A multicenter study of shock pathways for subcutaneous implantable defibrillators

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Devices

Background:

• Subcutaneous implantable cardioverter-defibrillators (ICDs) offer a potential alternative to transvenous systems.
• Higher energy requirements are a challenge for purely subcutaneous ICDs.

Purpose of the Study:

• To identify anteroposterior subcutaneous shock pathways and waveforms for defibrillation efficacy.
• To achieve efficacy comparable to transvenous implantable cardioverter-defibrillators (ICDs).

Main Methods:

• Defibrillation testing in 141 patients with temporary subcutaneous electrodes.
• Evaluation of different electrode pocket locations (inframammary, infraclavicular) and parasternal additions.
• Assessment of various shock waveforms (750 V/270 μF and 1,000 V/160 μF) at 70 J.

Main Results:

• The IM-1-1000 (93%) and IC-2-1000 (86%) configurations showed the highest success rates (≥50 J).
• The IC-2-750 configuration achieved 44% success, while IM-1-750 achieved 74% and IC-1-750 only 11%.

Conclusions:

• Anteroposterior subcutaneous ICD configurations with 160 μF capacitance and 1,000 V can achieve transvenous-comparable defibrillation efficacy.
• Infraclavicular pocket placement is feasible for subcutaneous ICDs when a parasternal coil is added.