Subcutaneous Implantable Cardioverter-defibrillator Research Articles

Comparison of infection and complication rates associated with transvenous vs. subcutaneous defibrillators in patients with stage 4 chronic kidney disease: a multicenter long-term retrospective follow-up.

Patients 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. We 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. The 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 < 0.05), device-associated complications (n = 13, 26.5% vs. n = 1, 4.8%; p < 0.05) and device associated hospitalizations (n = 10, 20.4% vs. n = 1, 4.8%; p < 0.05). In this long-term FU of patients with stage 4 CKD and an indication for a prophylactic ICD, the S-ICD was associated with significantly fewer device associated infections, complications and hospitalizations compared with TV-ICDs.

Erector Spinae Plane Block Decreases Narcotic Requirements in Patients Undergoing Subcutaneous Implantable Cardioverter-defibrillator Placement Under Sedation.

Providing adequate analgesia perioperatively during subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation can be a challenge. The objective of our study was to assess the efficacy and safety of the erector spinae plane (ESP) block technique in providing analgesia and minimizing the risk of opioid use in high-risk patient populations. We enrolled consecutive patients >18 years of age undergoing S-ICD implantation from February 2020 to February 2022 at our center prospectively. Patients were randomly assigned to receive the ESP block or traditional wound infiltration. A total of 24 patients were enrolled, including 13 patients randomized to ESP block and 11 patients as controls who received only wound infiltration. The primary outcome assessed was the overall use of perioperative analgesic medications in the ESP block group versus the surgical wound infiltration group. A significant reduction in intraoperative fentanyl use was observed [median ([interquartile range]) in the ESP block group (0 [0-50] μg) compared to the wound infiltration block group (75 [50-100] μg) (P = .001). The overall postoperative day (POD) 0 fentanyl use was also significantly decreased (75 [50-100] μg) in the ESP block group compared to the surgical wound infiltration group (100 [87.5-150] μg) (P = .049). There was also a trend of decreased POD 0 oxycodone-acetaminophen use. Finally, the number of days to discharge was less in the ESP block group. These results indicate that ESP block is an innovative, safe, and effective technique that decreases intraoperative and postoperative opioid consumption and may be a useful adjunct pain-management technique in these high-risk patients. Larger studies are needed to further validate its use.

Subcutaneous air entrapment after subcutaneous implantable cardioverter defibrillator implantation evaluated by computed tomography.

Inappropriate shock (IAS) caused by subcutaneous air entrapment (AE) in an early period after subcutaneous implantable cardioverter defibrillator (S-ICD) implantation has been reported, however, no detailed data on air volume are available. We evaluated the subcutaneous air volume after implantation and its absorption rate one week after implantation. Patients who underwent S-ICD implantation in our hospital received chest CT scans immediately after implantation and followed up 1 week later. The total subcutaneous air volume, air around the generator, the distal electrode, and the proximal electrode within 3cm were calculated using a three-dimensional workstation. Fat areas at the level of the lower edge of the generator were also analyzed. Fifteen patients received CT immediately after implantation. The mean age was 45.6±17.9 (66.7% of men), and the mean body mass index was 24.3±3.3. The three-incision technique was applied in seven patients and two-incision technique was in the latter eight patients. The mean total subcutaneous air volume was 18.54±7.50mL. Air volume around the generator, the distal electrode, and the proximal electrode were 11.05±5.12, 0.72±0.72, and 0.88±0.87mL, respectively. Twelve patients received a follow-up CT 1 week later. The mean total subcutaneous air was 0.25±0.45mL, showing a 98.7% absorption rate. Although subcutaneous air was observed in all patients after S-ICD implantation, most of the air was absorbed within 1 week, suggesting a low occurrence of AE-related IAS after a week postoperation.

Postoperative intravenous patient-controlled analgesia improves pain management after subcutaneous implantable defibrillator implantation.

Postoperative pain is a major issue with subcutaneous implantable cardioverter defibrillators (S-ICD). In 2020, we introduced intravenous patient-controlled analgesia (IV-PCA) in addition to the conventional, request-based analgesia for postoperative pain control in S-ICD. To determine the effect and safety, we quantitatively assessed the effect of IV-PCA after S-ICD surgery over conventional methods. During the study period, a total of 113 consecutive patients (age, 50.1 ± 15.5 years: males, 101) underwent a de novo S-ICD implantation under general anesthesia. While the postoperative pain was addressed with either request-based analgesia (by nonsteroid anti-inflammatory drugs, N = 68, dubbed as "PCA absent") or fentanyl-based IV-PCA in addition to the standard care (N = 45, dubbed as "PCA present"). The degree of postoperative pain from immediately after surgery to 1 week were retrospectively investigated by the numerical rating scale (NRS) divided into four groups at rest and during activity (0: no pain, 1-3: mild pain, 4-6: moderate pain, 7-10: severe pain). Although IV-PCA was removed on Day 1, it was associated with continued better pain control compared to PCA absent group. At rest, the proportion of patients expressing pain (mild or more) was significantly lower in the PCA present group from Day 0 to Day 4. In contrast to at rest, a better pain control continued through the entire study period of 7 days. No serious adverse events were observed. A few patients experienced nausea in both groups and the inter-group difference was not found significant. IV-PCA suppresses postoperative pain in S-ICD without major safety concerns.

Subcutaneous cardioverter defibrillator implanted intermuscularly in patients with end-stage renal disease requiring hemodialysis: 5-year follow-up.

The aim of the present study was to evaluate the long-term safety and effectiveness of the subcutaneous implantable cardioverter defibrillator (S-ICD) when implanted intermuscularly in patients with end-stage renal disease and hemodialysis. This study is a retrospective analysis of 21 consecutive patients implanted with S-ICDs at three experienced centers in Germany with comorbid renal insufficiency requiring hemodialysis, as well as being at risk of sudden cardiac death. The S-ICD was placed intermuscularly in all patients. Follow-ups (FUs) were performed every 6months. The mean ± standard deviation FU duration was 60.0 ± 11.4months, with a range of 39 to 78months. There were no deaths due to arrhythmia, or device-associatedinfections and complications. Four patients (19.1%) died during FU due to respiratory insufficiency during dialysis, systolic heart failure, septic infection of the urogenital tract, and colorectal cancer, respectively. There were six non-device-related hospitalizations with a duration of 12.7 ± 5.1days and a hospitalization rate of 4.1 per 100 patient years. In the long-term FU of this small population of seriously compromised hemodialysis patients at risk of sudden cardiac death, the intermuscularly implanted S-ICD system was safe and effective. No arrhythmic complications, device-associated infections, or complications compromised survival. These data are encouraging and support testing in a larger group of similarly compromised patients.

Utility of routine follow-up defibrillation safety margin testing in young patients with epicardial implantable cardioverter-defibrillators.

Routine defibrillation threshold testing (DFT) of transvenous implantable defibrillators (ICDs) has largely been in decline. In patients with non-transvenous ICDs that utilize subcutaneous and pleural ICD leads, serial DFT testing can detect a significant number of failures. Data about the utility of follow-up defibrillation safety margin testing (DSM) testing in pediatric patients and young adults with an epicardial ICD are lacking. Patients aged<25 years old who underwent epicardial ICD placement at Mayo Clinic from 2014 to 2023 with at least one follow-up DSM test were included. The patients were divided into a "routine" (R) and "clinically indicated" (CI) group based on the index of clinical concern. Inadequate DSM was defined as unsuccessful defibrillation at an output of less than 10 J below the maximum output of the device. The purpose of this study was to assess the utility of follow-up DSM testing. An epicardial ICD system was placed in 122 patients. A total of 26 patients met inclusion criteria and underwent a total of 47 DSM follow up tests. Inadequate DSM occurred in 1/33 (3%) in the R group and 2/14 (14%) DSM tests in the CI group. The median follow-up period was 54 and 36 months for the R and CI group, respectively. Our data suggest that epicardial ICDs are reliable and routine follow-up DSM testing may not be necessary for all patients. DSM testing should be performed in individuals with epicardial ICD systems when there is clinical concern about lead or coil performance.

Safety of Sports for Patients with Subcutaneous Implantable Cardioverter Defibrillator (SPORT S-ICD): study rationale and protocol

Background– Recent studies suggest that participation in recreational and even competitive sports is generally safe for patients with implantable cardioverted defibrillators (ICD). However, these studies included only patients with implanted transvenous ICD (TV-ICD). Nowadays, subcutaneous ICD (S-ICD) is safe and effective alternative and is increasingly implanted in younger ICD candidates. Data on the safety of sport participation for patients with implanted S-ICD systems is urgently needed. ObjectivesThe goal of the study is to quantify the risks (or “determine the safety”) of sports participation for athletes with an S-ICD, which will guide shared-decision making for athletes requiring an ICD and/or wishing to return to sports after implantation. MethodsThe SPORT S-ICD study is an international, multicenter, prospective, non-interventional, observational study, designed specifically to collect data on the safety of sports participation among patients with implanted S-ICD systems who regularly engage in sports activities. Results450 patients will undergo baseline assessment including baseline characteristics, indication for S-ICD implantation, arrhythmic history, S-ICD data and programming, and data regarding sports activities. Latitude Home-Monitoring information will be regularly transferred to the study coordinator for analysis. ConclusionsThe results of the study will aid in shaping clinical decision-making and if the tested hypothesis will be proven, it will allow the safe continuation of sports for patients with an implanted S-ICD.

Validation of the PRAETORIAN score in a large subcutaneous implantable cardioverter-defibrillator collective: Usefulness in clinical routine

BackgroundTo 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. ObjectiveThe purpose of this study was to validate the PRAETORIAN score in a large S-ICD collective. MethodsA 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. ResultsOverall, 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. ConclusionPRAETORIAN 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.

Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial

BackgroundThe PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events. ObjectiveThis prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias. MethodsThis multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm. ResultsIn total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13–279.95; P < .001). ConclusionA PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Ten years of subcutaneous defibrillator therapy: Consolidated clinical evidence and future perspectives.

The subcutaneous implantable cardioverter defibrillator (S-ICD) was developed as an alternative to the traditional transvenous implantable cardioverter defibrillator (TV-ICD), aiming to provide easier implantation, simplified detection algorithm of malignant ventricular arrhythmias and prevention from placing components in the cardiovascular system. The S-ICD is implanted subcutaneously or intramuscularly with the generator placed in the left midaxillary line and the lead tunneled subcutaneously in the left para-sternal region. Preimplant electrocardiogram screening is recommended to prevent implantation in patients at high risk of T wave over-sensing. Currently, the S-ICD is unsuitable for patients requiring pacing or cardiac resynchronization. Since the beginning, the S-ICD underwent extensive preclinical investigation until the first prospective multicentre trial demonstrating high efficacy and safety led to market release. While earlier studies focused on younger patients with higher ejection fraction, more recent studies showed favorable outcomes even in patients with comorbidities similar to those typically observed in patients receiving TV-ICD. The development of second and third generation devices has contributed to reduce inappropriate shocks and overcome previous limitations. The aim of this paper is to review the evidence in the literature over the past decade supporting S-ICD as a valid alternative to TV-ICD in terms of safety and efficacy, highlighting the improvements in technology, as well as outcomes.

Left ventricular assist device in the presence of subcutaneous implantable cardioverter defibrillator: Data from a multicenter experience

BackgroundLeft ventricular assist devices (LVADs) are an increasingly used strategy for the management of patients with advanced heart failure (HF). Subcutaneous implantable cardioverter defibrillator (S-ICD) might be a viable alternative to conventional ICDs with a lower risk of short- and long-term of device-related complications and infections.The aim of this multicenter study was to evaluate the outcomes and management of S-ICD recipients who underwent LVAD implantation. MethodsThe study population included patients with a preexisting S-ICD who underwent LVAD implantation for advanced HF despite optimal medical therapy. ResultsThe study population included 30 patients (25 male; median age 45 [38–52] years).The HeartMate III was the most common LVAD type. Median follow-up in the setting of concomitant use of S-ICDs and LVADs was 7 months (1–20).There were no reports of inability to interrogate S-ICD systems in this population. Electromagnetic interference (EMI) occurred in 21 (70%) patients. The primary sensing vector was the one most significantly involved in determining EMI. Twenty-seven patients (90%) remained eligible for S-ICD implantation with at least one optimal sensing vector. The remaining 3 patients (10%) were ineligible for S-ICD after attempts of reprogramming of sensing vectors. Six patients (20%) experienced inappropriate shocks (IS) due to EMI. Six patients (20%) experienced appropriate shocks. No S-ICD extraction because of need for antitachycardia pacing, ineffective therapy or infection was reported. ConclusionsConcomitant use of LVAD and S-ICD is feasible in most patients. However, the potential risk of EMI oversensing, IS and undersensing in the post-operative period following LVAD implantation should be considered. Careful screening for EMI should be performed in all sensing vectors after LVAD implantation.

Differences in underlying cardiac substrate among S-ICD recipients and its impact on long-term device-related outcomes: Real-world insights from the iSUSI registry

BackgroundOutcome comparisons among subcutaneous implantable cardioverter-defibrillator (S-ICD) recipients with nonischemic cardiomyopathies are scarce. ObjectiveThe aim of this study was to evaluate differences in device-related outcomes among S-ICD recipients with different structural substrates. MethodsPatients 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. ResultsAmong 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). ConclusionMost 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.

Use of subcutaneous cardioverter-defibrillator. First cases reported from National Institute of Cardiology Ignacio Chávez-Mexico.

The transvenous implantable cardioverter defibrillator (ICD) is the treatment of choice for the prevention of sudden cardiac death (SCD). Its use could be restricted when device-related infections occurs or in the pediatric population. In the later, an ICD represents a challenge, due to the minimal dimensions of the venous system in children, the length of the electrodes, the size of the generator, as well as the anatomical complexity in cases with associated congenital heart disease. This article presents the first Mexican patients with a subcutaneous ICD (SC-ICD) implant as a therapy for the prevention of SCD. The first four cases were implanted at the Ignacio Chávez National Institute of Cardiology with a SC-ICD (Emblem, Boston Scientific, USA), three of them were pediatric patients, including the first implant of this type of device in a pediatric patient in Latin America. The 3-incision and 2-incision techniques were used under general anesthesia. A successful implantation was obtained with the 3-incision technique in the first 2 cases and the last 2 with the 2-incision technique. Proper functioning of the device was corroborated in the operating room with proof of appropriate therapy (65 J) for ventricular fibrillation induced with 50 Hz stimulation. No immediate complications were observed. One patient had appropriate shocks two months after the implant. During follow-up, one child developed skin erosion at the level of the curve of the electrode on the sternum, with no signs of infection. In the operating room, the damaged skin was resected, the barrel and the fixation silk were removed, surgical lavage was performed, and the skin was closed again, thus avoiding removal of the system. The SC-ICD is an alternative therapy to the transvenous ICD. It can be considered first choice in subjects who do not require ventricular pacing, including pediatric patients. Skin complications can occur but do not pose a threat as venous complications of conventional ICDs.

Subcutaneous ICD in pediatric patients: safety matches necessity

Subcutaneous ICD in pediatric patients: safety matches necessity

Correlation between high- and low-voltage impedance measurements following subcutaneous implantable cardioverter-defibrillator implantation

Correlation between high- and low-voltage impedance measurements following subcutaneous implantable cardioverter-defibrillator implantation

Unanticipated subcutaneous ICD end-of-service due to premature battery depletion and occurrence of lead fracture: A single centre experience

The use of subcutaneous ICDs (S-ICD) is growing over years despite increasing alerts on premature battery depletion (PBD) and lead fractures leading to unanticipated device replacements. In our single-centre study including 192 patients, per year analysis demonstrated that incidence of PBD is higher than previously reported with overall greatest battery replacement requirements around the fifth year of follow-up. The underlying issue appears to be limited to old series devices, but only a longer follow-up will clarify the real impact of this phenomenon on patient outcomes. PBD is an underestimated S-ICDs issue and if the hereby demonstrated trend were to be confirmed in latest device series, this would bring significant concerns to patient safety and huge economic expense to health system.

The Psychological, Social, and Quality of Life Outcomes of People with a Cardiac Implantable Electronic Device: An Umbrella Review.

To synthesise the psychological, social, and quality of life outcomes of people with a cardiac implantable electronic device. An umbrella review of systematic reviews that reported the psychological, social, or quality of life outcomes of adults with a cardiac implantable electronic device was conducted. This umbrella review was preregistered with PROSPERO (CRD42023437078) and adhered to JBI and PRISMA guidelines. Seven databases (CINAHL, Cochrane Library, Embase, Emcare, Psycinfo, PubMed, and the Web of Science) were searched alongside citation and bibliographic searches. Methodological quality was assessed using the JBI Checklist of Systematic Reviews and Research Syntheses. Due to the heterogeneity of included reviews, findings were reported narratively. Fourteen systematic reviews met the inclusion criteria; eleven considered quality of life and three considered psychological outcomes. Little difference in quality of life was found between people with an implantable-cardioverter defibrillator and controls, however, a high prevalence of psychological disorders was present. Cardiac resynchronisation therapy devices demonstrated improvements in quality of life compared to control groups, alongside possible cognitive benefits. Quality of life did not differ between subcutaneous and transvenous implantable cardioverter-defibrillators. Pacemakers were associated with improved post-implantation quality of life. Research on the psychosocial and quality of life outcomes of people with a cardiac implantable electronic device is limited and inconsistent. Given the heterogeneity of current research, conclusions are uncertain. Nevertheless, some recipients may experience adverse psychosocial complications. Further research employing rigorous methodologies is needed and healthcare practitioners should provide care that acknowledges the potential for adverse psychosocial experiences. PROSPERO (CRD42023437078).

Comparison of Preoperative ECG Screening and Device-Based Vector Analysis in Patients Receiving a Subcutaneous Implantable Cardioverter-Defibrillator.

Background and Objectives: Subcutaneous implantable cardioverter-defibrillators (S-ICDs) provide protection against sudden cardiac death from outside the cardiovascular system. ECG screening is a prerequisite for implantation, but the reproducibility of its results post-operatively in the device is only partial. We aimed to compare the results of ECG screening with device-based sensing vector analysis. Materials and Methods: We screened the hospital records of all S-ICD recipients in our clinic. All of them had pre-operative ECG screening performed (primary, secondary, and alternate vectors). The results were compared with device-based vector analysis to determine the relation of the pre- and post-operative vector availability. Results: Complete ECG screening and device-based vector analysis were obtained for 103 patients. At least two acceptable vectors were found in 97.1% of the patients pre-operatively and in 96.1% post-operatively. When comparing vectors in terms of agreement (OK or FAIL) pre- and post-operatively, in 89.3% of the patients, the result for the primary vector was the same in both situations; for the secondary, it was in 84.5%, and for the alternate, it was in 74.8% of patients, respectively. In 55.3% of patients, all three vectors were labeled the same (OK or FAIL); in 37.9%, two vectors had the same result, and in 6.8%, only one vector had the same result pre- and post-operatively. The number of available vectors was the same pre- and post-operatively in 62.1% of patients, while in 15.5%, it was lower, and in 22.3% of patients, it was higher than observed during screening. Conclusions: Routine clinical pre-operative screening allowed for a good selection of candidates for S-ICD implantation. All patients had at least one vector available post-operatively. The final number of vectors available in the device-based analysis in most patients was at least the same (or higher) than during screening. The repeatability of the positive result for a single vector was high.

Two-incision versus three-incision implantation technique of subcutaneous implantable cardioverter defibrillator: Systematic review and meta-analysis of 2076 patients.

The implantable cardioverter-defibrillator (ICD) was designed to detect and treat ventricular arrhythmias, which account for nearly half of all cardiovascular fatalities. Transvenous ICD (TV-ICD) complications were reduced by introducing subcutaneous ICD (S-ICD). S-ICD can be implanted using a three (3IT)- or two (2IT)-incision technique. This systematic review and meta-analysis was conducted to compare the 3IT to the 2IT. We searched medical electronic databases of Cochrane Central, Embase, PubMed, Scopus, and Web of Science (WOS) from the study's inception until March 8, 2023. We compared 2IT and 3IT techniques of S-ICDs in terms of procedural, safety, and efficacy outcomes. We used Review Manager software for the statistical analysis. We calculated the risk ratio (RR) with its 95% confidence interval (CI) for dichotomous variables; and the mean difference with its 95% CI for continuous variables. We measured the heterogeneity using the chi-squared and I-squared tests. If the data were heterogeneous, the random-effect (RE) model was applied; otherwise, the fixed-effect model (FE) was used. We included three retrospective observational studies of 2076 patients, 1209 in the 2IT group and 867 in the 3IT. There was no statistically significant difference in erosion after S-ICD when 2IT compared with 3IT (RR=0.27, 95% CI: [0.07, 1.02]; P=.05) (I2=0%, P=.90). There was no difference in risk of infection, lead dislocation, or inappropriate shock with either incision technique (RR=0.78, 95% CI: [0.48, 1.29]; P=.34) (I2=0%, P=.71) and (RR=0.37, 95% CI: [0.02, 8.14]; P=.53) (I2=66%, P=.05) respectively. Our meta-analysis showed that the efficacy of both techniques is comparable; Appropriate shock (RR=0.94, 95% CI: [0.78, 1.12]; P=.48) (I2=0%, P=.81) and first shock efficacy (RR=0.89, 95% CI: [0.44, 1.82]; P=.76) (I2=0%, P=.87). 2IT and 3IT of S-ICD have comparable efficacy and complication rates; however, the 3IT exposes patients to an additional incision without any additional benefits. These findings may provide clinicians with a simpler method for subcutaneous ICD implantation and likely result in improved cosmetic outcomes. Before the 2IT technique can be considered the standard of care, randomized controlled trials (RCTs) must be conducted to assess its long-term safety and efficacy.

Defibrillation threshold in elective subcutaneous implantable defibrillator generator replacements: Time to reduce the size of the pulse generator?

IntroductionThe first step-down defibrillation studies in the subcutaneous implantable cardioverter-defibrillator (S-ICD) described a defibrillation threshold (DFT) of 32.5 ± 17.0 J and 36.6 ± 19.8 J. Therefore, the default shock output of the S-ICD was set at 80 J. In de novo implants, the DFT is lower in optimally positioned S-ICDs. However, a retrospective analysis raised concerns about a high DFT in S-ICD replacements, possibly related to fibrosis. ObjectiveWe aimed to find the DFT in patients undergoing S-ICD generator replacement. MethodsThis prospective study enrolled patients who underwent S-ICD generator replacement with subsequent defibrillation testing. A pre-specified defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that effectively terminated the induced ventricular arrhythmia. ResultsA total of 45 patients were enrolled, 6.0 ± 2.1 years after initial implant. Mean DFT during replacement in the total cohort was 27.4 ± 14.3 J. In patients with a body mass index (BMI) 18.5–25 kg/m2 (N = 22, BMI 22.5 ± 1.6), median DFT was 20 J (IQR 17.5–30). In 18/22 patients, the DFT was ≤30 J and 5/22 patients were successfully defibrillated at 10 J. One patient with hypertrophic cardiomyopathy had a DFT of 65 J. In patients with a BMI >25 kg/m2 (N = 23, BMI 29.5 ± 4.2), median DFT was 30 J (IQR 20–40). In 15/23 patients, the DFT was ≤30 J and 4/23 patients had a successful defibrillation test at 10 J. ConclusionsThis study eases concerns about a high DFT after S-ICD generator replacement. The majority of patients had a DFT ≤30 J, regardless of BMI, suggesting that the shock output of the S-ICD could be safely reduced.