Shock Testing to Unmask RV Lead and GEnerator Malfunction in ICD Patients: the SURGE-ICD Registry

Inclusion Criteria: * Age ≥ 18 years * Informed, written consent * Status post ICD implantation, including CRT-D * Battery in EOL, ERM or ERI, ERT with indication for elective ICD generator replacement or patients presenting for electrical cardioversion for atrial arrhythmia. Exclusion Criteria: * Age \< 18 years * Pregnancy * Patients under guardianship or with mental disorders/disabilities * Recent adequate and successful ICD shock therapy (within the past 12 months) * Patients in the cardioversion arm with low battery (\<1 year to ERI/RRT) * Patients with intracardiac thrombus * Participation in any other investigational study that may interfere with interpretation of the study and registry results * Indications of an already compromised RV lead (Pacing impedance \<200 or \>2000 Ohm, Pacing threshold \>5V/0.4ms, RV Sensing \<4mV, HV impedance \>80, presence of lead noise) * Systems with recalled leads or leads known to have an elevated failure risk: Riata™ and Riata ST™ (St. Jude Medical, St. Paul, Minnesota, USA), Sprint Fidelis™ (Medtronic, Minneapolis, Minnesota, USA)