Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial

BACKGROUND

The PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events.

OBJECTIVE

This prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias.

METHODS

This multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm.

RESULTS

In total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13-279.95; P < .001).

CONCLUSION

A PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Outcome and safety of intraoperative defibrillation testing during device replacement: the Simpler trial

AIMS

Intraoperative defibrillation testing (DT) during implant or replacement of implantable cardioverter-defibrillators (ICDs) has been a matter of debate for many years. This debate was put to rest by the Simple and Nordic ICD trials, and the practice of testing during new implantations has essentially been almost abandoned. Old registries demonstrated an increased incidence of significant findings in DT during replacements. The aim of the present study was to evaluate frequency of significant findings and safety of DT in subjects undergoing device replacement.

METHODS AND RESULTS

A prospective observational multi-centre study included consecutive patients undergoing ICD generator replacement. The primary outcome was a failure to terminate induced ventricular fibrillation (VF) with a single shock 10 J below the maximal capacity of the device. Secondary outcomes included complications of DT. Patients were followed-up at 1- and 6-months post-procedure.  A total of 92 patients were eligible, and consented to the study, of which 84 underwent DT during battery replacement. The median age was 68 years and 79.8% were males. Induction of VF was successful in 84 patients as was a successful conversion on the first attempt in all. There were no procedure-related complications. During follow up one patient had two appropriate ICD shock events. In four patients, ICD programming was changed. None suffered inappropriate shock. There was no evidence of lead malfunction. Two deaths occurred, none of which was related to arrhythmia.

CONCLUSION

The present study found DT was not associated with complications in patients undergoing ICD generator replacement but produced no clinically important information.

2019 HRS/EHRA/APHRS/LAHRS focused update to 2015 expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer’s ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient’s clinical status and desired outcome via a shared clinical decision-making process.

Subcutaneous implantable cardioverter-defibrillator and defibrillation testing: A propensity-matched pilot study

BACKGROUND

To date, only a few comparisons between subcutaneous implantable cardioverter-defibrillator (S-ICD) patients undergoing and those not undergoing defibrillation testing (DT) at implantation (DT+ vs DT-) have been reported.

OBJECTIVE

The purpose of this study was to compare long-term clinical outcomes of 2 propensity-matched cohorts of DT+ and DT- patients.

METHODS

Among consecutive S-ICD patients implanted across 17 centers from January 2015 to October 2020, DT- patients were 1:1 propensity-matched for baseline characteristics with DT+ patients. The primary outcome was a composite of ineffective shocks and cardiovascular mortality. Appropriate and inappropriate shock rates were deemed secondary outcomes.

RESULTS

Among 1290 patients, a total of 566 propensity-matched patients (283 DT+; 283 DT-) served as study population. Over median follow-up of 25.3 months, no significant differences in primary outcome event rates were found (10 DT+ vs 14 DT-; P = .404) as well as for ineffective shocks (5 DT- vs 3 DT+; P = .725). At multivariable Cox regression analysis, DT performance was associated with a reduction of neither the primary combined outcome nor ineffective shocks at follow-up. A high PRAETORIAN score was positively associated with both the primary outcome (hazard ratio 3.976; confidence interval 1.339-11.802; P = .013) and ineffective shocks alone at follow-up (hazard ratio 19.030; confidence interval 4.752-76.203; P = .003).

CONCLUSION

In 2 cohorts of strictly propensity-matched patients, DT performance was not associated with significant differences in cardiovascular mortality and ineffective shocks. The PRAETORIAN score is capable of correctly identifying a large percentage of patients at risk for ineffective shock conversion in both cohorts.

Defibrillation testing during implantation of the subcutaneous implantable cardioverter-defibrillator: a necessary standard or becoming redundant?

Since the publication of the SIMPLE and NORDIC trials, defibrillation testing (DFT) is rarely performed during routine implantation of transvenous implantable cardioverter-defibrillators (ICD). However, the results of these trials cannot be extrapolated to the later introduced subcutaneous ICD (S-ICD) and a class I recommendation to perform DFT during the implantation of these devices remains in the current guidelines. Due to the high conversion success rate of DFT on one hand, and the risk of complications on the other, a significant number of physicians omit DFT in S‑ICD recipients. Several retrospective analyses have assessed the safety of the omission of DFT and report contradicting results and recommendations. It is known that implant position, as well as device factors and patient characteristics, influence defibrillation success. A better comprehension of these factors and their relationship could lead to more reliable and safer alternatives to DFT. An ongoing randomised clinical trial, which is expected to end in 2023, is the first study to implement a method that assesses implant position to identify patients who are likely to fail their DFT.

Impact of defibrillation threshold testing on burden of heart failure hospitalizations

Background: Defibrillation threshold testing (DT) following implantable cardioverter defibrillator (ICD) implantation has not shown to improve mortality. However, the impact of DT on burden of heart failure (HF) hospitalisations has not been well defined.Methods: We studied retrospectively consecutive patients who underwent ICD implantation or generator change between 2008 and 2014. Primary outcome was burden of HF hospitalisations within 30 days following implantation. Secondary outcomes were mortality, stroke, and ICD shock within 30 days and one-year mortality.Results: Three hundred and eleven of 501 patients (62%) were in DT+ group versus 190 (38%) were in DT- group. The percentage of new implantations was higher in DT+ group than in DT- group (69% vs 39%, p < .001) but the distributions of NYHA function classes were similar between two groups. The burden of HF hospitalisations at 30-days was significantly higher in DT+ group than in DT- group (17.4% vs 4.7%, HR 0.842, 95% CI 0.774-0.915, p < .0001). No difference in mortality, stroke or ICD shocks was found between two groups at 30 days and mortality at 1 year.Conclusions: DT after new ICD or generator replacement was associated with increased HF hospitalisation rates at 30 days after ICD implant in a non-trial HF population. However, there was no association between DT and mortality, stroke and ICD shocks at 30 days or mortality at 1 year. The increased burden of HF hospitalisation in this observational study requires validation by randomised studies.

2019 HRS/EHRA/APHRS/LAHRS focused update to 2015 expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing

The 2015 HRS/EHRA/APHRS/SOLAECE Expert Consensus Statement on Optimal Implantable Cardioverter-Defibrillator Programming and Testing provided guidance on bradycardia programming, tachycardia detection, tachycardia therapy, and defibrillation testing for implantable cardioverter-defibrillator (ICD) patient treatment. The 32 recommendations represented the consensus opinion of the writing group, graded by Class of Recommendation and Level of Evidence. In addition, Appendix B provided manufacturer-specific translations of these recommendations into clinical practice consistent with the recommendations within the parent document. In some instances, programming guided by quality evidence gained from studies performed in devices from some manufacturers was translated such that this programming was approximated in another manufacturer's ICD programming settings. The authors found that the data, although not formally tested, were strong, consistent, and generalizable beyond the specific manufacturer and model of ICD. As expected, because these recommendations represented strategic choices to balance risks, there have been reports in which adverse outcomes were documented with ICDs programmed to Appendix B recommendations. The recommendations have been reviewed and updated to minimize such adverse events. Notably, patients who do not receive unnecessary ICD therapy are not aware of being spared potential harm, whereas patients in whom their ICD failed to treat life-threatening arrhythmias have their event recorded in detail. The revised recommendations employ the principle that the randomized trials and large registry data should guide programming more than anecdotal evidence. These recommendations should not replace the opinion of the treating physician who has considered the patient's clinical status and desired outcome via a shared clinical decision-making process.

A novel tool to evaluate the implant position and predict defibrillation success of the subcutaneous implantable cardioverter-defibrillator: The PRAETORIAN score

BACKGROUND

Suboptimal positioning of the subcutaneous implantable cardioverter-defibrillator (S-ICD) increases the defibrillation threshold and risk of conversion failure.

OBJECTIVE

Our objective is to develop a tool to evaluate the implant position and predict defibrillation success of the S-ICD: the PRAETORIAN score.

METHODS

The PRAETORIAN score is based on clinical and computer modeling knowledge of determinants affecting the defibrillation threshold: subcoil fat, subgenerator fat, and anterior positioning of the S-ICD generator. The score evaluates these determinants on the postoperative anterior-posterior and lateral chest radiographs and has 3 categories: 30-<90 points representing a low risk, 90-<150 points representing an intermediate risk, and ≥150 points representing a high risk of conversion failure. The score was developed using 2 separate S-ICD data sets for derivation and validation. The performance metrics are the positive and negative predictive values.

RESULTS

The development data set consisted of 181 patients with S-ICD, and the validation cohort consisted of 321 patients from the S-ICD Investigational Device Exemption trial. The distribution of scores was 93%-98% low risk (<90 points), 2%-5% intermediate risk (90-<150 points), and 1% high risk (≥150 points). The positive predictive value for an intermediate or high PRAETORIAN score for a failed conversion test was 51%, while a low PRAETORIAN score predicted a successful conversion in 99.8% of patients.

CONCLUSION

The PRAETORIAN score allows the identification of patients with high defibrillation thresholds by using the routine chest radiograph and provides feedback to implanters on S-ICD positioning. The PRAETORIAN-DFT trial will prospectively validate the score by randomizing to standard conversion testing vs using the score without conversion testing.

Defibrillation testing and clinical outcomes after implantable cardioverter-defibrillator implantation in patients in atrial fibrillation at the time of implant: An analysis from the SIMPLE trial

BACKGROUND

The Shockless IMPLant Evaluation (SIMPLE) trial showed that defibrillation testing (DT) at the time of implantable cardioverter-defibrillator (ICD) implant did not improve shock efficacy or reduce mortality. There are no data regarding the risk of complications, including stroke, among patients with atrial fibrillation (AF) who undergo DT.

OBJECTIVE

The purpose of this prospectively planned substudy of SIMPLE was to evaluate the effect of DT vs no DT on clinical outcomes among patients with AF.

METHODS

We compared efficacy (failed appropriate shock/arrhythmic death) and safety between patients who had AF on their immediate preprocedural ECG to the rest of the study patients. Then among patients with AF we compared these outcomes between patients randomized to DT vs no DT.

RESULTS

Of the 2500 patients enrolled in SIMPLE, 251 (10%) were in AF immediately before ICD implant. AF patients had an increased risk of failed appropriate shock/arrhythmic death (adjusted hazard ratio [HR] 1.64; 95% confidence interval [CI] 1.13-2.39; P = .009) and higher all-cause mortality (adjusted HR 1.58; 95% CI 1.2-2.08; P = .001). Among AF patients, perioperative complications and stroke did not significantly differ between DT vs no-DT groups (9.2% vs 5.4%; P = .2; and 1.7% vs 1.5%; P >.999, respectively). Failed appropriate shock or arrhythmic death occurred in 35 of 251 AF patients (14%), and the no-DT group proved not inferior to the DT group (HR 0.58; 95% CI 0.30-1.15; P_{noninferiority} = .006).

CONCLUSION

ICD recipients with AF are at increased risk for adverse outcomes; however, DT does not improve arrhythmic survival or shock efficacy. There is no evidence that DT increased the occurrence of perioperative stroke.

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.

Riata silicone defibrillation lead with normal electrical measures at routine ambulatory check: The role of high-voltage shock testing

AIM

To describe our experience with shock testing for the evaluation of patients with Riata™ leads.

METHODS

Among 51 patients with normal baseline electrical parameters, 20 died during follow-up. Of the remaining 31 patients, 15 underwent the test: In 10 cases a defibrillation testing with ventricular fibrillation (VF) induction and in 5 cases a R-wave-synchronized shock (> 20 J, without inducing VF). The test was performed under sedation with Midazolam.

RESULTS

Twelve patients (80%) had a normal behavior during shock testing: In 8 cases induced VF was correctly detected and treated; in 4 cases of R-wave-synchronized shock electrical parameters remained stable and normal. Three patients (20%) failed the test. One patient with externalized conductors showed a sudden drop of high-voltage impedance (< 10 Ohm) after a 25 J R-wave-synchronized shock. Two other patients with externalized conductors, undergoing defibrillation testing, showed a short-circuit during shock delivery and the implantable cardioverter defibrillator was unable to interrupt VF.

CONCLUSION

In Riata™ leads the delivery of a low current during routine measurement of high-voltage impedance may not reveal a small short circuit, that can only be evident by attempting to deliver a true shock, either for spontaneous arrhythmias or in the context of a shock 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.

Troponin levels after ICD implantation with and without defibrillation testing and their predictive value for outcomes: Insights from the SIMPLE trial

BACKGROUND

The Shockless IMPLant Evaluation trial randomized 2500 patients receiving a first implantable cardioverter-defibrillator (ICD)/cardiac resynchronization therapy-defibrillator device to have either defibrillation testing (DT) or no DT. It demonstrated that DT did not improve shock efficacy or reduce mortality.

OBJECTIVE

This prospective substudy evaluated the effect of DT on postoperative troponin levels and their predictive value for total and arrhythmic mortality.

METHODS

Troponin levels were measured between 6 and 24 hours after ICD implantation in 2200 of 2500 patients.

RESULTS

A postoperative serum troponin level above the upper limit of normal (ULN) was more common in patients undergoing DT (n = 509 [46.4%]) than in those not subjected to DT (n = 456 [41.3%]; P = .02). After excluding patients with known preoperative troponin levels above the ULN, consistent findings were observed (42.1% vs 37.5%; P = .04). During a mean follow-up of 3.1 ± 1.0 years, the annual mortality rate was increased in patients with postoperative troponin levels above the ULN (adjusted hazard ratio [HR] 1.43; 95% confidence interval [CI] 1.15-1.76; P = .001) irrespective of DT or no DT. Likewise, patients with elevated troponin levels had a significantly higher risk of arrhythmic death (adjusted HR 1.80; 95% CI 1.23-2.63; P = .002). The rate of first appropriate ICD shock (adjusted HR 0.89; 95% CI 0.71-1.12; P = .32) or failed appropriate shock (adjusted HR 1.02; 95% CI 0.59-1.76; P = .95) was similar in patients with or without troponin elevation.

CONCLUSION

DT at the time of ICD implantation is associated with increased troponin levels, indicating subclinical myocardial injury caused by the procedure. Elevated troponin levels but not DT seem to predict clinical outcomes in ICD recipients.

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.

Cardiac troponin levels following implantable cardioverter defibrillation implantation and testing

AIMS

Previous studies have reported the defibrillation testing during implantable cardioverter defibrillator (ICD) implantation is associated with elevated cardiac biomarkers and ST-segment electrocardiogram (ECG) changes suggesting that shocks during testing may cause harm. However, the effects of testing have not been isolated from the implant procedure itself, where lead deployment may cause myocardial damage. This prospective study examined high sensitivity troponin T (hs-TnT) levels and ECG changes during ICD implanting alone, ICD implantation with testing and device testing as a stand-alone procedure.

METHODS AND RESULTS

We examined hs-TnT at baseline, and 6-8 h post procedure and 12 lead ECG at baseline, and 30 s, 5 min, and 10 min post right ventricle lead deployment and post defibrillation. There was no significant change in hs-TnT levels in a group of patients (n = 11) undergoing defibrillation testing alone, while hs-TnT was significantly elevated in patients undergoing implantation alone (n = 13, median increase 96%, P = 0.005) and in patients undergoing implantation and testing (n = 13, median increase 161%, P = 0.005). There was a significant correlation between the number of lead deployments and the percentage change in hs-TnT (r = -0.51, P = 0.01), but no correlation between either the number of shocks (r = 0.26, P = 0.25) or the total delivered energy (r = 0.24, P = 0.30) and percentage change in hs-TnT.

CONCLUSION

Implantation of ICD leads was associated with release of troponin, but we did not observe any evidence that ICD shocks alone cause myocardial injury.

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.