Worldwide Experience With a Totally Subcutaneous Implantable Defibrillator

Early Results From the EFFORTLESS S-ICD Registry

Pier D. Lambiase; Craig Barr; Dominic A.M.J. Theuns; Reinoud Knops; Petr Neuzil; Jens Brock Johansen; Margaret Hood; Susanne Pedersen; Stefan Kääb; Francis Murgatroyd; Helen L. Reeve; Nathan Carter; Lucas Boersma


Eur Heart J. 2014;35(25):1657-1665. 

In This Article

Abstract and Introduction


Aims. 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.

Methods and 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).

Conclusion. 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. 


Sudden cardiac death (SCD) occurs in ~50,000–70,000 patients annually in the UK, proportionate numbers of patients in other European countries and >350,000 patients in the USA.[1] Implantable cardioverter-defibrillators (ICDs) were first introduced into clinical practice in 1980[2] and since then multiple randomized, multicentre trials have shown significant survival benefits in primary and secondary prevention populations.[3–6] Despite the recognized mortality benefit, there are significant co-morbidities associated with ICD therapy especially in young primary prevention patients due to the high incidence of acute and chronic transvenous lead complications.[7,8] These include systemic infections, acute and chronic displacement, pneumothorax, cardiac perforation, and tamponade as well as inappropriate shocks associated with insulation failure or lead fractures.[9,10] Cumulative data suggest that there may be at least a 20% risk of transvenous lead failure at 8–10 years post-implant[11,12] and complication rates may also be higher in the paediatric ICD population where long term (5–12 year) reports indicate rates of at least 40%.[13,14] Since complications increase with multiple procedures, this further places younger ICD patients at considerable risk of long-term device-related morbidities.

The entirely subcutaneous ICD system (S-ICD System, Cameron Health/Boston Scientific) was developed to provide an alternative to the transvenous ICD system, as it is implanted with no transvenous/epicardial leads. Early studies demonstrating its feasibility and safety have been published[15] as well as small cohorts, single country, and individual case studies.[16–21] However to date, there is no long-term 'real-world' data demonstrating the performance of the system in a multicentre, heterogeneous ICD population. The purpose of the ongoing Evaluation oF FactORs ImpacTing CLinical Outcome and Cost EffectiveneSS of the S-ICD (EFFORTLESS S-ICD) Registry is to document clinical-, system-, and patient-related outcome data from S-ICD patients implanted since the commercial release of the S-ICD.[22] This paper documents the early results from the EFFORTLESS S-ICD Registry.