The objective of this study is to demonstrate the efficacy of the ENDOTAK® RELIANCE™ defibrillation leads connected to a defibrillator or a cardiac resynchronization defibrillator from implant until 12 months.

Baseline and clinical data were collected at inclusion, as were data on procedural characteristics, device implantation-related adverse events and device programming at the time of hospital discharge. Patients were subsequently divided in two groups: patients who underwent VF induction at implantation or before hospital discharge(VF induction group); and patients who did not undergo VF induction (untested group).The patients were followed up at 3-6 months and at12 months after the implantation. VF induction procedures were left to the investigator's discretion, but reasons for not performing a VF induction at implantation were recorded prospectively. ICD programming parameters for tachycardia or bradycardia were also left at the investigator's discretion.

Inclusion Criteria:

• ICD indication according to current guidelines with or without cardiac resynchronization therapy, being implanted with a Guidant ENDOTAK RELIANCE defibrillation lead as first implant, age above 18 years, able to understand the nature of the study and to be available for all follow-ups, having given consent in writing for anonymous data collection, life expectancy > 1 year.

Exclusion Criteria:

• device replacement without concomitant implant of a Reliance defibrillation lead, pregnancy or of birth bearing age without contraception, participation in another clinical study, short life expectancy due to other medical conditions, not willing to sign the consent form, geographically unstable for a defibrillator follow-up as required per protocol, having a ventricular arrhythmia, that can be treated by drugs or surgery

Consecutive patients with the indication for an implantable ICD are invited to participate.