Elective Generator Replacement of the Subcutaneous Implantable Defibrillator-Always a Simple Pit Stop?

Area of Science:

• Cardiology
• Medical Devices
• Electrophysiology

Background:

• Subcutaneous implantable cardioverter-defibrillator (S-ICD) safety and efficacy are established.
• Limited data exists on S-ICD device replacement strategies.
• Understanding long-term performance and replacement impacts is crucial.

Purpose of the Study:

• Evaluate long-term shock efficacy during S-ICD replacement.
• Analyze trends in shock impedance over time.
• Assess the impact of a specific replacement strategy on device performance.

Main Methods:

• Retrospective analysis of 99 S-ICD replacements (Jan 2018 - Nov 2022).
• Measured shock impedance pre- and post-replacement.
• Interventions included lead/generator repositioning and capsulectomy for high impedance.

Main Results:

• Initial shock efficacy was 87%, decreasing to 85% before replacement.
• Shock impedance significantly increased from 82±23 Ω to 98±37 Ω post-implantation (p=0.004).
• Post-replacement interventions (capsulectomy, repositioning) reduced impedance to 81±25 Ω, improving 65J shock efficacy to 95%.

Conclusions:

• Optimized S-ICD replacement strategies achieve high conversion rates.
• Capsulectomy and repositioning are safe and effective for reducing shock impedance.
• These interventions enhance overall S-ICD system performance and reliability.