The entirely subcutaneous implantable defibrillator (S-ICD) (Emblem, Boston Scientific, Marlborough, MA, USA) was introduced as a new therapeutic alternative to the conventional transvenous ICD in 2009 and implantations are rapidly expanding since then.1 Implantation of the S-ICD seems to reduce implant-related perioperative complications such as pneumothorax, hematoma and cardiac tamponade.

The aim of this multicenter registry is thus to assess the outcome of patients following an S-ICD implantation in a real-world setting.

The S-ICD has a CE mark and is FDA approved since 2012 and is mentioned as a potential therapy strategy in the current AHA guidelines on the management of patients with ventricular arrhythmias.2 However, although implant-related complications seem to be reduced by the S-ICD in randomized controlled trials, the rate of inappropriate shocks remains high in S-ICD patients (10-13%).3-5 The most common reason for inappropriate shocks is cardiac oversensing, mostly due to T-wave oversensing or low amplitude of the subcutaneous signal, which not commonly found in patients with transvenous ICDs. Data on the role of the Defibrillation Threshold Testing (DFT), the rate of infectious complications (lead or device complications), the use of the S-ICD in children and adolescents, and the outcome of patients with an S-ICD according to their underlying cardiac substrate are sparse. The aim of this multicenter registry is thus to assess the outcome of patients following an S-ICD implantation in a real-world setting with a special focus on perioperative complication rate, the role of DFT testing in S-ICD, the use of the S-ICD in cohorts that are underrepresented in clinical studies (adolescents and geriatrics), the outcome and risk factors of ineffective, inappropriate and appropriate shocks and the differences in outcomes according to the underlying cardiac disease.

Inclusion Criteria:

• Implantation of an S-ICD, regardless of the technique
• At least 1 month of follow up
• At least 1 post-implantation assessment, in accordance to the routine clinical practice of every center (e.g. in person visit or remote follow up)

Exclusion Criteria:

- none

Patients in whom a S-ICD was implanted for primary or secondary prevention