LAUSR

The implantable cardioverter defibrillator (ICD) is a firmly established therapy for primary and secondary prevention of sudden cardiac death. Since the first human implantation in 1980, significant advances in ICD technology have been made. Modern transvenous ICDs are miniaturized pectoral devices connected to one or more leads inserted into the venous circulation, and are capable not only of defibrillation but also of pacing and cardiac resynchronization therapy (CRT). Despite continuous technological advances and the proven efficacy of the transvenous ICD, the implantation of these devices continues to carry a non-negligible risk of acute and long-term complications, which are essentially attributable to the endovascular lead(s). Overall, 2.8% to 3.6% of transvenous ICD recipients suffer some lead-related adverse event, such as pneumothorax, hemothorax, pericardial effusion and tamponade, or lead dislodgement during hospitalization for implantation.1 Moreover, lead-related adverse events after hospitalization occur in <0.1 to 6.4% of ICD patients during 2to 70-month follow-up; these include central vein thrombosis and occlusion, tricuspid valve insufficiency, systemic infections and endocarditis, and lead malfunction due to insulation defects or lead fractures, with consequent inappropriate/ineffective therapies and recall/withdrawal of the malfunctioning lead from the market.1 The array of devices that defibrillate the heart has expanded in recent years to include the subcutaneous implantable cardioverter-defibrillator (S-ICD). Introduced in Europe in 2009, the first-generation S-ICD was FDA approved in the United States in September 2012 and the second-generation (EmblemTM, Boston Scientific, Marlborough, MA, USA) in March 2015. The S-ICD consists of a pulse generator implanted in the left mid-axillary line at the fifth intercostal space and an extravascular lead tunneled in the subcutaneous space from the lateral pocket medially to the xiphoid process and then cephalad to the sternum-manubrium just to the left (or right) of the parasternal margin. The subcutaneous lead is equipped with two sensing electrodes separated by an 8-cm shock coil, the proximal electrode usually being placed at the xiphoid process and the distal one at the sterno-manubrium level; this lead has