The EFFORTLESS ICD Registry is an observational, standard of care evaluation designed to demonstrate the early, mid and long-term clinical effectiveness the Boston Scientific S-ICD System. In addition, analysis of resource utilization and costs will be performed to document treatment costs for periods defined by Registry endpoints. Protocol 90904928 restricts enrolment to patients over 18 years of age while protocol 90904925 allows all patients to be included.

EFFORTLESS is an observational, post market, standard of care, Registry to be conducted at approximately 50 centers worldwide in patients requiring an ICD for the treatment of ventricular tachyarrhythmias. Patients included in the registry will have been implanted with the S-ICD system since its CE mark (commercial regulatory approval) and will be followed for up to 60 months. The patients' perception of their therapy will be evaluated using Quality of Life assessments and the Registry will include an exploratory analysis of resource utilization and costs based on measures of clinical outcome such as complication rates, unscheduled hospitalizations and length of stay. The objective will be to enable comparison of costs of the S-ICD system versus a standard transvenous system.

An Extension Phase Sub-Study will extend the EFFORTLESS S-ICD Registry in order to achieve an average of approximately 8 years of follow-up from index procedure. A subgroup of approximately 200 patients will be enrolled at a sub-set of EFFORTLESS sites. The data analysis will focus on long-term S-ICD system-related adverse events, S-ICD replacements and device longevity.

Main study:

Inclusion Criteria

1. Age >/= 18yrs
2. Eligible for implantation of an S-ICD system per local clinical guidelines or currently implanted with an S-ICD system (Software (SW) version 1.59.0 or later)
3. Willing and able to provide written informed consent or have informed consent as provided by a legal representative

Exclusion Criteria:

1. Participation in any other investigational study that may interfere with interpretation of the Registry results
2. Incessant ventricular tachycardia and/or spontaneous, frequently recurring ventricular tachycardia that is reliably terminated with anti-tachycardia pacing
3. Patients with unipolar pacemakers or implanted devices that revert to unipolar pacing

Extension Phase Sub-study:

Inclusion Criteria

1. Subjects who are actively enrolled in the EFFORTLESS S-ICD Registry OR Subjects who completed the 5-year follow-up in the EFFORTLESS S-ICD Registry. All clinical events, spontaneous and induced episode data and system replacement or revision data since the last EFFORTLESS S-ICD Annual Follow-Up of the main study must be available in medical files or equivalent.
2. Subjects who are actively implanted with an S-ICD pulse generator (SQ-RX, EMBLEM or EMBLEM MRI) and an S-ICD electrode (Q-TRAK or EMBLEM) or any other future commercial available versions
3. Willing and able to provide written informed consent or have informed consent as provided by a legal representative and willing to participate in all testing and follow-ups as described the Sub-Study protocol
4. Age 18 or above, and of legal age to give informed consent specific to national laws

Exclusion Criteria

1. Subjects with device replacement from the S-ICD to a transvenous ICD
2. Subjects with unipolar pacemakers or implanted devices that revert to unipolar pacing
3. Subjects that are participating in any other investigational study that may interfere with interpretation of the Registry results, without the written approval of Boston Scientific

Post CE mark ICD patients eligible for implantation of the S-ICD system