No benefit from defibrillation threshold testing in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial).
OBJECTIVE
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.
Blatt
Joseph A
JA
Department of Cardiology, University of Washington, Box 356422, 1959 NE Pacific Street, Seattle, Washington 98195, USA. jablatt@u.washington.edu
Poole
Jeanne E
JE
Johnson
George W
GW
Callans
David J
DJ
Raitt
Merritt H
MH
Reddy
Ramakota K
RK
Marchlinski
Francis E
FE
Yee
Raymond
R
Guarnieri
Thomas
T
Talajic
Mario
M
Wilber
David J
DJ
Anderson
Jill
J
Chung
Kiyon
K
Wong
Wai Shun
WS
Mark
Daniel B
DB
Lee
Kerry L
KL
Bardy
Gust H
GH
D000638:Amiodarone / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D016757:Death, Sudden, Cardiac / Q000209:etiology / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D004056:Differential Threshold; D022062:Electrophysiologic Techniques, Cardiac; D006333:Heart Failure / Q000150:complications / Q000188:drug therapy / Q000401:mortality* / Q000628:therapy; D006801:Humans; D011237:Predictive Value of Tests; D013318:Stroke Volume; D014693:Ventricular Fibrillation / Q000150:complications / Q000517:prevention & control*
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone