Assessment of Efficacy and Necessity of Routine Defibrillation Threshold Testing in Patients Undergoing Implantable Cardioverter-Defibrillator (ICD) Implantation

Abstract

SummaryDefibrillation threshold (DFT) testing is performed routinely in patients undergoing implantable cardioverter-defibrillator (ICD) implantation to verify the ability of the ICD to terminate ventricular fibrillation (VF). However, neither the efficacy nor the safety of DFT testing has been proven; thus, the necessity of such testing is controversial. We conducted a retrospective study of the efficacy of DFT testing, particularly with respect to long-term outcomes of ICD implantation.The study included 150 patients (125 men, 25 women, aged 59.0 ± 17.6 years) who underwent ICD or cardiac resynchronization therapy defibrillator implantation, with (n = 73) or without (n = 77) intraoperative DFT testing, between June 1996 and September 2007. VF was induced by delivery of a T-wave shock, and a 20-25-J shock was then delivered. If the 20-25-J shock failed to terminate VF, 30 J was delivered. We assessed whether undersensed VF events occurred during DFT testing and/or during patient follow-up and checked for any association between undersensing and delayed shock delivery. During DFT testing, fine VF was sensed, and shocks were delivered in a timely manner. Nevertheless, 2 patients in the DFT testing group died from VF within 3 years after device implantation.DFT testing, in comparison to non-DFT testing, appeared to have no influence on the long-term outcomes of our patients, suggesting that DFT testing at the time of ICD implantation is limited. (Int Heart J 2015; 56: 618-621) Key words: Ventricular arrhythmia, Mortality I mplantable cardioverter-defibrillators (ICDs) have been shown to reduce mortality resulting from both ischemic 1,2) and non-ischemic cardiomyopathies 2) and to terminate potentially fatal ventricular arrhythmias.3,4) Current indications for an ICD include not only a near-fatal arrhythmic event 5) and ischemic cardiomyopathy but also severe nonischemic cardiomyopathy with a low left ventricular ejection fraction (LVEF).Defibrillation threshold (DFT) testing during ICD implantation has been considered necessary for appropriate shock delivery, 6) and a DFT safety margin of 10 J is the standard recommendation.6,7) However, neither the efficacy nor benefit of DFT testing has been proven. [8][9][10][11] Induction of ventricular fibrillation (VF) during DFT can cause hemodynamic compromise, clinical deterioration, and life-threatening cerebrovascular accidents.12-15) Thus, we conducted a retrospective study to assess the effect of DFT testing on long-term outcomes in patients with an ICD or cardiac resynchronization therapy defibrillator (CRT-D). MethodsStudy patients: The study included 150 patients (125 men, 25 women) who received an ICD (n = 85) or CRT-D (n = 65) at our hospital between June 1996 and September 2007. Hospital records were obtained, from which we extracted the patient clinical characteristics, follow-up times, ICD intracardiac recordings, and clinical outcomes. The ICDs and CRT-Ds were implanted in a standard transvenous manner. We divided the patients into 2 groups, those in whom DFT...

Updated Meta-Analysis of Randomized Trials Comparing Safety and Efficacy of Intraoperative Defibrillation Testing with No Defibrillation Testing On Implantable Cardioverter-Defibrillator Implantation

“…Our results are consistent with previous observational data [12][13][14][15][16][17][18][19][20][21][22] and meta-analyses [5,23] and provide further support to the recommendation to omit defibrillation efficacy testing in patients undergoing initial transvenous ICD implantation procedures [24]. Nonetheless, these results do not apply to specific subgroups, which were excluded or poorly represented in this meta-analysis, such as patients with right-sided ICD pocket or non-transvenous systems; patients with congenital heart diseases, channelopathies or hypertrophic cardiomyopathy; and patients who undergo device replacement.…”

Routine DFT testing in patients undergoing ICD implantation does not improve mortality: A systematic review and meta‐analysis

“…Step‐down protocol for DFT testing was used only in two studies (Hall et al and Pires et al). Three studies included patients with hypertrophic cardiomyopathy, while only one study included patients with congenital heart disease. Analysis of the funnel plot for the primary analysis showed no significant publication bias (Figure A).…”

Midterm Results of Implantable Cardioverter Defibrillators in Children and Young Adults from a Single Center in Turkey

“…However, DFT testing can cause refractory VF, myocardial ischemia, hemodynamic compromise, cardiac arrest, respiratory depression, life‐threatening cerebrovascular accidents, and thromboembolism, resulting in clinical deterioration . Moreover, recent studies have shown no influence on clinical outcomes related to DFT testing . We do not perform routine DFT testing during the implantation in our clinical practice, and one of the reasons for unsuccessful shocks in some of our patients might be the inappropriately low initial programmed energy because of lack of DFT testing.…”

“…36 Moreover, recent studies have shown no influence on clinical outcomes related to DFT testing. 36,37 We do not perform routine DFT testing during the implantation in our clinical practice, and one of the reasons for unsuccessful shocks in some of our patients might be the inappropriately low initial programmed energy because of lack of DFT testing. We think that if we can recognize that the initial energy might have been inappropriately low, we can also recognize that either initial energy should be selected based on DFT testing, which might prompt us to change our clinical practice, or that maximal energy should be programmed for all shocks.…”