The 4-SITE Field Following Study (4-SITE FF)

Inclusion Criteria: Study Specific: * ICD / CRT-D Indication according to normal clinical practice * Patients receiving: * a single or dual chamber 4-SITE compatible ICD * or a 4-SITE compatible CRT-D * one of the RELIANCE 4-SITE defibrillation leads * Patients currently implanted with a pacemaker * upgraded to a 4-SITE compatible ICD or CRT-D (4-SITE header) * one of the RELIANCE 4-SITE defibrillation leads General: * Willing and capable of providing informed consent for * undergoing a 4-SITE system implant, * participating in all testing associated with this clinical investigation at an approved clinical investigational centre and at the intervals defined by this protocol * Geographically stable patients who are available for follow-up at a study centre * Age 18 or above, or of legal age to give informed consent specific to national law Exclusion Criteria: Study Specific: * ICD and CRT-D Patients scheduled for a device replacement * CRM Patients who have or who would need an lead adaptor * All patients who have an active or non-active defibrillation lead other than 4-SITE General: * Not willing and not capable of providing informed consent, undergoing a device implant, participating in all testing associated with this clinical investigation (including VT/VF shock conversion) at an approved clinical investigational centre and at the intervals defined by this protocol * Patients who were in NYHA Class IV during the last 3 month * Patients with pre-existing diseases, which may confound study results * Patients currently requiring dialysis, * Cancer patients * Patients with drug and/or alcohol abuse history * Life expectancy \< 12 months (or expected heart transplant within 12 months) * Patients on a Heart Transplant List * Women who are pregnant or plan to become pregnant. Method of assessment per physician discretion. * Enrolled in any other concurrent study