Safety and efficacy of the totally subcutaneous implantable defibrillator: 2-year results from a pooled analysis of the IDE study and EFFORTLESS registry

Martin C. Burke*, Michael R. Gold, Bradley P. Knight, Craig S. Barr, Dominic A.M.J. Theuns, Lucas V.A. Boersma, Reinoud E. Knops, Raul Weiss, Angel R. Leon, John M. Herre, Michael Husby, Kenneth M. Stein, Pier D. Lambiase

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

385 Scopus citations


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. Objectives 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).

Original languageEnglish (US)
Article number21046
Pages (from-to)1605-1615
Number of pages11
JournalJournal of the American College of Cardiology
Issue number16
StatePublished - Apr 28 2015


  • pacing
  • rhythm disorders
  • tachyarrhythmias
  • ventricular fibrillation

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine


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