No Benefit From Defibrillation Threshold Testing in the SCD-HeFT

Title: No Benefit From Defibrillation Threshold Testing in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial)

Date Posted: 8/29/2008

Author(s): Blatt JA, Poole JE, Johnson GW, et al.
Citation: J Am Coll Cardiol 2008;52:551-556.

Clinical Trial: No Related Resources

Trial: locked content Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT)
Study Question: Does defibrillation threshold (DFT) testing have clinical value in patients with heart failure who receive an implantable cardioverter defibrillator (ICD) for 1° prevention of sudden death?

Methods: This was a post-hoc analysis of 717 patients in SCD-HeFT who underwent DFT testing at the time of ICD implantation. Ventricular fibrillation was induced with T-wave shocks. The first shock tested was 20 J and the second shock tested was 10 or 30 J, depending on whether the first shock was successful or unsuccessful. The ICDs were programmed with a first shock of 30 J if the DFT was >10 J or 20 J if the DFT was ≤10 J. Defibrillation efficacy of the first appropriate shock during follow-up was analyzed.

Results: The DFT was low (≤10 J) in 547 patients (76%) and high (>10 J) in 170 patients. Overall mortality was approximately 20%, with no difference between the low- and high-DFT groups. An appropriate shock occurred during follow-up in 22% of patients, and the first-shock efficacy was 83%, with no relationship between efficacy and DFT. The first-shock efficacy was 90% in 94 patients for whom no DFT data were available. Only 3 of 31 patients with an unsuccessful first shock died the same day.

Conclusions: There is no relationship between the results of DFT testing and shock efficacy or survival during follow-up.

Perspective: The results make a strong case for limited DFT testing in patients receiving an ICD for 1° prevention of sudden death. It is noteworthy that the DFT never was >30 J in this study, probably because of improvements in ICD technology. Fred Morady, M.D., F.A.C.C.