The subcutaneous array: a new lead adjunct for the transvenous ICD to lower defibrillation thresholds

Area of Science:

• Cardiovascular Medicine
• Medical Devices
• Electrophysiology

Background:

• Transvenous implantable cardioverter defibrillators (ICDs) are crucial for managing life-threatening arrhythmias.
• Patients with high defibrillation thresholds (DFTs) face safety concerns due to inadequate margins between DFT and maximum defibrillator energy.
• A novel approach is needed to improve safety margins in patients with high DFTs.

Purpose of the Study:

• To evaluate the efficacy of a new subcutaneous lead array (SQ Array) as an adjunct to transvenous ICD leads.
• To determine if the SQ Array can reduce DFTs and enhance safety margins in patients undergoing ICD implantation.
• To assess the potential of the SQ Array to obviate the need for thoracotomy in patients with high DFTs.

Main Methods:

• A prospective study involving 20 patients undergoing ICD implantation.
• Intraoperative comparison of transvenous lead-alone DFTs versus lead-SQ Array DFTs in the same patients.
• DFT measurements were performed using a standardized step-down/step-up protocol, with the proximal coil serving as the anode for lead-alone and the proximal coil and SQ Array as a common anode for the adjunct.

Main Results:

• The lead-SQ Array demonstrated a statistically significant reduction in mean monophasic DFT from 23.3 J (lead-alone) to 13.5 J (lead-SQ Array) (P < 0.001).
• This represents an average DFT reduction of 9.8 J (40.6%) with the SQ Array.
• Six patients with initial lead-alone DFTs > 25 J achieved adequate DFT reduction with the SQ Array, avoiding thoracotomy.

Conclusions:

• The subcutaneous lead array (SQ Array) is an effective adjunct for lowering DFTs in patients receiving transvenous ICDs.
• The SQ Array significantly improves safety margins, particularly in patients with high DFTs.
• This adjunct offers a viable alternative to thoracotomy for selected patients requiring ICD implantation with high DFTs.