title: Worldwide experience with a totally subcutaneous implantable defibrillator: early results from the EFFORTLESS S-ICD Registry.
abstract: OBJECTIVE
  The totally subcutaneous implantable-defibrillator (S-ICD) is a new alternative to the conventional transvenous ICD system to minimize intravascular lead complications. There are limited data describing the long-term performance of the S-ICD. This paper presents the first large international patient population collected as part of the EFFORTLESS S-ICD Registry.
  
  
  RESULTS
  The EFFORTLESS S-ICD Registry is a non-randomized, standard of care, multicentre Registry designed to collect long-term, system-related, clinical, and patient reported outcome data from S-ICD implanted patients since June 2009. Follow-up data are systematically collected over 60-month post-implant including Quality of Life. The study population of 472 patients of which 241 (51%) were enrolled prospectively has a mean follow-up duration of 558 days (range 13-1342 days, median 498 days), 72% male, mean age of 49 ± 18 years (range 9-88 years), 42% mean left ventricular ejection fraction. Complication-free rates were 97 and 94%, at 30 and 360 days, respectively. Three hundred and seventeen spontaneous episodes were recorded in 85 patients during the follow-up period. Of these episodes, 169 (53%) received therapy, 93 being for Ventricular Tachycardia/Fibrillation (VT/VF). One patient died of recurrent VF and severe bradycardia. Regarding discrete VT/VF episodes, first shock conversion efficacy was 88% with 100% overall successful clinical conversion after a maximum of five shocks. The 360-day inappropriate shock rate was 7% with the vast majority occurring for oversensing (62/73 episodes), primarily of cardiac signals (94% of oversensed episodes).
  
  
  CONCLUSIONS
  The first large cohort of real-world data from an International patient S-ICD population demonstrates appropriate system performance with clinical event rates and inappropriate shock rates comparable with those reported for conventional ICDs. Clinical trial registration URL: http://www.clinicaltrials.gov. Unique identifier NCT01085435.
authors.affiliation: Cardiology Department, The Heart Hospital, Institute of Cardiovascular Science, University College London, 16-18 Westmoreland Street, W1G 8PH London, UK pier.lambiase@uclh.nhs.uk.
authors.forename: Pier D
authors.initials: PD
authors.lastname: Lambiase
authors.affiliation: Cardiology Department, Russells Hall Hospital, Dudley, UK.
authors.forename: Craig
authors.initials: C
authors.lastname: Barr
authors.affiliation: Department of Clinical Electrophysiology, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Dominic A M J
authors.initials: DA
authors.lastname: Theuns
authors.affiliation: Department of Cardiology and Electrophysiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Reinoud
authors.initials: R
authors.lastname: Knops
authors.affiliation: Department of Cardiology, Homnolka Hospital, Prague, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Neuzil
authors.affiliation: Department of Cardiology, Electrophysiology Section, Odense University Hospital, Odense, Denmark.
authors.forename: Jens Brock
authors.initials: JB
authors.lastname: Johansen
authors.affiliation: Auckland City Hospital, Auckland, New Zealand.
authors.forename: Margaret
authors.initials: M
authors.lastname: Hood
authors.affiliation: Center of Research on Psychology in Somatic Diseases, Department of Medical and Clinical Psychology, Tilburg University, Tilburg, The Netherlands Department of Cardiology, Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Susanne
authors.initials: S
authors.lastname: Pedersen
authors.affiliation: Division of Electrophysiology, Campus Grosshadern, University of Munich, Munich, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kääb
authors.affiliation: King's College Hospital, London, UK.
authors.forename: Francis
authors.initials: F
authors.lastname: Murgatroyd
authors.affiliation: Boston Scientific Corporation, St Paul MN, USA.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Reeve
authors.affiliation: Boston Scientific Corporation, St Paul MN, USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Carter
authors.affiliation: St Antonius Ziekenhuis, Nieuwegein, The Netherlands.
authors.forename: Lucas
authors.initials: L
authors.lastname: Boersma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001145:Arrhythmias, Cardiac / Q000628:therapy*; D002648:Child; D017147:Defibrillators, Implantable / Q000009:adverse effects / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D019919:Prosthesis Implantation / Q000379:methods; D011788:Quality of Life; D012042:Registries; D061665:Time-to-Treatment; D016896:Treatment Outcome; D055815:Young Adult
keywords: Cardiac arrest; Primary prevention; Secondary prevention; Subcutaneous ICD; Ventricular arrhythmias