Cardioverter-defibrillator Systems Research Articles

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

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

Safety issues of subcutaneous cardioverter-defibrillator systems. Is everything so simple and definitely?

Safety issues of subcutaneous cardioverter-defibrillator systems. Is everything so simple and definitely?

Lead and generator dysfunction in children and adolescents with epicardial pacemaker and implantable cardioverter defibrillator systems: The challenge of early recognition.

A major issue of cardiac implantable electronic device therapy in pediatric patients is the high incidence of lead dysfunctions and associated reinterventions. This study aims to analyze the timing and mode of generator and lead dysfunction. Retrospective single-center analysis of 283 children and young adults with an epicardial pacemaker or implantable cardioverter defibrillator therapy from 1998 to 2018. Mean age at implant was 6.1 years (SD±5.8 years) and median follow-up 6.4 years (IQR, 3.4-10.4 years) with a total of 1998.1 patient-years of cardiac device therapy. A total of 120 lead-related complications were observed in 82 patients (29.0%). They were detected by device interrogation (n=86), symptoms (n=13), intraoperative findings (n=7), routine chest radiography (n=5), routine ECG (n=4), patient alert sound by device (n=3), and physical examination (n=2). It was possible to find the date of the event on the device memory in 21 out of 120 lead dysfunctions (18%) with a median time interval between occurrence and detection of 1.3 months (IQR, 0.2-5.0 months). Moreover, 20 generator-related complications were found in 13 patients. Early recognition of lead and generator dysfunction remains challenging in pediatric patients. As symptoms are relatively rare conditions in the context of PM and ICD dysfunction, close patient monitoring is mandatory, even in asymptomatic patients with a good clinical course. To further improve the safety of pediatric pacing systems, more durable epicardial electrodes are desirable.

Wearable cardioverter defibrillator after ICD-system explantation: data from a multicenter registry

Abstract Background Data on the use of wearable cardioverter defibrillator (WCD) among patients after cardiac implantable electronic device explantation of 1- to 3-chamber Implantable Cardioverter-defibrillator system (ICD) are sparse. Subsequently several guidelines give a different recommendation regarding WCD indication in this cohort. Objectives We aimed to study the baseline characteristics and outcome of patients treated with WCD after ICD explantation. The primary outcome is appropriate WCD shock. Methods 1104 patients were included in a multicenter registry from seven European centers. Among this cohort 109 patients received a WCD to bridge the time after ICD-system explantation until reimplantation due to a persistent ICD-indication. The mean follow-up time of the whole cohort was 824±773 days. Cardiovascular history and non-cardiovascular morbidities were evaluated. In addition, the presence of ventricular tachyarrhythmias and/or WCD shocks was evaluated in the explantation group. Furthermore, after ICD-reimplantation the rate of rehospitalization for ventricular tachyarrhythmias, atrial fibrillation, stroke and congestive heart failure was followed. Results In the explantation group patients were older (65±14 versus 59±15; p<0.001) and were hospitalized longer (21±15 days versus 14±12 days; p<0.001). The index LVEF differed significantly (35.7±14.1% versus 29.3±11.5%; p<0.001). The LVEF value did not differ significantly over short-term follow-up (35.7±14.2% versus 37.9±11.9%; p=0.204). Wear days among patients after ICD-system explantation were 61±46 days. An appropriate WCD shock was documented in 7.3% after ICD-system explantation during WCD use. Up to 80.6% of patients after ICD-system explantation received a reimplantation. The rate of rehospitalization due to ventricular tachyarrhythmias was 7.3%, due to heart failure 6.8% and due to atrial fibrillation 4.1%. After ICD-implantation the rate of appropriate shocks was 12/89 (13.4%). In the multivariable regression analysis myocarditis and ICD-system explantation were positive predictors for the risk of ventricular tachyarrhythmias, but nevertheless an improved left ventricular ejection fraction (LVEF) and use of aldosterone antagonists were negative predictors for the risk of ventricular tachyarrhythmias. Conclusions Cccurrence of malignant arrythmia after ICD-system explantation is high and the use of WCD among these patients could be beneficial in preventing sudden cardiac death.

Postapproval Study of a Subcutaneous Implantable Cardioverter-Defibrillator System

BackgroundThe subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to avoid complications related to transvenous implantable cardioverter-defibrillator (TV-ICD) leads. Device safety and efficacy were demonstrated previously with atypical clinical patients or limited follow-up. ObjectivesThe S-ICD PAS (Subcutaneous Implantable Cardioverter-Defibrillator System Post Approval Study) is a real-world, multicenter, registry of U.S. centers that was designed to assess long-term S-ICD safety and efficacy in a diverse group of patients and implantation centers. MethodsPatients were enrolled in 86 U.S. centers with standard S-ICD indications and were observed for up to 5 years. Efficacy endpoints were first and final shock efficacy. Safety endpoints were complications directly related to the S-ICD system or implantation procedure. Endpoints were assessed using prespecified performance goals. ResultsA total of 1,643 patients were prospectively enrolled, with a median follow-up of 4.2 years. All prespecified safety and efficacy endpoint goals were met. Shock efficacy rates for discrete episodes of ventricular tachycardia or ventricular fibrillation were 98.4%, and they did not differ significantly across follow-up years (P = 0.68). S-ICD–related and electrode-related complication-free rates were 93.4% and 99.3%, respectively. Only 1.6% of patients had their devices replaced by a TV-ICD for a pacing need. Cumulative all-cause mortality was 21.7%. ConclusionsIn the largest prospective study of the S-ICD to date, all study endpoints were met, despite a cohort with more comorbidities than in most previous trials. Complication rates were low and shock efficacy was high. These results demonstrate the 5-year S-ICD safety and efficacy for a large, diverse cohort of S-ICD recipients. (Subcutaneous Implantable Cardioverter-Defibrillator [S-ICD] System Post Approval Study [PAS]; NCT01736618)

Asymptomatic channelopathies : Risk stratification and primary prophylaxis

In general, asymptomatic patients with channelopathies are at increased risk of sudden cardiac death (SCD), due to pathogenic variants in genes encoding ion channels that result in pathological ion currents. Channelopathies include long-QT syndrome (LQTS), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and short-QT syndrome (SQTS). In addition to the patient's clinical presentation, history and clinical tests, the main diagnostic tools are electrocardiography and genetic testing to identify known gene mutations. Early and correct diagnosis as well as further risk stratification of affected individuals and their relatives are paramount for prognosis. The recent availability of risk score calculators for LQTS and BrS allows SCD risk to be accurately estimated. The extent to which these improve patient selection for treatment with an implantable cardioverter-defibrillator (ICD) system is currently unknown. In most cases, initiation of basic therapy in asymptomatic patients in the form of avoidance of triggers, which are usually medication or stressful situations, is sufficient and contributes to risk reduction. In addition, there are other risk-reducing prophylactic measures, such as permanent medication with nonselective β‑ blockers (for LQTS and CPVT) or mexiletine for LQTS3. Patients and their family members should be referred to specialized outpatient clinics for individual risk stratification in the sense of primary prophylaxis.

DX single-lead implantable cardioverter-defibrillator system with a floating atrial dipole: when, to whom, and why?

The article reflects information for cardiologists, cardiac surgeons, doctors pro­gramming implanted antiarrhythmic devices, employees and residents of the depart­ments of cardiology and cardiac surgery. Most often, we choose a model of an implantable cardioverter-defibrillator (ICD) strictly individually for each patient, based on the anamnesis characteristics, safety and highest efficiency of ICD systems offered on the market. With each new ICD model, manufacturing companies strive to minimize the number of implantable components and develop better algorithms to discriminate between atrial tachyarrhythmias and true ventricular tachyarrhythmias. However, the risk of inappropriate ICD therapy still remains high. Thus, attending physicians and cardiologists programming implantable antiarrhythmic devices often face difficulties in correcting ICD settings and planning further treatment of a patient with shocks caused by atrial tachyarrhythmias. The authors sought to form an idea about the features of a single-chamber ICD recording atrial potentials using a floating dipole, as well as the advantages of the DX system over classical single-chamber ICD systems, and to define a type of a patient for whom this implantable system would be the best choice preventing sudden cardiac death.

Single Lead Implantable Cardioverter Defibrillator (ICD) with a Floating Atrial Dipole: A Systematic Review and Non-Comparative Meta-Analysis

Background: A DX implantable cardioverter defibrillator (ICD) system consists of an ICD and a shock lead equipped with two ring electrodes positioned in the atrium, referred to as the DX-lead. This system allows the collection of atrial signals using a single lead. Multiple studies on the device have been conducted over more than a decade. Aims: The aim of this study is to summarise these data in a non-comparative meta-analysis. Methods: A systematic literature review targeting publications on studies including a certain type of ICD, VR-DX ICD, was conducted. Subsequently a meta-analysis of proportions was conducted. Endpoints selected for evaluation included p-wave amplitude (at day 0, <6 months, 6-12 months and >12 months), appropriate and inappropriate shock rates, and all-cause mortality. Results: One randomised controlled trial, 11 prospective cohort studies and registries, and two retrospective studies were selected for analysis. P-wave amplitudes were consistently in a range where they can support clinical decision making across studies and remained stable over a follow-up of up to two years. Pooled shock incidence was consistent with industry standard for appropriate (10.7%) and inappropriate shocks (2.4%) across studies. All-cause mortality was at an average of 5%, increasing, as expected, with duration of study follow-up. Like shock results, mortality was within the expected range. Conclusion: This analysis shows that the VR-DX ICD system works reliably and provides an added benefit compared to single chamber ICD in the form of atrial sensing. Atrial view without requiring a second lead provides clinicians with an attractive, hardware-sparing option for the continuous monitoring of atrial activity.

Implementation of an antibacterial envelope during de novo implantation of ICD system in secondary SCD prevention in a patient on immunosuppressive treatment

Implantation of cardioverter-defibrillator system is necessary and it needs to be performed as soon as possible in patients with secondary sudden cardiac death prevention including resynchronization therapy indications. Patients on active immunosuppressive treatment are at the highest risk of infective complications of every kind of surgical intervention. In the case of cardiac implantable devices implementation of an antibacterial envelope could be a relevant factor in infective risk prevention.

Bradycardia in Patients with Subcutaneous Implantable Defibrillators-An Overestimated Problem? Experience from a Large Tertiary Centre and a Review of the Literature.

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. 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%. 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.

Safety and Tolerability of Implanted Subcutaneous Cardioverter-Defibrillator Systems

Aim. To study the safety and tolerability of the subcutaneous implantable cardioverter defibrillator (S-ICD) after implantation.Material and methods. The results of 33 patients with implanted S-ICD 6 months follow-up. The criteria for inclusion in the observational study were: age over 18 years, indications for primary or secondary prevention of sudden cardiac death. The exclusion criteria were indications for implantation of transvenous ICD (patients with sustained monomorphic ventricular tachycardia, the need for anti-bradycardia or resynchronization therapy), as well as patients with a QRS complex of more than 130 msec. All patients underwent a standard preoperative examination (routine blood tests, chest X-ray, transthoracic echocardiography), quality-of-life questionnaires and transesophageal echocardiography. At follow-up, patients were examined after 6 months after implantation, the device was interrogated and a quality-of-life questionnaire was completed. All episodes of shock therapy and complications were documented.Results. Male patients predominated (84%), with a mean age of 57 [43;62] years. Left ventricular ejection fraction was 30% [26;34]. The mean QRS duration was 100 [94;108] msec. According to the of 24-hour Holter ECG monitoring, episodes of unstable VT were recorded in 42.4% of patients. The most common indications for S-ICD implantation were dilated (33%) and ischemic cardiomyopathy (42%). Primary prevention was indicated in 97% of patients. At the end of the implantation of the S-ICD, the patients underwent a defibrillation test and device configuration. In 63.6% of cases, during automatic tuning, the device selected the primary perception vector. In 27.2% of patients, optimal recognition of the subcutaneous signal was observed in the secondary vector, and in 9.2% of patients, the alternative vector was favorable. All patients underwent two-zone programming. The conditional shock zone was programmed at an average rate of 192 beats/min (range 180-210 beats/min) and the shock zone was programmed at an average rate of 222 beats/min (range 220-240 beats/min). Perioperative complications occurred in two patients. During the follow-up period, no shocks were recorded in 27 patients. Adequate shocks for 6 months were recorded in two patients. During 6 months of observation, one lethal outcome was noted due to complications of viral pneumonia. During the observation period, there were no rehospitalizations for cardiovascular diseases.Conclusion. The use of S-ICD, even in patients with structural myocardial disease who do not require antibradycardia pacing, is effective in preventing SCD. The number of inadequate discharges and the number of complications in clinical practice is comparable to the data of multicenter studies. S-ICD implantation was not accompanied by a decrease in quality of life. Careful selection of candidates, along with state-of-the-art device programming, is an important parameter for the selection and success of S-ICD application.

Real-Life Inter-Rater Variability of the PRAETORIAN Score Values.

(1) Background: The PRAETORIAN score is a tool developed for postoperative evaluation of the position of subcutaneous implantable cardioverter-defibrillator systems. The aim of our study was to evaluate the real-life inter-rater variability of the PRAETORIAN score, based on chest radiographs of S-ICD patients reviewed by independent clinical raters. (2) Methods: Postoperative chest X-rays of patients that underwent S-ICD implantation were evaluated by five clinical raters who gave values of the PRAETORIAN score. Ratings were then compared in a fully crossed manner to determine the inter-rater variability of the attributed scores. (3) Results: In total, 87 patients were included in the study. In the case of the most important final risk category of the PRAETORIAN score, the mean Light’s kappa was 0.804, the Fleiss’ kappa was 0.249, and the intraclass correlation was 0.38. The final risk category was identically determined by all five raters in 75.86% of patients, by four raters in 14.94%, and by three raters in 9.20% of patients. (4) Conclusions: The overall inter-rater variability of the PRAETORIAN score in a group of electrophysiologists experienced in S-ICD implantation, yet previously naive to the PRAETORIAN score, and self-trained in its utilization, was only modest in our study. Appropriate use of the score might require training of clinical raters.

Subcutaneous finger cardioverter-defibrillator in low weight paediatric patients: a case series.

Placement of traditional transvenous implantable cardioverter defibrillator (ICD) system in low-weight children is often difficult because of their vessel size, the elevated risk of lead malfunction and failure, children's growth and various anatomic constraints, creating the need for alternative solutions. Subcutaneous array leads combined with an abdominally placed ICD device can minimize the surgical approach. In this case series, we analyse the data behind indications for subcutaneous finger cardioverter defibrillator (SFCD) and discuss the preliminary clinical experience in low-weight children. We considered 4 consecutive children (mean age 3.9 years, range 3-5.5 years, mean body weight 17.6 Kg, range 14-23 Kg) who underwent SFCD implant from April 2016 to August 2020. All patients showed a good compliance to the device system with no complications (infections or skin erosions). No patients experienced in the observation period (mean time 44.5±21.5 months) sustained ventricular arrhythmias requiring shocks. No inappropriate shocks released by the device occurred. No significant changes were observed in LET (lowest energy tested) performed around 24 months of follow-up. All patients showed a good compliance and stable atrio-ventricular sensing and pacing thresholds. In smaller children in whom a transvenous approach is not feasible or not possible for anatomic reasons, the SFCD appears to be a safe method to prevent SCD with little surgical trauma and preservation of an intact vascular system, providing an adequate bridge to transvenous ICD or subcutaneous ICD implant late in the life.

Age-related differences and associated mid-term outcomes of subcutaneous implantable cardioverter-defibrillators: A propensity-matched analysis from a multicenter European registry.

A few limited case series have shown that the subcutaneous implantable cardioverter-defibrillator (S-ICD) system is safe for teenagers and young adults, but a large-scale analysis currently is lacking. The purpose of this study was to compare mid-term device-associated outcomes in a large real-world cohort of S-ICD patients,stratified by age at implantation. Two propensity-matched cohorts of teenagers + young adults (≤30 years old) and adults (>30 years old) were retrieved from the ELISIR Registry. The primary outcome was the comparison of inappropriate shock rate. Complications, freedom from sustained ventricular arrhythmias, and overall and cardiovascular mortality were deemed secondary outcomes. Teenagers + young adults represented 11.0% of the entire cohort. Two propensity-matched groups of 161 patients each were used for the analysis. Median follow-up was 23.1 (13.2-40.5) months. In total, 15.2% patients experienced inappropriate shocks, and 9.3% device-related complications were observed, with no age-related differences in inappropriate shocks (16.1% vs 14.3%; P = .642) and complication rates (9.9% vs 8.7%; P = .701). At univariate analysis, young age was not associated with increased rates of inappropriate shocks (hazard ratio [HR] 1.204 [0.675-2.148]: P = .529). At multivariate analysis, use of the SMART Pass algorithm was associated with a strong reduction in inappropriate shocks (adjusted HR 0.292 [0.161-0.525]; P <.001), whereas arrhythmogenic right ventricular cardiomyopathy (ARVC) was associated with higher rates of inappropriate shocks (adjusted HR 2.380 [1.205-4.697]; P = .012). In a large multicenter registry of propensity-matched patients, use of the S-ICD in teenagers/young adults was safe and effective. The rates of inappropriate shocks and complications between cohorts were not significantly different. The only predictor of increased inappropriate shocks was a diagnosis of ARVC.

The need for a subsequent transvenous system in patients implanted with subcutaneous implantable cardioverter-defibrillator

The absence of pacing capabilities may reduce the appeal of subcutaneous implantable cardioverter-defibrillator (S-ICD) devices for patients at risk for conduction disorders or with antitachycardia pacing (ATP)/cardiac resynchronization (CRT) requirements. Reports of rates of S-ICD to transvenous implantable cardioverter-defibrillator (TV-ICD) system switch in real-world scenarios are limited. The purpose of this study was to investigate the need for a subsequent transvenous (TV) device in patients implanted with an S-ICD and its predictors. All patients implanted with an S-ICD were enrolled from the multicenter, real-world iSUSI (International SUbcutaneouS Implantable cardioverter defibrillator) Registry. The need for a TV device and its clinical reason, and appropriate and inappropriate device therapies were assessed. Logistic regression with Firth penalization was used to assess the association between baseline and procedural characteristics and the overall need for a subsequent TV device. A total of 1509 patients were enrolled (age 50.8 ± 15.8 years; 76.9% male; 32.0% ischemic; left ventricular ejection fraction 38% [30%-60%]). Over 26.5 [13.4-42.9] months, 155 (10.3%) and 144 (9.3%) patients experienced appropriate and inappropriate device therapies, respectively. Forty-one patients (2.7%) required a TV device (13 bradycardia; 10 need for CRT; 10 inappropriate shocks). Body mass index (BMI) >30 kg/m2 and chronic kidney disease (CKD) were associated with need for a TV device (odds ratio [OR] 2.57 [1.37-4.81], P = .003; and OR 2.67 [1.29-5.54], P = .008, respectively). A low rate (2.7%) of conversion from S-ICD to a TV device was observed at follow-up, with need for antibradycardia pacing, ATP, or CRT being the main reasons. BMI >30 kg/m2 and CKD predicted all-cause need for a TV device.

Age-related differences and associated outcomes of S-ICD: insights from a large, european, multicenter, real-world registry

Abstract Funding Acknowledgements Type of funding sources: None. Background Young patients often represent the most suitable candidates for an entirely subcutaenous implantable cardioverter defibrillator (S-ICD) system, since they have to face a lifetime of device therapy and they rarely have a pre-existing or concurrent pacing or cardiac resynchronization therapy (CRT) indication. Moreover, S-ICD offers lower rate and a safer management of lead and major procedure-related complications. To date, a few limited case series and experiences with S-ICD in teenagers and young adults have shown that the S-ICD system is safe and feasible in this population, with a rate of inappropriate shocks (IS) comparable to transvenous (TV) ICD, but focused analysis on a large scale are currently lacking in this setting. Purpose The aim of the current study was to compare the age-related differences observed in patient selection, baseline characteristics, and device long-term associated outcomes in a large real world cohort of S-ICD recipients. The primary outcome of the study was defined as the comparisons of the IS rate observed during the entirety of follow up in the teenagers/young adult vs the adult populations. Rate of complications, freedom from sustained ventricular arrhythmic events, overall and cardiovascular mortality were also assessed in the two cohorts and assessed as secondary outcomes. Methods All S-ICD recipients in the ELISIR project were enrolled in the current study. Patients were classified into teenagers + young adults (≤ 30 years old) vs adults (&amp;gt; 30 years old), depending from patient age at device implantation (Figure 1). Rates of device-related complications and IS were compared between the cohorts. Results A total of 1349 patients were extracted from the ELISIR project. Teenagers and young adults represented 12.4% of the registry (n=56 teenagers; n=112 young adults). Patients were followed-up for a median of 23.1 [12.6–37.9] months. Overall, 117 (8.7%) patients experienced inappropriate S-ICD shocks and 100 (7.4%) device related complications were observed, with no age-related differences. IS resulted more frequent in the teenager and young adult cohort (14.3% vs 7.9%; p=0.006). Figure 2 reports Kaplan Meier curves for the occurrence of IS. At univariate analysis, young age was associated with IS, but after correcting for differences in arrhythmic substrate, this association resulted non-significant (aHR: 1.428 [0.883–2.331]; p=0.146). The use of SMART pass algorithm was instead associated to a strong reduction in IS (aHR 0.367 [0.245–0.548]; p&amp;lt;0.001). Conclusion The use of S-ICD in teenagers/young adults resulted safe and effective. Indeed, the rate of complications between teenagers/young adults and adults was not significantly different. Although a higher rate of IS was observed in the teenagers/young adults, when accounting for differences in baseline substrate and comorbidities, young age did not result associated with an increased risk of IS.

The development of the extravascular defibrillator with substernal lead placement: A new Frontier for device-based treatment of sudden cardiac arrest.

IntroductionThe extravascular implantable cardioverter‐defibrillator (EV ICD) system with substernal lead placement is a novel nontransvenous alternative to current commercially available ICD systems. The EV ICD provides defibrillation and pacing therapies without the potential long‐term complications of endovascular lead placement but requires a new procedure for implantation with a safety profile under evaluation.MethodsThis paper summarizes the development of the EV ICD, including the preclinical and clinical evaluations that have contributed to the system and procedural refinements to date.ResultsExtensive preclinical research evaluations and four human clinical studies with >140 combined acute and chronic implants have enabled the development and refinement of the EV ICD system, currently in worldwide pivotal study.ConclusionThe EV ICD may represent a clinically valuable solution in protecting patients from sudden cardiac death while avoiding the long‐term consequences of transvenous hardware. The EV ICD offers advantages over transvenous and subcutaneous systems by avoiding placement in the heart and vasculature; relative to subcutaneous systems, EV ICD requires less energy for defibrillation, enabling a smaller device, and provides pacing features such as antitachycardia and asystole pacing in a single system.

AP-518-04 INCIDENCE OF INAPPROPRIATE SHOCK IN PATIENTS WITH SUBCUTANEOUS IMPLANTABLE CARDIOVERTER-DEFIBRILLATORS WITH CONCOMITANT CARDIAC IMPLANTABLE ELECTRONIC DEVICES: A SINGLE-CENTER COHORT STUDY

The subcutaneous implantable cardioverter-defibrillator (S-ICD) system does not require the placement of intracardiac instrumentation. Therefore, S-ICDs avoid adverse events related to the implantation of a transvenous implantable cardioverter-defibrillator system. However, as S-ICDs do not have a pacing function, an additional implanted device is required for patients who are clinically indicated for a S-ICD and require pacing therapy. It is unclear whether the incidence of inappropriate shock is increased in patients with S-ICDs with concomitant cardiac implantable electronic devices (CIEDs).

PO-687-02 THE EXTRAVASCULAR IMPLANTABLE CARDIOVERTER - DEFIBRILLATOR: A CASE FOR CONCERN

The investigational Extravascular Implantable Cardioverter Defibrillator (Medtronic EV-ICD) system with its substernal lead placement may offer an alternative to transvenous ICD while reducing the risks associated with transvenous system such as infection requiring extraction, vascular injury, and venous obstruction. The EV-ICD lead is placed just beneath the sternum in the retrosternal space. Patients with prior or planned sternotomy and prior chest radiotherapy are excluded from the EV-ICD trials due to increased surgical risk. We describe a patient with cardiac sarcoidosis in whom we decided not to implant the EV-ICD due to pericardial adhesions noted on preoperative imaging. N/A A 55-year-old man with history of chronic systolic heart failure due to cardiac sarcoidosis and family history of sudden cardiac death was noted to have non sustained ventricular tachycardia on an event monitor. He underwent an electrophysiologic study which showed inducible monomorphic ventricular tachycardia. ICD implantation was recommended. Due to an active lifestyle and no pacing indication, he opted for an EV-ICD. As part of the pre-operative protocol, a chest X ray is obtained but is not used to determine device eligibility. However, in this case it was noted that the right ventricle was closely approximated to the sternum. Due to history of inflammatory cardiomyopathy, a gated cardiac CT was obtained to evaluate the retrosternal space. Cardiac CT showed adhesion of the right ventricular pericardium to the midline sternum. The right ventricle was tethered but not adherent to the sternum. The EV-ICD procedure was cancelled due to increased surgical risk associated with tunneling with an adherent pericardium. He later underwent a transvenous ICD placement. Pericardial adhesions may be associated with inflammatory cardiomyopathies such as cardiac sarcoidosis. Thorough preoperative evaluation of the retrosternal space is recommended in such patients prior to considering substernal lead tunneling.

Trends in Use of Single- vs Dual-Chamber Implantable Cardioverter-Defibrillators Among Patients Without a Pacing Indication, 2010-2018

Use of dual-chamber implantable cardioverter-defibrillator (ICD) systems among patients without a pacing indication is an example of low-value care given higher procedural risks, higher costs, and little evidence for benefit from an atrial lead. However, variation in the use of dual-chamber systems was present among patients without a pacing indication. To examine the temporal trends and hospital variation in use of single- and dual-chamber ICD implantation among patients without a pacing indication undergoing first-time ICD implantation. A multicenter cross-sectional study was conducted using the US National Cardiovascular Data Registry ICD Registry. A total of 266 182 patients undergoing initial implantation of a single- or dual-chamber transvenous ICD without a bradycardia pacing indication, class I or II cardiac resynchronization therapy indication, or history of atrial fibrillation or atrial flutter were included. The study was conducted from April 1, 2010, to December 31, 2018; data analysis was performed from October 19, 2020, to January 5, 2022. Implantation of a single- or dual-chamber ICD. Temporal trends among patients undergoing single- vs dual-chamber ICDs were determined using the Cochran-Armitage trend test, and hospital-level variation using adjusted hospital median odds ratios was examined. A total of 266 182 patients (single-chamber ICD, 134 925; dual-chamber ICD, 131 257) were included in this analysis; mean (SD) age was 58.0 (14.0) years and 91 990 patients (68.2%) were men. The use of dual-chamber ICDs decreased from 64.7% (n = 15 694) in 2010 to 42.2% (n = 9762) in 2018 (P < .001). Adjusted for patient characteristics, the median hospital-level proportion of single-chamber ICDs increased from 42.9% (95% CI, 42.6%-45.0%) in 2010 to 50.0% (95% CI, 47.8%-51.0%) in 2018. The median odds ratio for the use of dual-chamber ICDs, adjusted for patient characteristics, was 1.6 (95% CI, 1.6-1.8) in 2010 and 1.5 (95% CI, 1.5-1.8) in 2018, indicating decreasing but persistent variation in use. In this national study of US patients undergoing first-time ICD implantation without a clinical indication for an atrial lead, the use of dual-chamber devices decreased. However, institutional variability in the use of atrial leads persists, suggesting differences in individual or institutional cultures of real-world practice and opportunity to reduce this low-value practice.