Inappropriate Shocks Research Articles

Real-world evidence for the use of subcutaneous implantable cardioverter-defibrillators in China: Asingle-center experience.

Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have been shown to be non-inferior to transvenous ICDs in the prevention of sudden cardiac death (SCD), but there is still alack of evidence from clinical trials in China. We investigated whether S‑ICD implantation in the Chinese population is safe and feasible and should be promoted in the future. Consecutive patients undergoing S‑ICD implantation at our center were enrolled in this retrospective study. Data were collected within the median follow-up period of 554days. Data concerning patient selection, implantation procedures, complications, and episodes of shock were analyzed. In total, 70.2% of all 47patients (median age = 39years) were included for secondary prevention of SCD with different etiologies. Vector screening showed that 98% of patients were with > 1 appropriate vector in all postures. An intraoperative defibrillation test was not performed on six patients because of the high risk of disease deterioration, while all episodes of ventricular fibrillation induced post implantation were terminated by one shock. As expected, no severe complications (e.g., infection and device-related complications) were observed, except for one case of delayed healing of the incision. Overall, 15patients (31.9%) experienced appropriate shocks (AS) with all episodes terminated by one shock. Two patients (4.3%) experienced inappropriate shocks (IAS) due to noise oversensing, resulting in ahigh Kaplan-Meier IAS-free rate of 95.7%. Based on appropriate patient selection and standardized implantation procedures, this real-world study confirmed the safety and efficacy of S‑ICD in Chinese patients, indicating that it may help to promote the prevention of SCD in China.

Subcutaneous Implantable Cardioverter-Defibrillators in Patients With Congenital Heart Disease

BackgroundVery few data have been published on the use of subcutaneous implantable cardioverter-defibrillators (S-ICDs) in patients with congenital heart disease (CHD). ObjectivesThe aim of this study was to analyze outcomes associated with S-ICDs in patients with CHD. MethodsThis nationwide French cohort including all patients with an S-ICD was initiated in 2020 by the French Institute of Health and Medical Research. Characteristics at implantation and outcomes were analyzed in patients with CHD. ResultsFrom October 12, 2012, to December 31, 2019, among 4,924 patients receiving an S-ICD implant in 150 centers, 101 (2.1%) had CHD. Tetralogy of Fallot, univentricular heart, and dextro-transposition of the great arteries represented almost one-half of the population. Patients with CHD were significantly younger (age 37.1 ± 15.4 years vs 50.1 ± 14.9 years; P < 0.001), more frequently female (37.6% vs 23.0%; P < 0.001), more likely to receive an S-ICD for secondary prevention (72.3% vs 35.9%; P < 0.001), and less likely to have severe systolic dysfunction of the systemic ventricle (28.1% vs 53.1%; P < 0.001). Over a mean follow-up period of 1.9 years, 16 (15.8%) patients with CHD received at least 1 appropriate shock, with all shocks successfully terminating the ventricular arrhythmia. The crude risk of appropriate S-ICD shock was twice as high in patients with CHD compared with non-CHD patients (annual incidences of 9.0% vs 4.4%; HR: 2.1; 95% CI: 1.3-3.4); however, this association was no longer significant after propensity matching (especially considering S-ICD indication, P = 0.12). The burden of all complications (HR: 1.2; 95% CI: 0.7-2.1; P = 0.4) and inappropriate shocks (HR: 0.9; 95% CI: 0.4-2.0; P = 0.9) was comparable in both groups. ConclusionsIn this nationwide study, patients with CHD represented 2% of all S-ICD implantations. Our findings emphasize the effectiveness and safety of S-ICD in this particularly high-risk population. (S-ICD French Cohort Study [HONEST]; NCT05302115)

Prevention of Early Sudden Cardiac Death after Myocardial Infarction Using the Wearable Cardioverter Defibrillator-Results from a Real-World Cohort.

After acute myocardial infarction (AMI), patients are at risk of sudden cardiac death. The VEST trial failed to show a reduction in arrhythmic mortality in AMI patients with an LVEF ≤ 35% prescribed with a WCD, having a lower-than-expected WCD wearing compliance. The aim was to investigate on outcomes of patients in a real-world Austrian cohort with good compliance. A retrospective analysis of all eligible Austrian WCD patients according to the VEST trial inclusion and exclusion criteria between 2010 and 2020 was performed. In total, 105 Austrian patients (64 ± 11 years, 12% female; LVEF 28 ± 6%) received a WCD for a median of 69 (1; 277) days after AMI (wearing duration 23.5 (0; 24) hours/day). Within the first 90 days, 4/105 (3.8%) patients received 9 appropriate shocks (2 (1; 5) shocks). No inappropriate shocks were delivered, and 3/105 (2.9%) patients died during follow-up. Arrhythmic mortality (1.9% Austria vs. 1.6% VEST, p = 0.52), as well as all-cause mortality (2.9% vs. 3.1%, p = 0.42) was comparable in both cohorts. The WCD is a safe treatment option in a highly selected cohort of patients with LVEF ≤ 35% after AMI. However, despite excellent WCD wearing duration in our cohort, the arrhythmic mortality rate was not significantly different.

Appropriate Implantable Cardioverter-Defibrillator Therapy in Patients with Ventricular Arrhythmia of Unclear Cause in Secondary Prevention of Sudden Cardiac Death.

In this study, we sought to investigate the occurrence of appropriate implantable cardioverter-defibrillator (ICD) therapies and inappropriate shocks in secondary prevention ICD recipients with ventricular arrhythmia of unclear cause and ventricular arrhythmia in the context of underlying heart disease. In this retrospective study, consecutive patients with an ICD implanted for secondary prevention in the University Medical Center Groningen (UMCG), the Netherlands between 1 January 2012 and 31 December 2018 were included. Patients were classified as having ventricular arrhythmia of unclear cause if no clear cause was found which could explain the index ventricular arrhythmia. The primary outcome was appropriate ICD therapy. The study population consisted of 257 patients. In 220 patients, an underlying heart disease could be identified as the cause of ventricular arrhythmia, while 37 patients had an unclear cause of ventricular arrhythmia. The median age was 64 years (interquartile range (IQR) 53-72 years). Forty-five (18%) patients were women. During a median duration of follow-up of 6.2 years (IQR 4.8-7.8 years), appropriate ICD therapy occurred in 95 (37%) patients. This number was 90 (41%) in the group with a clear etiology and 5 (14%) in the group with an unclear etiology. In multivariable analysis, index ventricular arrhythmia of unclear cause was associated with fewer appropriate ICD therapies (HR 0.37 [95% CI 0.14-0.99]; p = 0.048), as well as an increased risk of inappropriate ICD shocks (HR 3.71 [95% CI 1.17-11.80]; p = 0.026). Index ventricular arrhythmia of unclear cause was significantly associated with fewer appropriate ICD therapies.

Predictors of mortality and clinical outcomes following implantable cardioverter-defibrillator therapy in elderly patients: A retrospective single-center cohort study.

Implantable cardioverter-defibrillators (ICDs) are frequently used to prevent sudden cardiac death in patients with high-risk arrhythmias. However, the use of ICD therapy in elderly patients beyond the predicted age of life expectancy is still controversial. We aimed to evaluate the predictors of mortality and clinical outcomes following ICD implantation in elderly patients. We conducted a retrospective analysis of 145 elderly patients aged 72 years and older who received ICD implantation between January 2010 and August 2015. We collected and analyzed baseline data, including clinical, demographic, and medical history, the reason for ICD therapy, procedural data, and echocardiography results. Follow-up data included the development of complications and mortality. The predictors of mortality were identified using the univariate and multivariable Cox regression models. During the median follow-up duration of 30.5 [18.0-48.0] months, 141 cases completed follow-up (mean age = 76.0 ± 3.7 years). Forty-four patients experienced at least one episode of ICD therapy. Inappropriate shock, recurrent shock, and device-related infection were the most frequent complications observed in our study. Of the 145 patients, 42 died during the follow-up period, with an average survival time of 22.4 months after ICD implantation. Among these patients, 11 received ICD for primary prevention, and 31 received it for secondary prevention. Cardiovascular problems were the leading cause of death. We found that a low baseline ejection fraction (EF) was an independent predictor of mortality (hazard ratio = 0.93, 95% confidence interval: 0.90-0.98; p = 0.008). Our study suggests that ICD therapy is a valuable treatment option for elderly patients beyond their predicted age of life expectancy. The study highlights the importance of baseline EF as a significant predictor of mortality in these patients.

A comparison of biphasic manual and semi-automatic external defibrillation

Background: Biphasic manual defibrillation (MD) is advocated as the preferred strategy for paramedics ahead of semi-automatic external defibrillation (SAED) for out-of-hospital cardiac arrest (OHCA). Methods: A systematic review involved searching CINAHL, MEDLINE and Embase academic databases. Comparative studies where both strategies were tested for time to first defibrillation (TTFD) and related Utstein-based model outcomes were examined to discern which strategy was superior. Results: Two studies met the criteria. One study found that in 4552 SAED episodes of defibrillation (30.8% of the 14 776 total defibrillation episodes), a decrease of &gt;10% in mean TTFD (P&lt;0.001) of an intial shockable rhythm was recorded. The same study reported an overall decrease in TTFD within 2 minutes (95% CI/P&lt;0.001), with a 68% improved odds of receiving a shock within two minutes. SAED was associated with a 26% reduction in the risk-adjusted odds of survival (95% CI/P&lt;0.009), attributed to cardiopulmonary resuscitation (CPR) delays. The other examined 160 defibrillations in OHCA. The MD median TTFD was 7 seconds faster (95% CI/P&lt;0.0001) and responsible for 20% more inappropriate shocks. Conclusions: Modern SAED is superior in reducing TTFD and inappropriate shocks. The modern SAED and MD strategies can be enhanced by interruption-reducing technology. New SAED algorithms can detect shockable rhythms in 3 seconds. More randomised studies need to be conducted using up-to-date devices. A multifaceted approach incorporating technological advancements, ongoing research and training is necessary to ensure that the most effective defibrillation strategy is employed.

Prognostic impact of implantable cardioverter defibrillators and associated adverse events in patients with continuous flow left ventricular assist devices.

Implantation of implantable cardioverter defibrillators (ICD) reduces the risk of all-cause mortality in symptomatic heart failure (HF) patients with severe left ventricular (LV) dysfunction. Nevertheless, the prognostic impact of ICD therapy in continuous flow left ventricular assist device (LVAD) recipients remains controversial. 162 consecutive HF patients, who underwent LVAD implantation at our institution between 2010 and 2019, were categorized according to the presence (n = 94, ICD-group) or absence (n = 68, Control-group) of ICDs. Apart from clinical baseline and follow-up parameters, adverse events (AEs) related to ICD therapy and overall survival rates were retrospectively analyzed. Out of 162 consecutive LVAD recipients 79 patients (48.8%) were preoperatively categorized as Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile ≤2. The prevalence of severe HF symptoms and preoperative use of short-term circulatory support devices (54.4% vs. 13.8%, p < 0.001) was higher within the Control-group, although baseline severity of LV and RV dysfunction was similar. Apart from an increased prevalence of perioperative right heart failure (RHF) within the Control-group (45.6% vs. 17.0%; p < 0.001), procedural characteristics and perioperative outcome were similar. Overall-survival during a median follow-up of 14 (3.0-36.5) months was similar within both groups (p = 0.46). During the first 2 years after LVAD implantation 53 ICD-related AEs occurred within the ICD-group. Thereof, lead-dysfunction occurred in 19 patients and unplanned ICD-reintervention in 11 patients. Furthermore, in 18 patients appropriate shocks without loss of consciousness occurred, whereas inappropriate shocks occurred in 5 patients. ICD therapy in LVAD recipients was not associated with a survival benefit or reduced morbidity after LVAD implantation. Conservative ICD-programming seems to be justified to avoid ICD-related complications and "awake shocks" after LVAD implantation.

Assessing the Cost and Resource Use Impact of Implantable Cardiac Defibrillator Shocks in the UK CareLink Population.

High voltage devices (implantable cardiac defibrillators (ICDs) and cardiac resynchronization therapy defibrillators referred to jointly as ICDs) reduce rates of sudden cardiac death in patients with cardiovascular disease. However, shocks from ICDs may be associated with healthcare resource use (HCRU) and costs. The aim of this study was to estimate the costs associated with both appropriate and inappropriate shocks from ICDs. Patients with appropriate and inappropriate shocks from ICDs were identified via CareLink data from Liverpool Heart and Chest Hospital between March 2017 and March 2019. The devices were SmartShock activated, with anti-tachycardia pacing. Costs were estimated according to the dominant episode of healthcare, from an NHS payer perspective. There were 2445 patients on the CareLink system with ICDs. Over the two-year period, HCRU data from 143 shock episodes among 112 patients were reported. The total cost for all shocks was £252,552 with mean costs of £1608 and £2795 for appropriate and inappropriate shocks respectively. There was substantial variation in HCRU between shock episodes. While there was a low rate of inappropriate shocks from ICDs, there were still substantial HCRU and costs incurred. In this study, the specific HCRU was not costed independently, meaning the costs reported are likely to be a conservative estimate. Whilst every attempt to reduce shocks should be made, appropriate shocks cannot be avoided. Strategies to reduce the incidence of inappropriate and unnecessary shocks should be implemented to reduce overall health care costs associated with ICDs.

Intermuscular two-incision technique for implantation of the subcutaneous implantable defibrillator: 3-year follow-up

Abstract Funding Acknowledgements Type of funding sources: None. Background data on long-term outcome of the intermuscular (IM) two-incision implantation technique for the subcutaneous implantable cardioverted defibrillator (S-ICD) are lacking. Purpose the aim of the present study was to evaluate the outcome of patients underwent S-ICD implantation with the IM two-incision technique during 3-year follow-up. Methods the study population consisted of 105 consecutive patients (79 male; median 50 [13-77] years) underwent S-ICD implantation with the IM two-incision technique. Results according to the PRAETORIAN score, the risk of conversion failure was classified as low in 99 patients (94.3%), intermediate in 6 (5.7%).Ventricular fibrillation was successfully converted at ≤65 J in 97.4% of patients. During a median follow-up of 39 (16-53) months, 10 patients (9.5%) experienced device-related complications and 9 (8.5%) patients reported inappropriate shocks (IAS). Lead-associated complications were the most common (4.7%), including 2 cases of lead failure (1.9%). Pocket complications were reported in 2 patients (1.9%). Extra-cardiac oversensing (3.8%) represented the leading cause of IAS. No T-wave oversensing episodes were recorded. Twelve patients (11.4%) experienced appropriate shocks. Eight patients (7.6%) died during follow-up. IAS or device-related complications did not impact on mortality (HR 0.5; 95%CI 0-4.3; P=0.5; HR 0.7; 95%CI 0.1-6.0; P=0.8, respectively). Conclusions according to our findings, the IM two-incision technique allows for optimal positioning of the device achieving a low PRAETORIAN score with a high conversion rate. IM two-incision technique allows low incidence of pocket complications, shifting the type of complications towards lead-related complications, which represent the most common complications. The IM two-incision technique would not seem to impact the occurrence of IAS. Management of complications are safe without impact on the outcome.

Subcutaneous implantable cardioverter-defibrillator generator removal: a multicenter analysis

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): University Hospital Cologne Introduction The subcutaneous implantable cardioverter-defibrillator (S-ICD) was a significant recent advance in sudden cardiac death prevention. Device-related complications, including infection or lead fracture, or changes in the medical status, such as necessity for cardiac pacing, may necessitate device removal. (1) Real-world multicenter data on S-ICD removal are sparse. Purpose This multicenter analysis sought to assess the incidence and indications for S-ICD generator removal. Methods Retrospective data and the most recent follow-up data on S-ICD devices implanted at 14 participating centers in Europe, the US and Canada, and information on subsequent device removal was submitted to an online database (2). Limited baseline patient information and the incidence of and reasons for S-ICD generator removal or failure were reported. Premature device removal was defined as device removal for any reason other than regular battery depletion (&amp;gt;5 years of longevity). Results Data from 1106 devices was analyzed. Devices were implanted between 15.10.2009 and 16.04.2021 at the participating centers. The first-generation model 1010 generator was implanted in 55 (5%), the newer models A209 or A219 were implanted in 457 (41.3%) and 594 (53.7%) respectively. Patients were aged 46.7±16.1 years and the indication for ICD therapy was primary prevention in 616 (55.7%) and secondary prevention in 484 (43.8%). During the follow-up period, 37 (3%) patients deceased, and 96 patients were excluded from the analysis due to lack of follow-up (&amp;lt;4 weeks). Premature device removal was performed in 103 (9.3%) during the follow-up period of 31.3±19.5 months. The most common reasons for removal were battery depletion (52%), of which premature, defined as &amp;lt;5 years longevity, depletion accounted for 57%, upgrade to transvenous ICD or CRT (17%) and infection (11%). Other indications for removal included heart transplantation (4%) or ventricular assist device implantation (1.5%), noise detection or inappropriate shocks (6.5%), and patient discomfort (0.7%). (see figure 1) Regular battery depletion occurred in 34 devices after 69.2±5.3 months. There was no difference in device longevity between the different generator models (1010, A209, and A219). There were no significant differences between the different generator models with respect to indications for explanation. Conclusions In this real-world retrospective multicenter analysis, premature S-ICD generator removal was necessary in 9.3% of patients. Premature battery depletion, infections, and the need for pacing were the most common indications for unplanned generator removal.

Ventricular tachycardia as presenting arrhythmia as a determinant of appropriate implantable cardioverter-defibrillator therapy in secondary prevention

Abstract Funding Acknowledgements Type of funding sources: None. Background Sudden cardiac death (SCD) is a leading cause of death. The implantable cardioverter-defibrillator (ICD) is an established therapy to prevent SCD in patients with prior ventricular tachycardia (VT) or ventricular fibrillation (VF). Determination of patient characteristics related to ICD therapies may provide targets for more intensive monitoring or management of ventricular arrhythmias. Therefore, we aimed to find determinants of appropriate ICD therapy. Methods In this retrospective, single-centre study, 223 consecutive secondary prevention ICD recipients were included. Data was obtained on medical history, laboratory measurements, electrocardiography and echocardiography. The primary outcome was appropriate ICD therapy, which included shock and antitachycardia pacing (ATP) given for VF or VT. Backward stepwise Cox regression analysis was performed to find determinants of appropriate therapy. Results The median age of the study population was 65.3 years (interquartile range (IQR) 55.4 – 72.0 years). 188 (84.3%) patients were male. 153 (68.6%) patients had ischemic heart disease. During a median follow-up duration of 6.00 years (interquartile range (IQR) 4.85 – 7.70 years), appropriate ICD therapy occurred in 89 (39.9%) patients, appropriate ICD shock in 65 (29.1%) patients, death in 55 (24.7%), inappropriate shock in 11 (4.9%) and device-related complications in 18 (8.1%). VT as index arrhythmia, QRS fragmentation and diminished right ventricular function were determinants of appropriate device therapy. Interestingly, whereas the majority of patients (141 (63.2%)) had an ICD implanted for initial presentation with VF, the first occurrence of appropriate therapy during follow-up was for monomorphic VT in the majority of patients (84 (94.4%)). Conclusion In patients with a secondary prevention ICD indication, VT as presenting arrhythmia is a determinant of appropriate ICD therapy during follow-up. Most ICD therapies during follow-up were applied for monomorphic VT.

Subcutaneous ICD therapy results in a similar quality of life compared with transvenous ICD therapy during both short- and long-term follow-up

Abstract Funding Acknowledgements Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Boston Scientific Medical device company St. Paul, Minnesota, USA Introduction The PRAETORIAN trial showed that the subcutaneous implantable cardioverter defibrillator (S-ICD) is noninferior to the transvenous ICD (TV-ICD) with respect to device-related complications and inappropriate shocks in a conventional ICD population. It is unknown whether there is a difference in quality of life (QoL) between the two patient groups. The generator size and implant location differ between both devices. This may cause a variation in mental health status and pain perception between treatment arms, in particular in older patients, patients with low BMI, and females. Purpose This prespecified analysis of the PRAETORIAN trial compares the impact of the S-ICD and TV-ICD on QoL. Methods In the PRAETORIAN trial, 849 patients were randomised to S-ICD (n=426) or TV-ICD (n=423) therapy. QoL was prospectively measured at baseline, discharge and 12 and 30 months after ICD implant, by measuring cardiac-specific physical functioning with the Duke Activity Status Index (DASI) and psychological and physical well-being with the 36-Item Short Form Health Survey (SF-36, divided in 8 subscales). Patients who completed the questionnaires at baseline were included in this analysis. At each time point the mean change in score from baseline was calculated. Subgroups were made based on age (tertiles, &amp;lt; 58, 58-67 and &amp;gt;67 years), BMI categories (&amp;lt;25, 25-30, and ≥30 kg/m2) and sex. In these subgroups, we only looked at differences in pain and mental health between arms. Treatment effects, 95% CIs and interactions were calculated by regression models. Results A total of 823/849 patients completed the QoL questionnaires at baseline. Questionnaires were also completed by these patients at discharge (92%), 12 months (85%) and 30 months (69%). There was no difference in QoL between the arms at any time point (p&amp;gt;0.05, figure). Age, BMI and sex were not associated with a difference between the arms in SF-36 subscale bodily pain (p=0.73, 0.72 and 0.92 respectively), or SF-36 subscale mental health (p=0.15, 0.39 and 0.76) at 30 months. Similar results were seen at discharge and 12 months. Conclusion There were no differences in QoL between S-ICD and TV-ICD treatment in the first 30 months after implant. In addition, no differences in pain and mental health were seen in older patients, patients with low BMI and females. These results confirm that the S-ICD is a good alternative for the TV-ICD.

Deep learning and hyperparameter optimization for assessing one’s eligibility for a subcutaneous implantable cardioverter-defibrillator

It is standard cardiology practice for patients suffering from ventricular arrhythmias (the main cause of sudden cardiac death) belonging to high risk populations to be treated via the implantation of Subcutaneous Implantable cardioverter-defibrillators (S-ICDs). S-ICDs carry a risk of so-called T wave over sensing (TWOS), which can lead to inappropriate shocks that carry an inherent health risk. For this reason, according to current practice patients’ Electrocardiograms (ECGs) are manually screened by a cardiologist over 10 s to assess the T:R ratio—the ratio between the amplitudes of the T and R waves which is used as a marker for the likelihood of TWOS—with a plastic template. Unfortunately, the temporal variability of a patient’ T:R ratio can render such a screening procedure, which relies on an inevitably short ECG segment due to its manual nature, unreliable. In this paper, we propose and investigate a tool based on deep learning for the automatic prediction of the T:R ratios from multiple 10-second segments of ECG recordings capable of carrying out a 24-hour automated screening. Thanks to the significantly increased screening window, such a screening would provide far more reliable T:R ratio predictions than the currently utilized 10-second, template-based, manual screening is capable of. Our tool is the first, to the best of our knowledge, to fully automate such an otherwise manual and potentially inaccurate procedure. From a methodological perspective, we evaluate different deep learning model architectures for our tool, assess a range of stochastic-gradient-descent-based optimization methods for training their underlying deep-learning model, perform hyperparameter tuning, and create ensembles of the best performing models in order to identify which combination leads to the best performance. We find that the resulting model, which has been integrated into a prototypical tool for use by clinicians, is able to predict T:R ratios with very high accuracy. Thanks to this, our automated T:R ratio detection tool will enable clinicians to provide a completely automated assessment of whether a patient is eligible for S-ICD implantation which is more reliable than current practice thanks to adopting a significantly longer ECG screening window which better and more accurately captures the behavior of the patient’s T:R ratio than the current manual practice.

A 25-year single-center experience with transvenous and subcutaneous ICD patients under thirty years of age

Abstract Funding Acknowledgements Type of funding sources: None. Background Young implantable cardioverter-defibrillator (ICD) recipients present high rate of inappropriate shocks and complications. Some of them seem to be underestimated. The subcutaneous ICD(S-ICD) system was developed to eliminate lead-related complications and was proved to be effective, avoiding intracardiac and endovascular adhesions. Aims To report on our clinical experience with transvenous (TV-ICD) and S-ICD therapy in patients under thirty years of age. Methods We reviewed database of ICD recipients in our institution between 1996 and 2022(25 years) and have chosen 125 pts consecutively implanted up to and including the age of 30 years. We retrospectively analyzed the rate of appropriate(AI) and inappropriate interventions(IS), lead complications rate, infection rate, mortality and treatment options. Results The study group: 84 TV-ICD(age: 6-30, BMI: 16,3-22,2) and 41 S-ICD( age: 15-30, BMI; 15,6-31,1) patients. The mean follow-up in analyzed groups was 159±48 and 40± 2 months respectively. Abnormal ventricular function: EF≤30 occurred in compared groups: 12/84(14%) and 5/41(12%) respectively, p=0,3. 24/84pts(28%) received ≥1 AI for VT/VF(ATP or shock) in TV-ICD and 4/40pts(10%) in S-ICD groups. 25/84 pts(30%) received one or multiple (IS) and 1/40pts(2,5%) in compared groups respectively, p=0,02. There were 18/84 (21.5%) ventricular lead dysfunctions(reimplantation of a new system) in TV-ICD and 0% in S-ICD groups, p=0,025. An infection rate (endocarditis or device pocket )was 8/84 (10%) in TV-ICD group with complete system removal and 1 pts (2,5%) wound infection(staphylococcus aureus) in S-ICD group successfully treated with antibiotics. 1 left ventricular assist device was implanted in end-stage heart failure S-ICD patient with good result. There were 2 S-ICD implantations as a concomitant device i.e. conversion of TV-ICD(with therapy OFF) to S-ICD due to ventricular lead dysfunction. 4(10%) pts required generator elective replacement due to early battery depletion in S-ICD group. In 2(5%)pts right sternal lead location was chosen due to better sensing results. Mortality rate was 6/84 pts (7%), caused by ventricular lead dysfunction, end-stage heart failure or heart transplantation fatal result in TV-ICD group. There was no death in S-ICD group. Conclusions TV- ICD implantation in children and young adults is a feasible and effective procedure in a 25-year follow-up but the rate of complications is high in this population. S-ICD recipients did not experienced lead failures or systematic infections. S-ICD appears to be a good therapy option and an alternative to TV-ICD in pediatric and young patients population, preventing from some serious lead complications and tricuspid valve regurgitation. The method and follow-up period effect is present between the TV-ICD and S-ICD in analyzed groups.

Automatic subcutaneous defibrillator screening in patients with intracardiac devices: comparative study depending on the point of pacing

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Subcutaneous defibrillator (S-ICD) has been shown to be effective in the prevention of sudden cardiac death with the advantage of avoiding intravascular access. Although it should not be indicated when pacing indications exists, the need for pacing may arise in the course of underlying heart disease. Before implantation, it is necessary to screen the surface electrocardiogram (ECG) to avoid inappropriate shocks due to overdetection. Published studies so far show a drastic reduction in the percentage of patients eligible for screening with conventional pacing techniques (right ventricular apex, right ventricular outflow tract or resynchronisation with coronary sinus pacing). Purpose The change in screening signal produced by cardiac pacing during is unknown. So far, no studies have been published comparing the outcome of S-ICD screening between different pacing sites, including conduction system pacing (CSP, his and left bundle branch pacing). Our aim is to analyse the success rate of screening and its predictors in patients with cardiac pacing according to the pacing point. Methods A total of 102 patients were screened for S-ICD and divided into 5 groups according to pacing type: His bundle pacing (HBP), left bundle pacing (LBP), right ventricular apex (RVA), right ventricular outflow tract (RVOT) and biventricular cardiac resynchronisation (CRT). There were no significant differences in any variable between the HBP and LBP group, so they were unified as the CSP group. We used a control group of 10 healthy patients with no implantable devices or ECG abnormalities. All patients underwent automatic screening with paced rhythm using the automatic algorithm (Boston Scientific). We considered a suitable screening when at least one vector (primary, secondary or alternative) was positive in both decubitus and standing position, in left or right parasternal position. Results Baseline characteristics by group are summarised in table1. Paced QRS width was lower in the CSP group (135 [120-160] vs 120 [106-120] p=0,001). All healthy controls passed the screening (100%). 39 (97.5%) CSP patients passed the screening, compared to 15 (71.4%) CRT, 14 (70%) RVOT and 4 (19%) RVA. The differences were statistically significant, p &amp;lt; 0.001 (image 1 A &amp; B). In multivariate analysis, only pacing type was shown to be a predictor of positive screening (p 0.001), independent of paced QRS width. Conclusions In our experience, the probability of obtaining a positive screening of the S-ICD is higher with conduction system stimulation than with the other pacing points (AVD, RVOT or CRT).

A tertiary centre experience of routine exercise testing as part of subcutaneous ICD vector mapping

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The pre-implant patient screening process (vector mapping) for subcutaneous defibrillators (S-ICD) seeks to determine eligibility for implantation. It broadly requires at least one of three available vectors (primary, secondary or alternate) to pass under all conditions to mitigate risk of inappropriate device therapies. Vector mapping protocols currently require only supine and sitting/standing ECG. However, the standard operating procedure (SOP) in our centre also includes mapping at peak exercise, actioned after audit data highlighted an association between exercise and sensing complications (T and R wave changes, rate-related bundle branch block and noise/myopotential over-sensing). Aim To determine whether routine exercise testing during screening alters the outcome of vector mapping, and whether this correlates with inappropriate therapies post-implant. Method This was a single-centre retrospective study of 121 patients (79% male, mean BMI 29) who completed S-ICD vector mapping between October 2016 and August 2022. 10 patients were excluded as they were unable to tolerate exercise. Emblem automated screening tool (AST) and AST 2.0 was used to complete vector mapping and a revised SOP was devised in conjunction with their technical support team. Post- implant vector programming was based on device optimisation algorithms rather than exercise-inclusive screening recommendation, which provided additional observational data only. Results 75% were primary prevention devices and the 3 most prevalent aetiologies were dilated (22%), ischaemic (20%) and hypertrophic (18%) cardiomyopathies. In 29.7% (33/111) of participant’s, inclusion of exercise screening altered vector mapping success: The alternate vector saw the largest decrease (23.2%) in successful mapping once exercise was incorporated (69 participants passed supine and sitting/standing, 16 of those failed post-exercise), followed by secondary 13.1% (13/99) then primary 3.9% (4/103) – see Figure 1. Further retrospective analysis showed that in 16.2% (18/111) of patients, post-implant vector selection opposed screening recommendation. 6 of these patients experienced exercise-induced sensing complications with 4 leading to inappropriate shocks. After reprogramming in-line with screening, all but 1 patient have had no further issues. Conclusions Incorporation of exercise mapping into S-ICD screening protocols may improve vector selection to reduce inappropriate device therapies.

Appropriate therapy for implantable cardioverter defibrillators used as primary versus secondary prophylaxis

Abstract Funding Acknowledgements Type of funding sources: None. Background Implantable cardioverter defibrillators (ICD) are used for primary prevention in children highly suspicious of life-threatening arrhythmias due to family history and malignant syncope. This practice might potentially result in a lower incidence of appropriate therapy compared with ICDs implanted for secondary prevention following documented ventricular arrhythmias. Purpose We aimed to compare the rate of appropriate therapy after ICD implantation for primary versus secondary prevention in young children. Method Using national ICD registry, this retrospective nationawide cohort study included children aged ≤15 years who received their first ICD between 1988 and 2020. Patient characteristics, medical history including mortality, device indication, therapy and complications were retrieved from electronic medical files. The primary endpoint was time to appropriate therapy, defined as shock or anti-tachycardia pacing for ventricular tachycardia or fibrillation. Results During the study period, a total of 81 ICDs (39 ICDs pr. million live births) were implanted. Among these, 79 were included in the outcome analysis due to retrievable follow-up data. At baseline, the majority had channelopathies (44%) or structural heart diseases (42%), whereas 25 (32%) and 54 (68%) devices were implanted as primary and secondary prophylaxis, respectively. The median age at primary implantation was 13.9 and 11.6 years (p&amp;lt;0.05), respectively. During a median follow-up of 9.0 (IQR: 4.8–13.9) years, 44 patients experienced appropriate device therapy and 6 died, with no difference for primary and secondary prevention recipients (p=0.34 and p=0.83). The 10-year cumulative incidence of appropriate therapy was 56% for primary prevention recipients and 68% for secondary prevention recipients, whereas 10-year survival probability was 90% (95% CI: 76-100%) and 81 % (95% CI: 63%-99%), respectively. All deaths were of cardiovascular cause. Bleeding occurred in 0 versus 2, infection in 5 versus 4, and inappropriate shock therapy in 2 versus 11 patients, with an overall combined trend towards more events for ICDs implanted as secondary prophylaxis (p=0.08). Conclusions ICD implantation in young children was relatively rare. The rate of appropriate therapy was similar among primary and secondary ICD recipients, indicating too restrictive primary prophylaxis implantation, which should be investigated in future studies. The incidence of complications was highest among secondary ICD recipients.

Genetic testing in children with Brugada syndrome: results from a large prospective registry

Abstract Funding Acknowledgements Type of funding sources: None. Background/introduction A pathogenic/likely pathogenic (P/LP) variant can be found in 20-25% of patients with Brugada syndrome (BrS) and a P/LP variant in SCN5A is associated with a worse prognosis. However, the diagnostic yield and the prognosis of gene testing in pediatric BrS syndrome is unclear. Purpose The aim of this study is to define the diagnostic yield of SCN5A gene testing with ACMG standardized variant classification in a large cohort of pediatric BrS. Furthermore, a correlation between the clinical outcomes and the genetic background of children with BrS in comparison with adult BrS is aimed. Methods All consecutive patients diagnosed with BrS, between 1992 and 2022 were enrolled in a prospective monocentric registry. Inclusion criteria were: 1) BrS diagnosis; 2) Genetic analysis for SCN5A gene and 3) classification of gene variants following current ACMG guidelines. Pediatric patients were defined if ≤ 12 years of age. The primary endpoint was ventricular arrhythmias (VA) occurrence, defined as documented SCD, aborted SCD, ventricular tachycardia or ventricular fibrillation or appropriate ICD intervention. Results A total of 500 BrS patients were included, 41 pediatric patients and 459 adult patients. Among children with BrS, 19 patients (46.3%) had a P/LP variant (P+) in SCN5A gene. No P/LP variants could be identified in 22 (53.7%) pediatric patients (P-). After a mean follow-up of 140.2 months, 3 children (7.3%) experienced a VA, treated with appropriate ICD shock. Inappropriate shocks occurred in 3 pediatric patients (7.3%). At survival analysis, P- pediatric patients had higher VA free survival during the follow-up, compared with P+ pediatric patients (Log-Rank p=0.021), Figure 1. There was no difference in VA free survival between pediatric and adult BrS patients both without (P-), (Log-Rank p=0.19) and with (P+) a P/LP variant (Log-Rank p=0.91), Figure 2. Conclusion In a large BrS cohort, the diagnostic yield for SCN5A P/LP variants in the pediatric population is 46.3%. P+ children with BrS have a worse arrhythmic prognosis.

Electric cars and high power chargers: Are they safe for patients with cardiac implantable electronic devices?

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Deutsche Stiftung für Herzforschung research grant Background Electromagnetic interference (EMI) poses a risk to patients with cardiac implantable devices (CIEDs) and can result in device malfunction including pacing inhibition or inappropriate shock therapy. Such EMI sources are ubiquitous in the modern world. Battery electric vehicles (BEVs) represent such a potential EMI source. We have previously investigated the EMI risk of driving eCars and found that the largest electromagnetic field is located along the charging cable. New high power chargers deliver higher currents (facilitating rapid recharging), potentially associated with greater electromagnetic fields and higher risk for clinically relevant EMI. This present study aims to evaluate this EMI-risk to address this clinically important question. Methods A consecutive group of 130 patients with a range of CIEDs were recruited to participate. After a complete device interrogation each had their device programmed to optimise EMI detection with ensured ventricular pacing and ICD therapies were disabled. Under continuous 6-lead ECG monitoring each patient then plugged in and charged four different BEVs (Porsche Taycan Turbo, VW ID3 pro, Tesla Model 3 and Audi e-tron 55 Quattro) in addition to a ‘dummy’ eCar (which permitted the maximal charging power flow of 350kW) with the charging cable placed directly over the device. During charging both the magnetic field and electric field was measured. A further complete device interrogation was then performed to evaluate for spontaneous reprogramming and tachycardia detection. Results In total 561 separate charging events were performed by 130 patients with the four eCars and one dummy car. The maximal magnetic field along the charging cable was 38.65µT and at the charging column was 77.9µT. There were no incidences of EMI, specifically there was no pacing inhibition due to oversensing, no spontaneous reprogramming and no tachycardia over-detection. This results in a patient-based risk of 0% (95% CI; 0% - 2.8%) and a charging event-based risk of 0% (95% CI; 0% - 0.6%). Conclusions and Discussion We found that there was no EMI induced during the use of high power charger technology for BEV despite device programming and charging cable placement being optimised for a worst-case scenario and maximising the chance of clinical EMI. Our study suggests that there is a very low risk, if any, posed by BEVs and the new high power chargers. CIED patients should reassured that their use is safe. We would still recommend not to place the charging cable directly above the CIED during use to maximise safety of high power charging.

Causes and clinical consequences of inappropriate shocks experienced by patients wearing a cardioverter-defibrillator

The LifeVest® wearable cardioverter-defibrillator (WCD) prevents sudden cardiac death in at-risk patients who are not candidates for an implantable defibrillator. The safety and efficacy of the WCD may be impacted by inappropriate shocks (IAS). The purpose of this study was to assess the causes and clinical consequences of WCD IAS in survivors of IAS events. The Food and Drug Administration's Manufacturers and User Facility Device Experience database was searched for IAS adverse events (AE) that were reported during 2021 and2022. A total of 2568 IAS-AE were found (average number of IAS per event: 1.5 ± 1.9; range 1-48). IAS were caused by tachycardias (1255 [48.9%]), motion artifacts (840 [32.7%]), and oversensing (OS) of low-level electrical signals (473 [18.4%]) (P <.001). Tachycardias included atrial fibrillation (AF) (828 [32.2%]), supraventricular tachycardia (SVT) (333 [13.0%]), and nonsustained ventricular tachycardia/fibrillation (NSVT/VF) (87 [3.4%]). Activities responsible for motion-induced IAS included riding a motorcycle, lawnmower, or tractor (n = 128). In 19 patients, IAS induced sustained ventricular tachycardia or ventricular fibrillation that subsequently were terminated by appropriate WCD shocks. Thirty patients fell and suffered physical injuries. Conscious patients (n = 1905) did not use the response buttons to abort shocks (47.9%) or used them improperly (20.2%). IAS resulted in 1190 emergency room visits or hospitalizations, and 17.3% of patients (421/2440) discontinued the WCD after experiencing IAS, especially multiple IAS. The LifeVest WCD may deliver IAS caused by AF, SVT, NSVT/VF, motion artifacts, and oversensing of electrical signals. These shocks may be arrhythmogenic, result in injuries, precipitate WCD discontinuation, and consume medical resources. Improved WCD sensing, rhythm discrimination, and methods to abort IAS are needed.