Acute Feasibility Investigation of a New S-ICD Electrode

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD, EMBLEM®, Boston Scientific Corp) delivers 80 J shocks from an 8 cm left-parasternal coil (LPC) to a 59 cc left lateral pulse generator (PG). A system that defibrillates with lower energy could significantly reduce PG size. Computer modeling and animal studies suggest a 2nd shock coil either parallel (P) to LPC or transverse (T) from xiphoid to PG pocket would significantly reduce shock impedance and defibrillation threshold (DFT).

Objective: Acutely test defibrillation efficacy of P and T configurations in patients receiving an S-ICD.

Methods: Testing was performed in patients receiving a conventional S-ICD system (C) for standard indications. Patients at risk for conversion failure, stroke or infection were excluded. A 65 J success with the conventional S-ICD was required prior to investigational testing. A second electrode was temporarily inserted from the xiphoid incision using the same introducer and sheath tools and connected to the PG with an investigational Y-adapter (Model 3598, Boston Scientific). Phase 1 (n=11) tested only P at a starting energy of 50 J with subsequent tests at 65 or 30 J then 40 or 20 J depending upon outcome. Phase 2 (n=21) tested both P and T in random order, starting at 30 J then either 40 or 20 J.

Key Inclusion Criteria:

• Subject is scheduled to receive a de novo S-ICD system implant per labeled indication.
• Passing S-ICD screening ECG performed per applicable user's manual.
• Subject is willing and capable of providing informed consent specific to local and national laws.
• Subject is age 18 or above, or of legal age to give informed consentspecific to local and national law.

Key Exclusion Criteria:

• Subject has an unusual chest anatomy (eg. pectus excavatum and pectus carinatum) that might impede the ability to temporarily insert a second S-ICD electrode.
• Subject has a left ventricular ejection fraction ≤ 20% within 3 months prior to enrollment.
• Subject has NYHA Class IV or unstable Class III heart failure.
• Subject that, in the opinion of the investigator, cannot tolerate the DFT testing required by this protocol.
• Subject is morbidly obese, defined as BMI ≥ 35.
• Subject has an active infection or has been treated for infection within the past 30 days.
• Subject that, in the opinion of the investigator, has an increased risk of infection.
• Subject is currently requiring/receiving dialysis.
• Subject has insulin-dependent diabetes.
• Subject had/has any prior or planned other surgical procedure within ±30 days of enrollment.
• Subject that, in the opinion of the investigator, has an increased risk for thromboembolic event.
• Subject that, in the opinion of the investigator, has an increased risk of excessive bleeding.
• Subject is currently on an active heart transplant list.