Implantable Cardioverter Defibrillator Research Articles

Transitioning from 0.5 to 0.9 mT: Protecting against inadvertent activation of magnet mode in active implants.

The "5 gauss line" is a phrase that is likely to be familiar to everyone working with MRI, but what is its significance, how was it defined, and what changes are currently in progress? This review explores the history of 5 gauss (0.5 mT) as a threshold for protecting against inadvertently putting cardiac pacemakers, implantable cardioverter defibrillators, and other active implantable medical devices into a "magnet mode." Additionally, it describes the background to the recent change of this threshold to 9 gauss (0.9 mT) in the International Standard IEC 60601-2-33 edition 4.0 that defines basic safety requirements for MRI. Practical implications of this change and some ongoing and emerging issues are also discussed.

Prognostic yield of echocardiographic measures of cardiac structure and function in HFrEF patients with vs without an ICD or CRT-D

Abstract Background Selected echocardiographic measures of cardiac structure and function are known to be associated with mortality in patients with Heart Failure with reduced Left Ventricular (LV) Ejection Fraction (HFrEF). Whether the predictive ability of measures of cardiac structure and function remain after implantation of an Implantable Cardioverter Defibrillator (ICD) or Cardiac Resynchronization Therapy-Defibrillator (CRT-D) is unknown among patients with HFrEF. Purpose To compare the predictive ability of echocardiographic measures of cardiac structure and function in HFrEF patients with or without an ICD/CRT-D. Methods Echocardiographic examinations were performed between 2003 and 2013 and retrieved from 2168 patients with HFrEF. Patients that had an ICD or CRT-D implanted during follow-up were identified through registries. The endpoint was all-cause mortality and follow-up was 100% to date. Images were analyzed offline in accordance with current guidelines. Associations were assessed by Cox multivariable regression and Cox univariable interaction models. Results After a median of 169 days, 677 patients had an ICD or CRT-D implanted. In total, 68% vs 80% of patients with and without an ICD, respectively, were men (p<0.001) and the median age were 70 vs 71 years (p=0.192). There was a significant difference in resting heart rate (median 74 vs 69, p<0.001) and frequency of ischemic heart disease (64% vs 81%, p<0.001) between the groups. Patients with an ICD had a higher mortality rate (69 per 1000 people/year vs 92 per 1000 people/year, p<0.001) and died significantly faster (median 9.3 vs 8.2 years, p<0.001). Patients with an ICD had higher Left Atrial (LA) End Systolic Volume (59.2 vs 67.3, p<0.001), LA Volume Index (28.5 vs 33.9, p<0.001), LV End Diastolic Volume (137.7 vs 153.7, p<0.001), and LV Mass Index (114.5 vs 124.5, p<0.001), as well as lower LA strain (9.8 vs 6.3, p<0.001) and TAPSE (2.0 vs 1.7, p<0.001). In patients without an ICD, Right Ventricular strain was associated with mortality (HR = 1.05 per 1% decrease mm/m2 [1.005, 1.11] when adjusting for covariates whereas in patients with an ICD, LA Volume Index (HR 1.14 per 1 increase [1.03, 1.25], and LV Ejection Fraction (HR 0.96 per 1% increase [0.92, 0.99]) were associated with mortality when adjusting for covariates. ICD/CRT-D implantation significantly modified the prognostic yield of LV End Diastolic Volume (HR per 1 ml increase: 0.99 without vs 1.01 with an ICD/CRT-D, p=0.005) and LV Mass Index (HR per 1 g/m2 increase: 1.00 without and 1.01 with an ICD/CRT-D, p=0.031). Conclusion Different echocardiographic measures were stronger prognosticators in HFrEF patients with and without an ICD or CRT-D, respectively, and ICD implantation modified the prognostic yield of LV End Diastolic Volume and LV Mass Index in HFrEF patients.Table 1Forest plot

Implantable cardioverter defibrillators among elderly survivors of out-of-hospital cardiac arrest

Abstract Background Survivors of out-of-hospital cardiac arrest (OHCA) with a shockable rhythm are at increased risk of cardiac arrest, and clinical practice guidelines recommend placement of an implantable cardioverter defibrillator (ICD) in the absence of a reversible cause and an expected meaningful survival of at least one year. Contemporary data on the prevalence of secondary prevention ICD placement among OHCA survivors remain limited. Purpose Examine patterns of secondary prevention ICD implantation in survivors of OHCA due to a shockable rhythm in a large national registry. Methods Using 2013-2019 data from the Cardiac Arrest Registry to Enhance Survival (CARES) linked to Medicare files, we identified 3,226 patients aged >65 years who survived to discharge following OHCA due to an initial shockable rhythm from January 1, 2013 to December 31, 2019. Patients with severe neurological disability, prior history of cancer, and those discharged to hospice were excluded. We calculated cumulative prevalence of ICD implantation at discharge, 90 days, and 6 months post cardiac arrest. Multivariable hierarchical regression models with random hospital effects were used to determine the adjusted association of patient characteristics with ICD implantation and quantify the extent of variation in ICD implantation across sites, using a median odds ratio (OR) and 95% confidence interval (CI). Results Patients’ mean age was 72.2 years; 23.5% were women, 10% were Black and 4% Hispanic. Among 3,226 OHCA patients, 997 (30.9%) received an ICD before discharge; 1,266 (39.2%) received an ICD within 90 days of cardiac arrest, and 1,287 (39.9%) received an ICD by 6 months. After adjusting for differences in demographics and co-morbidities, the odds of receiving an ICD at discharge were significantly lower in patients aged 85 years and older, women, patients with prior history of stroke or diabetes, patients who presented with acute myocardial infarction (P<0.05 for all). There was no significant difference in ICD implantation by race and ethnicity (P=0.94) (Table 1). Even after adjusting for patient demographics, co-morbidities, and presentation with acute myocardial infarction, there was large variation in hospital rate of ICD implantation at discharge, with a median odds ratio of 1.65 (95% CI 1.41-1.86). Conclusion Fewer than 1 in 3 patients with OHCA due to a shockable rhythm are discharged with a secondary prevention ICD. Although implantation of ICD was associated with patient variables, there was no difference in ICD implantation by race and ethnicity. There was large variation across hospitals in ICD implantation even after adjusting for patient variables highlighting an opportunity for improving post-arrest management of cardiac arrest survivors.

Comparison of ICD implantation approach in children. The IChilDren study

Abstract Background Without dedicated device, implantable cardioverter defibrillators (ICD) implantation in children is a real challenge for physicians. Types of implantation include transvenous, surgical and subcutaneous-ICD approach, but with a lack of reliable data comparing their respective efficacy and safety. Objective We here aim to compare the results of these 3 ICD implantation approaches in children. Methods Consecutive children (<16yo) implanted with an ICD from 2005 to 2021 in 19 french tertiary centers of the French Pediatric and Congenital heart disease network, were retrospectively enrolled in the study. The primary endpoints were the occurrence of lead failure, device infection or inappropriate shock. Results Among 306 patients (mean age 12,6 yo), 34% received a transvenous ICD, 28% a S-ICD and 38% a surgical ICD. During a median follow-up of 4.7 years, endpoints occurred in 24.2% of the total population, more often in the surgical group (p<0.05). After adjustment for age, ICD type and stratification by heart disease, there was an excess risk of lead failure or infection with the surgical ICD compared with the S-ICD (HR 7.54, 95% CI 1.73;32.91, p<0.05). However, when inappropriate shocks were included, the difference was reduced (HR 2.28, 95% CI 1.03;5.04, p>0.05). In addition, no significant difference between transvenous and surgical ICDs was observed in the multivariate analysis. Conclusions We demonstrate a high rate of complication in children implanted with an ICD. The transvenous and surgical approaches are quite similar. S-ICD appears as a promising approach with the lowest serious adverse event rate. Limitation of inappropriate shock remain the main challenge of this technique.Late complications

Similar incidence of ICD-shocks in diabetic compared to non-diabetic patients receiving implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D)

Abstract Background and aims Recent studies have suggested that diabetes patients with implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) may experience a reduced incidence of appropriate ICD-shocks and an increased mortality rate. This study aims to assess whether there is parity in ATP-treatment and ICD-shocks between patients with and without type 2 diabetes mellitus (T2DM), and to analyze associated mortality rates. Methods Using the Danish pacemaker and ICD registry we included patients who received a first-time ICD or CRT-D implantation with a primary or secondary prophylactic indication, between January 1st 2000 to December 31st 2018. Outcomes were analyzed individually for each outcome. Cause specific Cox was used for i) appropriate ATP therapy or ICD-shock, ii) inappropriate ATP therapy or ICD-shock, and a standard Cox regression model was used for iii) all-cause mortality, iv) mortality rate following an ATP-therapy or ICD-shock. Cumulative incidence curves, generated using the Aalen Johansen estimator, were utilized to compare the incidence rates for ATP therapy and ICD-shock while accounting for competing risk of death, while Kaplan-Meier methodology was utilized for survival curves. Analyses were conducted in the total population and in subgroups divided on indication and device type. Results Out of 14 747 patients who received an ICD or CRT-D, 4377 (30%) had T2DM, 4593 (31%) patients received first-time appropriate ATP therapy or ICD-shock, and 1244 (8,4%) experienced first-time inappropriate treatments, 5 112 (35%) experienced death during the follow-up time (mean 3.9 years (SD 2.7)). T2DM patients were more likely to be male (85% vs 80%), slightly older (66 vs 65 years) and burdened with more comorbidities. No significant differences were seen between T2DM and non-T2DM patients for appropriate ATP therapy (HR 0.96[0.88:1.04] p=0.31), appropriate ICD-shock (HR 0.95[0.86:1.05] p=0.32), inappropriate ATP therapy (HR 0.92 [0.77;1.09] p=0.32) and inappropriate ICD-shock (HR 0.96 [0.78;1.18] p=0.71). In the subgroup analyses, no difference was seen in the primary prophylactic subgroups (Figure 1.), only significant difference was observed in the secondary prophylactic ICD group who received less ATP-therapy at 5-year follow-up (HR0.83[0.70;0.99] p=0.04), and in the secondary prophylactic CRT-D group, were T2DM patients seemed to experience more appropriate ICD-shock treatments (HR 2.07[1.23;3.48] p=0.006). Further, we found a higher mortality rate in T2DM with primary prophylactic ICD (HR 1.46[1.31;1.62] p<0.001) and secondary prophylactic ICD (HR 1.30[1.13;1.51] p<0.001), (Figure 2.) this mortality rate remained largely unchanged post appropriate ATP or ICD-shock in the ICD subgroups. Conclusions Despite similar incidence of ATP-therapy and ICD-shocks, T2DM patients with ICD-device experienced a significantly higher post-treatment mortality and all-cause mortality rate.

Risk stratification for a primary prevention ICD: Performance of the MADIT-ICD Benefit Score in contemporary real world patients

Abstract Background We have recently developed the MADIT-ICD Benefit Score to improve risk stratification for primary implantable cardioverter defibrillator (ICD) implantation by assessing the competing risk of life-threatening ventricular tachyarrhythmia (VTA) vs. non-arrhythmic mortality based using simple clinical variables. Patients with a MADIT-ICD Benefit Score of < 50 are more likely to experience non-arrhythmic mortality than life-threatening VTA, and therefore derive limited benefit from a prophylactic ICD. Purpose We aimed to provide data on the performance of the MADIT-ICD Benefit Score in a real world population, comprising patients with HFrEF and either ischemic or nonischemic cardiomyopathy (ICM/NICM) who are treated with contemporary guideline-directed medical therapy (GDMT). Methods The study population comprised 2875 patients who were implanted with a primary prevention ICD and prospectively followed in a large tertiary healthcare system (the University of Rochester Medical Center, including 3 affiliated hospitals in Upstate New York) between 2017 through 2023. Arrhythmic events were captured from device interrogation data, which were blindly adjudicated by 2 electrophysiologists. Results Among the 2875 study patients, mean age was 62 ± 15 years, 1265 (44%) were women, and 1667 (58%) had ICM. Guideline-directed medical therapies, including angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, angiotensin receptor/neprilysin inhibitors, beta-blockers, mineralocorticoid receptor antagonists, and sodium-glucose transport protein 2 (SGLT2) inhibitors, were prescribed to 43%, 36%, 96%, 67% and 32% of study patients, respectively. The 2-year cumulative incidence of VTA, after accounting for the competing risk of death, was 19% vs. 11% in patients with a Score of ≥50 vs. <50, respectively (p<0.001; Figure 1A). Findings regarding ICD shocks were consistent (8% vs. 4%, respectively, p<0.001; Figure 1B) The rate of VTA events at 4 years was directly correlated with increasing quartiles of the MADIT-ICD Benefit Score, while the corresponding rates of non-arrhythmic mortality were inversely correlated with score quartiles (Figure 1C). A similar direct correlation with increasing Benefit Score quartiles was observed when the endpoint of ICD shocks was assessed (Figure 1D). Accordingly, the benefit of the ICD (calculated as the difference between predicted rates of VTA/shock events and corresponding rates of non-arrhythmic mortality) was attenuated with decreasing quartiles of the MADIT-ICD Benefit Score (Figures 1C and 1D; right column). Conclusions We show good performance of the MADIT-ICD Benefit Score in a large cohort of real world ICD recipients who are treated with contemporary GDMT. These data support the use of the MADIT-ICD Benefit Score for improved risk stratification and for shared decision-making in contemporary candidates for a primary prevention ICD.

Remote monitoring of implantable cardioverter defibrillators: a systematic review and meta-analysis of randomised controlled trials

Abstract Background Remote monitoring (RM) of implantable cardioverter defibrillators (ICD) has been widely adopted as the standard follow-up strategy [1]. Observational data [2,3] has suggested morbidity and mortality reduction associated with RM compared to traditional in-person ICD follow-up, however, randomised controlled trials (RCTs) demonstrate heterogeneous results. Purpose To assess the impact of RM of ICDs on morbidity and mortality through a systematic review and meta-analysis of RCTs comparing RM versus in-person follow-up. Methods PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL) and reference lists were searched for RCTs evaluating RM compared to in-person follow-up of patients with ICDs or cardiac resynchronisation therapy with defibrillator (CRT-D) devices. Meta-analyses of all-cause mortality, cardiovascular (CVD) hospitalisation and inappropriate ICD shock rates were performed. Results Literature search identified 1011 relevant publications, out of which 15 RCTs [4-18] involving a total of 7579 patients (13 RCTs reporting mortality rate, 7 RCTs reporting CVD hospitalisation rate, 6 RCTs reporting inappropriate ICD shock rate) met the inclusion criteria. Pooled analyses demonstrated that RM is not associated with a significant reduction in all-cause mortality (OR 0.95; 95% CI 0.78-1.16; p=0.60)(Figure 1, panel a) or odds of CVD hospitalisation (OR 0.95; 95% CI 0.72-1.25; p=0.70) (Figure 1, panel b). RM was, however, shown to be associated with significantly lower odds of receiving an inappropriate ICD shock compared to the control group (OR 0.63; 95% CI 0.46-0.88; p=0.006) (Figure 1, panel c). The IN-TIME study (the only RCT that independently reached statistical significance in terms of RM effect on mortality) enrolled patients exclusively with a Biotronik ICD or CRT-D; this raised the question as to whether the choice of vendor had an impact on mortality. Our subgroup analysis of the Biotronik device studies demonstrated that there was no significant all-cause mortality benefit (OR 0.87, 95% CI 0.59-1.27; p=0.46). Conclusions This meta-analysis of 15 RCTs including 7579 patients suggests that RM of ICDs is associated with a reduction in inappropriate ICD shocks, without a significant reduction in mortality or CVD hospitalisation when compared to in-person follow-up. Further studies comparing different RM processing and alert response models are warranted.

Long term follow up of Implantable Cardioverter Defibrillators (ICD) in hypertrophic cardiomyopathy: is subcutaneous the way forward?

Abstract Introduction Young patients have greater risks of longer-term complications including inappropriate therapy (IT) from Implantable Cardioverter Defibrillators (ICD) than older ICD patients. In prevention of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM), these complications are critical in determining treatment thresholds. When comparing transvenous ICDs (TV), subcutaneous ICDs (SICD) may have different risks & benefits that define their relative utility. We investigated TV & SICD outcomes in a propensity matched cohort of HCM patients. Methods We used electronic health records in a retrospective study of HCM patients receiving an ICD between 2006-22 at tertiary centre. Indications for ICD implantation, including type of device, were determined by the treating cardiomyopathy team according to ESC guidance. All TV device types were included & eligibility for SICD included passing screening in at least 1 sensing vector. Outcome data included patients lost to follow-up until the last device check & patients who had both device types were included twice. Patients were censored after their first IT for an analysis of IT, & their first ‘ICD complication’ for that analysis. ICD complications are defined as all other complications that resulted in a re-intervention procedure (excl SICD battery advisory), or extra procedure at box change. The audit was registered with local institutional review board for ethical approval. Propensity scoring was used for stratification and covariate adjustment. Matching was conducted using the 12 baseline variables. Associations with IT, ICD complications and their composite were assessed using proportional hazard regression (Cox) models, with time to event starting at implant date. Univariable & multivariable regression analyses were used as appropriate. Hazard ratios (HRs) of 95% confidence intervals were estimated by fitting a model with the propensity score and dichotomous variable (TV vs SICD). A p value of <0.05 was considered statistically significant. Analyses were conducted using R- Version 2023.06.0+421. Results Mean age was 55±14.2 years with follow-up of 73±63 months; 70.7% were male. Of a total of 611 patients, with 469 in the TV group & 164 in the SICD. SICD patients had fewer complications, with no differences in IT across all and propensity matched analyses (CI 0.64), fig 1. Conclusion In HCM, when compared to TV, SICDs are associated with fewer ICD complications & not associated with more frequent IT. Intriguingly, there was a higher rate of IT with the first generation SICD, causing the wide IT errors at longer durations. Complications over long term follow up require more assessment, but the absence of TV lead intervention creates reduced risks for SICD complications. In HCM patients without pacing needs, SICDs may be preferred for HCM-SCD prevention. In addition, the lower risks associated with SICD could lead to lower treatment thresholds for people with elevated lifetime HCM-SCD risk.

Outcomes and complications of transvenous implantable cardioverter defibrillator systems in the pediatric population: a systematic review and meta-analysis

Abstract Background Implantable cardioverter defibrillators (ICDs) are an important therapy for prevention of sudden cardiac death (SCD). Data on transvenous (TV) ICD therapy rates, complications, and system survival in children ≤ 21 years is limited by absolute numbers and inclusion of adults with congenital heart disease. Purpose To determine ICD therapy rates and complications in pediatric patients ≤ 21 years of age. Methods A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Medline, Embase, PubMed Ahead-of-Print and in-process records, and Cochrane Database of Systematic Reviews were searched for full-text articles on pediatric ICD. Articles were assessed for inclusion by two authors via a consensus process; the exclusion criteria included: case reports, review articles, abstracts, editorials, articles not in English, articles solely on epicardial or subcutaneous leads, articles on unrelated topics, articles with <50% ICD leads, and articles with any patients >21 years old. Data were extracted by 1 author and verified by a 2nd author. Meta-analysis of aggregate data was performed, where possible. Random effects models were used for pooled inferences. All reported rates are annualized rates based on reported follow-up times in each study. Results Of 1325 articles, 23 met all inclusion and no exclusion criteria (Figure) representing 1700 patients implanted from 1987-2020. The average age of patients was 12.8 years (95% confidence interval [CI]: 11.9 – 13.7) with weight of 51.1 kg (95% CI: 42.2 – 60.0) (Table). Primary prevention was the indication in 56.4 % (95% CI: 45.0% – 67.7%). Only 14.8% (95% CI: 10.6% – 19.0%) of the patients had congenital heart disease while 22.6% (95% CI: 15.8% – 29.3%) had long QT syndrome. The annualized rate of appropriate shock was 7.0% (95% CI: 5.6% – 8.8%) and the rate of inappropriate shock was 4.8% (95% CI: 3.8% – 6.0%). Annualized rates of reported adverse events included lead failure: 2.3% (95% CI: 1.6% – 3.3%) and infection: 0.8% (95% CI: 0.4% – 1.6%), which could have led to system revision: 4.4% (95% CI: 2.1% – 9.4%). The all-cause mortality rate was 0.8% (95% CI: 0.6% – 1.2%) across 17 studies. In 9 studies with 719 patients, the heart transplant rate was 1.6% (95% CI: 0.6% – 3.9%). Conclusion In this first systematic review and meta-analysis of ICDs in pediatric patients, ICD therapy was effective for prevention of SCD with a 7.0% annualized rate of appropriate ICD shocks. This is comparable to the annualized rate of appropriate ICD shock for secondary prevention of SCD in adult randomized controlled trials. Most common adverse events in the pediatric population were lead failure and system revision. Further refinements in patient selection criteria for implantation and improvements in lead and device technology are needed for pediatric patients.FigureTable

Risk for appropriate ICD intervention and complications in patients implanted after an out-hospital cardiac arrest compared to patients implanted for primary and other secondary prevention indication

Abstract Background Few data are available about patients implanted with an implantable cardioverter defibrillators (ICDs) after an out-of-hospital cardiac arrest (OHCA). In particular, it is unclear if these patients have a higher risk of appropriate device therapy than patients implanted for primary and other secondary prevention. Purpose To assess if appropriate device interventions (ATP/shocks) are higher in patients implanted after OHCA compared to patients implanted for primary and secondary prevention other than OHCA. To verify also if mortality, implantation-related complications (pneumothorax, hemothorax, hematoma, cardiac tamponade), device-related complications (lead displacement and fracture, infections) and inappropriate shocks/ATP are higher in OHCA patients compared to other patients. Methods This is a retrospective multicenter international study. All the patients implanted with an ICD between January 2015 and December 2016 in the participating centers were included. Follow-up was considered concluded in case of death or at the last follow-up available until December 2023. Patients were divided according to ICD implantation indication (secondary prevention after OHCA, other secondary prevention, primary prevention). Results 1386 patients (79% males; median age 67, IQR 59-74) from 15 centers were included with a median follow-up of 83 months: 111 patients in OHCA group, 134 in other secondary prevention group and 1141 in primary prevention group. Considering the first appropriate intervention, a significant difference among the three groups was observed (Fig.1A) and, at post-hoc comparison, the OHCA group was at higher risk than primary prevention (HR 1.51, 95%CI 1.06-2.17, p=0.02), but was at similar risk than other secondary prevention (HR 0.79, 95%CI 0.51-1.23, p=0.3). This was confirmed also after correction for age, gender, history of atrial fibrillation, aetiology and multi-comorbidity (Fig.2A). However, considering the number of appropriate interventions during follow-up, the risk of OHCA group was lower than other secondary prevention (IRR 0.28, 95%CI 0.11-0.68, p<0.01) and similar to primary prevention (IRR 0.97, 95%CI 0.47-1.96, p=0.93), also after correction for the other predictors (Fig.2B). The three groups showed no differences in survival (Fig.1B), implantation-related complication, device-related complications (Fig.1C) and inappropriate shocks/ATP. Conclusion Patients implanted with an ICD after an OHCA have a risk similar to those implanted for other secondary prevention, when considering the first appropriate intervention, but a risk similar to those implanted for primary prevention when considering the number of appropriate interventions during follow-up. Our study confirms that OHCA patients represents a peculiar population with the same chance of survival and rate of complications compared to primary and other secondary prevention patients suggesting the need of more studies to improve their long-term treatment.Figure 1 (Panel A, B and C)Figure 2 (Panel A and B)

Half of implantable cardioverter-defibrillator patients remain at risk of painful shocks in the last moments of life

Abstract Background Patients with implantable cardioverter-defibrillators (ICDs) are at risk of receiving painful shocks near the end of life due to ongoing tachytherapy. Position papers of various international societies emphasize the need for advance care planning and timely deactivation of tachytherapy. This study aims to assess the real world practice of deactivating ICD tachytherapy prior to death over a consecutive 18-year period and strives to identify areas for improvement. Methods Medical records were reviewed of all patients who were carriers of an ICD or CRT-D and under follow-up at our university medical center. Those who deceased between 2006 and 2023 were identified from the municipal civil registry and their follow-up data were extracted from electronic patient records. The cause of death and status of ICD therapy at the time of death was analysed. Results During the study period, 1724 patients with an ICD expired (mean age 73 ± 10 years; 265 (15%) females; 1396 (81%) primary prevention; median time from initial ICD implantation 7.5 [interquartile range: 4 to 12] years. Baseline characteristics of patients who had tachytherapy deactivated prior to death did not differ significantly from those who did not. Overall, 769 (43%) devices were deactivated before death. The proportion of patients with deactivated tachytherapy prior to death gradually increased over time, surpassing to just >50% in the past decade (p<0.001), Figure 1. Causes of death differed between the two groups (p=0.022), Figure 2. The majority of patients with deactivated tachytherapy prior to death died due to: heart failure (38%); non-cardiac causes (23%) e.g. myocardial infarction or valvular disease; malignancy (23%) and other non-cardiac causes such as infectious diseases, stroke and trauma (31%). However, substantial proportions of patients dying from causes that could potentially be identified as an end-of-life phase, remained at risk of shocks in the last moments of life due to active tachytherapy (30% heart failure, 11% malignancy, 25% other non-cardiac causes). Conclusions The rate of patient with deactivated ICD tachytherapy before death doubled within the initial 4 years of the study period and more or less stabilized thereafter, thus leaving nearly half of ICD patients susceptible to painful shocks in their final moments of life. This underlines the necessity of timely advance care planning, including discussions regarding discontinuation of ICD therapy during the end-of-life phase.

Atrial rates during treated ventricular tachycardia in patients with implantable cardioverter defibrillators: clinical implications of a vagal sinus node response

Abstract Introduction Autonomic tone plays an important role in the genesis and sustenance of ventricular tachycardia (VT). Whilst sympathetic hyperactivity is an established driver of ventricular arrhythmias, sinus node response during VT varies broadly between patients, and can be paradoxical. Purpose We hypothesized that device-detected changes in sinus node rate could be an important surrogate of the autonomic response to VT, and may exert significant – and potentially modifiable – haemodynamic consequences independent of ventricular activity. Methods Device electrograms were analysed from consecutive patients with dual chamber implantable cardioverter defibrillators (ICDs) requiring anti-tachycardia pacing (ATP) or defibrillation for sustained monomorphic VT. Atrial rates were measured before VT onset (‘baseline’) and again at the point of detection by the device. Sinus node response was characterized as ‘stable’ (atrial rate remained within 10% of baseline), ‘sympathetic’ (atrial rate increased >10%) or ‘vagal’ (atrial rate decreased >10%). Patients who did not maintain ventriculoatrial dissociation or who presented in atrial tachyarrhythmia were excluded. Symptoms and electrical response to ICD therapies were recorded. Results 172 treated episodes of VT were included from 97 patients (median age: 69 years, 65% male, 31% ischaemic cardiomyopathy, median ventricular rate: 205bpm, median ejection fraction: 30%). Sinus node response was stable in 55%, sympathetic in 24% and vagal in 21%. A vagal response was associated with ATP-refractory VT (OR: 2.2 (1.1-4.8) p=0.03) and, when adjusting for ventricular rate, was independently associated with symptoms of presyncope or syncope (adjusted OR: 6 (2.7-13.7), p<0.0001). Conclusions This preliminary analysis suggests that a vagal sinus node response during VT is associated with adverse outcomes in ICD patients. Vagolytic therapy has recently been demonstrated to improve haemodynamic tolerance during VT ablation; whether supportive atrial pacing during VT could mitigate symptoms and potentiate arrhythmia termination in ICD patients warrants further exploration. Figure 1: Change in sinus node rate during sustained monomorphic ventricular tachycardia in patients with dual chamber ICDs, stratified by the occurrence of presyncopal symptoms or syncopeFigure 1

Impact of left ventricular lead position on echocardiographic response after upgrading from right to biventricular pacing - Insights from the BUDAPEST CRT Upgrade Trial

Abstract Introduction Left ventricular (LV) lead position is strongly associated with the long-term outcome of patients undergoing de novo cardiac resynchronization therapy (CRT) implantation. However, data is scarce about patients who undergo upgrade CRT from right ventricular (RV) pacing. Aims To investigate the impact of the LV lead location on the primary outcome of heart failure (HF) hospitalization, all-cause mortality, or echocardiographic reverse remodelling in the BUDAPEST CRT Upgrade trial cohort. Methods Heart failure patients with reduced ejection fraction (HFrEF), with previously implanted pacemaker (PM) or implantable cardioverter defibrillator (ICD) and intermittent or permanent RV pacing, who were randomly assigned to the CRT-D arm (n=215) and those who were cross-overs from the ICD arm (n=27) were investigated. Short-axis position (anterior / posterior / lateral) of the LV lead was assessed. Primary endpoint encompassed HF hospitalization, all-cause mortality, and the end-systolic volume (ESV) decrease less than 15% from baseline to 12 months follow-up. Echocardiographic response was evaluated by percent change of ESV and LVEF. Results LV lead location was available for 223 patients (age 72.8 ± 8 years, 14% female, 38% diabetic, 49% with prior myocardial infarction, 30% with prior ICD) with a median follow-up time of 12.4 months. There was no difference in the occurrence of the primary endpoint by the lead positions (anterior vs. lateral OR 0.33; 95%CI 0.09-1.22, p=0.10, anterior vs. posterior OR 0.58; 95%CI 0.14-2.50, p=0.47). However, LVEF change was more pronounced in those with lateral LV lead location compared with anterior position (adjusted LVEF difference 7.43%, 95%CI 1.25 – 13.62; p=0.02), while those with posterior leads did not differ from the anterior ones (adjusted LVEF difference 3.00%, 95%CI -3.92 – 9.93; p=0.39). Decrease in ESV was also more remarkable with a lateral position as compared to the other locations (lateral vs. anterior adjusted ESV difference -0.17 mL, 95%CI -0.32 – (-0.01); p=0.03, posterior vs. anterior adjusted ESV difference -0.09 mL, 95%CI -0.26– 0.08; p=0.31). Conclusion Upgrade CRT results in better outcomes as compared to ICD alone; however, lateral LV lead position is associated with the most beneficial mid-term echocardiographic response as compared to other short-axis locations. This finding may translate into better clinical outcomes in the long term.

Microbial specturm and antibiotic sensitivity of pocket swabs in ICD patients undergoing device replacement or lead revision surgery- findings from a ICD registry observational study

Abstract Introduction Infection is a serious complication of implantable cardioverter defibrillator (ICD) therapy, necessitating effective preventive measures during implantation or revision surgery. The intraoperative use of antibacterial envelopes containing rifampicin and minocycline has shown promising results in reducing infection, yet, it is expensive and not cost-effective. Gentamicin sponges might be an alternative to the antibacterial envelope, however its efficacy on targeting the specific microbial spectrum found in device infection must be further investigated. Aim of the study was to identify the bacterial species obtained from pocket swabs of ICD patients undergoing revision surgery, and assess their sensitivity to gentamicin, rifampicin and minocycline. Methods A total of 459 intraoperative pocket swabs were collected from consecutive ICD patients who underwent elective device replacement, system upgrade or lead revision between 2017 and 6/2023. The baseline characteristics were similar in both groups (Table 1). Results Out of the 459 swabs analysed: 416 (90.6%) were negative for microbial growth. The remaining 43 swabs (9.4%) were tested positive for microbial growth (Table 2). Coagulase-negative- staphylococci (CoNS) were the most commonly isolated bacteria, accounting for 56% of cases. Bacteria with available antibiograms exhibited a sensitivity of 92% to gentamicin, 96% to rifampicin and 96% to Minocycline (Table 2). Conclusion The antibiotic sensitivity of the bacteria obtained from the pocket swabs to gentamycin, rifampicin and minocycline was similar. Thus, gentamicin sponges might be an alternative to the antibacterial envelope in patients with ICD undergoing generator replacement or revision surgery.

Assessment of quality of life and ICD shock-related anxiety in Asian patients with implantable cardioverter defibrillator in the PainFree SST study

Abstract Background The implantable cardioverter defibrillator (ICD) reduces mortality in patients at risk of sudden cardiac death. However, it is not known if the psychological status of ICD patients differs by geography. The aim of this analysis is to compare Quality of Life (QoL) and ICD shock-related anxiety between ICD patients in Asian with those in other countries. Methods The PainFree SST study was a prospective, multicenter, global study that enrolled 2770 patients including 225 from from Asia (181 from Japan, 25 from India, and 19 from Malaysia). The EuroQol 5-D (EQ-5D) measured QoL and the Florida Shock Anxiety Scale (FSAS) measured ICD shock-related anxiety. These questionnaires were administered bi-annually and monthly for 6 months after a shock. Change in QoL and shock anxiety was analyzed used linear mixed models for repeated measures. Results: Both the EQ-5D health score and FSAS score were higher in Asian patients compared to patients in the other countries post-implant (EQ-5D: 69.5 ± 18.3 points vs 66.5 ± 19.3 points, p<0.0001, FSAS: 19.7 ± 9.4 points vs 16.4 ± 7.7 points, p<0.0001), and stayed higher for the entire follow-up period (Figure 1). The EQ-5D health score was significantly reduced after a shock (Asian: -18.1 points, p<0.0001; other countries: -7.5 points, p<0.0001) with a greater reduction in Asian patients (p=0.0035) . Recovery in the month following a shock was greater in Asian patients (+19.8 vs +3.6 points, p<0.0001). The FSAS score was significantly increased after a shock (Asian: +6.4 points, p<0.0001; other countries: +4.8 points, p<0.0001) and the increase was similar between geographies (p=0.20). The recovery effect at 1 month was greater in Asian patients (-5.8 vs -1.7 points, p=0.0003) (Figure 2). Conclusions Asian patients were more anxious about a shock in spite of greater QoL, compared with those in other countries. After a shock, Asian patients had a greater decrease in QoL and a similar increase in anxiety but recovery was greater in both measures in the month following a shock.Figure 1Figure 2

Targeting ventricular tachycardia originating from the anterolateral papillary muscle with stereotactic body radioablation therapy

Abstract Background Ventricular Tachycardia (VT) is prevalent in the setting of non-ischaemic cardiomyopathy (NICM), a heterogeneous group of conditions characterized by myocardial dysfunction in the absence of coronary artery disease. Challenges of catheter ablation to treat VT in NICM patients are well known, and recurrence rates can be as high as 58%. Stereotactic body radioablation therapy (SBRT) involves precise delivery of radiation to arrhythmogenic substrates, and represents a novel treatment to reduce recurrent implantable cardioverter defibrillator (ICD) therapies in patients with refractory VT. Though SBRT has shown preliminary effectiveness in reducing VT episodes, its effectiveness in NICM patients has not been widely evaluated. Purpose To evaluate SBRT effectiveness in NICM patients with scars at the basal anterolateral papillary muscle at a tertiary care center between November-December 2022. Methods Eligible patients had their VT substrate mapped using a single-use ECGI vest and a 4D-CT simulation scan. In addition, MRI scans were used to aid anatomical identification of the anterolateral papillary muscle which could not be seen on the non-contrast diagnostic CTs. SBRT was delivered in a single fraction of 25 Gy under image guidance. Effectiveness of the treatment was evaluated as changes in frequencies of total antitachycardia pacing (ATP) and ICD shock episodes from 6 months pre-, and within to 3, 6, and 12 months follow up post SBRT. Results Participants were 3 males with NICM, aged 56, 60, and 73 with previous dual chamber ICD implantation, 2 of whom had a history of VT ablation/ VT storm and paroxysmal atrial fibrillation. All participants had basal lateral scar, and were receiving beta blockers, mexiletine, and amiodarone with refractory VT before SBRT treatment. Prior to SBRT, ICD device interrogation showed a total of 119 (77, 7, and 35 in patients 1-3 respectively) ATPs, and 27 (10, 1, and 16 in patients 1-3 respectively) ICD shocks delivered. At 12 month follow-up, none of the participants experienced any episodes of ATP or ICD shock. Ejection fraction remained consistent pre-post SBRT. Conclusion SBRT showed remarkable success in reducing ATP and ICD shock episodes, facilitating uncomplicated 1 year follow-up in 3 male patients with NICM and VT from the anterolateral papillary muscle.

Defibrillation deactivation state and activation status in patients with implantable cardioverter-defibrillators at the end of life

Abstract Background Implantable cardioverter-defibrillators (ICDs) are effective in preventing sudden cardiac death due to lethal arrhythmias. Defibrillation is also known to cause physical and emotional distress to patients, and guidelines on palliative care for cardiovascular disease recommend that when patients with ICDs reach the end of life, the benefits and burdens of ICDs should be fully explained to patients and a policy regarding the cessation of defibrillation discussed. However, there are few reports on the treatment status and defibrillation deactivation in patients with ICDs in the terminal phase. Aim To investigate defibrillation activation and defibrillation deactivation in terminally ill patients with ICDs. Results Death was confirmed in 146 patients in the medical record, and a DNAR policy was decided in 46 patients. The decision to deactivate defibrillation was informed to 24 patients (16%), and 15 patients (10%) were deactivated (11 patients in terminal heart failure and 4 patients in others). Four of the nine patients (6%) who did not deactivate defibrillation had a shock before death.Of the 22 patients (14 cardiovascular deaths and 8 others) who were not explained about the deactivation of defibrillation, 4 had shock activation before death.Of the 24 patients who received explanation about defibrillation deactivation, 6 (25%) had the policy decided by the patient and family, and 18 (75%) had the policy decided by the family because the patient's will could not be confirmed due to deterioration of end-stage condition. Discussion This study showed that defibrillation was deactivated in only 10% of Japanese patients with end-stage ICDs.ICD patients do not always reach the end of life due to heart failure. It is important for physicians, clinical engineers, and device nurses involved in device care to provide information and to confirm the wishes of patients and their families regarding the deactivation of defibrillation so that they can be supported in their decision-making regarding defibrillation no matter under what circumstances they reach the end of life. Conclusion Discussion of ICD deactivation in palliative care is needed to reduce the risk of painful shock and distress at the end of life.

The MADIT-ICD benefit risk score for Japanese patients -from Nippon Storm study-

Abstract Background Implantable cardioverter-defibrillators (ICDs) play a crucial role in preventing sudden death due to lethal arrhythmias such as ventricular tachycardia and ventricular fibrillation. However, like any medical intervention, ICD implantation is not without its complications. It is essential to carefully consider the risks and benefits, and appropriately stratify the risk of sudden death in order to make informed decisions. In 2020, the MADIT-ICD benefit risk score was proposed to utilize personalized integrated assessment of the competing risk of lethal arrhythmias vs. non-arrhythmic mortality in implantable cardioverter-defibrillator (ICD) candidates. Purpose To evaluate the risk stratification of using the MADIT-ICD benefit risk score in Japanese patients. Methods We analyzed the data of 451 patients, enrolled in the Nippon Storm Study, with left ventricular ejection fraction (LVEF) ≤35% who underwent ICD implantation for primary prophylaxis of sudden cardiac death (men, 78%; age, 65±12 years; LVEF, 25±6.4%; cardiac resynchronization therapy, 73%; ischemic cardiomyopathy (ICM), 33%). Results A total of 336 patients were enrolled iln this study. The MADIT-ICD benefit risk scores, except systolic blood pressure, was calculated (Figure 1). These patients were classified into 3 groups (Lowest, Intermediate, Highest). There were no significant differences between the three groups in all-cause mortality, cardiovascular death, non-arrhythmic death, and appropriate ICD therapy (Figure 2). The multivariate analysis demonstrated that LVEF ≤25% was significantly associated with all-cause mortality, cardiovascular death, non-arrhythmic death (p=0.0487, 0.0150, 0.0387). Conclusion The MADIT-ICD benefit risk score may not be appropriate to risk stratification in Japanese patients using ICD for primary prophylaxis.Figure 1Figure 2

Epicardial ablation in patients with Brugada syndrome: a single centre experience

Abstract Introduction Brugada syndrome (BrS) is a rare disease associated with an increased risk of ventricular fibrillation (VF), ventricular tachycardia (VT), and sudden cardiac death (SCD). The standard prevention of SCD in patients with BrS is the implantation of an implantable cardioverter-defibrillator (ICD), especially in patients who have previously suffered cardiac arrest or arrhythmogenic syncope. Catheter ablation is an effective method to prevent recurrences of VF/VT in these patients. Purpose Retrospective analysis of the results of catheter ablation by epicardial approach and genetic testing in patients with a diagnosis of BrS and repeated adequate ICD interventions. Methods In 2013-2024, catheter ablation by epicardial approach was performed in our centre in 9 patients diagnosed with Brugada syndrome (mean age 41±6 years, nine males, left ventricular ejection fraction 57±4%). All patients had an ICD implanted for secondary prevention of SCD and presented with adequate ICD therapies (mean 9±11 shocks/patient in the last six months before catheter ablation). Before catheter ablation, two patients were treated with quinidine. Patients underwent cardiogenetic testing by next-generation sequencing of 228 genes. Results Type 1 electrocardiogram (ECG) pattern was present at baseline ECG in four (44%) patients; in five (56%) patients, type 1 was induced after ajmaline administration. Genetic testing was performed in seven patients, and only one patient (14%) was found to have a relevant pathogenic mutation in the SCN5A gene. Prior to ablation, sustained VT/VF could be induced by programmed electrical stimulation in three patients (33%). Epicardial ablation was targeted at areas of abnormal electrograms located over the right ventricular outflow tract. No complications were noted. The mean follow-up period was 25±30 months. In one patient (11%), reablation was required to suppress ventricular arrhythmias successfully. After the last ablation, no recurrence of VT/VF was observed in any patient. Conclusions Epicardial ablation is an effective method that leads to the suppression of ventricular arrhythmias in patients with a diagnosis of BrS and repeated ICD interventions. Despite the malignant arrhythmic phenotype, patients in our cohort had a rather low prevalence of signs associated with a high risk of VT/VF, such as spontaneous ECG pattern of BrS, inducibility of VT/VF during electrical programmed stimulation, or the presence of a causative genetic mutation.

All-cause mortality and incidence of appropriate therapy from a primary preventive implantable cardioverter defibrillator in patients with non-ischemic dilated cardiomyopathy

Abstract Background The DANISH study published in 2016 indicated limited benefit of primary prevention implantable cardioverter-defibrillator (ICD) in patients with non-ischemic dilated cardiomyopathy (niDCM). We aimed to investigate the long-term outcome and incidence of ICD therapy in patients with niDCM implanted on primary prevention indication during 2014-2022. Methods A total of 116 patients with niDCM were prospectively included for primary prevention ICD implantation between 2014 and 2022 in the multicenter IMPROVE study (clinical trials NCT02286908). All patients were examined with electrocardiogram, echocardiography and blood sampling at inclusion. The primary outcome was all-cause mortality, and the secondary outcome was appropriate ICD therapy. Outcomes were compared in patients included from 2014 to end of 2016 (DCM2014-16, n=49) and from 2017-2022 (DCM2017-22, n=67). Results At inclusion, patients in DCM2017-22 were younger (54 years [interquartile range (IQR) 44-68] vs. 64 years [IQR 55-70], p=0.001), had higher left ventricular ejection fraction (LVEF) (33% [IQR 25-38] vs. 24% [IQR 21-31], p<0.001) and less frequently received cardiac-resynchronization therapy defibrillator (6% vs. 29%, p=0.001) compared to DCM2014-16. Over a median 4.4-year follow-up, the all-cause mortality was 14%, of which 10% occurred in the DCM2017-22 patients (2.6 events/100 person-years), and 18% in the DCM2014-16 patients (4.0 events/100 person-years), p=0.38. There was no difference in appropriate ICD therapy between the two groups (p=0.90). Conclusion Patients receiving primary prevention ICD for niDCM after publication of the DANISH study were younger with higher LVEF, indicating a change in clinical practice after the publication. Despite this, there was no significant reduction in all-cause mortality or difference in appropriate ICD therapies. Unchanged mortality and event-rates may indicate the correct identification of high-risk patients.