title: Safety and Efficacy of the Totally Subcutaneous Implantable Defibrillator: 2-Year Results From a Pooled Analysis of the IDE Study and EFFORTLESS Registry.
abstract: BACKGROUND
  The entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) is the first implantable defibrillator that avoids placing electrodes in or around the heart. Two large prospective studies (IDE [S-ICD System IDE Clinical Investigation] and EFFORTLESS [Boston Scientific Post Market S-ICD Registry]) have reported 6-month to 1-year data on the S-ICD.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the safety and efficacy of the S-ICD in a large diverse population.
  
  
  METHODS
  Data from the IDE and EFFORTLESS studies were pooled. Shocks were independently adjudicated, and complications were measured with a standardized classification scheme. Enrollment date quartiles were used to assess event rates over time.
  
  
  RESULTS
  Eight hundred eighty-two patients who underwent implantation were followed for 651±345 days. Spontaneous ventricular tachyarrhythmia (VT)/ventricular fibrillation (VF) events (n=111) were treated in 59 patients; 100 (90.1%) events were terminated with 1 shock, and 109 events (98.2%) were terminated within the 5 available shocks. The estimated 3-year inappropriate shock rate was 13.1%. Estimated 3-year, all-cause mortality was 4.7% (95% confidence interval: 0.9% to 8.5%), with 26 deaths (2.9%). Device-related complications occurred in 11.1% of patients at 3 years. There were no electrode failures, and no S-ICD-related endocarditis or bacteremia occurred. Three devices (0.3%) were replaced for right ventricular pacing. The 6-month complication rate decreased by quartile of enrollment (Q1: 8.9%; Q4: 5.5%), and there was a trend toward a reduction in inappropriate shocks (Q1: 6.9% Q4: 4.5%).
  
  
  CONCLUSIONS
  The S-ICD demonstrated high efficacy for VT/VF. Complications and inappropriate shock rates were reduced consistently with strategic programming and as operator experience increased. These data provide further evidence for the safety and efficacy of the S-ICD. (Boston Scientific Post Market S-ICD Registry [EFFORTLESS]; NCT01085435; S-ICD® System IDE Clinical Study; NCT01064076).
authors.affiliation: Heart Rhythm Center, University of Chicago, Chicago, Illinois. Electronic address: mburke@bsd.uchicago.edu.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Burke
authors.affiliation: Medical University of South Carolina, Charleston, South Carolina.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gold
authors.affiliation: Northwestern University, Chicago, Illinois.
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Knight
authors.affiliation: Russells Hall Hospital, Dudley, United Kingdom.
authors.forename: Craig S
authors.initials: CS
authors.lastname: Barr
authors.affiliation: Erasmus Medical Center, Rotterdam, the Netherlands.
authors.forename: Dominic A M J
authors.initials: DAMJ
authors.lastname: Theuns
authors.affiliation: St. Antonius Ziekenhuis, Nieuwegein, the Netherlands.
authors.forename: Lucas V A
authors.initials: LVA
authors.lastname: Boersma
authors.affiliation: Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Reinoud E
authors.initials: RE
authors.lastname: Knops
authors.affiliation: The Ohio State University, Columbus, Ohio.
authors.forename: Raul
authors.initials: R
authors.lastname: Weiss
authors.affiliation: Emory University, Atlanta, Georgia.
authors.forename: Angel R
authors.initials: AR
authors.lastname: Leon
authors.affiliation: Sentara Cardiology Specialists, Norfolk, Virginia.
authors.forename: John M
authors.initials: JM
authors.lastname: Herre
authors.affiliation: Boston Scientific, St. Paul, Minnesota.
authors.forename: Michael
authors.initials: M
authors.lastname: Husby
authors.affiliation: Boston Scientific, St. Paul, Minnesota.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Stein
authors.affiliation: The Heart Hospital, London, United Kingdom.
authors.forename: Pier D
authors.initials: PD
authors.lastname: Lambiase
mesh_terms: D017147:Defibrillators, Implantable / Q000009:adverse effects; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012042:Registries; D017180:Tachycardia, Ventricular / Q000628:therapy; D016896:Treatment Outcome; D014693:Ventricular Fibrillation / Q000628:therapy
keywords: pacing; rhythm disorders; tachyarrhythmias; ventricular fibrillation