrical dysfunction had occurred based on predefined criteria.
  
  
  RESULTS
  Seven hundred seventy six patients with Riata/Riata ST silicone leads (8Fr/7Fr = 66.6%/33.4%; single-/dual-coil = 12.9%/87.1%) across 23 centers were analyzed. Implant duration was 4.8 ± 0.9 years for 7Fr and 6.5 ± 1.6 years for 8Fr leads (P <.001). The prevalence of EC was significantly lower in 7Fr compared with 8Fr leads for the entire study population (9.3% vs 24.2%, P < .001) and for leads implanted ≤6 years (9.4% vs 18.8%, P = .006). Other than lead size, there were no significant differences in lead, patient, or electrical characteristics between leads with and without EC. Over a period of 9.8 ± 2.0 months, the overall prevalence of electrical dysfunction was 1.3% (confidence interval 0.49%-2.1%), with only 3 of 10 cases occurring in leads with EC.
  
  
  CONCLUSIONS
  Larger-diameter Riata leads were more prone to EC than smaller-diameter Riata ST leads. The prevalence of electrical dysfunction was not associated with EC.
authors.affiliation: Mayo Clinic, Rochester, Minnesota. Electronic address: dhayes@mayo.edu.
authors.forename: David
authors.initials: D
authors.lastname: Hayes
authors.forename: Roger
authors.initials: R
authors.lastname: Freedman
authors.forename: Anne B
authors.initials: AB
authors.lastname: Curtis
authors.forename: Mark
authors.initials: M
authors.lastname: Niebauer
authors.forename: G
authors.initials: G
authors.lastname: Neal Kay
authors.forename: Jay
authors.initials: J
authors.lastname: Dinerman
authors.forename: Scott
authors.initials: S
authors.lastname: Beau
mesh_terms: D000368:Aged; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000628:therapy*; D002933:Cineradiography; D017147:Defibrillators, Implantable; D004553:Electric Conductivity; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012826:Silicone Elastomers; D013318:Stroke Volume; D014481:United States / Q000453:epidemiology
chemical_list: D012826:Silicone Elastomers
keywords: BMI; EC; ETFE; Externalized conductors; HVLI; High-voltage leads; ICD; Implantable cardioverter-defibrillator; RV; body mass index; ethylene tetrafluoroethylene; externalized conductors; high-voltage lead impedance; implantable cardioverter-defibrillator; right ventricular