Focus of the Report: The use of the Subcutaneous Implantable Cardioverter Defibrillator (S-ICD) System for prevention of sudden cardiac death in patients with recurrent ventricular tachycardia.

Technology Description: The S-ICD (Boston Scientific Corp.) is an entirely extrathoracic device that provides cardioversion and defibrillation therapy. It is intended to deliver the same heart-regulating electrical shocks as a transvenous implantable cardioverter defibrillator (TV-ICD) during episodes of ventricular tachyarrhythmia; however, to avoid potential harms associated with transvenous lead placement, the S-ICD employs subcutaneous leads. The S-ICD includes a pulse generator, subcutaneous electrode that contains both sensing and defibrillating components, electrode insertion tool, and device programmer. The system may be implanted under local anesthesia and sedation or under general anesthesia. The S-ICD is implanted in the left lateral thoracic region. The lead is inserted under the skin and the pulse generator is implanted either in a subcutaneous pocket or intramuscularly. Remote monitoring of patients implanted with the S-ICD is possible, which could lead to optimized patient care and early interventions.

Controversy: TV-ICD is the standard technology employed in patients with recurrent arrhythmias for the prevention of sudden cardiac death. Although transvenous lead placement avoids the need for open-chest surgery, it is associated with infection; pneumothorax; venous occlusion; cardiac tamponade; and lead-related problems such as lead adhesion, lead dislocation, lead malfunction, and infection. S-ICD poses potential advantages in patients with vascular access challenges and a high risk of bacteremia, those who are immunocompromised or had a previous TV-ICD removed for infection, and in younger patients who could have lifelong complications from a TV-ICD. S-ICD does not provide anti-tachycardia pacing, pacemaking for bradycardia, or cardiac resynchronization therapy. S-ICD may have a higher cost than TV-ICD, and it needs to be determined whether the comparative safety and efficacy profiles justify use of this more costly device.

Key Questions:

  • Are S-ICDs effective in preventing sudden cardiac death?

  • How do S-ICDs compare with single-chamber or dual-chamber TV-ICDs?

  • Are S-ICDs safe?

  • Have definitive patient selection criteria been identified for the use of S-ICDs?

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