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'Effect of CRT on Defibrillation Threshold Estimates' Study

This study has been completed.
Information provided by (Responsible Party):
St. Jude Medical Identifier:
First received: February 7, 2008
Last updated: January 18, 2013
Last verified: January 2013
The purpose of this prospective study is to evaluate the effect of cardiac resynchronization therapy (CRT) on the defibrillation threshold (DFT) estimates in cardiac resynchronization therapy defibrillators (CRT-D) patients. The hypothesis of the study is that defibrillation threshold (DFT) will decrease with 6 months of cardiac resynchronization therapy (CRT).

Condition Intervention Phase
Sudden Cardiac Death
Device: Cardiac Resynchronization Therapy - Defibrillator (CRT-D)
Phase 4

Study Type: Interventional
Study Design: Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Effect of Cardiac Resynchronization Therapy (CRT) on the Defibrillation Threshold (DFT) Estimates

Further study details as provided by St. Jude Medical:

Primary Outcome Measures:
  • Defibrillation Threshold Difference Obtained in Volts (V) Between Implant and 6 Months [ Time Frame: Baseline and 6 months ]
    All patients underwent defibrillation threshold testing at cardiac resynchronization therapy-defibrillator (CRT-D) implant and then at 6 months. The outcome measure is the difference in DFT (defibrillation threshold) in volts between implant and 6 months.

Secondary Outcome Measures:
  • Defibrillation Threshold Difference Obtained in Joules (J) [ Time Frame: Baseline and 6 months ]

Enrollment: 77
Study Start Date: January 2008
Study Completion Date: April 2010
Primary Completion Date: April 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Cardiac Resynchronization Therapy - Defibrillator (CRT-D)
Patients in the study who received a Cardiac Resynchronization Therapy - Defibrillator (CRT-D) are indicated for it. It's a single arm study in which patients underwent defibrillation threshold (DFT) testing at implant and 6 months.
Device: Cardiac Resynchronization Therapy - Defibrillator (CRT-D)
  • Patients in the study who receive Cardiac Resynchronization Therapy - Defibrillator (CRT-D) are indicated for Cardiac Resynchronization Therapy (CRT).
  • Patient undergoes Defibrillation threshold (DFT) testing at implant and at 6 months. Defibrillation threshold (DFT) testing will include 3 ventricular fibrillation (VF) inductions.
Other Name: Epic HF,Atlas+ HF,Epic II HF,Atlas II HF,Promote CRT-D

Detailed Description:

Cardiac Resynchronization Therapy (CRT) has emerged as a promising therapeutic addition in patients with drug refractory heart failure (HF). Along with providing relief of symptoms of HF, cardiac resynchronization therapy defibrillators (CRT-D) are used for the prevention of sudden cardiac death (SCD). Although there are concerns that the defibrillation threshold (DFT) estimates are elevated in the heart failure (HF) patient population due to lower LV ejection fraction (EF) and left ventricular (LV) dysfunction, there is paucity of data available to evaluate this theory.

Recently, two different studies in a retrospective manner evaluated the energy requirements in patients receiving cardiac resynchronization therapy defibrillators (CRT-D). Burke et al analyzed DFTs in 50 patients each implanted with a cardiac resynchronization therapy defibrillators (CRT-D) device and an implantable cardioverter defibrillator (ICD). Although the ejection fraction (EF) in cardiac resynchronization therapy defibrillators (CRT- D) group was lower than the implantable cardioverter defibrillator (ICD) group, the mean defibrillation thresholds (DFTs) between the two groups were not significantly different (10.2 ± 6.1 J for the cardiac resynchronization therapy (CRT) group vs. 9.5 ± 5.0 J for the control group)14. In the ASSURE study, Doshi et al. showed that patients receiving cardiac resynchronization therapy defibrillators (CRT-D) devices do not have higher energy requirements when compared to patients receiving modern single or dual chamber implantable cardioverter defibrillators (ICDs). Although, there was a trend toward higher energy requirements found among patients with higher degrees of heart failure.

Major cardiac resynchronization therapy (CRT) trials have showed that cardiac resynchronization therapy (CRT) therapy has positive effects on ejection fraction (EF) and the heart failure (HF) condition of the patient over time. But, there is no study that has evaluated the defibrillation thresholds (DFTs) in the heart failure (HF) patients over time of receiving cardiac resynchronization therapy (CRT). This information will help the clinicians decide if they need to perform more invasive procedures during device implant to lower DFTs in patients who do not meet the defibrillation safety margin or they should just wait over time for the CRT to reduce the defibrillation threshold (DFT). Also, there is no published data about the stability of defibrillation thresholds (DFTs) in heart failure (HF) patients over time. The results from this study will also help to clarify whether it is safe to never test the defibrillation thresholds (DFTs) post-implant in this patient population.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patient meets standard indications for a Cardiac Resynchronization Therapy - Defibrillator (CRT-D).
  • Patient will be implanted with an FDA approved St Jude Medical (SJM) Cardiac Resynchronization Therapy - Defibrillator (CRT-D) and compatible defibrillation lead system.
  • Patient is able to tolerate defibrillation threshold (DFT) testing.
  • Patient is geographically stable and willing to comply with the required follow-up schedule.
  • Patient has a life expectancy of greater than 6 months from the time of implant.
  • Patient has stable heart failure (HF) medications at least one month prior to enrollment.

Exclusion Criteria:

  • Inability to successfully implant an intravascular lead Cardiac Resynchronization Therapy - Defibrillator (CRT-D) device. (i.e. exclude epicardial leads).
  • Patient is getting his Cardiac Resynchronization Therapy - Defibrillator (CRT-D) device replaced.
  • Inability to successfully obtain the defibrillation threshold (DFT) at implant.
  • Currently participating in a clinical trial that includes an active treatment arm or another data collection registry.
  • Recent (within 24 hours) administration of Nesiritide™.
  • Patient is on amiodarone (other antiarrhythmic agents known to affect defibrillation thresholds - DFTs) at the time of enrollment.
  • Patient is pregnant.
  • Patient is less than 18 years old.
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Please refer to this study by its identifier: NCT00626093

United States, California
Pacific Heart Institute
Santa Monica, California, United States, 90404
United States, Colorado
Penrose Hospital
Colorado Springs, Colorado, United States, 80907
Sponsors and Collaborators
St. Jude Medical
Principal Investigator: Amir Hedayati, MD Glendale Heart Institute
Principal Investigator: Michael Gold, MD, PhD Medical University of South Carolina
  More Information

Responsible Party: St. Jude Medical Identifier: NCT00626093     History of Changes
Other Study ID Numbers: CRD 388
Study First Received: February 7, 2008
Results First Received: July 21, 2011
Last Updated: January 18, 2013

Additional relevant MeSH terms:
Death, Sudden, Cardiac
Pathologic Processes
Heart Arrest
Heart Diseases
Cardiovascular Diseases
Death, Sudden processed this record on May 22, 2017