Study Description The purpose of this study is to compare the defibrillation efficacy between the 50/50% tilt biphasic waveform and the Tuned biphasic waveform utilizing High Voltage Lead Integrity Check (HVLIC) impedance.

Hypothesis The Tuned waveform reduces defibrillation thresholds (DFTs) when compared to the 50/50% tilt waveform.

Study Methods

• This is an acute, paired-sample, randomized (waveform testing sequence) study
• Patients are implanted with an Food and Drug Administration (FDA) approved St. Jude Medical (SJM) EpicTM+ DR/VR Implantable Cardioverter Defibrillator (or any other standard output ICD after Epic+) and defibrillation lead system.
• All study testing is completed at implant.
• Patients are randomized to begin DFT testing with either the 50/50% tilt or Tuned waveform.
• The HVLIC feature is used to measure the high voltage lead impedance and to program the Tuned and 50/50% tilt waveform pulse widths.
• The DFT is determined by an optimized binary search method that is designed to reduce the overall number of VF inductions to an average of 5.13 while maintaining very high resolution and accuracy.
• Total # of centers - 15 centers
• Sample size - 60 patients

Inclusion Criteria:

• Patient is a candidate for ICD implantation.
• Patient is able to tolerate DFT testing.

Exclusion Criteria:

• Patient has a mechanical valve in the tricuspid position.
• Patient is pregnant.
• Patient is less than 18 years old.