Safety and Performance of the Subcutaneous Implantable Cardioverter Defibrillator Detection Algorithm INSIGHT^TM in...

Area of Science:

• Cardiology
• Biomedical Engineering

Background:

• Subcutaneous implantable cardioverter-defibrillators (S-ICDs) offer protection but lack backup pacing.
• Combining S-ICDs with pacemakers is a potential solution, but compatibility data are limited.
• This study investigates the safety and efficacy of S-ICD use in patients with pacemakers.

Purpose of the Study:

• To evaluate the safety and efficacy of using a subcutaneous implantable cardioverter-defibrillator (S-ICD) in patients who also have a pacemaker.
• To identify potential issues, specifically oversensing, arising from the combination of these devices.

Main Methods:

• 74 patients with bipolar pacemakers were prospectively enrolled.
• Pacemaker stimulation modes were tested for T-wave oversensing (TWOS).
• A functional S-ICD dummy was used with epicutaneous placement to record S-ECG in all vectors and stimulation settings.

Main Results:

• 21.6% of patients experienced oversensing events during programmed stimulation, potentially leading to inappropriate VT/VF detection.
• Oversensing was triggered by pacing spikes, QRS complexes, PVCs, and TWOS.
• Oversensing occurred even with bipolar stimulation and was linked to lung emphysema and reduced QRS amplitude.

Conclusions:

• Combining S-ICDs with pacemakers can lead to inadequate shock delivery due to oversensing, even with bipolar pacing.
• Standard screening may not adequately predict oversensing in pacemaker patients.
• Testing with an epicutaneous S-ICD dummy across all vectors and stimulation settings is recommended for patients with pre-existing pacemakers.