Clinical trial NCT00626093: 'Effect of CRT on Defibrillation Threshold Estimates' Study
Official title: Effect of Cardiac Resynchronization Therapy (CRT) on the Defibrillation Threshold (DFT) Estimates
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE4
Conditions: Sudden Cardiac Death
Lead sponsor: Abbott Medical Devices
Sponsor class: INDUSTRY
First posted: 2008-02-29
Enrollment: 77
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: 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).

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.

Eligibility criteria: 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.

Primary outcomes:
measure: Defibrillation Threshold Difference Obtained in Volts (V) Between Implant and 6 Months
timeFrame: Baseline and 6 months
Secondary outcomes:
measure: Defibrillation Threshold Difference Obtained in Joules (J)
timeFrame: Baseline and 6 months
Other outcomes:
Locations:
city: Santa Monica
country: United States
facility: Pacific Heart Institute
state: California
city: Colorado Springs
country: United States
facility: Penrose Hospital
state: Colorado
Study officials:
affiliation: Glendale Heart Institute
name: Amir Hedayati, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: Medical University of South Carolina
name: Michael Gold, MD, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Gold MR, Hedayati A, Alaeddini J, Payne JP, Bailin S, Sturdivant JJ, Pradhan S, Oza AL. Temporal stability of defibrillation thresholds with cardiac resynchronization therapy. Heart Rhythm. 2011 Jul;8(7):1008-13. doi: 10.1016/j.hrthm.2011.02.006. Epub 2011 Feb 9.