Usefulness of the Lead Repositioning to Improve Subcutaneous Electrocardiogram Sensing in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy with the Subcutaneous Implantable Cardioverter-Defibrillator

The EMBLEM entirely subcutaneous implantable cardioverter-defibrillator (S-ICD) system (Boston Scientific, Marlborough, MA) was introduced as a new alternative to the conventional transvenous ICD and has been expected to reduce device-related complications, especially in young patients who require long-term lead placement.1,2 Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a well-known hereditary disease recognized as a cause of sudden cardiac death (SCD) in young adults.3 However, the usefulness of S-ICD in patients with ARVC has not been established because of the low QRS amplitude of subcutaneous electrocardiogram (S-ECG) followed by the high incidence of inappropriate shock (IAS) delivery owing to oversensing.4,5 Here we report 2 cases of ARVC in which S-ECG had sensing problems, which were resolved by repositioning the S-ICD leads. Key Teaching Points • Temporal change of QRS amplitude in subcutaneous electrocardiogram (S-ECG) can occur in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). • Repositioning of subcutaneous implantable cardioverter-defibrillator lead is useful for achieving better S-ECG in patients with ARVC. • Exercise test after lead repositioning is necessary for prevention of oversensing and achieving optimal sensing.