The purpose of the study is to evaluate the benefit of interventricular (V-V) delay optimization in reducing the non-responder rate in patients with cardiac resynchronization defibrillator (CRT-D) devices. The primary endpoint of this study is CRT responder rate.

For patients enrolled with new CRT-D systems, patients are considered non-responders if BOTH of the following requirements are fulfilled:

• < 10% improvement in 6-minute hall walk, and
• no class improvement or worsening in New York Heart Association (NYHA) scale.

For those receiving CRT-D devices as replacements of older CRT-D systems, patients are considered non-responders if BOTH of the following requirements are fulfilled:

• > 1 heart failure (HF) related hospitalization, and
• no class improvement or worsening in NYHA scale.

Study Methods

• This is a prospective, randomized (simultaneous biventricular (BiV) pacing vs. sequential BiV pacing) study.

• Any patient that receives an FDA approved St. Jude Medical (SJM) CRT-D with V-V timing is eligible for enrollment.

• At 3 months post enrollment (or at implant for CRT-D replacements), patients screened as non-responders are randomized to either simultaneous or sequential BiV pacing. Patients requiring a replacement CRT-D device that are identified as non-responders to CRT are enrolled at the screening/randomization visit.

• Patients are followed for a period of 6 months post randomization:

  • Enrollment (1 week pre CRT-D implant to < 2 weeks post CRT-D implant)
  • Screening/Randomization Visit (3 months post enrollment)
  • Follow-up Visit (6 months post randomization)

• Total # of centers - 80 centers

• Sample size - 800 patients screened for CRT non-responders

Inclusion Criteria:

• Patient has a standard indication for a CRT-D.

• Patient has the ability to complete a 6-minute hall walk with the only limiting factor to be fatigue or shortness of breath.

• Patient is geographically stable and willing to comply with the required follow-up schedule.

• Prior to 1 month of randomization, patient's HF medications are maintained stable and remain stable throughout the study.

• Patients requiring a CRT-D replacement must comply with BOTH of the following:

  • > 1 HF related hospitalization
  • No class improvement or worsening in NYHA scale

Exclusion Criteria:

• Patient's life expectancy is less than 12 months.
• Patient has had cardiac surgery within 6 months of enrollment.
• Patient has an epicardial ventricular lead system.
• Patient is less than 18 years old.
• Patient is pregnant.

Due to the lower than expected non-responder rate at 3 months, the study did not reach the target randomized sample size.