Defibrillation threshold testing at implantation: can we predict the patient with a high defibrillation threshold?

Abstract

Defibrillation threshold (DFT) testing is an integral part of implantable cardioverter-defibrillator (ICD) implantation. The primary functions of defibrillation assessment are to confirm appropriate sensing of ventricular fibrillation and to establish an adequate safety margin for defibrillation. However, recent publications question the necessity of DFT testing during implantation, quoting the effectiveness of the current generation of devices and the rate of complications associated with testing.1–3 The recently published Canadian experience of 19 067 ICD implantations revealed eight serious testing-related complications (three deaths and five strokes), indicating an incidence of 0.042%.4 Accordingly, the risk of severe testing-related complications appears to be negligible. Over the years, defibrillator and lead technology has advanced. Current ICD systems use one or two intracavitary defibrillation coils, biphasic waveforms, and active can technology. These systems provide a mean DFT of 8–10 J with the maximum output of current devices typically 35–40 J. Thus, the remaining question is: do we still encounter patients with a ‘high DFT’ with … *Corresponding author. Department of Clinical Electrophysiology, Erasmus MC, Room Bd416, PO Box 2040, 3000 CA, Rotterdam, The Netherlands; Tel: +31 10 703 2938; fax: +31 10 703 4420, Email: d.theuns{at}erasmusmc.nl