Fractally coated defibrillation electrodes - Is an improvement in defibrillation threshold possible?

Aims In patients with implantable cardioverter-defibrillators (ICD), the go als of lowering the defibrillation threshold (DFT) can be achieved by means of higher defibrillation safety margins. more rapid charging of capacitors , improved battery longevity, implying smaller devices. Whether an increase in the electrically active surface of ICD leads by fractal coating results in decreased DFTs is unknown. Methods and Results In this prospective randomized cross-over study the def ibrillation efficacy of a novel right ventricular endocardial defibrillatio n electrode fractally coated with iridium was compared with an uncoated but otherwise identical electrode in 30 patients undergoing ICD implantation. In each patient, DFT testing was performed twice according to a binary sear ch protocol introducing the two different electrodes in a random order. The mean DFT was 8.4 +/- 4.1 J with the fractally coated lead and 9.6 +/- 3.6 J using the uncoated lead. The improvement of 1.2 J was statistically not s ignificant (P=0.11). No differences were observed between the patients with an improved DFT (n=12) and those with an unchanged or worsened DFT (n=18) concerning age, underlying cardiac disease, NYHA class, or left ventricular ejection fraction, respectively. Conclusion Increasing the electrical surface of defibrillation leads by fra ctal coating does not lead to a substantial clinically relevant reduction i n defibrillation thresholds. Defibrillation impedance is not influenced by the increased electrical surface of the defibrillation lead. (Europace 2000 ; 2: 154-159) (C) 2000 The European Society of Cardiology.