Z Kardiol 94: Suppl 2 (2005)

Long-Term Efficacy of Defibrillator Treatment in Patients undergoing Subcutaneous Array Electrode Placement for Enhanced Defibrillation Threshold

U. Backenköhler1, G. Hindricks2, C. Piorkowski2, H. H. Tillmanns3, G.C. Schuler2, H. Kottkamp2

1Allgemeines Krankenhaus Celle, Celle, BusinessLogic.Land; 2Abt. für Rhythmologie, Herzzentrum der Universität Leipzig, Leipzig; 3Med. Klinik und Poliklinik V, Universitätsklinikum Giessen, Giessen;

In a small number of patients receiving an active can defibrillator (ICD), an effective and safe defibrillation threshold (DFT) cannot be achieved. In these cases implantation of an additional subcutaneous array electrode (SQE) may lower DFT. However, in some cases DFT cannot be reduced below < 20 Joule (J). To assess safety of therapy in these cases, we compared long-term shock efficacy in patients with a persistently high DFT of > 20 J after SQE placement to clinical data of patients who underwent additional SQE-implantation that allowed for a DFT < 20 J. Methods: Over a period of > 2 years 7 Patients underwent additional SQE placement for ineffective ICD-testing and elevated DFT values respectively. Patients were assigned to group A (n=4) when DFT was < 20 J after SQE placement and to group B (n=3) if DFT was > 20 J. All shock therapies were programmed to assure immediate maximum energy of 30 J in all ICD-recipients. Stored episodes of arrhythmia as well as efficacy of defibrillator therapies were evaluated. Results: Baseline characteristics of clinical status and medication were similar in both groups A and B. Mean follow-up with scheduled visits was 2,3±1,39 years in group A and  2,45±1,4 years (p=ns) in group B. The average number of adequately and successfully delivered shocks per patient did not significantly differ between the two groups (2±0,81 in group A versus 1,5±0,6 in the risk group B) respectively. Average DFT as tested after SQ-implantation in group A was 16±1 J versus 24±1 J  in group B. All patients of both groups were subject to ICD shocks and all episodes of ventricular tachycardia and fibrillation were adequately detected and terminated. Conclusion: Patients with intraoperatively ineffective ICD-testing and persistently increased DFT of >20 J after implantation of SQE appear to have a reliable vital benefit from their additional electrodes over clinical long-term follow-up of > 2 years after ICD implantation that is comparable to patients with a DFT < 20 after SQE placement.

http://www.abstractserver.de/dgk2005/ht/abstracts/P441.htm