Intraoperative testing of the implantable cardioverter-defibrillator: how much is enough?

Safety, efficacy, and reliability evaluation ofa novel small-diameter defibrillation lead: Global LEADR pivotal trial results

BACKGROUND

Implantable cardioverter-defibrillators last longer, and interest in reliable leads with targeted lead placement is growing. The OmniaSecure defibrillation lead is a novel, small-diameter, catheter-delivered lead designed for targeted placement, based on the established SelectSecure SureScan MRI Model 3830 lumenless pacing lead platform.

OBJECTIVE

This trial assessed safety and efficacy of the OmniaSecure defibrillation lead.

METHODS

The worldwide LEADR pivotal clinical trial enrolled patients indicated for de novo implantation of a primary or secondary prevention implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator, all of whom received the study lead. The primary efficacy end point was successful defibrillation at implantation per protocol. The primary safety end point was freedom from study lead-related major complications at 6 months. The primary efficacy and safety objectives were met if the lower bound of the 2-sided 95% credible interval was >88% and >90%, respectively.

RESULTS

In total, 643 patients successfully received the study lead, and 505 patients have completed 12-month follow-up. The lead was placed in the desired right ventricular location in 99.5% of patients. Defibrillation testing at implantation was completed in 119 patients, with success in 97.5%. The Kaplan-Meier estimated freedom from study lead-related major complications was 97.1% at 6 and 12 months. The trial exceeded the primary efficacy and safety objective thresholds. There were zero study lead fractures and electrical performance was stable throughout the mean follow-up of 12.7 ± 4.8 months (mean ± SD).

CONCLUSION

The OmniaSecure lead exceeded prespecified primary end point performance goals for safety and efficacy, demonstrating high defibrillation success and a low occurrence of lead-related major complications with zero lead fractures.

Efficacy and Safety of an Extravascular Implantable Cardioverter-Defibrillator

BACKGROUND

The extravascular implantable cardioverter-defibrillator (ICD) has a single lead implanted substernally to enable pause-prevention pacing, antitachycardia pacing, and defibrillation energy similar to that of transvenous ICDs. The safety and efficacy of extravascular ICDs are not yet known.

METHODS

We conducted a prospective, single-group, nonrandomized, premarket global clinical study involving patients with a class I or IIa indication for an ICD, all of whom received an extravascular ICD system. The primary efficacy end point was successful defibrillation at implantation. The efficacy objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients with successful defibrillation was greater than 88%. The primary safety end point was freedom from major system- or procedure-related complications at 6 months. The safety objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients free from such complications was greater than 79%.

RESULTS

A total of 356 patients were enrolled, 316 of whom had an implantation attempt. Among the 302 patients in whom ventricular arrhythmia could be induced and who completed the defibrillation testing protocol, the percentage of patients with successful defibrillation was 98.7% (lower boundary of the one-sided 97.5% confidence interval [CI], 96.6%; P<0.001 for the comparison with the performance goal of 88%); 299 of 316 patients (94.6%) were discharged with a working ICD system. The Kaplan-Meier estimate of the percentage of patients free from major system- or procedure-related complications at 6 months was 92.6% (lower boundary of the one-sided 97.5% CI, 89.0%; P<0.001 for the comparison with the performance goal of 79%). No major intraprocedural complications were reported. At 6 months, 25 major complications were observed, in 23 of 316 patients (7.3%). The success rate of antitachycardia pacing, as assessed with generalized estimating equations, was 50.8% (95% CI, 23.3 to 77.8). A total of 29 patients received 118 inappropriate shocks for 81 arrhythmic episodes. Eight systems were explanted without extravascular ICD replacement over the 10.6-month mean follow-up period.

CONCLUSIONS

In this prospective global study, we found that extravascular ICDs were implanted safely and were able to detect and terminate induced ventricular arrhythmias at the time of implantation. (Funded by Medtronic; ClinicalTrials.gov number, NCT04060680.).

Safety and Long-term Outcomes of Defibrillator Therapy in Patients With Right-Sided Implantable Cardiac Devices in Adults With Congenital Heart Disease

BACKGROUND

Implantable cardioverter-defibrillators (ICDs) have been proven to prevent sudden cardiac death in adult congenital heart disease (ACHD) patients. Although the left side is chosen by default, implantation from the right side is often required. However, little is known about the efficacy and safety of right-sided ICDs in ACHD patients.

METHODS

In this study we reviewed a total of 191 ACHD patients undergoing ICD/cardioverter resynchronisation therapy-defibrillator (CRT-D) implantation at our hospital between 2001 and 2019 (134 men and 57 women; age [mean ± standard deviation], 41.5 ± 14.8 years).

RESULTS

Twenty-seven patients (14.1%) had right-sided devices. The most common causes of right-sided implantation were persistent left superior vena cava and vein occlusion (37.0%). Although procedure time (202.8 ± 60.5 minutes vs 143.8 ± 69.1 minutes, P = 0.008) was longer and the procedural success was lower (92.6% vs 99.4%, P = 0.008) for right-sided devices, no difference in R-wave and pacing threshold were noted. Among the 47 patients (24.6%) who underwent defibrillation threshold testing (DFT), no difference in DFT was observed (25.2 ± 5.3 J vs 23.8 ± 4.1 J, P = 0.460). During the median follow-up of 42.4 months, appropriate ICD therapy was observed in 5 (18.5%) and 30 (18.3%) patients for right- and left-sided ICDs/CRTDs, respectively (P = 0.978). No significant difference was seen in complications between them.

CONCLUSIONS

Implantation of an ICD on the right side is technically challenging, but it is feasible as an alternative approach for ACHD patients with contraindications to left-sided device implantation.

Defibrillation threshold testing during implantable cardioverter defibrillator implantation: 5-year follow-up

PURPOSE

Defibrillation threshold (DFT) testing is a routine practice in some Asian countries for patients receiving an implantable cardioverter defibrillator (ICD). However, there are few long-term data about the necessity of intraoperative DFT testing in an Asian population. We investigated the safety of DFT testing and the long-term clinical outcomes in Asian patients undergoing ICD implantation.

METHODS

All patients undergoing de novo transvenous ICD implantation were randomized to undergo periprocedural DFT testing. The study included 67 patients (50 males; 51.5 ± 16.9 years) who underwent ICD implantation with (n = 33) or without (n = 34) intraoperative DFT testing between March 2012 and February 2014. We compared first-shock success, composite safety end points (the sum of complications recorded at 30 days), arrhythmic death, and all-cause mortality.

RESULTS

The baseline clinical characteristics and the procedural-related adverse event rate (3.0% with DFT vs. 0% with non-DFT, p = 0.214) did not differ between groups. The programmed output of the first shock was lower in the DFT testing group (22.9 ± 4.4 J vs. 25.3 ± 5.4 J, p = 0.007). However, there were no significant differences between groups for all-cause mortality (12.1% vs. 17.6%, p = 0.526) or first-shock success rate for ventricular arrhythmia (100% vs. 88.2%, p = 0.471).

CONCLUSIONS

There were no between-group differences in periprocedural safety, complications, and long-term clinical outcomes. Our results suggest that DFT testing in Asian patients allows reduction of the programmed output of the first shock, but does not affect long-term clinical outcomes.

Analysis of Temporal Trends and Variation in the Use of Defibrillation Testing in Contemporary Practice

IMPORTANCE

Defibrillation testing (DFT) is performed during implantable cardioverter-defibrillator (ICD) implantation to assess the capacity of the device to detect and terminate ventricular arrhythmias. However, DFT can result in complications and omission of its use has been shown to be safe.

OBJECTIVE

To describe temporal trends and variation in the use of DFT in contemporary practice in the United States.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cross-sectional study used data from the National Cardiovascular Data Registry ICD Registry. A total of 499 211 patients from 1794 different facilities undergoing first-time ICD implantation from April 2010 to December 2015 were included. Data analysis was performed from May 20, 2015, to August 15, 2019.

EXPOSURE

Defibrillation testing was assessed using the National Cardiovascular Data Registry ICD Registry.

MAIN OUTCOMES AND MEASURES

Defibrillation testing rates and median odds ratios (MORs) were assessed over time. The MOR represents the odds that a randomly selected patient receiving testing at a hospital with high testing rates would be tested compared with if he or she had received care at a hospital with low testing rates.

RESULTS

Of the 499 211 patients from 1794 different facilities included in this analysis, the mean (SD) age of the population was 65.5 (13.4) years and 356 681 patients (71.4%) were men. The use of DFT declined from 71.6% in the first calendar quarter of 2010 to 36.4% in the fourth quarter of 2015 (P < .001). Patients undergoing DFT were more likely than those without testing to have ischemic heart disease (170 569 [58.1%] vs 116 295 [56.6%]), ventricular tachycardia (91 500 [31.2%] vs 58 949 [28.7%]), and less advanced heart failure (New York Heart Association class I and II, 153 188 [52.2%] vs 91 215 [44.4%]) (P < .001 for all). The MOR for the use of defibrillation testing was 3.78 (95% CI, 3.54-4.03) in 2010, increasing to 6.05 (95% CI, 5.61-6.52) in 2015, indicating that by 2015 a randomly selected patient receiving testing at a hospital with high testing rates would have a 6-fold higher odds of being tested than if they had received care at a hospital with low testing rates.

CONCLUSIONS AND RELEVANCE

Defibrillation testing at the time of ICD placement in the United States may have declined over time; however, institutional variation in its use appears to be marked and increased. This variability in the reduced use of defibrillation testing could reflect differences in individual or institutional cultures of practice.

Evolution of extravascular implantable defibrillator technologies

The implantable cardioverter-defibrillator (ICD) has been successfully treating patients with lethal ventricular arrhythmias for decades. The main acute and chronic complications of this therapy modality are related to the use of a transvenous lead. An entirely extravascular ICD concept was developed over the last 20 years, with emergence of the subcutaneous ICD (S-ICD). This device was approved for clinical use seven years ago, and accumulating real-life experience confirms its safety and efficacy. The main limitations related to this system include the lack of pacing capabilities for bradycardia, tachycardia or resynchronization therapy, a large size, and relatively high energy requirements for effective defibrillation. This review article summarizes current knowledge and potential future developments of the extravascular ICD technologies.

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

Defibrillation threshold (DFT) testing has been an integral part of implantable cardioverter-defibrillator (ICD) implantation to confirm appropriate sensing of ventricular fibrillation and to establish an adequate safety margin for defibrillation. However, there is a lack of evidence regarding benefits of routine DFT testing. Therefore, we performed a meta-analysis to assess its mortality benefit. We searched MEDLINE for studies comparing mortality outcomes in ICD recipients who underwent DFT testing to those who did not. For the second analysis, studies comparing outcomes in patients with high- vs low-energy DFT were included. Odds ratio and standard errors were calculated, and inverse variance method in a random-effect model was used to combine effect sizes. Fifteen studies with 10,975 subjects comparing outcomes in patients who underwent routine DFT testing during ICD implantation and those who did not were included. There was no difference in the group that did not undergo DFT testing with regards to all-cause mortality (OR 0.935; CI 0.725-1.207; P = 0.606), cardiac mortality (OR 0.709; CI 0.385-1.307; P = 0.271), noncardiac mortality (OR 0.921; CI 0.701-1.210; P = 0.554), and arrhythmic mortality (OR 1.152; CI 0.831-1.596; P = 0.396). Percentage of successful appropriate first shocks among the two groups showed no difference. Five studies with 2278 subjects were included in the second analysis comparing patients with low DFT vs high DFT. Patients with high DFT had no significant increase in all-cause mortality compared to patients with low DFT (OR 0.527; CI 0.034-8.107; P = 0.646). Patients requiring higher DFT had no increased all-cause mortality compared to patients with lower DFT. Routine DFT testing during ICD implantation does not confer any significant benefit.

Should Single-Coil Implantable Cardioverter Defibrillator Leads Be Used in all Patients?

The historical preference for dual-coil implantable cardioverter defibrillator leads stems from high defibrillation thresholds associated with old device platforms. The high safety margins generated by contemporary devices have rendered the modest difference in defibrillation efficacy between single- and dual-coil leads clinically insignificant. Cohort data demonstrating worse lead extraction outcomes and higher all-cause mortality have brought the incremental utility of an superior vena cava coil into question. This article summarizes the current literature and re-evaluates the utility of dual-coil leads in the context of modern device technology.

Implantable Cardioverter Defibrillator Implantation with or Without Defibrillation Testing

Defibrillation testing (DFT) during implantable cardioverter-defibrillator (ICD) implantation is still considered standard of care in some, but in increasingly fewer centers. The goal is to ensure that the device system functions as intended by testing in the controlled laboratory setting. Although safe, complications can occur and DFT is associated with an increased procedural time and cost. DFT is useful in assessing device function when programming changes or patient characteristics raise concerns regarding ICD efficacy. DFT remains standard of practice following implantation of subcutaneous ICDs and other specific circumstances. Implanting physicians should remain familiar with the process of DFT and situations where it is useful for individual patients.

Critical analysis of ineffective post implantation implantable cardioverter-defibrillator-testing

AIM

To test of the implantable-cardioverter-defibrillator is done at the time of implantation. We investigate if any testing should be performed.

METHODS

All consecutive patients between January 2006 and December 2008 undergoing implantable cardioverter-defibrillator (ICD) implantation/replacement (a total of 634 patients) were included in the retrospective study.

RESULTS

Sixteen patients (2.5%) were not tested (9 with LA/LV-thrombus, 7 due to operator’s decision). Analyzed were 618 patients [76% men, 66.4 + 11 years, 24% secondary prevention (SP), 46% with left ventricular ejection fraction (LVEF) < 20%, 56% had coronary artery disease (CAD)] undergoing defibrillation safety testing (SMT) with an energy of 21 + 2.3 J. In 22/618 patients (3.6%) induced ventricular fibrillation (VF) could not be terminated with maximum energy of the ICD. Six of those (27%) had successful SMT after system modification or shock lead repositioning, 14 patients (64%) received a subcutaneous electrode array. Younger age (P = 0.0003), non-CAD (P = 0.007) and VF as index event for SP (P = 0.05) were associated with a higher incidence of ineffective SMT. LVEF < 20% and incomplete revascularisation in patients with CAD had no impact on SMT.

CONCLUSION

Defibrillation testing is well-tolerated. An ineffective SMT occurred in 4% and two third of those needed implantation of a subcutaneous electrode array to pass a SMT > 10 J.

The association between defibrillation shock energy and acute cardiac damage in patients with implantable cardioverter defibrillators

BACKGROUND

The aim of this study was to establish a minimally invasive defibrillation testing (DT) protocol for patients with implantable cardioverter defibrillators (ICDs).

METHODS

Two different energy DTs were performed, immediately after (15 J-DT) and 7 days after (≤10 J-DT) device implantation, in 20 consecutive ICD implantation patients. Cardiac-troponin T (c-TNT) and heart-type fatty acid binding protein (H-FABP) levels were measured before implantation, 2 h after implantation, and 1 day after each DT. For an additional 122 patients with ICD, we retrospectively analyzed 203 DTs immediately and 7 days after device implantation.

RESULTS

Serum c-TNT levels were significantly elevated 2 h after 15 J-DT [0.008 (0.004-0.019) vs. 0.053 (0.037-0.068) ng/mL, p<0.001], but not ≤10 J-DT [0.007 (0.004-0.018) ng/mL]. Similarly, serum H-FABP levels were significantly elevated 2 h after 15 J-DT (2.9±1.5 vs. 6.4±3.4 ng/mL, p<0.001), but not ≤10 J-DT (2.7±1.5 ng/mL). The changes in c-TNT and H-FABP levels between baseline and 2 h after DT were significantly greater for 15 J-DT compared with ≤10 J-DT [c-TnT: 0.039 (0.029-0.060) vs. 0 (0-0.003) ng/mL, p<0.001; H-FABP: 3.6±2.8 vs. -0.16±1.1 ng/mL, p<0.001]. The success rates of the initial shocks delivered for ventricular fibrillation were no different between ≤10 J-DT (85% [78/92]) and ≥15 J-DT (92% [103/111]).

CONCLUSIONS

Elevated levels of myocardial damage markers such as c-TNT and H-FABP were not found after ≤10 J-DT. In addition, an acceptable success rate was confirmed in ≤10 J-DT.

Systematic Review of Defibrillation Threshold Testing at De Novo Implantation

Background—

Recent results from the largest multicenter randomized trial (Shockless IMPLant Evaluation [SIMPLE]) on defibrillation threshold (DFT) testing suggest that while shock testing seems safe, it does not reduce the risk of failed shocks or prolong survival. A contemporary systematic review of DFT versus no-DFT testing at the time of implantable cardioverter–defibrillator implantation was performed to evaluate the current evidence and to assess the impact of the SIMPLE study.

Methods and Results—

Electronic searches were performed using 6 databases from their inception to March 2014. Relevant studies investigating implant DFT were identified. Data were extracted and analyzed according to predefined clinical end points. Predefined outcomes for interrogation were all-cause mortality, composite end point of implantable cardioverter–defibrillator efficacy (arrhythmic deaths and ineffective shocks), and composite safety end point (the sum of complications recorded at 30 days). Meta-analysis was performed including 13 studies and 9740 patients. No significant differences between DFT versus no-DFT cohorts were found in terms of all-cause mortality (risk ratio, 0.90; 95% confidence interval, 0.71–1.15; P =0.41), composite efficacy outcome (risk ratio, 1.24; 95% confidence interval, 0.65–3.37; P =0.51), and 30-day postimplant complications (risk ratio, 1.18; 95% confidence interval, 0.87–1.60; P =0.29). No significant difference was found in the trends observed when the results of the SIMPLE study were excluded or included.

Conclusions—

This systematic review of contemporary data suggests a modest average effect of DFT, if any, in terms of mortality, shock efficacy, or safety. Therefore, DFT testing should no longer be compulsory during de novo implantation. However, DFT testing may still be clinically relevant in specific patient populations.

Complications of defibrillation testing. A review of the literature

Defibrillation testing (DT) has traditionally been performed at the time of implantable cardioverter defibrillator (ICD) insertion. However, there has been a trend away from conducting DT, in part due to observational studies showing uncommon but serious complications related to DT. More recently, several randomized trials have shown no improvement in the efficacy of clinical shocks among patients assigned to have DT. These trials also suggest a modest increase in perioperative complications related to DT; however, the overall rate of complications was very low. This review focuses on the prevalence of complications associated with DT and elaborates on a number of indications for DT.

The role of defibrillation testing

The induction and termination of ventricular fibrillation at the time of defibrillator insertion (defibrillation testing [DT]) has traditionally been an integral component of implantable cardioverter-defibrillator (ICD) implantation. However, over the last 10 years, published series suggested a high rate of first-shock efficacy for clinical ventricular arrhythmias, even if no DT was done. Over the same time, several published reports and series have shown uncommon but serious complications related to DT. Throughout the world, there has been a steady decline in the proportion of patients receiving an ICD who undergo DT, which, in many regions, is less than 50%.

Intra-operative defibrillation testing and clinical shock efficacy in patients with implantable cardioverter-defibrillators: the NORDIC ICD randomized clinical trial

AIMS

This trial was designed to test the hypothesis that shock efficacy during follow-up is not impaired in patients implanted without defibrillation (DF) testing during first implantable cardioverter-defibrillator (ICD) implantation.

METHODS AND RESULTS

Between February 2011 and July 2013, 1077 patients were randomly assigned (1 : 1) to first time ICD implantation with (n = 540) or without (n = 537) DF testing. The intra-operative DF testing was standardized across all participating centres, and all ICD shocks were programmed to 40 J irrespective of DF test results. The primary end point was the average first shock efficacy (FSE) for all true ventricular tachycardia and fibrillation (VT/VF) episodes during follow-up. The secondary end points included procedural data, serious adverse events, and mortality. During a median follow-up of 22.8 months, the model-based FSE was found to be non-inferior in patients with an ICD implanted without a DF test, with a difference in FSE of 3.0% in favour of the no DF test [confidence interval (CI) -3.0 to 9.0%, Pnon-inferiority <0.001 for the pre-defined non-inferiority margin of -10%). A total of 112 procedure-related serious adverse events occurred within 30 days in 94 patients (17.6%) tested compared with 89 events in 74 patients (13.9%) not tested (P = 0.095).

CONCLUSION

Defibrillation efficacy during follow-up is not inferior in patients with a 40 J ICD implanted without DF testing. Defibrillation testing during first time ICD implantation should no longer be recommended for routine left-sided ICD implantation.

Cardioverter defibrillator implantation without induction of ventricular fibrillation: a single-blind, non-inferiority, randomised controlled trial (SIMPLE)

BACKGROUND

Defibrillation testing by induction and termination of ventricular fibrillation is widely done at the time of implantation of implantable cardioverter defibrillators (ICDs). We aimed to compare the efficacy and safety of ICD implantation without defibrillation testing versus the standard of ICD implantation with defibrillation testing.

METHODS

In this single-blind, randomised, multicentre, non-inferiority trial (Shockless IMPLant Evaluation [SIMPLE]), we recruited patients aged older than 18 years receiving their first ICD for standard indications at 85 hospitals in 18 countries worldwide. Exclusion criteria included pregnancy, awaiting transplantation, particpation in another randomised trial, unavailability for follow-up, or if it was expected that the ICD would have to be implanted on the right-hand side of the chest. Patients undergoing initial implantation of a Boston Scientific ICD were randomly assigned (1:1) using a computer-generated sequence to have either defibrillation testing (testing group) or not (no-testing group). We used random block sizes to conceal treatment allocation from the patients, and randomisation was stratified by clinical centre. Our primary efficacy analysis tested the intention-to-treat population for non-inferiority of no-testing versus testing by use of a composite outcome of arrhythmic death or failed appropriate shock (ie, a shock that did not terminate a spontaneous episode of ventricular tachycardia or fibrillation). The non-inferiority margin was a hazard ratio (HR) of 1·5 calculated from a proportional hazards model with no-testing versus testing as the only covariate; if the upper bound of the 95% CI was less than 1·5, we concluded that ICD insertion without testing was non-inferior to ICD with testing. We examined safety with two, 30 day, adverse event outcome clusters. The trial is registered with ClinicalTrials.gov, number NCT00800384.

FINDINGS

Between Jan 13, 2009, and April 4, 2011, of 2500 eligible patients, 1253 were randomly assigned to defibrillation testing and 1247 to no-testing, and followed up for a mean of 3·1 years (SD 1·0). The primary outcome of arrhythmic death or failed appropriate shock occurred in fewer patients (90 [7% per year]) in the no-testing group than patients who did receive it (104 [8% per year]; HR 0·86, 95% CI 0·65-1·14; pnon-inferiority <0·0001). The first safety composite outcome occurred in 69 (5·6%) of 1236 patients with no-testing and in 81 (6·5%) of 1242 patients with defibrillation testing, p=0·33. The second, pre-specified safety composite outcome, which included only events most likely to be directly caused by testing, occurred in 3·2% of patients with no-testing and in 4·5% with defibrillation testing, p=0·08. Heart failure needing intravenous treatment with inotropes or diuretics was the most common adverse event (in 20 [2%] of 1236 patients in the no-testing group vs 28 [2%] of 1242 patients in the testing group, p=0·25).

INTERPRETATION

Routine defibrillation testing at the time of ICD implantation is generally well tolerated, but does not improve shock efficacy or reduce arrhythmic death.

FUNDING

Boston Scientific and the Heart and Stroke Foundation (Ontario Provincial office).

The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial: concept and design of a randomized, controlled trial of intra-operative defibrillation testing during de novo defibrillator implantation

AIMS

Although defibrillation (DF) testing is still considered a standard procedure during implantable cardioverter-defibrillator (ICD) insertion and has been an essential element of all trials that demonstrated the survival benefit of ICD therapy, there are no large randomized clinical trials demonstrating that DF testing improves clinical outcome and if the outcome would remain the same by omitting DF testing.

METHODS AND RESULTS

Between February 2011 and July 2013, we randomly assigned 1077 patients to ICD implantation with (n = 540) or without (n = 537) DF testing. The intra-operative DF testing was standardized across all participating centres. After inducing a fast ventricular tachycardia (VT) with a heart rate ≥240 b.p.m. or ventricular fibrillation (VF) with a low-energy T-wave shock, DF was attempted with an initial 15 J shock. If the shock reversed the VT or VF, DF testing was considered successful and terminated. If unsuccessful, two effective 24 J shocks were administered. If DF was unsuccessful, the system was reconfigured and another DF testing was performed. An ICD shock energy of 40 J had to be programmed in all patients for treatment of spontaneous VT/VF episodes. The primary endpoint was the average efficacy of the first ICD shock for all true VT/VF episodes in each patient during follow-up. The secondary endpoints included the frequency of system revisions, total fluoroscopy, implantation time, procedural serious adverse events, and all-cause, cardiac, and arrhythmic mortality during follow-up. Home Monitoring was used in all patients to continuously monitor the system integrity, device programming and performance.

CONCLUSION

The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial is one of two large prospective randomized trials assessing the effect of DF testing omission during ICD implantation.

CLINICALTRIALSGOV IDENTIFIER

NCT01282918.

ICD implantation without intraoperative testing does not increase the rate of system modifications and does not impair defibrillation efficacy tested in follow-up

AIM

The need for implantable cardioverter-defibrillator (ICD) defibrillation testing (DT) and subsequent intraoperative system modifications is discussed controversially. The study's goal was to prove that consequent abdication of intraoperative DT does not impair defibrillation efficacy and does not increase the rate of postoperative system revisions.

METHODS

In a prospective single-center observational study, 609 out of 648 consecutive patients underwent transvenous ICD implantation (left-sided, active can, dual coil lead, and biphasic shock waveform) waiving intraoperative DT. Defibrillation efficacy was validated prior to hospital discharge (PHD) by applying two 10 J safety margin (SM) shocks.

RESULTS

Following "schockless" implantation 580 out of 609 patients (95.2 %) met a 10 J SM with default programming. Shock path reversal provided 10 J SM in 13 out of 29 cases with initially failed DT. In four patients (0.7 %) maximum energy shocks were ineffective. There was no morbidity or mortality related to DT. The total rate of surgical ICD revisions was 1.8 %.

CONCLUSION

Routine ICD implantation without intraoperative DT does not lead to an increased rate of postoperative system modifications and does not decrease defibrillation efficacy as tested PHD.

Intraoperative defibrillation threshold testing and postoperative long-term efficacy of cardioverter-defibrillator implantation

The aim of this study was to determine the defibrillation threshold (DFT) of implantable cardioverter-defibrillators (ICDs) and outcomes of treatment. Sixty-four patients received cardioverter-defibrillator implantation. During implantation, the DFT was determined by the defibrillation safety margin (DSM). All patients were followed up for 12–48 months after the implantation. The overall DFT was 14.27±2.56 J and the DSM was 18.40±1.89 J. Malignant ventricular arrhythmias occurred in 42 patients following cardioverter-defibrillator implantation including 500 episodes of non-sustained ventricular tachycardia (VT) and 289 episodes of persistent VT. VT was treated using antitachycardia pacing (ATP); 265 episodes were treated successfully by a single ATP treatment (91.69%) and 12 episodes were treated successfully by two ATP treatments (4.15%). Twelve episodes were converted by low-energy electrical cardioversion (4.15%). A total of 175 ventricular fibrillation (VF) episodes were identified, of which 18 episodes automatically terminated prior to treatment. In total, 146 episodes were converted by a single cardioversion with a defibrillation energy of 13.21±2.58 J and 11 episodes were converted by two cardioversions with a defibrillation energy of 16.19±2.48 J. It is safe and feasible to determine the DFT by DSM measurement during cardioverterdefibrillator implantation.

Prolonged burst as a new method for cardioverter-defibrillator testing

AIM

To find out whether it is possible to anaesthetize patients safely without analgesia and sedation, using burst pacing prolonged until the patient becomes unconscious.

METHODS

One hundred and four patients undergoing implantation or reimplantation of a cardioverter-defibrillator were included. Patients randomized into Group B underwent prolonged burst pacing without analgesia and sedation. Patients in Group T underwent a T-wave shock under analgesia and sedation. Blood samples for measurement of serum neuron-specific enolase were taken before surgery and 6, 24, and 48 h after the procedure.

RESULTS

From the 104 patients, 51 were randomly assigned to Group B and 53 to Group T. Four patients from Group B were switched to Group T (ventricular fibrillation not induced by burst pacing). The clinical characteristics of both groups were similar. The mean total time of cardiac arrest was significantly longer in Group B (23.0 ± 4.4 s, median 22.7) vs. Group T (10.3 ± 3.0 s, median 10.0), P < 0.0001 (Mann-Whitney U-test). The effectiveness of both induction methods was similar (92.1% in Group B and 100% in Group T). The mean neuron-specific enolase levels after 6, 24, and 48 h were similar in Groups B and T (13.1 ± 6.3 and 11.6 ± 5.8 mg/L, 14.5 ± 7.5 and 13.4 ± 6.0 mg/L, and 14.9 ± 5.9 and 12.2 ± 6.0 mg/L, respectively) as were these levels compared with baseline neuron-specificenolase levels (14.0 ± 5.9 and 13.4 ± 4.0 mg/L, respectively), P = NS for all.

CONCLUSION

Despite a longer time of total cardiac arrest, prolonged burst pacing appears to be a safe and effective method for induction of ventricular fibrillation during cardioverter-defibrillator testing, which enables omission of analgesia and sedation or general anaesthesia.

The rationale and design of the Shockless IMPLant Evaluation (SIMPLE) trial: a randomized, controlled trial of defibrillation testing at the time of defibrillator implantation

Defibrillation testing (DT) has been an integral part of defibrillator (implantable cardioverter defibrillator [ICD]) implantation; however, there is little evidence that it improves outcomes. Surveys show a trend toward ICD implantation without DT, which now exceeds 30% to 60% in some regions. Because there is no evidence to support dramatic shift in practice, a randomized trial is urgently needed. The SIMPLE trial will determine if ICD implantation without any DT is noninferior to implantation with DT. Patients will be eligible if they are receiving their first ICD using a Boston Scientific device (Boston Scientific, Natick, MA). Patients will be randomized to DT or no DT at the time of ICD implantation. In the DT arm, physicians will make all reasonable efforts to ensure 1 successful intraoperative defibrillation at 17 J or 2 at 21 J. The first clinical shock in all tachycardia zones will be set to 31 J for all patients. The primary outcome of SIMPLE will be the composite of ineffective appropriate shock or arrhythmic death. The safety outcome of SIMPLE will include a composite of potentially DT-related procedural complications within 30 days of ICD implantation. Several secondary outcomes will be evaluated, including all-cause mortality and heart failure hospitalization. Enrollment of 2,500 patients with 3.5-year mean follow-up will provide sufficient statistical power to demonstrate noninferiority. The study is being performed at approximately 90 centers in Canada, Europe, Israel, and Asia Pacific with final results expected in 2013.

Clinical evaluation of defibrillation testing in an unselected population of 2,120 consecutive patients undergoing first implantable cardioverter-defibrillator implant

OBJECTIVES

The purpose of this study is to assess the effectiveness of defibrillation testing (DT) in patients undergoing implantable cardioverter-defibrillator (ICD) insertion.

BACKGROUND

Although DT is considered a standard procedure during ICD implantation, its usefulness has not been definitively proven.

METHODS

The SAFE-ICD (Safety of Two Strategies of ICD Management at Implantation) study is a prospective observational study designed to evaluate the outcome of 2 strategies: performing defibrillation testing (DT+) versus not performing defibrillation testing (DT-) during de novo ICD implants. No deviation from the centers' current practice was introduced. In all, 2,120 consecutive patients (836 DT+ and 1,284 DT-) age ≥18 years were enrolled at 41 Italian centers from April 2008 to May 2009 and followed up for 24 months until June 2011. The primary endpoint was a composite of severe complications at ICD implant and sudden cardiac death or resuscitation at 2 years.

RESULTS

The primary endpoint occurred in 34 patients: 12 intraoperative complications (8 in DT+ group; 4 in DT- group) and 22 during follow-up (10 in DT+ group; 12 in DT- group). Overall, the estimated yearly incidence (95% confidence interval) was DT+ 1.15% (0.73 to 1.83) and DT- 0.68% (0.42 to 1.12). The difference between the 2 groups was negligible: 0.47% per year (-0.15 to 1.10). Mortality from any cause was similar at 2 years (adjusted hazard ratio: 0.97 [0.76 to 1.23], p = 0.80).

CONCLUSIONS

In this large cohort of new ICD implants, event rates were similar and extremely low in both groups. These data indicate a limited clinical relevance for DT testing, thus supporting a strategy of omitting DT during an ICD implant. (Safety of Two Strategies of ICD Management at Implantation [SAFE-ICD]; NCT00661037).

Defibrillation testing during implantable cardioverter-defibrillator implantation in Italian current practice: the Assessment of Long-term Induction clinical ValuE (ALIVE) project

BACKGROUND

Clinical practice with regard to defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation varies considerably, even among experienced implanting centers. International guidelines do not as yet mandate DFT testing.

OBJECTIVE

The objective of this project is to assess current clinical decision making regarding DFT testing during ICD implantation.

METHODS

The ALIVE project collected data on DFT testing from a multicenter network of Italian clinicians sharing a common system for the collection, management, analysis, and reporting of clinical and diagnostic data from patients with Medtronic (Minneapolis, MN) implantable devices.

RESULTS

Data on 2,082 consecutive patients implanted with a Medtronic ICD in 111 Italian centers, over the period 2007 to 2010, were analyzed. Defibrillation threshold testing was performed in 33% of cases (678/2,082). The main reasons for performing the test were physician's clinical practice ("I always perform DFT") (80%) and secondary prevention implantation (12%). The main reasons for not performing DFT testing were centers' practice (44%), primary prevention (31%), and device replacement (15%). In 22 patients, ventricular fibrillation induction was not achieved; 656 patients completed DFT testing: 633 patients (96%) performed a single test, 19 patients (3%) performed a second induction test, and 4 patients (0.6%) underwent an additional induction test.

CONCLUSIONS

The preliminary results of the ALIVE project show that a great number of implant procedures are performed without DFT testing in the common practice of the participating centers. We also measured an inhomogeneous, center-dependent DFT testing behavior, which suggests the importance of defining a common guideline for ICD implant testing. Follow-up data on our patients will provide more information on the clinical value of the test.

Defibrillation threshold testing fails to show clinical benefit during long-term follow-up of patients undergoing cardiac resynchronization therapy defibrillator implantation

BACKGROUND

The utility of defibrillation threshold testing in patients undergoing implantable cardioverter-defibrillator (ICD) implantation is controversial. Higher defibrillation thresholds have been noted in patients undergoing implantation of cardiac resynchronization therapy defibrillators (CRT-D). Since the risks and potential benefits of testing may be higher in this population, we sought to assess the impact of defibrillation safety margin or vulnerability safety margin testing in CRT-D recipients.

METHODS AND RESULTS

A total of 256 consecutive subjects who underwent CRT-D implantation between January 2003 and December 2007 were retrospectively reviewed. Subjects were divided into two groups based on whether (n= 204) or not (n= 52) safety margin testing was performed. Patient characteristics, tachyarrhythmia therapies, procedural results, and clinical outcomes were recorded. Baseline characteristics, including heart failure (HF) severity, were comparable between the groups. Four cases of HF exacerbation (2%), including one leading to one death, were recorded in the tested group immediately post-implantation. No complications were observed in the untested group. After a mean follow-up of 32 ± 20 months, the proportion of appropriate shocks in the two groups was similar (31 vs. 25%, P = 0.49). There were three cases of failed appropriate shocks in the tested group, despite adequate safety margins at implantation, whereas no failed shocks were noted in the untested group. Survival was similar in the two groups.

CONCLUSION

Defibrillation efficacy testing during implant of CRT-D was associated with increased morbidity and did not predict the success of future device therapy or improve survival during long-term follow-up.

[Is intraoperative ICD-testing still necessary?]

Intraoperative ICD-testing is traditionally performed in many hospitals in order to ensure reliable sensing, detection, and defibrillation of induced ventricular fibrillation. The technical progress of defibrillators allows rapid detection and delivery of high energy shocks which defibrillates effectively in the vast majority all patients at implant. This review describes arguments pro and contra of systematic testing of the defibrillation threshold in all patients. Many reasons argue against testing in all patients: experimental considerations, patients' specific and nonspecific factors, e.g., underlying severity of cardiac disease, ischemia, and medication, as well as factors specific to the ICD system, e.g., implanted type and location of electrodes and active cans. Finally, the testing method is very important, since it bears the risk of false negative test results because the a priori probability of a positive test result is >95%. Therefore, data from prospective randomized studies are necessary in order to abandon the tradition of ICD-testing on an evidence-based background.

Intraoperative defibrillation threshold testing during implantable cardioverter-defibrillator insertion: do we really need it?

BACKGROUND

The assessment of defibrillation efficacy using a safety margin of 10 J has long been the standard of care for insertion of implantable cardioverter-defibrillator (ICD), but physicians are concerned about complications related to induction test. Therefore, the need for testing has been recently questioned. The aim of our study was to assess the impact of defibrillation threshold (DFT) testing of ICD on the efficacy of ICD therapy.

METHODS

We analyzed data obtained from follow-up visits of 122 consecutive patients who underwent ICD implantation at our institute from April 1996 to June 2008, with (n = 42) or without (n = 80) DFT testing. Patients in the DFT group were less likely to be men (83.3% vs 96.3%, P < .031) than those in the non-DFT group. Conversely, the 2 groups were similar in age, left ventricular ejection fraction at baseline, functional class, and underlying cardiovascular disease. Results during a 12-month follow-up, 13 (31.0%) and 30 (37.5%) ventricular tachyarrhythmic episodes were recorded in the DFT and non-DFT groups, respectively (P = .472). Antitachycardia pacing (ATP) terminated most of episodes, reducing the need of defibrillation at 7.7% in the DFT group and 3.3% in the non-DFT group (P = .533). Similar percentages of inappropriate ATP interventions (7.1% vs 3.8%, P = .413) and shock deliveries (2.4% vs 5.0%, P = .659) were recorded between DFT and non-DFT groups.

CONCLUSIONS

At 1-year follow-up, the performance of DFT testing does not seem to add any significant efficacy advantage in patients undergoing ICD implantation. Prospective randomized trials and long-term follow-up are warranted to clarify whether routine DFT testing may be safely abandoned leading to a revision of current guidelines.