Abstract 16979: Impact of ICD Shock Testing and Non-Testing on Arrhythmia Therapy Efficacy
Background: Defibrillation testing is often performed during implantation of implantable cardioverter defibrillators (ICD) to confirm therapy efficacy, even though there are no prospective data suggesting that outcome is improved by this procedure when modern ICDs are implanted. The aim of the study was to investigate whether shock testing during ICD implantation is feasible for predicting future effectiveness of ICD therapy.
Methods: The retrospective analysis included a cohort of consecutive patients who received an ICD device with telemedicine capacity in our clinic, with each tachycardia episode monitored and evaluated online. All devices were implanted by means of standard surgical techniques, and shock testing was conducted or desisted due to the attending cardiologist's and surgeon's discretion.
Results: 357 patients who received either an ICD or CRT-ICD with home monitoring capacity could be enclosed in the study. From 219 patients, in which ICD shock testing was performed during implantation, initial shock testing revealed satisfactory results in 210 cases; otherwise, additional surgical measures led to shock testing success. 138 patients were not tested. Compared to the shock testing group, implantation for primary prevention was more common in the non-testing group. In the shock testing group, 124 patients had VT/VF requiring ICD shock therapy. First shock efficacy was 99% for the first VT event in this group, with only one patient undergoing an ineffective first shock delivery. In this patient, the VT could be terminated with the second shock. However, in the long run 7 patients had at least one documented episode with an ineffective shock, despite the fact that previous shocks had been successful. In the non-testing group, 76 patients required ICD shock therapy and first shock efficacy was 100% for the first VT event in this group. Accordingly, there was no significant difference regarding first shock efficacy between patients with ICD for primary or secondary prevention.
Conclusions: Shock efficacy for treatment of the first ventricular tachycardia was generally high, regardless whether shock testing was performed during implantation or not. This result challenges the current paradigm of ICD shock testing during implantation.
- © 2011 by American Heart Association, Inc.