Subcutaneous implantable cardioverter defibrillators in children, young adults and patients with congenital heart disease

The demonstration of severe complications in patients implanted with a transvenous implantable cardioverter defibrillator (ICD) has led to the development of devices equipped with a subcutaneous lead. This new technique offers numerous advantages but also certain disadvantages. Various studies or anecdotal clinical cases have specifically been conducted with this subcutaneous defibrillation system in children and/or patients with congenital heart disease. Results of these studies suggest: 1) a high feasibility despite being limited by a selection process that excludes patients requiring permanent pacing and patients declared ineligible during pre-screening; 2) good efficacy of electrical shocks in reducing induced or spontaneous ventricular arrhythmias; 3) in this specific subset of patients, 2 types of complications have been particularly described: a risk of device exteriorization and infection, and a large number of inappropriate therapies primarily related to T-wave oversensing. The subcutaneous ICD could therefore constitute the gold standard for patients with complex congenital heart disease with no venous access to the heart or with a persistent shunt increasing the risk of systemic emboli as well as in young patients with channelopathy or hypertrophic cardiomyopathy not requiring long-term pacing. Technological change (reduction in device size, better differentiation between R- and T-waves, possibility of pacing if device coupled with a leadless pacemaker) could reduce the limitations and complications and thereby increase the indications in this sub-group of patients.