Algorithm-Based Screening May Improve Patient Selection for the Subcutaneous Implantable Defibrillator.

Area of Science:

• Cardiology
• Medical Devices
• Electrophysiology

Background:

• Standard screening for subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy can yield false positive and false negative results.
• Accurate patient selection is crucial for effective S-ICD implantation and therapy.

Purpose of the Study:

• To describe and evaluate algorithm-based screening using an external S-ICD.
• To assess the device's rhythm discrimination algorithm for sensing capabilities.
• To determine if this method improves upon standard screening accuracy.

Main Methods:

• Algorithm-based screening was performed on 15 patients using an external S-ICD, assessing sensing at rest and during exercise across three vectors.
• Patients were categorized into two groups: those who failed standard screening (Group 1) and those who passed with abnormal ECGs (Group 2).
• Implantation decisions were based on adequate sensing during algorithm-based screening, with follow-up for appropriate/inappropriate shocks.

Main Results:

• Six of eight patients who failed standard screening demonstrated adequate sensing with the external S-ICD and were implanted.
• Among the implanted patients in Group 1, one inappropriate shock occurred during a median 17-month follow-up; two ventricular fibrillation episodes were successfully treated.
• In Group 2, two of seven patients showed inadequate sensing with the external S-ICD; no shocks were observed during 10 months of follow-up.

Conclusions:

• Algorithm-based screening with an external S-ICD may enhance patient selection for S-ICD therapy.
• This approach has the potential to decrease false positive and false negative outcomes associated with standard screening methods.
• Further evaluation is warranted to confirm the clinical utility of algorithm-based screening in S-ICD patient selection.