Amiodarone does not significantly affect the success rate of ventricular fibrillation induction tests performed during or after ICD implantation. Insights from the German DEVICE registry

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: Other. Main funding source(s): The DEVICE registries were financed by “Stiftung Institut für Herzinfarktforschung (IHF)”, with additional support by grants from Biotronik, Medtronic, and St. Jude Medical. BACKGROUND: Experimental data and early clinical trials suggested that amiodarone may alter the defibrillation threshold of ICD systems. However, because of its potent antiarrhythmic effect and lack of alternatives, amiodarone is frequently used for antiarrhythmic therapy in ICD or CRT-D patients, leading to the question of whether ICD testing with ventricular fibrillation induction should be repeated in these patients after starting amiodarone. OBJECTIVE: This study was designed to assess the impact of amiodarone therapy on the success of ventricular fibrillation induction tests in this "real life" cohort of ICD recipients of the German DEVICE registry. METHODS: 3,680 patients who underwent ICD implantation, revision, or upgrade in 49 centers participating in the German DEVICE Registry were enrolled 03/2007-02/2014. RESULTS: Intraoperative defibrillation testing was conducted in 2,705 patients receiving only beta-blockes as antiarrhythmic therapy and in 422 patients under betablocker plus amiodarone therapy. With regard to ineffective defibrillation tests, no difference could be described between the two groups (0.6% vs. 0.5%; p=0.77). In a similar fashion 488 patients receiving beta-blockers only and 65 patients under beta-blocker plus amiodarone therapy who were scheduled for postoperative defibrillation testing showed comparable rates of ineffective testing (14.5% vs. 15.4%; p=0.86). CONCLUSIONS: Based on 3,127 intraoperative and 553 postoperative defibrillator testings, our study failed to show a significant association of amiodarone therapy and ineffective defibrillator testings in this "real life" cohort of ICD recipients of the German DEVICE registry. Our results thus underline that, apart from special situations such as right-sided implantation, HCM, extravenous ICD systems, etc., it might not be necessary to perform a DFT test after the start of an amiodarone therapy in ICD patients. [Figure: see text]