Intraoperative ICD defibrillation testing has to be recommended according to multicenter data – final results

Objectives: In recent years increased number of reports highlighted the low benefit/risk ratio of intraoperative defibrillation testing (DT) and thereby argued against its routine application. Moreover, implementation of high energy-defibrillators into the clinical practice seemed to make the intraoperative DT obsolete. Currently, some clinical trials were launched in order to underline this opinion. In order to explain the bias of our clinical experience with some of these reports we evaluated the effectiveness and necessity of intraoperative DT in a multicenter study.

Methods: 4572 consecutive patients undergoing implantable cardioverter-defibrillator (ICD) implantation or replacement in participating centers were retrospectively analyzed for the efficacy of intraoperative DT.

Results: From 4572 patients 3917 were tested (overall 5460 testshocks), while 611 (13.4%) were not tested for medical reasons (intracardial thrombus, prolonged insufficient anticoagulation, poor clinical status, pneumothorax), missing data occurred in 1.1%. DT was primarily effective in 3608 (95.9%) and ineffective in 154 (4.1%) cases. After system optimization (51% increase of DT energy, 8.4% SQ-Array, 1.2% high energy-device, 17.9% lead reposition, 4.0% lead exchange, 17.5% pulse width optimization) in 146 patients DT was successful, in 4 remained ineffective and for 4 patients the data are missing. 89.5% of ICDs were placed subpectorally, 11.0% subfascially and 0.5% abdominally. DT was performed in 2465 new implantations (95.4% primary effective vs. 4.6% ineffective), 779 ICD replacements (97.4 vs. 2.6%) and 673 system revisions (95.9 vs. 4.1%). DT-associated complications were not noted.

Conclusion: The overall number of patients with inappropriate intraoperative DT is higher than perceived. The highest primary DT failure rate was observed in patients undergoing ICD implantation, the lowest in the group with ICD replacements. Nevertheless, performance of the leads drops with age. Therefore, since ongoing clinical trials testing the non-inferiority of ICD implantation without DT in composite endpoint of ineffective first appropriate clinical shock or arrhythmic death are prospective, they would neglect the increasing amount of patients with already implanted ICD system and aging leads. According to our data the historical reports highlighting the number of DT-associated complications seems to be overestimated. Therefore, we advocate the clinical necessity of intraoperative DT.