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Introduction: The risk of complications associated with transvenous ICDs make the subcutaneous implantable cardiac defibrillator (S-ICD) a valuable alternative in patients with adult congenital heart disease (ACHD). However, higher S-ICD ineligibility and higher inappropriate shock rates-mostly caused by T wave oversensing (TWO)- are observed in this population. We report a novel application of deep learning methods to screen patients for S-ICD eligibility over a longer period than conventional screening. Methods: Adult patients with ACHD and a control group of normal subjects were fitted with a 24-h Holters to record their S-ICD vectors. Their T:R ratio was analysed utilising phase space reconstruction matrices and a deep learning-based model to provide an in-depth description of the T: R variation plot for each vector. T: R variation was compared statistically using t-test. Results: 13 patients (age 37.4 ± 7.89 years, 61.5 % male, 6 ACHD and 7 control subjects) were enrolled. A significant difference was observed in the mean and median T: R values between the two groups (p

Background: Implantable cardioverter defibrillators (ICD) prevent sudden cardiac death (SCD). Patients with end-stage renal disease (ESRD) requiring dialysis are at a very high risk of infection from cardiac implantable electronic device (CIED) implantation as well as mortality. In the present study, we compared the long-term complications and outcomes between subcutaneous ICD (S-ICD) and transvenous ICD (TV-ICD) recipients. Methods: In this retrospective analysis, we analyzed a total of 43 patients with ESRD requiring dialysis who received either a prophylactic S-ICD (26 patients) or a single right ventricular lead TV-ICD (17 patients) at seven experienced centers in Germany. Follow-up was performed bi-annually, at the end of which the data concerning comorbidities and, if applicable, reason for death were checked and confirmed with patients' general practitioner, nephrologist and cardiologist. Results: The median follow up duration was 95.6 months (range 42.8–126.3 months). Baseline characteristics were without noteworthy significant differences between groups. During follow-up (FU), there were significantly more device-associated infections (HR 8.72, 95% confidence interval (CI), 1.18 to 12.85, p < 0.05) and device-associated hospitalizations (HR 10.20, 95% CI 1.22 to 84.61, p < 0.001), as well as a higher cardiovascular mortality (HR 9.17, 95% CI 1.12 to 8.33, p < 0.05), in the TV-ICD group. The number of patients requiring hospitalization for any reason was significantly higher in the TV-ICD group (HR 2.59, 95% CI 1.12 to 6.41, p < 0.05). There was no significant difference in overall mortality (HR 1.92, 95% CI 0.96 to 6.15, p = 0.274). Conclusions: Our data suggest that, in this extended follow-up in seriously compromised renal patients on dialysis, the S-ICD patients have statistically fewer device infections and hospitalizations as well as lower cardiac mortality compared with the TV-ICD cohort. [ABSTRACT FROM AUTHOR]

Background: Electromagnetic interference (EMI) encompasses electromagnetic field signals that can be detected by a device's circuitry, potentially resulting in adverse effects such as inaccurate sensing, pacing, device mode switching, and defibrillation. EMI may impact the functioning of Cardiac Implantable Electronic Devices (CIEDs) and lead to inappropriate therapy. Method: An experimental measuring device, a loop antenna mimicking the implantable cardioverted defibrillator (ICD) antenna, was developed, and validated at the US Food and Drug Administration (FDA) and sent to Wright State University for testing. Two sets of measurements were conducted while the vehicle was connected to a 220‐Volt outlet with charging at ON and OFF. Each measurement set involved three readings at various locations, with the antenna oriented in three different positions to account for diverse patient postures. The experiment utilized a Tesla Model 3 electric vehicle (EV), assessing scenarios both inside and outside the car, including the driver's seat, driver's seat floor, passenger's seat, rear seat, rear seat floor, cup holder, charging port (car), and near the charging station. Results: The detected voltage (max 400 to 504 millivolts) around the cup holder inside the car differed from all other measurement scenarios. Conclusion: The investigation highlights the identification of EMI signals originating from an EV) that could potentially interrupt the functionality of a Subcutaneous Implantable Cardioverter‐Defibrillator (S‐ICD). These signals fell within the R‐wave Spectrum of 30–300 Hz. Further in‐vivo studies are essential to determine accurately the level of interference between S‐ICDs and EMI from Electric Vehicles. [ABSTRACT FROM AUTHOR]

To assess the risk of unsuccessful conversion of ventricular fibrillation during defibrillation testing (DFT) with the subcutaneous implantable cardioverter-defibrillator (S-ICD), the PRAETORIAN score has been proposed. The purpose of this study was to validate the PRAETORIAN score in a large S-ICD collective. A retrospective single-center analysis of S-ICD patients receiving intraoperative DFT was performed. DFT was performed using a stepwise protocol with 65-J standard polarity, change of polarity, increase to 80 J, and repositioning if necessary. If all DFTs failed, we switched to a transvenous ICD. Overall, 398 patients were analyzed (268 male [67.3%]; mean age 42.4 ± 15.9 years; mean body mass index [BMI] 25.9 ± 4.8 kg/m2). Successful DFT with the first ICD shock was observed in 264 patients (66.3%). One hundred fourteen patients were defibrillated with the second (n = 104) or third (n = 10) DFT after changing shock polarity and/or shock energy. Overall, 20 patients needed at least 3 DFT (ie, 80 J and/or re-positioning). The majority (n = 88 [65.7%]) of DFT failures occurred before 2015 with the first-generation S-ICD. PRAETORIAN score was an independent predictor of DFT failure (odds ratio [OR] 1.007; 95% confidence interval [CI] 1.003–1.011 P ≤.001), while whereas BMI alone was not (P =.31). Presence of hypertrophic cardiomyopathy (HCM) (OR 2.6; 95% CI 1.3–4.4; P =.004) was predictive for at least 1 unsuccessful DFT in our multivariate regression analysis. PRAETORIAN score proved to be a useful and valid predictive tool for successful DFT, whereas BMI only had a limited role. Patients with HCM were at increased risk for DFT failure or needed higher DFT energy. [ABSTRACT FROM AUTHOR]

Aims Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have become established in preventing sudden cardiac death, with some advantages over transvenous defibrillator systems, including a lower incidence of lead failures. Despite technological advancements, S-ICD carriers may suffer from significant complications, such as premature battery depletion (PBD), that led to an advisory for nearly 40 000 patients. This multicentre study evaluated the incidence of PBD in a large set of S-ICD patients. Methods and results Data from patients implanted with S-ICD models A209 and A219 between October 2012 and July 2023 across nine centres in Europe and the USA were reviewed. Incidence and implications of PBD, defined as clinically observed sudden drop in battery longevity, were analysed and compared to PBD with the definition of battery depletion within 60 months. Prospectively collected clinical data were obtained retrospectively from medical records, device telemetry, and manufacturer reports. This registry is listed on ClinicalTrials.gov (NCT05713708). Of the 1112 S-ICD devices analysed, 547 (49.2%) were equipped with a potentially affected capacitor linked to PBD occurrence, currently under Food and Drug Administration advisory. The median follow-up time for all patients was 46 [inter-quartile range (IQR) 24–63] months. Clinically suspected PBD was observed in 159 (29.1%) of cases, with a median time to generator removal or replacement of 65 (IQR 55–72) months, indicative of significant deviations from expected battery lifespan. Manufacturer confirmation of PBD was made in 91.7% of devices returned for analysis. No cases of PBD were observed in devices that were not under advisory. Conclusion This manufacturer-independent analysis highlights a notable incidence of PBD in patients equipped with S-ICD models under advisory, and the rate of PBD in this study corresponds to the rate currently estimated by the manufacturer. To the best of our knowledge, this provides the largest contemporary peer-reviewed study cohort investigating the actual incidence of PBD in S-ICD patients. These findings emphasize the importance of post-market registries in collaboration between clinicians and the manufacturer to optimize safety and efficacy in S-ICD treatment. [ABSTRACT FROM AUTHOR]

Aims Women have been historically underrepresented in implantable cardioverter-defibrillator (ICD) trials. No data on sex differences regarding subcutaneous ICDs (S-ICD) carriers have been described. Aim of our study was to investigate sex-related differences among unselected S-ICD recipients. Methods and results Consecutive patients enrolled in the multicentre, international i-SUSI registry were analysed. Comparisons between sexes were performed using a 1:1 propensity matching adjusted analysis for age, body mass index (BMI), left ventricular function, and substrate. The primary outcome was the rate of appropriate shocks during follow-up. Inappropriate shocks and other device-related complications were deemed secondary outcomes. A total of 1698 patients were extracted from the i-SUSI registry; 399 (23.5%) were females. After propensity matching, two cohorts of 374 patients presenting similar baseline characteristics were analysed. Despite similar periprocedural characteristics and a matched BMI, women resulted at lower risk of conversion failure as per PRAETORIAN score (73.4% vs. 81.3%, P = 0.049). Over a median follow-up time of 26.5 [12.7–42.5] months, appropriate shocks were more common in the male cohort (rate/year 3.4% vs. 1.7%; log-rank P = 0.049), while no significant differences in device-related complications (rate/year: 6.3% vs. 5.8%; log-rank P = 0.595) and inappropriate shocks (rate/year: 4.3% vs. 3.1%; log-rank P = 0.375) were observed. After controlling for confounders, sex remained significantly associated with the primary outcome (aHR 1.648; CI 0.999–2.655, P = 0.048), while not resulting predictor of inappropriate shocks and device-related complications. Conclusion In a propensity-matched cohort of S-ICD recipients, women are less likely to experience appropriate ICD therapy, while not showing higher risk of device-related complications. Clinical trial registration ClinicalTrials.gov Identifier: NCT0473876. [ABSTRACT FROM AUTHOR]

Outcome comparisons among subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients with nonischemic cardiomyopathies are scarce. The aim of this study was to evaluate differences in device-related outcomes among S-ICD recipients with different structural substrates. Patients enrolled in the i-SUSI (International SUbcutaneouS Implantable cardioverter defibrillator registry) project were grouped according to the underlying substrate (ischemic vs nonischemic) and subgrouped into dilated cardiomyopathy, hypertrophic cardiomyopathy, Brugada syndrome (BrS), arrhythmogenic right ventricular cardiomyopathy (ARVC). The main outcome of our study was to compare the rates of appropriate and inappropriate shocks and device-related complications. Among 1698 patients, the most common underlying substrate was ischemic (31.7%), followed by dilated cardiomyopathy (20.5%), BrS (10.8%), hypertrophic cardiomyopathy (8.5%), and ARVC (4.4%). S-ICD for primary prevention was more common in the nonischemic cohort (70.9% vs 65.4%; P =.037). Over a median (interquartile range) follow-up of 26.5 (12.6–42.8) months, no differences were observed in appropriate shocks between ischemic and nonischemic patients (4.8%/y vs 3.9%/y; log-rank, P =.282). ARVC (9.0%/y; hazard ratio [HR] 2.492; P =.001) and BrS (1.8%/y; HR 0.396; P =.008) constituted the groups with the highest and lowest rates of appropriate shocks, respectively. Device-related complications did not differ between groups (ischemic: 6.4%/y vs nonischemic: 6.1%/y; log-rank, P =.666), nor among underlying substrates (log-rank, P =.089). Nonischemic patients experienced higher rates of inappropriate shocks than did ischemic S-ICD recipients (4.4%/y vs 3.0%/y; log-rank, P =.043), with patients with ARVC (9.9%/y; P =.001) having the highest risk, even after controlling for confounders (adjusted HR 2.243; confidence interval 1.338–4.267; P =.002). Most S-ICD recipients were primary prevention nonischemic cardiomyopathy patients. Among those, patients with ARVC tend to receive the most frequent appropriate and inappropriate shocks and patients with BrS the least frequent appropriate shocks. [ABSTRACT FROM AUTHOR]

Background: Early repolarization pattern (ERP) has been associated with idiopathic ventricular fibrillation (IVF) and with cardiovascular mortality in the general population. As there is limited data about long- term outcome of IVF, the aim of our study was to observe ventricular arrhythmia (VA) recurrences in these patients and to identify a possible correlation of VA with ECG markers of early repolarization. Methods and results: We investigated 56 consecutive IVF patients who received an implantable cardioverter-defibrillator for secondary prevention. ERP was defined as a J-point elevation ≥ 0.1 mV in two or more contiguous inferior or lateral leads. Markers of early repolarization were present in 32.1% of cases with a preponderance of QRS slurring (77.8%). During a mean follow-up of 41.2 months, 11 patients (19.6%) received in total 18 adequate ICD-therapies. VF was most the common cause for ICDtherapy (61.1%) but monomorphic VT also occurred in four patients. Presence of ERP was associated with a significant trend towards arrhythmia recurrences. 38.9% patients with ERP received appropriate ICD-therapies whereas only 10.5% of patients without ERP had arrhythmia recurrence (p = 0.05). Inappropriate ICD-therapies occurred in seven patients (12.5%) with a non-significant trend towards a higher incidence in patients with a transvenous ICD (p = 0.15). Conclusion: A significant correlation between ERP and VA recurrences in patients with IVF could be observed. Though monomorphic VA also play a role in the studied IVF-population, our data support the use of the S-ICD in this collective. [ABSTRACT FROM AUTHOR]

BackgroundPatients with progressive chronic kidney disease (CKD) are at higher risk of infections and complications from cardiac implantable electronic devices (CIED). In patients with a primary or secondary prophylactic indication, implantable cardiac defibrillators (ICD) can prevent sudden cardiac deaths (SCD). We retrospectively compared transvenous-ICD (TV-ICD) and intermuscularly implanted subcutaneous-ICD (S-ICD) associated infections and complication rates together with hospitalizations in recipients with stage 4 kidney disease.MethodsWe retrospectively analyzed 70 patients from six German centers with stage 4 CKD who received either a prophylactic TV-ICD with a single right ventricular lead, 49 patients, or a S-ICD, 21 patients. Follow-Ups (FU) were performed bi-annually.ResultsThe TV-ICD patients were significantly older. This group had more patients with a history of atrial arrhythmias and more were prescribed anti-arrhythmic medication compared with the S-ICD group. There were no significant differences for other baseline characteristics. The median and interquartile range of FU durations were 55.2 (57.6–69.3) months. During FU, patients with a TV-ICD system experienced significantly more device associated infections (n = 8, 16.3% vs. n = 0; p

We report a case of successful implantation of a subcutaneous implantable cardioverter-defibrillator in a young patient with severe pectus excavatum presenting with out-of-hospital ventricular fibrillation arrest who was recently surgically repaired with a MIRPE–Nuss procedure. No complications in lead positioning were observed, and the device was tested to determine that it functioned properly.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is a new technology for the management of ICD patients. But what is the patients' perspective? Previous studies on the transvenous ICD (TV-ICD) showed that device implantation is related not only to anxiety and depression because of the fear of ICD shocks, but also to many biopsychosocial factors like body image changes, perceived reduction of socialization and limitation in professional and sports activities. Anxiety and distress are more evident in younger women because of aesthetic reasons. The scar size and the position of the S-ICD can help these patients and positively influence their social relationships. Moreover, the position of the S-ICD reduces possible complications from catheters due to stress injury and can improve patients' professional life by avoiding some work activity limitations. An S-ICD can be also a good option for athletes in avoiding subclavian crash and reducing inappropriate shocks. However, some questions remain unsolved because an S-ICD is not suitable for patients with indications for pacing, cardiac resynchronization therapy or anti-tachycardia pacing. In conclusion, the use of an S-ICD can assist physicians in reducing the negative impact of implantation on the well-being of some groups of patients by helping them to avoid depression and anxiety as well as improving their noncompliance with their medical treatment. [ABSTRACT FROM AUTHOR]

Hypertrophic cardiomyopathy (HCM) carries an increased risk of sudden cardiac death. Ventricular fibrillation (VF) is thought to be the common culprit arrhythmia. The purpose of this study was to describe the incidence and predictors of sustained ventricular arrhythmias (VTAs) in HCM patients. We retrospectively analyzed all patients with HCM and an implantable cardioverter-defibrillator (ICD) from a prospectively derived registry in 2 tertiary medical centers. Clinical, electrocardiographic, echocardiographic, ICD interrogation, and genetic data were collected and compared, first between patients with and without VTAs and then between patients with only VF and those with ventricular tachycardia (VT) with or without VF. Of the 1328 HCM patients, 207 (145 [70%] male; mean age 33 ± 16 years) were implanted with ICDs. Over a mean follow-up of 10 ± 6 years, 37 patients with ICDs (18%) developed sustained VTAs. These were associated with a family history of sudden cardiac death and a personal history of VTAs (P =.036 and P =.001, respectively). Sustained monomorphic VT was the most common arrhythmia (n = 26, 70%) and was linked to decreased left ventricular (LV) ejection fraction and increased LV end-systolic and end-diastolic diameters. Antitachycardia pacing (ATP) successfully terminated 258 (79%) of the 326 VT events. Mortality rates were comparable between patients with and without VTAs (4 [11%] vs 29 [17%]; P =.42) and between those with and without ICDs (24 [16%] vs 85 [20%]; P =.367). VT rather than VF is the most common arrhythmia in patients with HCM; it is amenable to ATP and is associated with lower LV ejection fraction and higher LV diameters. Therefore, ATP-capable devices may be considered in HCM patients with these LV features. [ABSTRACT FROM AUTHOR]

Inappropriate shock (IAS) is the most frequent device-related complication among patients with subcutaneous implantable cardioverter-defibrillator (S-ICD). Air entrapment (AE) has been described as an underdiagnosed cause of early postimplant IAS. We report 6 consecutive cases of early IAS after S-ICD implant, in whom the electrogram analysis (EGM) and/or chest radiography (CXR) were consistent with AE.

Background and purpose: Subcutaneous implantable cardioverter defibrillators (S-ICDs) have emerged in recent years as a valid alternative to traditional transvenous ICDs (TV-ICDs). Therefore, the number of S-ICD implantations is rising, leading to a consequent increase in S-ICD-related complications sometimes requiring complete device removal. Thus, the aim of this systematic review is to gather all the available literature on S-ICD lead extraction (SLE), with particular reference to the type of indication, techniques, complications and success rate. Methods: Studies were identified by searching electronic databases (Medline via PubMed, Scopus and Web of Science) from inception to 21 November 2022. The search strategy adopted was developed using the following key words: subcutaneous, S-ICD, defibrillator, ICD, extraction, explantation. Studies were included if they met both of the following criteria: (1) inclusion of patients with S-ICD; (2) inclusion of patients who underwent SLE. Results: Our literature search identified 238 references. Based on the abstract evaluation, 38 of these citations were considered potentially eligible for inclusion, and their full texts were analyzed. We excluded 8 of these studies because no SLE was performed. Eventually, 30 studies were included, with 207 patients who underwent SLE. Overall, the majority of SLEs were performed for non-infective causes (59.90%). Infection of the device (affecting either the lead or the pocket) was the cause of SLE in 38.65% of cases. Indication data were not available in 3/207 cases. The mean dwelling time was 14 months. SLEs were performed using manual traction or with the aid of a tool designed for transvenous lead extraction (TLE), including either a rotational or non-powered mechanical dilator sheath. Conclusions: SLE is performed mainly for non-infective causes. Techniques vary greatly across different studies. Dedicated tools for SLE might be developed in the future and standard approaches should be defined. In the meantime, authors are encouraged to share their experience and data to further refine the existing variegated approaches. [ABSTRACT FROM AUTHOR]

Implantable cardioverter-defibrillators have become an established therapy for the prevention of sudden cardiac death due to life-threatening ventricular arrhythmias in the last decades. In all those years, the use of transvenous leads has proven to be the most vulnerable part of the system. The development of the completely subcutaneous implantable cardioverter-defibrillator opened a new era of device therapy outside of the vascular system. The next step, enabling extravascular devices with the option of antitachycardia pacing, is just around the corner. This may become an important option for all patients without a bradycardia pacing indication that are in need for antitachycardia pacing because of monomorphic ventricular tachycardia.

Manuela Thienel,1,&ast; Magda Haum,1,&ast; Sebastian Sadoni,2 Julia Novotny,1 Heidi L Estner,1 Stephanie Fichtner,1 Korbinian Lackermair1 1Department of Medicine I, Munich University Hospital, Ludwig-Maximilian-University, Munich, Germany; 2Department of Cardiac Surgery, Munich University Hospital, Ludwig-Maximilian-University, Munich, Germany&ast;These authors contributed equally to this workCorrespondence: Korbinian Lackermair, Department of Medicine I, Munich University Hospital, Ludwig-Maximilian-University, Marchioninistr. 15, Munich, 81377, Germany, Email Korbinian.lackermair@med.uni-muenchen.deBackground: The subcutaneous cardioverter defibrillator (S-ICD) has been shown to be a viable alternative to transvenous ICDs (TV-ICD) in all patients at risk of sudden cardiac death (SCD) but without pacing indication.Aim: The aim of this study was to examine the impact of therapy with current S-ICD devices on quality of life (QoL) in comparison to patients with TV-ICD devices.Methods: In our single-centre study, 52 consecutive patients with S-ICD and 52 matched patients with TV-ICD were analysed. QoL has been assessed by a standardized questionnaire (EQ-5D-3L, modified). Additionally, clinical baseline and follow-up data were evaluated.Results: Two-thirds of the total study population reported restrictions in daily routine compared to their life before ICD implantation. A total of 27.7% of S-ICD patients stated to expect an improvement of QoL by deactivation or explantation of their defibrillator compared to only 6.4% of patients with TV-ICD (p=0.006), which was mainly caused by discomfort and pain from the S-ICD pocket (relevant discomfort and pain in 32.6% vs 11.5%; p< 0.01).Limitations: Main limitation of the study is that quality of life was assessed for one single time point only and time since implantation differed significantly between S-ICD and TV-ICD. Furthermore our collective is younger, and, due to the high proportion of patients without cardiomyopathy, the mean EF is better than usual ICD collective. The absence of heart failure in about the half of our patients might have relevant impact on our QoL analysis.Conclusion: A relevant proportion of S-ICD patients expects an improvement of QoL by explantation of the device. Of note, this impression was not driven by the fear of receiving shocks but mainly by discomfort and pain caused by the pulse generator.Keywords: subcutaneous cardioverter defibrillator, S-ICD, transvenous cardioverter defibrillator, quality of life

Aims The SMART Pass™ (SP) algorithm is a high-pass filter that aims to reduce inappropriate therapy (IT) in subcutaneous internal cardiac defibrillator (S-ICD), but SP can deactivate due to low amplitude sensed R waves or asystole. The association between IT and SP deactivation and management strategies were evaluated, hypothesizing SP deactivation increases the risk of IT and device re-programming, or lead/generator re-positioning could reduce this risk. Methods and results Retrospective single-centre audit of Emblem™ S-ICD devices implanted 2016 to 2020 utilizing health records and remote monitoring data. Cox regression models evaluated associations between SP deactivation and IT. A total of 348 patients (27 ± 16.6 months follow-up) were studied: 73% primary prevention. Thirty-eight patients (11.8%) received 83 shocks with 27 patients (7.8%) receiving a total of 44 IT. Causes of IT were oversensing (98%) and aberrantly conducted atrial fibrillation (2%). SP deactivation occurred in 32 of 348 patients (9%) and was significantly associated with increased risk of IT (hazard ratio 5.36, 95% CI 2.37-12.13). SP deactivation was due to low amplitude R waves (94%), associated with a higher defibrillation threshold at implant and presence of arrhythmogenic right ventricular cardiomyopathy. No further IT occurred 16 ± 15.5 months after corrective interventions, with changing the sensing vector being successful in 59% of cases. Conclusion To reduce the risk of IT, the cause of the SP deactivation should be investigated, and appropriate reprogramming, device, or lead modifications made. Utilizing the alert for SP deactivation and electrograms could pro-actively prevent IT. [ABSTRACT FROM AUTHOR]

Transvenous implantable cardioverter-defibrillators (TV-ICDs) are associated with greater tricuspid regurgitation (TR) severity, which leads to increased mortality. The pathophysiology is assumed to be lead-related, hence, treatment includes lead extraction. However, TR may also naturally occur in the high-risk ICD population, or may be caused by right ventricular pacing. We sought to evaluate the effect of ICD type (with or without lead) and pacing percentage on post-implantation TR severity. In this retrospective cohort study, consecutive patients were included with a primary S-ICD or TV-ICD implantation between 2009 and 2019 and echocardiography studies ≤3 months before and ≤ 3 years post-implantation. The effect of ICD type on TR severity at follow-up was estimated adjusting for ventricular pacing percentage and potential confounders. The effect of ventricular pacing percentage on TR severity at follow-up was adjusted for potential confounders. 118 patients were included (mean age 52 ± 21): 31 (26%) with an S-ICD and 87 (74%) with a TV-ICD. Median 20 months post-implantation, worsening TR was found in 11/31 (34%) S-ICD patients and 45/87 (52%) TV-ICD patients (p = 0.15). Adjusted for age, atrial fibrillation, baseline TR and mitral regurgitation, ventricular pacing percentage, ICD dwelling time, BMI, hypertension and left ventricular ejection fraction, TV-ICDs were significantly associated with greater TR severity (OR 9.90, p = 0.002). Ventricular pacing percentage was very low, and not significantly associated with greater TR severity (OR 0.95, p = 0.066). Our results suggest that greater TR severity in ICD patients is mainly caused by the transvenous lead, rather than natural progression in the ICD population. • Tricuspid regurgitation (TR) often occurs in patients with an implantable cardioverter-defibrillator (ICD). • It is unclear whether this is caused by the lead or due to natural progression in the ICD population. • In this study, TR severity after ICD implantation is compared between patients with a transvenous versus a subcutaneous ICD. • Transvenous ICDs were independently associated with TR severity after ICD implantation. • These results support the hypothesis that the transvenous lead causes TR in ICD patients. [ABSTRACT FROM AUTHOR]

Introduction: Defibrillation testing (DFT) is recommended during subcutaneous implantable cardioverter‐defibrillator (S‐ICD) implantation. Previous studies analyzing the potential interference of propofol with defibrillation threshold are inconsistent. The purpose of this study was to analyze whether propofol affects DFT post S‐ICD placement. Methods: All patients with S‐ICD implantation between 01/2017 and 11/2020 at the University Heart Center Freiburg were retrospectively analyzed. Two groups were generated depending on the success of the first shock during DFT. Implantation characteristics and dose of anesthetics were analyzed. Results: In 12 of the included 80 (15%) patients, first shock during DFT failed. The absolute dose of propofol was significantly higher in patients with first shock failure (median 653 mg [IQR 503–855]) compared to patients with first shock termination (376 mg [200–600]; p = 0.027). Doses of opioids and midazolam as well as type of anesthesia did not differ between the groups. A multivariable binary logistic regression analysis confirmed an independent association of first shock termination and propofol dose (per 100 mg: OR 0.73 (95% CI: 0.56–0.95); p = 0.021). Conclusion: There is an independent association of propofol dose and first shock failure in routine S‐ICD defibrillation testing. [ABSTRACT FROM AUTHOR]

Currently the cornerstone of therapy for ventricular arrhythmic complications and sudden cardiac death prevention in Brugada syndrome (BrS) is an implantable cardioverter-defibrillator (ICD). BrS patient population differs from the majority of patients with an ICD implanted for structural heart disease, and as widely known, transvenous ICD (TV-ICD) systems have been associated with high complication rates in patients with BrS. Technological evolution of these devices has certainly reduced complications due to the device itself, but a careful preimplant screening of these patients is still essential. To date, criteria for an adequate screening process to select suitable candidates for a subcutaneous implantable cardioverter-defibrillator (S-ICD) from patients with BrS are sometimes nonstandardized and often lack important precautions that are instead fundamental to select the most suitable type of ICD for these patients. To better select suitable candidates for an S-ICD from patients with BrS, a full screening process should include screening during or immediately after an exercise test and after a drug provocation challenge test. We report an analysis of the "lights and shadows" of S-ICD for a correct use of this device in patients with BrS. [ABSTRACT FROM AUTHOR]

Aims: Subcutaneous implantable cardioverter defibrillators (S-ICDs) are well established. However, inappropriate shocks (IAS) remain a source of concern since S-ICDs offer very limited troubleshooting options. In our multicentre case series, we describe several patients who experienced IAS due to a previously unknown S-ICD system issue.Methods and Results: We observed six patients suffering from this novel IAS entity. The IAS occurred exclusively in primary or alternate S-ICD sensing vector configuration (therefore called 'Sense-B-noise'). IAS were caused by non-physiologic oversensing episodes characterized by intermittent signal saturation, diminished QRS amplitudes, and disappearance of the artefacts after the IAS. Noise/oversensing could not be provoked by manipulation, X-ray did not show evidence for lead/header issues and impedance measurements were within normal limits. The pooled experience of our centres implies that up to ∼5% of S-ICDs may be affected. The underlying root cause was discussed extensively with the manufacturer but remains unknown and is under further investigation.Conclusion: Sense-B-noise is a novel cause for IAS due to non-physiologic signal oversensing, arising from a previously unknown S-ICD system issue. Sense-B-noise may be suspected if episodes of signal saturation in primary or alternate vector configuration are present, oversensing cannot be provoked, and X-ray and electrical measurements appear normal. The issue can be resolved by reprogramming the device to secondary sensing vector. [ABSTRACT FROM AUTHOR]

Background: The subcutaneous ICD (S-ICD) has developed as a valuable alternative to transvenous implantable cardioverter defibrillator (ICD) systems. However there are certain peculiarities which are immanent to the S-ICD and may limit its use. Besides oversensing the main issue is the missing option for antibradycardia pacing. To evaluate the actual need for pacing during follow-up and changes to transvenous ICD we analyzed our large tertiary centre registry and compared it with data from other large cohorts and trials. Methods and Results: We found out that in the 398 patients from our centre, there was a need for changing to a transvenous ICD in only 2 patients (0.5%) during a follow-up duration of almost 3 years. This rate was comparable to data obtained from other large data sets so that in the pooled analysis of almost 4000 patients the rate of bradycardia-associated complications was only 0.3%. Conclusions: The use of the S-ICD is safe in a variety of heart diseases and the need for antibradycardia stimulation is a very rare complication throughout many different large studies. Clinicians may take these results into account when opting for a certain ICD system and the S-ICD may be chosen more often also in elderly patients, in whom the risk for bradycardia is deemed higher. [ABSTRACT FROM AUTHOR]

Sudden cardiac death is the final event caused in several cases by ventricular arrhythmias. Transvenous implantable cardioverter-defibrillators have been the standard therapy for the prevention of sudden cardiac death. The most frequent complications associated with TV-ICD is related to intracavitary electrodes. S-ICD has been developed as an alternative system. Novel S-ICD device in prevention of SCA was implanted in 8 patients with an average follow up period of 2.5 years. Bleeding and inappropriate shock was reported in one patient. Appropriate shock for ventricular tachycardia was observed in 5 patients. There was no death reported in any of the patients.

In young patients with transvenous implantable cardioverter defibrillations (TV-ICDs), the possibility of device infection or lead fracture would be high in their long lifetimes. Furthermore, the risk of lead removal will gradually increase over the years. We reported two cases of subcutaneous ICDs implantation following removal of TV-ICDs. Patient 1, 35-year-old man, underwent TV-ICD implantation 9 years ago for idiopathic ventricular fibrillation, and Patient 2, 46-year-old man, underwent TV-ICD implantation 8 years ago for asymptomatic Brugada syndrome. In both cases, the electrical performance was stable, and there was no incidence of arrythmia or no pacing demand during the follow-up duration. Considering future risk of device infection or lead fracture, and difficulty in future lead removal, TV-ICDs were removed with sufficient informed consent, and then, subcutaneous ICDs (S-ICDs) implantation were performed as an alternative to them. Although indication of the TV-ICD removal should be carefully considered in individual cases, long-term risks leaving it in place should be also considered in the management of young patient. In young patient with TV-ICD, even for a normally functioning non-infected lead, S-ICD implantation following removal of the TV-ICD would represent a strategy associated with less long-term risks than leaving it in place. [ABSTRACT FROM AUTHOR]

Background: Air entrapment has been recently described as a cause of inappropriate shock (IAS) among patients who underwent subcutaneous implantable cardioverter‐defibrillator (S‐ICD) implantation. Data about this complication are lacking in the literature. Methods: In this meta‐summary 14 case reports describing IAS due to air entrapment were included. Patients' characteristics, S‐ICD implant technique and air entrapment properties were collected. Results: All patients experienced IAS within 4 days following S‐ICD implant. The subcutaneous air was demonstrated by chest x‐ray in 11 cases (73.3%). The sensing vector was reprogrammed in 11 cases (73.3%), and ICD was switched off in 2 cases (1.3%). Conclusions: IAS due to air entrapment is an early complication of S‐ICD implant. No association was observed between the implant technique and air retention. Diagnosis is confirmed by chest x‐ray and device interrogation. Management includes switching off the device or, preferably, changing the sensing vector. [ABSTRACT FROM AUTHOR]

Aims: Air entrapment (AE) has been reported as a potential cause of early inappropriate shocks (ISs) following subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, but a cause-effect relationship is not always evident. This systematic review aims to analyse this phenomenon concerning implantation techniques, electrogram (EGM) features, radiologic findings, and patient management.Methods and Results: A systematic search was conducted using PubMed, Embase, and Google Scholar databases following the PRISMA guidelines to obtain all available literature data since 2010 on S-ICD malfunctions possibly due to AE. The final analysis included 54 patients with AE as a potential cause of S-ICD malfunction. Overall, the aggregate incidence of this condition was 1.2%. Of ICD malfunctions possibly due to AE, 93% were ISs, and 95% were recorded within the first week following implantation. Radiologic diagnosis of AE was confirmed in 28% of the entire study cohort and in 68% of patients in whom this diagnostic examination was reported. At the time of device malfunction, EGMs showed artefacts, baseline drift, and QRS voltage reduction in 95, 76, and 67% of episodes, respectively. Management included ICD reprogramming or testing, no action (observation), and invasive implant revision in 57, 33, and 10% of patients, respectively. No recurrences occurred during follow-up, irrespective of management performed.Conclusions: Device malfunction possibly due to AE may occur in ∼1% of S-ICD recipients. Diagnosis is strongly suggested by early occurrence, characteristic EGM features, and radiologic findings. Non-invasive management, principally device reprogramming, appears to be effective in most patients. [ABSTRACT FROM AUTHOR]

Background: No data regarding subcutaneous-implantable cardioverter defibrillator (S-ICD) technology in patients actively engaging in sports activities are available., Objective: This study aims to compare S-ICD performance between athletes and nonathletes., Methods: The primary outcome of the study was the comparison of overall device-related complications between athletes and nonathletes. Appropriate shocks, inappropriate shocks, and individual device-related complications were secondary outcomes., Results: A total of 1493 patients were extracted from the International Subcutaneous Implantable Cardioverter Defibrillator Registry (iSUSI) registry, of whom 152 (10.2%) were athletes, mostly engaging in dynamic sports (54.2%). Brugada syndrome, myocarditis, and arrhythmogenic right ventricular cardiomyopathy (ARVC) were more common in athletes (11.2% vs 3.3%, P < .001; 19.1% vs 9.0%, P < .001; 8.6% vs 2.8%, P < .001, respectively). During a median follow-up time of 25.5 (12.0-41.2) months, athletes were more likely to experience appropriate shocks (yearly rate: 7.2 [4.9-10.7] % vs 4.3 [3.6-5.1] %, P = .028), occurring more frequently during exercise (3.9% vs 0.6%, P < .001). This finding lost significance when adjusting for confounders (adjusted hazard ratio [aHR] 1.440 [0.909-2.281], P = .120). No differences were found in overall device-related complications (yearly rate: 3.3% vs 3.4%, P = .448) and inappropriate shocks (yearly rate: 5.3% vs 3.7%, P = 0.111). Myopotential oversensing (4.0% vs 1.3%, P = .011) was more common in athletes, as were lead infections (3.3% vs 0.9%, P =.008), with the latter clustering in the early postimplantation period., Conclusion: The S-ICD is a valid therapeutic option for preventing sudden cardiac death in athletes. Sports practice was not associated with an increased risk of complications or inappropriate shocks, although athletes are exposed to a higher risk of S-ICD infections in the early postoperative period., Competing Interests: Disclosures Dr Breitenstein has received consultant/speaker fees from Boston Scientific. Dr Martinek has received speaker`s honoraria from Boston Scientific. Dr Kaiser has received proctor fees from Boston Scientific. Dr Tilz consults for and has received speaker`s honoraria from Boston Scientific. Dr Tondo is a member of Boston Scientific advisory board. The other authors have no conflicts of interest to disclose., (Copyright © 2024 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

BackgroundThe subcutaneous implantable cardioverter-defibrillator (S-ICD) has been designed to overcome lead-related complications and device endocarditis. Lacking the ability for pacing or resynchronization therapy its usage is limited to selected patients at risk for sudden cardiac death (SCD).ObjectiveThe aim of this single-center study was to assess clinical outcomes of S-ICD and single-chamber transvenous (TV)-ICD in an all-comers population.MethodsThe study cohort comprised a total of 119 ICD patients who underwent either S-ICD (n = 35) or TV-ICD (n = 84) implantation at the University Hospital Frankfurt from 2009 to 2017. By applying an inverse probability-weighting (IPW) analysis based on the propensity score including the Charlson Comorbidity Index (CCI) to adjust for potential extracardiac comorbidities, we aimed for head-to-head comparison on the study composite endpoint: overall survival, hospitalization, and device-associated events (including appropriate and inappropriate shocks or system-related complications).ResultsThe median age of the study population was 66.0 years, 22.7% of the patients were female. The underlying heart disease was ischemic cardiomyopathy (61.4%) with a median LVEF of 30%. Only 52.9% had received an ICD for primary prevention, most of the patients (67.3%) had advanced heart failure (NYHA class II–III) and 16.8% were in atrial fibrillation. CCI was 5 points in TV-ICD patients vs. 4 points for patients with S-ICD (p = 0.209) indicating increased morbidity. The composite endpoint occurred in 38 patients (31.9 %), revealing no significant difference between patients implanted with an S-ICD or TV-ICD (unweighted HR 1.50, 95 % confidence interval (CI) 0.78–2.90; p = 0.229, weighted HR 0.94, 95% CI, 0.61–1.50, p = 0.777). Furthermore, we observed no difference in any single clinical endpoint or device-associated outcome, neither in the unweighted cohort nor following inverse probability-weighting.ConclusionClinical outcomes of the S-ICD and TV-ICD revealed no differences in the composite endpoint including survival, freedom of hospitalization and device-associated events, even after careful adjustment for potential confounders. Moreover, the CCI was evaluated in a S-ICD cohort demonstrating higher survival rates than predicted by the CCI in young, polymorbid (S-)ICD patients.

Background Dextrocardia is a congenital anomaly in which the apex of the heart is abnormally located on the right side of the chest. Situs solitus describes viscera that are in the normal position, with the stomach on the left side. In these patients, implantation of transvenous implantable cardioverter-defibrillator (ICD) can be limited by anatomical abnormalities commonly associated with this condition. Case summary We present the case of a young female patient with absent right atrioventricular connection, morphologically left systemic ventricle, muscular restrictive ventricular septal defect, and dextrocardia with situs solitus who was indicated for secondary prophylactic ICD implantation after resuscitation for polymorphic ventricular tachycardia. Due to a bilateral bidirectional Glenn anastomosis, transvenous access via the vena cava superior to the right ventricle could not be achieved. For this reason, we successfully implanted a subcutaneous ICD (S-ICD) with an individually optimized right parasternal electrode position. Potential complications of epimyocardial implantation via re-thoracotomy could thus be circumvented. Discussion In patients with complex congenital heart disease, the S-ICD is an effective method of preventing sudden cardiac death. Our case report demonstrates the feasibility of left S-ICD implantation even in the presence of dextrocardia with situs solitus. [ABSTRACT FROM AUTHOR]

Background: Current evidence describing the characteristics of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy, its trend, and perioperative outcomes compared with transvenous implantable cardioverter-defibrillator (TV-ICD) based on a real-world, large-scale database is scarce.Objective: The purpose of this study was to identify the characteristics of current S-ICD therapy using a nationwide database.Methods: A retrospective analysis of ICD implantation was performed using a nationwide database obtained between 2016 and 2020. A total of 8690 patients implanted with ICD (median age 65 [52-72] year; 6902 men; 2021 S-ICD recipients) were analyzed.Results: Younger patients were more prone to have S-ICD (P <.001). A history of ventricular fibrillation (VF) (odds ratio [OR] 2.45; 95% confidence interval [CI] 2.04-2.93), nonsustained ventricular tachycardia (VT) (OR 1.73; 95% CI 1.36-2.21), Brugada syndrome (BrS) (OR 3.14; 95% CI 2.48-4.00), and dialysis treatment (OR 2.02; 95% CI 1.44-2.82) were independent predictors of S-ICD selection on mixed-model logistic analysis. The proportion of S-ICD implantations has been increasing (P <.001), especially in patients with BrS (P <.001) and dialysis (P = .04). The proportion of combined complications after S-ICD implantation was low (1.3%) in the unmatched cohort and was comparable to TV-ICD in the 1:1 propensity-matched cohort of 3354 patients (1.5% vs 2.3%; OR 0.65; 95% CI 0.38-1.10).Conclusion: S-ICD was more likely to be implanted in younger patients and those with a history of VF, nonsustained VT, BrS, and dialysis treatment. The proportion of S-ICD implantation increased, especially in patients with BrS. The incidence of in-hospital complications was low in S-ICD recipients. [ABSTRACT FROM AUTHOR]

In patients with Hypertrophic Cardiomyopathy (HCM) S-ICD is usually the preferred option as pacing is generally not indicated. However, limited data are available on its current practice adoption and long-term follow-up. Consecutive HCM patients with S-ICD implanted between 2013 and 2021 in 3 international centers were enrolled in this observational study. Baseline, procedural and follow-up data were regularly collected. Efficacy and safety were compared with a cohort of HCM patients implanted with a tv-ICD. Seventy patients (64% males) were implanted with S-ICD at 41 ± 15 years, whereas 168 patients with tv-ICD at 49 ± 16 years. For S-ICD patients, mean ESC SCD risk score was 4,5 ± 1.9%: 25 (40%) at low-risk, 17 (27%) at intermediate and 20 (33%) at high-risk. Patients were followed-up for 5.1 ± 2.3 years. Two patients (0.6 per 100-person-years, vs 0.4 per 100 person-years with tv-ICD, p = 0.45) received an appropriate shock on VF, 17 (24%) were diagnosed with de-novo AF. Inappropriate shocks occurred in 4 patients (1.2 per 100-person-years, vs 0.9 per 100 person-years with tv-ICD, p = 0.74), all before Smart-Pass algorithm implementation. Four patients experienced device-related adverse events (1.2 per 100-person-years, vs 1 per 100 person-years with tv-ICD, p = 0.35%). S-ICDs were often implanted in patients with an overall low-intermediate ESC SCD risk, reflecting both the inclusion of additional risk markers and a lower decision threshold. S-ICDs in HCM patients followed for over 5 years showed to be effective in conversion of VF and safe. Greater scrutiny may be required to avoid overtreatment in patients with milder risk profiles. Abbreviations: S-ICD: Sub-Cutaneous ICD; HCM: Hypertrophic Cardiomyopathy; AF: Atrial fibrillation. [Display omitted] • S-ICDs were often implanted in patients with an overall low-intermediate ESC SCD risk. • Life-threatening arrhythmias intermediate-low risk occurred less often than predicted, supporting latest ESC guidelines. • S-ICD was effective, generally safe and useful in the detection of sub-clinical AF occurring in 9% of the patients. [ABSTRACT FROM AUTHOR]

Introduction: Haemodialysis patients who require defibrillator therapy are expected to benefit from the entirely avascular subcutaneous defibrillator (S-ICD), but haemodialysis is associated with dynamic changes in R and T wave amplitude which can impact S-ICD eligibility. A continuous assessment of S-ICD eligibility during haemodialysis has not previously been performed.Material and Methods: Continuous surface ECG recordings were obtained from a cohort of patients undergoing maintenance haemodialysis, but without an indication for an ICD. Automated vector screening was retrospectively performed at one-minute intervals throughout the dialysis session. Variations in S-ICD eligibility were calculated and in vectors with high degrees of variation, the underlying mechanism was identified.Results: 72 vector recordings (mean duration 254.1 ± 6.0 min) were obtained from 24 patients (mean age 64.3 ± 5.5 years, 68% male). At the start of haemodialysis 47 vectors were S-ICD eligible (65.2%). At the end of session, all of these vectors had remained eligible, and an additional 6 vectors had also become eligible (73.6%). High vector score variability was observed in 7 patients and the commonest cause was a progressive change in R:T ratio (71.5%).Conclusion: In a haemodialysis population, a single haemodialysis session can be associated with a potential change in S-ICD eligibility in 8.4% of vectors, with up to 12.5% of vectors showing high degrees of variability, most commonly due to variations in R:T ratio. In an S-ICD population with similar characteristics S-ICD screening prior to haemodialysis would be expected to more accurately identify vectors that retain eligibility. [ABSTRACT FROM AUTHOR]

The subcutaneous implantable cardioverter defibrillator (S-ICD) is currently in its third generation and has been adopted in guidelines and in mainstream clinical practice. Considerable improvements have been made since the introduction of this device over a decade ago. A literature search was undertaken in Pubmed on articles relating to the S-ICD. The therapy has been proven to be safe and effective and is a valuable option in selected patients. Nevertheless, there remain many shortcomings of the S-ICD which are discussed in this review, and which hopefully will be addressed by future generations of the device. [ABSTRACT FROM AUTHOR]

Introduction: Pre‐implant ECG screening is performed to ensure that S‐ICD recipients have at least one suitable sensing vector, yet cardiac over‐sensing remains the commonest cause of inappropriate shock therapy in the S‐ICD population. One explanation would be the presence of dynamic variations in ECG morphology that result in variations in vector eligibility. Methods: Adult ICD patients had a 24‐h ambulatory ECG performed using a digital Holter positioned to record all three S‐ICD vectors. Using an S‐ICD simulator, automated screening was then performed at one‐minute intervals. In vectors with a mean vector score > 100 (the accepted value for a passing vector when screened on a single occasion), the percentage of all screening assessments that passed, eligible vector time (EVT), was calculated. EVT was compared statistically to QRS duration, corrected time to peak T (pTc) and mean vector score. Results: Ambulatory monitoring was performed in 14 patients (mean age 63.7 ± 5.2 years, 71.4% male) with 42 vectors analysed. In 19 vectors the mean vector score was > 100. Within this "passing" cohort EVT varied between 42.7% and 100%. In 7/19 (37%) the EVT was <75%. A negative correlation was found between QRS duration and EVT (Pearson correlation ‐.60, p =.007). No correlation was found between EVT and mean vector score or pTc. Conclusion: Vector eligibility is dynamic. When "passing" vectors are subjected to repeated screening, 37% are found to be ineligible, more than a quarter of the time. Further investigation is required to determine the clinical significance of these findings. [ABSTRACT FROM AUTHOR]

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Background: Recently, the Food and Drug Administration issued a recall for the subcutaneous implantable cardioverter-defibrillator (S-ICD) because of the possibility of lead ruptures and accelerated battery depletion.Objective: The aim of this study was to evaluate device-related complications over time in a large real-world multicenter S-ICD cohort.Methods: Patients implanted with an S-ICD from January 2015 to June 2020 were enrolled from a 19-institution European registry (Experience from the Long-term Italian S-ICD registry [ELISIR]; ClinicalTrials.gov identifier NCT0473876). Device-related complication rates over follow-up were collected. Last follow-up of patients was performed after the Boston Scientific recall issue.Results: A total of 1254 patients (median age 52.0 [interquartile range 41.0-62.2] years; 973 (77.6%) men; 387 (30.9%) ischemic) was enrolled. Over a follow-up of 23.2 (12.8-37.8) months, complications were observed in 117 patients (9.3%) for a total of 127 device-related complications (23.6% managed conservatively and 76.4% required reintervention). Twenty-seven patients (2.2%) had unanticipated generator replacement after 3.6 (3.3-3.9) years, while 4 (0.3%) had lead rupture. Body mass index (hazard ratio [HR] 1.063 [95% confidence interval 1.028-1.100]; P < .001), chronic kidney disease (HR 1.960 [1.191-3.225]; P = .008), and oral anticoagulation (HR 1.437 [1.010-2.045]; P = .043) were associated with an increase in overall complications, whereas older age (HR 0.980 [0.967-0.994]; P = .007) and procedure performed in high-volume centers (HR 0.463 [0.300-0.715]; P = .001) were protective factors.Conclusion: The overall complication rate over 23.2 months of follow-up in a multicenter S-ICD cohort was 9.3%. Early unanticipated device battery depletions occurred in 2.2% of patients, while lead fracture was observed in 0.3%, which is in line with the expected rates reported by Boston Scientific. [ABSTRACT FROM AUTHOR]

Abstract Sensing and defibrillation threshold for a S‐ICD are impacted by positioning at implant or revision. The intermuscular pocket prevents device migration and provides appropriate, stable sensing vectors.

Abstract Background The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to the transvenous implantable cardioverter defibrillator for the prevention of sudden cardiac death. Here, we report a rare case of refractoriness to an S-ICD after frequent therapies for ventricular fibrillation (VF) storms. Case presentation A 24-year-old man underwent a bout of syncope with vomiting and incontinence at home. He was brought to the emergency room and was witnessed to spontaneously go into VF successfully converted by external defibrillation. Previously, he was diagnosed with a type I Brugada electrocardiogram pattern by a pilsicainide administration test in another hospital. Although he had a family history of sudden cardiac death in 3 relatives, including his brother, he was followed closely without any therapies because he had never had an episode of syncope. He was implanted with an S-ICD without any trouble. Seven months later, frequent S-ICD shocks for VF storms occurred. His VF was controlled by using intravenous amiodarone, which was converted to an oral preparation. However, his VF recurred after another 2 months. The analysis of his S-ICD data revealed that 4 consecutive shock deliveries could not terminate his VF and the final shock delivered could fortunately terminate it because of a high defibrillation threshold test (DFT) due to an increasing shock impedance (64 to 90 Ω). First, we performed an epicardial Brugada syndrome ablation and subsequently replaced and repositioned the S-ICD lead from a left to a right parasternal site. After the re-implantation of the S-ICD, the DFT test improved to within normal range. According to the pathological analysis, infiltration of inflammatory cells and extensive fibrosis were confirmed in the subcutaneous tissue around the shock lead and S-ICD body. Conclusion Frequent S-ICD shocks for VF storms might cause various pathological changes around the device and lead to a high DFT.

Competing Interests: Disclosure The authors have no conflicts of interest to disclose.

Aims: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) have become established in preventing sudden cardiac death, with some advantages over transvenous defibrillator systems, including a lower incidence of lead failures. Despite technological advancements, S-ICD carriers may suffer from significant complications, such as premature battery depletion (PBD), that led to an advisory for nearly 40 000 patients. This multicentre study evaluated the incidence of PBD in a large set of S-ICD patients., Methods and Results: Data from patients implanted with S-ICD models A209 and A219 between October 2012 and July 2023 across nine centres in Europe and the USA were reviewed. Incidence and implications of PBD, defined as clinically observed sudden drop in battery longevity, were analysed and compared to PBD with the definition of battery depletion within 60 months. Prospectively collected clinical data were obtained retrospectively from medical records, device telemetry, and manufacturer reports. This registry is listed on ClinicalTrials.gov (NCT05713708). Of the 1112 S-ICD devices analysed, 547 (49.2%) were equipped with a potentially affected capacitor linked to PBD occurrence, currently under Food and Drug Administration advisory. The median follow-up time for all patients was 46 [inter-quartile range (IQR) 24-63] months. Clinically suspected PBD was observed in 159 (29.1%) of cases, with a median time to generator removal or replacement of 65 (IQR 55-72) months, indicative of significant deviations from expected battery lifespan. Manufacturer confirmation of PBD was made in 91.7% of devices returned for analysis. No cases of PBD were observed in devices that were not under advisory., Conclusion: This manufacturer-independent analysis highlights a notable incidence of PBD in patients equipped with S-ICD models under advisory, and the rate of PBD in this study corresponds to the rate currently estimated by the manufacturer. To the best of our knowledge, this provides the largest contemporary peer-reviewed study cohort investigating the actual incidence of PBD in S-ICD patients. These findings emphasize the importance of post-market registries in collaboration between clinicians and the manufacturer to optimize safety and efficacy in S-ICD treatment., Competing Interests: Conflict of interest: J.W. reports having received lecture fees from Abbott and Boston Scientific and educational fees from Boston Scientific and Johnson & Johnson. J.L. and D.S. report having received lecture fees from Johnson & Johnson, Abbott, and Boston Scientific. A.S. reports having received lecture fees from Medtronic, Boston Scientific, Abbott, and Johnson & Johnson. J.H.-L. reports having received educational fees from Boston Scientific, Medtronic, Abbott, and Biotronik and speaker fees from Abbott. N.T.S. reports having received research funding from Abbott. N.B. reports having received an educational grant from Biotronik and speaker fees from Medtronic and Abbott, all outside this submitted work. A.B. reports having received consultant and/or speaker fees from Abbott, Bayer Healthcare, Biosense Webster, Biotronik, Boston Scientific, Bristol-Myers Squibb, Cook Medical, Daiichi Sankyo, Medtronic, Pfizer, and Spectranetics/Philips. J.S. reports having received educational fees from Boston Scientific and Johnson & Johnson and lecture fees from Abbott. All other authors report nothing to declare., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Introduction: The risk of complications associated with transvenous ICDs make the subcutaneous implantable cardiac defibrillator (S-ICD) a valuable alternative in patients with adult congenital heart disease (ACHD). However, higher S-ICD ineligibility and higher inappropriate shock rates-mostly caused by T wave oversensing (TWO)- are observed in this population. We report a novel application of deep learning methods to screen patients for S-ICD eligibility over a longer period than conventional screening., Methods: Adult patients with ACHD and a control group of normal subjects were fitted with a 24-h Holters to record their S-ICD vectors. Their T:R ratio was analysed utilising phase space reconstruction matrices and a deep learning-based model to provide an in-depth description of the T: R variation plot for each vector. T: R variation was compared statistically using t-test., Results: 13 patients (age 37.4 ± 7.89 years, 61.5 % male, 6 ACHD and 7 control subjects) were enrolled. A significant difference was observed in the mean and median T: R values between the two groups (p < 0.001). There was also a significant difference in the standard deviation of T: R between both groups (p = 0.04)., Conclusions: T:R ratio, a main determinant for S-ICD eligibility, is significantly higher with more tendency to fluctuate in ACHD patients when compared to a population with normal hearts. We hypothesise that our novel model could be used to select S-ICD eligible patients by better characterisation of T:R ratio, reducing the risk of TWO and inappropriate shocks in the ACHD patient cohort., Competing Interests: Declaration of competing interest x The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: -Dr. Mohamed ElRefai has received an unrestricted grant from Boston Scientific. -Dr. Benedict Wiles has received unrestricted research funding and consultancy payments from Boston Scientific. -Dr. Paul Roberts receives consultancy fees from Boston Scientific and Medtronic. -Professor John Morgan is a medical director at Boston Scientific. - None of the other authors of this study has conflict of interest to declare., (Copyright © 2024 Indian Heart Rhythm Society. Published by Elsevier B.V. All rights reserved.)

Introduction: The PRAETORIAN score (PS) was developed to assess the implant position and predict defibrillation success of the subcutaneous implantable cardioverter defibrillators (S‐ICD). The main critique moved to the routine use of PS has been its postprocedural timing, that limits its usefulness on procedure guidance. The aim of this proof‐of‐concept study was to assess the feasibility of an intraprocedural use of PS. Methods: Forty consecutive patients undergoing S‐ICD implantation were enrolled. Intraprocedural PS (IP‐PS) obtained with fluoroscopy before closure of the pocket and postprocedural PS (PP‐PS) obtained with two‐views chest X‐ray were compared. Intraprocedural data and PS were compared with the historic cohorts of the involved institutions. Results: When assessing IP‐PS and PP‐PS, a complete overall agreement was observed (100%, 1.00‐κ; p <.001). When assessing a per‐step agreement, a very high‐degree of concordance in evaluating Step 1 of the PS was observed (95%, 0.81‐κ; p <.001). A complete agreement in Step 2–3 (100%, 1.00‐κ; p <.001) of the PS was reported. In comparison with our historical cohort, procedural time in the IP‐PS cohort did not increase (45 [41–52] vs. 45 [39–49] min; p =.351) while the expected increase in fluoroscopy time resulted scarce (15 [10–15] s). Conclusion: An IP‐PS can be reliably obtained using fluoroscopy guidance during S‐ICD implantation, without a significant increase in procedural duration and may serve as guidance for implanting physicians, to avoid postprocedural S‐ICD repositioning, leading to patient discomfort and significantly enhancing infective risks. IP‐PS showed a very high agreement with the PP‐PS obtained from two‐views chest X‐ray. [ABSTRACT FROM AUTHOR]

Combined implantation of cardiac contractility modulation (CCM) with subcutaneous implantable cardioverter‐defibrillator (S‐ICD) appears a suitable option to reduce the amount of intracardiac leads and complications for patients. Here we report on a patient with ischemic cardiomyopathy carrying an S‐ICD in which a CCM device was implanted. During crosstalk testing post‐CCM implantation, the S‐ICD misannotated QRS complexes and T waves. The problem was solved through reprogramming the CCM, while preserving S‐ICD functionality and improving heart failure symptoms. In conclusion, S‐ICD combined with CCM seems to be a good and safe option for patients when device interference is being ruled out. [ABSTRACT FROM AUTHOR]

A 26‐year‐old patient with prior surgery for Ebstein's anomaly and a pacemaker (placed for post‐surgical heart block and poor underlying rhythm) underwent SICD was placement. During defibrillation testing, device‐device interaction led to undersensing of ventricular fibrillation with failure to shock. Increasing the pacemaker sensitivity resolved the problem but post shock pacing was unable to capture the heart after both shocks. The patient underwent removal of both the pacemaker and the SICD and placement of a transvenous ICD. Complex device‐device interactions can occur in patients who are pacemaker dependent and undergo placement of a SICD. [ABSTRACT FROM AUTHOR]