Transvenous ICD Research Articles

Rates of and Indications for Subcutaneous ICD Extraction: A Multihospital Healthcare System Analysis.

The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to a transvenous ICD in patients who meet the criteria for ICD implantation without concurrent need for cardiac pacing. The objective of this study is to examine the rates of and indications for S-ICD removal and extraction. A retrospective analysis of all patients who underwent S-ICD implantation between 2010 and 2022 at a single multihospital healthcare system was performed. The primary endpoint was S-ICD removal or extraction. Patient and device characteristics were abstracted from the electronic medical record. Univariate and multivariate analyses were completed to determine factors associated with S-ICD extraction. A total of 372 patients (69.5% male; 48.6 ± 14.4 years old) underwent S-ICD implantation during the study period. There were 22 (5.9%) patients (81.8% male; 52.1 ± 13.2 years old) who underwent S-ICD extraction over a median follow-up period of 4.4 [2.0-6.5] years. The median length of time between implantation and extraction was 39.6 [8.3-64.6] months. The most common indications for S-ICD extraction were the need for bradycardia pacing (frequency among extractions, 18.2%), infection (22.7%), and inappropriate shocks due to oversensing (22.7%). A smoking history and higher body mass index were independently associated with S-ICD extraction. The overall rate of S-ICD extraction over 4.4 [2.0-6.5] years was 5.9%, with the most common indications for extraction being the need for bradycardia pacing, infection, and inappropriate shocks due to oversensing. A smoking history and high body mass index are associated with increased rates of S-ICD extraction. With appropriate patient selection for the S-ICD, the need to remove the device after implantation is low.

Quality of Life in Subcutaneous or Transvenous Implantable Cardioverter-Defibrillator Patients: A Secondary Analysis of the PRAETORIAN Trial.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) was developed to overcome the risk of lead-related complications associated with the transvenous implantable cardioverter-defibrillator (TV-ICD). In contrast to the TV-ICD, the S-ICD is a completely extrathoracic device. Subsequently, complications differ between these 2 implantable cardioverter-defibrillators, which might impact patient perceptions of the therapies. This prespecified secondary analysis of the PRAETORIAN trial evaluates differences in quality of life. The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) randomized patients with an implantable cardioverter-defibrillator indication, without the need for pacing to S-ICD or TV-ICD therapy. Two questionnaires were collected at baseline, discharge, 12 months, and 30 months. The Duke Activity Status Index measures cardiac-specific physical functioning, and the 36-Item Short Form Health Survey measures physical and mental well-being, with the subscales bodily pain and mental health being of interest in this analysis. Mann-Whitney U tests were used to compare study arms, and a mixed model was used to describe the questionnaire outcomes over time. Patients were randomized to S-ICD (n=426) and TV-ICD (n=423). In the S-ICD group, 20% were women versus 19% in the TV-ICD group. The median age was 63 (interquartile range, 54-69) years in the S-ICD group versus 64 (interquartile range, 56-69) years in the TV-ICD group. There were no significant differences in the Duke Activity Status Index and 36-Item Short Form Health Survey subscales for bodily pain and mental health between the groups at any time point. Patients with a shock in the last 90 days had significantly lower scores for social functioning (P=0.008) and role limitations due to emotional problems (P=0.001) than patients without a shock, but this effect did not differ between treatment arms. In a large randomized cohort of patients with an S-ICD or TV-ICD, no difference in overall quality of life was observed. However, implantable cardioverter-defibrillator shocks resulted in a reduction in quality of life, regardless of the device type or appropriateness. URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Long-Term Outcomes of Subcutaneous Versus Transvenous Implantable Cardioverter Defibrillator Use Among Patients on Maintenance Dialysis

Despite an elevated risk of sudden cardiac death among dialysis patients, implantable cardioverter defibrillators (ICDs) have not been shown to improve mortality and are associated with high complication rates. Subcutaneous (S-)ICDs may reduce the risk of complications for eligible dialysis patients, but safety and benefits versus transvenous (TV-)ICDs are unknown. To compare long-term outcomes between dialysis patients receiving S-ICD versus TV-ICDs. We performed a retrospective analysis of ICD implants among Fee-For-Service Medicare beneficiary dialysis patients in the National Cardiovascular Data Registry ICD Registry. Outcomes were ascertained from Medicare claims data. We compared survival outcomes, hospital admissions, and ICD- associated and dialysis vascular access-associated complications, between eligible S-ICD and single chamber TV-ICD recipients using stabilized inverse probability of treatment weighting. We identified 529 dialysis patients receiving S-ICDs and 842 receiving single chamber TV-ICDs who met the inclusion criteria. S-ICD recipients were younger, more often Black, and had a higher burden of cardiac disease and prior dialysis access interventions. After propensity weighting, there was no difference in the risk of death (HR 1.12, 95% CI 0.96-1.30), hospital admission (HR 1.01, 95% CI 0.88-1.16), bacteremia/sepsis (HR 1.01, 95% CI 0.80-1.26), device reoperation (HR 1.06, 95%CI 0.59-1.89) and subsequent dialysis access interventions (HR 1.12, 95% CI 0.86-1.46). In this representative longitudinal cohort study of dialysis patients, compared with TV-ICD, S-ICD was not associated with decreased risks of death, hospitalization, device complications, and dialysis access interventions.

Device Therapy in Cardiac Sarcoidosis: Current Review, Challenges, and Future Prospects.

Sarcoidosis is a complex disease characterized by inflammatory granulomas that can affect various organs, including the heart. The diagnosis of cardiac sarcoidosis poses challenges, and current criteria involve the use of advanced imaging techniques and histological confirmation. Clinical manifestations of cardiac sarcoidosis vary widely, ranging from heart block to ventricular tachycardia and heart failure. Sudden cardiac death (SCD) is a significant concern, and implantable cardioverter-defibrillators (ICDs) are recommended for preventing SCD in high-risk cases. However, some patients with cardiac sarcoidosis do not meet the current guidelines for ICD implantation, leaving them at risk. Traditional transvenous ICDs are associated with complications, especially in immunosuppressed patients. The subcutaneous implantable cardioverter-defibrillator (S-ICD) offers a potential solution, as it avoids vascular complications and reduces the risk of infections. However, concerns regarding inappropriate shocks and the lack of pacing therapy limit its widespread use. Leadless pacing combined with S-ICD represents a potential novel approach to managing cardiac sarcoidosis patients. Ongoing human clinical trials are expected to shed light on the safety and efficacy of this combined therapy. Cardiac sarcoidosis patients, who have been underserved by traditional device therapies, may benefit from this personalized approach. Further research is needed to guide the management of SCD risk in this population.

Routine chest X-ray post cardiac implantable electronic device implantation: is it really required? Experience from a tertiary centre

Abstract Introduction The 2021 EHRA expert consensus statement on pacemaker (PPM) and transvenous implantable cardioverter defibrillator (ICD) implant technique proposes a chest X-ray (CXR) prior to hospital discharge in all patients. This recommendation serves the dual purpose of excluding pneumothorax following subclavian or axillary access (SAA) and documenting lead position. Purpose Given that cephalic venous access (CA) precludes pneumothorax, the utility of CXR as a tool for identifying early lead displacement (LD) in these patients warrants further examination. We studied the yield of post implant CXR, device interrogation (DI), or both for the identification of pneumothorax and LD in patients undergoing transvenous PPM or ICD implant via SAA or CA. Methods 4,051 consecutive PPM or ICD devices were implanted at a tertiary centre between 2016-2019. Lead position was documented fluoroscopically on conclusion of all procedures. A subsequent post implant CXR was performed in cases of SAA, plus in those CA patients requiring imaging for another indication (e.g. pulmonary oedema). Post implant DI was only performed in patients with a high anticipated burden of ventricular pacing (e.g. high-grade atrioventricular block). All patients underwent clinical review with repeat DI at 30 days post implant. LD was defined as a clinically significant translocation of a lead requiring repositioning or reprogramming. Results For the whole cohort, the incidence of LD at 30 days was 2.2% (n=89), and the incidence of pneumothorax (within the SAA group) was 0.9% (n=11). The venous access method used, post implant investigations, and the incidence of LD is shown in Figure 1. 1,282 patients (31.6%) required SAA; CXR was performed in all, and 9 LDs were identified (0.7%). However, four patients (0.3%) with ‘normal’ CXRs had evidence of LD on inpatient DI, and a further 17 LDs (1.3%) were confirmed on the 30 day DI despite a ‘normal’ CXR. 2,769 patients (68.4%) underwent CA; 309 (11%) required CXR. This identified LD in four patients (1.3%), with three further patients (1%) found to have LD on subsequent inpatient DI despite a ‘normal’ CXR. A further four LDs (1.3%) were diagnosed at 30 day DI. The majority (89%, n=2,460) of CA patients were discharged without CXR. 30% (n=825) of these patients required inpatient DI; this identified 13 LDs (1.6%). Accordingly, 59% (n=1,635) of CA patients had no post procedural investigations; 24 (1.5%) were found to have LD at 30 day DI. Conclusions In patients who developed LD within 30 days of a PPM or ICD implant, a post implant CXR identified this in only 32% of cases (n=13/41), and the overall sensitivity of CXR for LD was low (50%). Additionally, the majority of LDs (54%) occurred after hospital discharge. We suggest that the utility of post implant CXR for identifying LD is limited, and that CXR should not be considered an essential investigation in CA device implants.Figure 1

Equal performance of the subcutaneous and transvenous implantable cardioverter defibrillator across all age groups in the PRAETORIAN trial

Abstract Introduction The subcutaneous ICD (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. In the PRAETORIAN trial the S-ICD proved to be non-inferior to the TV-ICD with regard to inappropriate shocks (IAS) and complications. However, the S-ICD is still mainly the preferred choice in young patients with a long life expectancy and therefore higher risk for lead-related complications. We aimed to evaluate the impact of age on complications and IAS between the S-ICD and TV-ICD. Methods The PRAETORIAN trial is an investigator-initiated, international, multicenter, randomized, two-arm noninferiority trial that was conducted in the United States and Europe. In total 849 patients with a class I or IIa indication for ICD therapy and no pacing indication were randomized to receive an S-ICD (N=426) or TV-ICD (N=423) and followed for a median of 49 months. We compare the occurrence of complications and IAS between increasing quartiles of age. Results Quartile 1 (Q1) consisted of 203 patients aged <55 (109 S-ICD, 94 TV-ICD), Q2 of 199 patients aged 55-62 (100 S-ICD, 99 TV-ICD), Q3 of 232 patients aged 63-69 (111 S-ICD, 121 TV-ICD) and Q4 of 215 patients aged ≥70 (106 S-ICD, 109 TV-ICD). Between the quartiles, there were no significant differences in occurrence of device-related complications (P = 0.32) or IAS (P = 0.66). In Q1, there were 15 (7.4%) complications (5 S-ICD, 10 TV-ICD) and 13 (6.4%) IAS (7 S-ICD, 6 TV-ICD), compared to 20 (10.1%) complications (7 S-ICD, 13 TV-ICD) and 17 (8.5%) IAS (9 S-ICD, 8 TV-ICD) in Q2, 22 (9.5%) complications (12 S-ICD, 10 TV-ICD) and 19 (8.2%) IAS (11 S-ICD, 8 TV-ICD) in Q3 and 18 (8.4%) complications (7 S-ICD, 11 TV-ICD) and 21 (9.8%) IAS (14 S-ICD, 7 TV-ICD) in Q4 (Figure 1.). Figure 2. shows forest plots of the hazard ratios per quartile. Conclusions The S-ICD performed equal to the TV-ICD with regard to IAS and complications between quartiles of age, making the S-ICD a good alternative across all age groups.

Comparison of ICD implantation approach in children. The IChilDren study

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

Sex differences in shocks and device-related complications in subcutaneous implantable-cardioverter defibrillator patients

Abstract Background The use of implantable cardioverter-defibrillators (ICDs) improves the life expectancy of patients at risk of sudden cardiac death. However, ICD treatment comes with the risk of device-related complications. As the lead is the Achilles heel of the transvenous ICD (TV-ICD), the subcutaneous ICD (S-ICD) was developed to overcome the risk of lead-related complications. It is reported for TV-ICDs that women receive less appropriate therapy, but are more likely to experience ICD-related complications than men. It is unclear whether these differences also exist among S-ICD recipients. Purpose This study investigates the differences in appropriate shocks (AS) and device-related complications in men and women implanted with an S-ICD. Methods Retrospective data was collected of all patients implanted with an S-ICD between 2009 and 2022 in our tertiary center. Propensity score matching was used to create two comparable groups that differed by sex. The numbers of patients with an AS and device related-complication requiring intervention were compared between men and women. Differences between the groups were tested using a Fisher’s exact or X2-test. Results A total of 108 men and 108 women were included in this analysis. The median age was 40 years in men and 41 years in women (p=0.747), 61% had a primary prevention indication, and the median follow-up duration was 8 years. AS were seen in 15 women versus 24 men (p=0.156). There were 6 women versus 12 men with a device-related complication requiring intervention (p=0.218) (figure). The most common complication in men was infection (4/12) whereas in women erosion of the pocket occurred most frequently (2/6). Conclusions In this study, there was no significant difference in the number of patients with AS or complication between men and women with an S-ICD. However, a trend was seen towards more shocks and complications in men. The S-ICD may be a more suitable device for women, but further research with a larger sample size is needed.sex differences in S-ICD recipients

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

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

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

Incidence and Predictors of Appropriate Implantable Cardioverter Defibrillator Therapy in Japanese Ischemic Heart Disease Patients.

Although the efficacy of an implantable cardioverter defibrillator (ICD) in preventing sudden cardiac death is well established, the incidence and predictors of appropriate ICD therapy in Japanese ischemic heart disease (IHD) patients remain unclear. We retrospectively studied Japanese 141 IHD patients undergoing transvenous ICD or cardiac resynchronization therapy with a defibrillator (CRT-D) implantation for primary or secondary prevention at Hirosaki University Hospital. Over a mean (±SD) follow-up period of 5.5±2.8 years, the incidence of appropriate ICD therapy was similar in the primary and secondary prevention groups, although it was relatively more frequent in the first 2 years in the secondary prevention group. Four patients died due to sustained ventricular tachycardia (VT) or ventricular fibrillation (VF), mainly due to post-shock pulseless electrical activity. Once patients had received their first appropriate ICD therapy, 49.2% received second appropriate ICD therapy within 6 months. Cox proportional hazard analysis revealed that sustained VT as an index life-threatening ventricular tachyarrhythmia before ICD/CRT-D implantation was an independent predictor of appropriate ICD therapy, but VF was not. The incidence of appropriate ICD therapy was comparable in primary and secondary prevention among Japanese IHD patients. We need to recognize the high-risk period for second appropriate ICD therapy after the first therapy and sustained VT as index life-threatening ventricular tachyarrhythmia as a risk factor for appropriate ICD therapy.

Synthesized V7 QRS Amplitude and Oversensing Episodes in Patients With Subcutaneous Implantable Cardioverter-Defibrillators.

Patients with subcutaneous implantable cardioverter-defibrillators (S-ICDs) experience an oversensing episode (OS) more frequently than those with transvenous ICDs. However, no established electrocardiography (ECG) parameters can accurately detect an OS. This study aimed to evaluate the incidence of an OS in real-world clinical practice and the association of synthesized 18-lead ECG (syn18-ECG) parameters with an OS. We retrospectively included 21 consecutive patients who underwent S-ICD implantation and collected syn18-ECG parameters. We placed the generator in a deep posterior position and defined an OS as an inappropriate charging episode caused by cardiac or noncardiac signals. A SMART pass filter and two tachyarrhythmia zones were programed. The most frequent underlying heart disease was Brugada/J wave syndrome (n = 7). During a median follow-up period of 1188 days, an OS was observed in six patients (28.6%). The QRS amplitude in synthesized V7 lead (synV7) was significantly lower in the OS group than in the non-OS group (0.59±0.17 vs. 0.91±0.35mV, p=0.019). The optimal cutoff value of synV7 QRS amplitude was 0.61mV, with a sensitivity of 80.0% and a specificity of 83.7% for predicting an OS. Univariate logistic analysis showed that a synV7 QRS amplitude of <0.61mV was only associated with an OS (odd ratio, 20.0; 95% confidence interval, 1.66-241.72; p=0.018). In patients with S-ICDs, an OS was not a rare complication during long-term follow-up. A low synV7 QRS amplitude was associated with a high OS incidence.

Predictors of death without prior appropriate therapy in ICD recipients: the comorbidities, frailty and functional status (COMFFORT study)

ObjectiveMost patients who have an implantable cardioverter-defibrillator (ICD) implant do not receive life-prolonging therapy from it. Little research has been undertaken to determine which patients benefit the least from ICD...

Performance and Safety of the Extravascular Implantable Cardioverter-Defibrillator Through Long-Term Follow-Up: Final Results From the Pivotal Study.

Substernal lead placement of the extravascular implantable cardioverter-defibrillator (EV ICD) permits both defibrillation at thresholds similar to those seen with transvenous ICDs and effective antitachycardia pacing (ATP), while avoiding the vasculature and associated complications. The global Pivotal study has shown the EV ICD system to be safe and effective through 6 months, but long-term experience has yet to be published. We aim to report the performance and safety of the EV ICD system throughout the study. The EV ICD Pivotal study was a prospective, global, single-arm, pre-market clinical study. Individuals with a class I or IIa indication for a single-chamber ICD per guidelines were enrolled. Freedom from major system- or procedure-related complications, as well as appropriate and inappropriate therapy rates, were assessed through 3 years using the Kaplan-Meier method. Anti-tachycardia pacing success was calculated using simple proportions. An implant was attempted in 316 patients [25.3% female, 53.8±13.1 years old, 81.6% primary prevention, LVEF 38.9%±15.4%]. Of 299 patients with a successful implant, 24 experienced 82 spontaneous arrhythmic episodes that were appropriately treated with either ATP only (38, 46.3%), shock only (34, 41.5%), or both (10, 12.2%) for a Kaplan-Meier-estimated rate of first any appropriate therapy of 9.2% at 3 years. Antitachycardia pacing was successful in 77.1% (37/48) of episodes, and ATP usage significantly increased from discharge to last follow-up visit (P<0.0001). Shock therapy was successful in 100% (27/27) of discrete, spontaneous ventricular arrhythmias. The inappropriate shock rates at 1 and 3 years were 9.8% and 17.5%, respectively, with P-wave oversensing the predominant cause. No major intraprocedural complications were reported and the estimated freedom from system- or procedure-related major complications was 91.9% at 1 year and 89.0% at 3 years. The most common major complications were lead dislodgement (10 events; n=9 patients, 2.8%), postoperative wound or device pocket infection (n=8, 2.5%), and device inappropriate shock delivery (n=4, 1.3%). Twenty-four system revisions were performed as a result of major complications related to the EV ICD system or procedure. From implant to study completion, the EV ICD Pivotal study demonstrated that a single integrated system with an extravascular lead placed in the substernal space maintains high ATP success, effective defibrillation, and a consistent safety profile.

Practical guidance for the implantation of non-transvenous ICD systems

As an alternative to transvenous ICD systems, two non-transvenous ICD systems have been established in recent years: The subcutaneous ICD (S-ICD), which has been established for several years, has apresternal electrode that is implanted subcutaneously and offers ashock function and, to alimited extent, post-shock pacing. In addition, the extravascular ICD (EV-ICD) has been available in Europe since 2023 which does not require transvenous electrodes and offers the option of providing patients with antibradycardic and antitachycardic stimulation in combination with aconventional ICD function. The lead of this device is implanted substernally. Initial implantation results are promising in terms of safety and effectiveness. Both systems avoid possible complications of transvenous electrodes. This article provides practical guidance for the implantation technique and possible complications.

Decision-making regarding subcutaneous implantable cardioverter defibrillator as primary prevention in patients with low ejection fraction.

Conventional transvenous implantable cardioverter-defibrillator (TV-ICD) is the standard device used for primary prevention of sudden cardiac death (SCD) in patients with reduced left ventricular ejection fraction (LVEF). Nonetheless its use is associated with lead-related complications including infection and malfunction. A subcutaneous implantable cardioverter-defibrillator (S-ICD) offers an alternative option without the need for a transvenous lead but has limitations. The decision to implant a TV-ICD or S-ICD in patients with impaired LVEF for primary prevention of SCD is controversial. Several randomised controlled trials and large observational studies have confirmed similar safety and efficacy of S-ICDs and TV-ICDs in such population. A literature review was conducted to compare the outcomes of subcutaneous (S-ICD) versus transvenous (TV-ICD) implantable cardioverter-defibrillators. Databases including PubMed, MEDLINE, and Cochrane were searched for relevant peer-reviewed articles. Studies were selected based on relevance and quality. Key outcomes like complication rates, efficacy, and patient survival were summarized in a comparative table. Different factors that influence the choice between an TV-ICD and S-ICD for primary prevention of SCD in patients with LVEF are highlighted to guide selection of the appropriate device in different patient populations. Moreover, future perspective on the combination of SICD with leadless pacemaker, and the latest development of the extravascular implantable cardioverter defibrillator are also discussed. S-ICD offers a safe and efficacious option to primary prevention in reduced ejection fraction. Future development including incorporation of leadless pacemaker will add to the arsenal of choice to protect patients from sudden cardiac death.

Subcutaneous versus Transvenous Implantable Cardioverter Defibrillator in Patients with End-Stage Renal Disease Requiring Dialysis: Extended Long-Term Retrospective Multicenter Follow-Up.

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. 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. 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). 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.

Incidence and economics of transvenous ICD lead complications: Implications for tricuspid valve function and interventions.

Implantable cardioverter-defibrillators are used globally and are reliable, but complications related to transvenous leads remain a concern. Evidence related to the incidence and costs of those complications is heterogeneous with respect to scope and healthcare system. This analysis aims to create estimates of the incidence and costs of tricuspid valve (TV) complications, lead failures, and lead extractions from a single large real-world data set. This retrospective longitudinal cohort study used the deidentified Medicare Fee for Service administrative claims database. A total of 116 036 patients with de novo transvenous ICD implant were analyzed. Mean hospital costs were $26 903 for tricuspid valve complications, $20 851 for lead failures, and $22 278 for lead extractions. Transvenous ICD lead complications incur significant costs to patients, hospitals, and payers when they occur. Advancements in lead technology that reduce these complications could bring significant clinical and economic value.

Effects of Implantable Cardioverter-Defibrillator Leads on the Tricuspid Valve and Right Ventricle: A Randomized Trial

BackgroundThere are no randomized data to inform the extent to which transvenous cardiac leads cause tricuspid regurgitation (TR). ObjectivesThis study sought to determine the effect of a transvenous implantable cardioverter-defibrillator (TV-ICD) on TR severity, and secondarily, on right ventricular (RV) size and function. MethodsWe evaluated TR severity before and 6 months after implantable cardioverter-defibrillator insertion in a post hoc analysis of adults randomized to receive a transvenous (n = 252) or subcutaneous implantable cardioverter-defibrillator (S-ICD) (n = 251) device. TR and RV size and systolic function were assessed by echocardiographic images analyzed in a core laboratory. ResultsAt baseline, at least mild TR was present in 30% of individuals. At 6 months, the proportion of participants with any TR in the TV-ICD group was 42% vs 19% in the S-ICD group (P < 0.001). The proportion with moderate or severe TR was 7% in the TV-ICD group vs 2% in the S-ICD group (P = 0.021). At 6 months, the OR of at least 1 grade worsening of TR in the TV-ICD group as compared with the S-ICD group was 7.2 (95% CI: 3.3-15.8; P < 0.001). There were no differences between groups with respect to RV size or systolic function. ConclusionsSix months following TV-ICD insertion, there was a 7-fold increase in the risk of at least 1 grade worsening of TR, with 7% of individuals having TR that was moderate or severe. There was no detectable difference in RV size or function; however, longer follow-up is needed.

Unexpected Genetic Twists in Patients with Cardiac Devices.

Objective: To assess the frequency and types of genetic mutations in patients with arrhythmias who underwent cardiac device implantation. Methods: Retrospective observational study, including 38 patients with different arrhythmias and cardiac arrest as a first cardiac event. Treatment modalities encompass pacemakers, transvenous defibrillators, loop recorders, subcutaneous defibrillators, and cardiac resynchronization therapy. All patients underwent genetic testing, using commercially available panels (106-174 genes). Outcome measures include mortality, arrhythmia recurrence, and device-related complications. Results: Clinical parameters revealed a family history of sudden cardiac death in 19 patients (50%), who were predominantly male (58%) and had a mean age of 44.5 years and a mean left ventricle ejection fraction of 40.3%. Genetic testing identified mutations in various genes, predominantly TMEM43 (11%). In two patients (3%) with arrhythmogenic cardiomyopathy, complete subcutaneous defibrillator extraction with de novo transvenous implantable cardioverter-defibrillator implantation was needed. The absence of multiple associations among severe gene mutations was crucial for cardiac resynchronization therapy response. Mortality in this group was around 3% in titin dilated cardiomyopathy patients. Conclusions: Integration of genetic testing into the decision-making process for patients with electronic devices represents a paradigm shift in personalized medicine. By identifying genetic markers associated with arrhythmia susceptibility, heart failure etiology, and cardiac resynchronization therapy response, clinicians can tailor device choices to optimize patient outcomes.