Related Experiment Video
Updated: Jul 3, 2026
Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
No benefit from defibrillation threshold testing in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial)
Joseph A Blatt1, Jeanne E Poole, George W Johnson
1Department of Cardiology, University of Washington, Box 356422, 1959 NE Pacific Street, Seattle, Washington 98195, USA. jablatt@u.washington.edu
Insights
Defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation did not predict clinical outcomes or shock efficacy in heart failure patients. Low DFTs were common and did not correlate with survival in this primary prevention cohort.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Defibrillation testing is standard during implantable cardioverter-defibrillator (ICD) implantation to ensure shock effectiveness.
- Prospective data are lacking to confirm if this testing improves outcomes for primary prevention of sudden cardiac death.
Purpose of the Study:
- To determine if defibrillation threshold (DFT) testing during ICD implantation predicts clinical outcomes.
- To evaluate the relationship between baseline DFT and long-term mortality or shock efficacy.
Main Methods:
- Analysis of 811 patients randomized to the ICD arm of the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).
- A specific DFT testing protocol was used, designed to limit testing in a primary prevention heart failure population.
- Baseline DFT data were available for 717 patients.
Main Results:
- All patients had a DFT of ≤30 J, with 97.8% having a DFT ≤20 J.
- No significant survival difference was observed between patients with lower DFT (≤10 J) and higher DFT (>10 J).
- First shock efficacy for ventricular tachyarrhythmias was high (83.0%) and not influenced by baseline DFT.
Conclusions:
- Low baseline DFTs are achievable in stable, optimally treated heart failure patients receiving ICDs for primary prevention.
- Baseline DFT testing did not predict long-term mortality or shock efficacy in this study population.
- High first shock efficacy was observed irrespective of baseline DFT results.
Objectives:
This study investigated whether defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation predicts clinical outcomes.
Background:
Defibrillation testing is often performed during insertion of ICDs to confirm shock efficacy. There are no prospective data to suggest that this procedure improves outcomes when modern ICDs are implanted for primary prevention of sudden death.
Methods:
The analysis included the 811 patients who were randomized to the ICD arm of the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) and had the device implanted. The DFT testing protocol in SCD-HeFT was designed to limit shock testing in a primary prevention heart failure population.
Results:
Baseline DFT data were available for 717 patients (88.4%). All 717 patients had a DFT of < or =30 J, the maximum output of the device in this study. The DFT was < or =20 J in 97.8% of patients. There was no survival difference between patients with a lower DFT (< or =10 J, n = 547) and a higher DFT (>10 J, n = 170) (p = 0.41). First shock efficacy was 83.0% for the first clinical ventricular tachyarrhythmia event; there were no differences in shock efficacies when the cohort was subdivided by baseline DFT.
Conclusions:
Low baseline DFTs were obtained in patients with stable, optimally treated heart failure during ICD implantation for primary prevention of sudden death. First shock efficacy for ventricular tachyarrhythmias was high regardless of baseline DFT testing results. Baseline DFT testing did not predict long-term mortality or shock efficacy in this study.
Related Concept Videos
01:23Cardiopulmonary Resuscitation III: AED Use
01:30Cardiomyopathy II: Dilated Cardiomyopathy
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
01:30Acute Coronary Syndrome III: Diagnostic Studies
01:20Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
01:25Imaging Studies for Cardiovascular System VI: Calcium -Scoring CT