Subcutaneous Implantable Cardioverter-defibrillator Therapy Research Articles

Short- and long-term patient-reported outcomes of subcutaneous implantable cardioverter-defibrillator therapy: Results from the RHYTHM DETECT Registry

Short- and long-term patient-reported outcomes of subcutaneous implantable cardioverter-defibrillator therapy: Results from the RHYTHM DETECT Registry

Short- and long-term patient-reported outcomes of subcutaneous implantable cardioverter-defibrillator therapy

Abstract Background The safety and efficacy of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy are well-established. However, there is a paucity of patient-reported outcome data, despite the increasing emphasis on incorporating patients' perspectives into quality care assessments. Current guidelines also recommend evaluating psychological status and addressing distress in defibrillator patients. Purpose This study aims to assess perioperative and postoperative pain during S-ICD implantation, along with patient acceptance during follow-up. We also explore associations between these outcomes, clinical characteristics, and implantation variables. Methods A total of 149 consecutive patients (87% male, mean age 53±13 years, body mass index 27±4 Kg/m², ejection fraction 39±14%) who underwent S-ICD implantation across 11 centers were analyzed. Short-term endpoints included pain during and 6 hours after the procedure. Pain intensity was rated on a 10-point visual analogue scale. Long-term endpoint was S-ICD patient acceptance measured (on a 0-to-100 point scale) by the Florida Patients Acceptance Survey (FPAS) score and its components: Return to Function (RTF), Device-Related Distress (DRD), Positive Appraisal (PA), and Body Image Concerns (BIC). The survey was administered 12 months post-implantation. Results The S-ICD generator was positioned in an intermuscular pocket in 140 (94%) patients. Serratus anterior plane block (SAPB) was performed in 103 (69%) patients. 72 (48%) patients underwent the defibrillation testing. Implantation success was reported in all patients without operative complications. Overall, pain intensity during implantation was 2 [25th-75th percentile: 1-4], and 1 [1-2] for static pain and 2 [1-3] for dynamic pain, 6 hours post-procedure. SAPB was associated with significantly lower pain intensity during implantation (2 [1-3] vs. 4 [2-5], p<0.001) and non-significantly lower values of dynamic pain intensity 6 hours post-procedure (1 [1-2] versus 2 [1-3], p=0.076). The other tested variables, i.e. age, sex, body habitus, ejection fraction, omission of defibrillation testing, were not associated with different pain levels. S-ICD acceptance scores were favorable overall (total FPAS 77 [63-87], RTF 69 [56-88], DRD 25 [10-45], PA 88 [75-100], BIC 13 [0-38]). Patients who underwent SAPB exhibited better RTF (75 [56-88] versus 63 [50-69], p=0.002) and PA (88 [75-100] versus 75 [69-94], p=0.004). Conclusions S-ICD implantation resulted in minimal discomfort, especially with novel anesthetic techniques. Overall, patients reported good acceptance of the S-ICD. Improved acceptance was observed in patients who underwent SAPB, highlighting the significance of enhanced patient implantation experience for long-term outcomes.

The clinical and economic impact of extended battery longevity of a substernal extravascular implantable cardioverter defibrillator.

The extravascular implantable cardioverter defibrillator (EV ICD) has extended projected battery longevity compared to the subcutaneous implantable cardioverter defibrillator (S-ICD). This study used modeling to characterize the need for generator changes, long-term complications, and overall costs for both the EV ICD and S-ICD in healthcare systems of various countries. Battery longevity data were modeled using a Markov model from averages reported in device labeling for the S-ICD and with engineering estimates based on real life usage from EV ICD Pivotal Study patient data to introduce variability. Clinical demographic data were derived from published literature. The primary outcomes were defined as the number of generator replacement surgeries, complications, and total healthcare system costs due to battery depletion over the expected lifetime of patients receiving EV ICD or S-ICD therapy. Average modeled battery longevity was determined to be 7.3 years for the S-ICD versus 11.8 years for the EV ICD. The probability of a complication after a replacement procedure was 1.4%, with an operative mortality rate of 0.02%. The use of EV ICD was associated with 1.4-1.6 fewer replacements on average over an expected patient lifetime as compared to S-ICD and a 24.3%-26.0% reduction in cost. A one-way sensitivity analysis of the model for the US healthcare system found that use of an EV ICD resulted in a reduction in replacement surgeries of greater than 1 (1.1-1.6) along with five-figure cost savings in all scenarios ($18 602-$40 948). The longer projected battery life of the EV ICD has the potential to meaningfully reduce long-term morbidity and healthcare resources related to generator changes from the perspective of multiple diverse healthcare systems.

Subcutaneous implantable cardioverter-defibrillator therapy in Poland: Results of the Polish S-ICD Registry.

The use of a subcutaneous implantable cardioverter-defibrillator (S-ICD) has been expanding in Poland since 2014. The Polish Registry of S-ICD Implantations was held by the Heart Rhythm Section of the Polish Cardiac Society between May 2020 and September 2022 to monitor the implementation of that therapy in Poland. To investigate and present the state-of-the-art of S-ICD implantation in Poland. Implanting centers reported clinical data of patients undergoing S-ICD implantations and replacements, including: age, gender, height, weight, underlying disease, history of pacemaker and defibrillator implantations, indications for S-ICD, electrocardiographical parameters, procedural techniques, and complications. 440 patients undergoing S-ICD implantation (411) or replacement (29) were reported by 16 centers. Most patients were in New York Heart Association class II (218 patients, 53%) or I (150 patients, 36.5%). Left ventricular ejection fraction was 10-80%, median (IQR) 33% (25%‒55%). Primary prevention indications were present in 273 patients (66.4%). Non-ischemic cardiomyopathy was reported in 194 patients (47.2%). The main reason for the choice of S-ICD were: young age (309, 75.2%), risk of infective complications (46, 11.2%), prior infective endocarditis (36, 8.8%), hemodialysis (23, 5.6%), and immunosuppressive therapy (7, 1.7%). Electrocardiographic screening was performed in 90% of patients. The rate of adverse events was low (1.7%). No surgical complications were observed. Qualification for S-ICD in Poland was slightly different when compared to the rest of Europe. The implantation technique was mostly consistent with the current guidelines. S-ICD implantation was safe, and the complication rate was low.

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

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

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

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

Standard and extended electrocardiographic screening for the subcutaneous implantable cardioverter-defibrillator

Abstract Funding Acknowledgements Type of funding sources: None. Background The subcutaneous implantable cardioverter-defibrillator (SICD) is effective therapy for sudden cardiac death prevention. The condition for implantation is an electrocardiographic screening test before procedure (ECG-s). Patients who don’t pass are regarded to be at risk of inappropriate detection of tachyarrhythmias with inappropriate interventions. A patient is considered suitable for implant if at least one surface ECG lead (sense vector) is acceptable for all tested postures. Objective The aim of the study was to identify the incidence of failure, the predicting factors and clinical importance of extended ECG-s with right sided lead position and lying on the left and right side of the body. Methods ECG-s to determine suitability for SICD is based and performed using a manufacturer –specific measurement tool. We performed this test in 75 consecutive pts with indication for SICD therapy on the basis of standard manufacturer protocol(lead at the left sternum border: sitting, standing and lying position), and extended for right sternal lead location and two additional body position: lying on the left and right side (10 position for each individual). We analyzed: age, gender, body mass index(BMI), heart rate, heart rhythm(sinus/atrial fibrillation), QRS duration, PR interval, corrected QT interval(QTc), echocardiography parameters, etiology. Results ECG-s failure occurred in 6/75(8%) of patients. Screening results: 1 vector failure rate with the standard device and lead positions: primary(P) 12%, seconadary(S) 17%, alternative(A) 40%, P vs. A and S vs. A p<0,001. Testing with an electrode positioned on the right sternum border- 1 vector failure: (P) 10%,seconadary(S) 17%, alternative(A) 48%, P vs. A and S vs. A p<0,001. In case of failure on left side 50%, 14% and 6% of pts passed the test with the right sided lead position for P, S and A vector respectively, p<0.001. Identified factors predicting ESG-s passing vs. failure included: QTc interval 445,32±35,4 vs. 480,6±37,6 ms for any vector(p=0,034), BMI:26,7±4,7 vs. 29,9±4,7 for vector A( p=0,008 ), EF: 43,3±20,1 vs. 34,0±16,2 for vector A( p=0,027). Sense vector failure rate with the left sternal lead location lying on the left and right side of the body was concordant with the rate lying on the back, p=0,05. For the right parasternal lead location the rate failure was lower lying on the right side for all sense vectors: P, S and A(p=0,045; 0,083 and 0,020) respectively. Conclusions ECG screening failure rate for SICD is comparable with previous reports. The right sternal lead location screening is effective and enables important clinical findings before implantation and in case of lead reposition( defibrillation threshold test failure) during procedure. We recommend to screen routinely on both sternum borders. Some additional body position testing: lying on the left and right side of the body, mimicking sleeping/rest could be an important element to determine eligibility for SICD.

The eligibility of patients with an inherited cardiac disease for therapy with a subcutaneous implantable cardioverter-defibrillator

Abstract Introduction The subcutaneous implantable cardioverter-defibrillator (S-ICD) is considered especially beneficial in young patients with an inherited cardiac disease, but data on these patient groups is limited. Purpose To evaluate the eligibility of patients with an inherited cardiac disease for therapy with a subcutaneous implantable cardioverter-defibrillator Methods We retrospectively analysed all patients with an inherited cardiac disease who received an S-ICD in our tertiary center between February 2009 and June 2021. ECG parameters and data on appropriate and inappropriate shocks were collected. Different diagnoses were compared using a chi-square test. Results We analysed 109 patients who were diagnosed with IVF (DPP6-based, N=41, 37.6%), HCM (N=36, 33.0%), Brugada syndrome (BrS, N=13, 11.9%), ARVC (N=9, 8.3%), PLN (N=3, 2.8%), LQTS (N=2, 1.8%) and other cardiomyopathies (N=5, 4.6%). Mean follow-up was 5.5±3.4 years. ECG parameters did not significantly change during follow-up. HCM patients were most likely to receive an appropriate shock (10/36, P=0.01), followed by ARVC (2/9, P=0.57) and Brugada patients (1/13, P=0.40). Patients with LQTS had most frequently inappropriate shocks (1/2, P=0.06), followed by BrS (4/13, P=0.008) and HCM patients (4/36, P=0.8). Conclusion Patients with an inherited cardiac disease are eligible for S-ICD therapy, but comes with a risk of inappropriate shocks, especially in patients with LQTS and BrS. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Dutch Heart Foundation (CVON 2018-10 PREDICT2)

Current clinical practice of subcutaneous implantable cardioverter-defibrillator: Analysis using the JROAD-DPC database

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

Reasons for replacement and extraction of the subcutaneous implantable cardioverter-defibrillator in a large cohort

Abstract Funding Acknowledgements Type of funding sources: None. Background The subcutaneous implantable cardioverter-defibrillator (S-ICD) is proven to be a safe and effective alternative to the transvenous ICD. However, battery longevity is estimated to be shorter in the S-ICD, although newer generations S-ICD are thought to have an increased battery longevity compared to the first generation. In addition, the S-ICD lacks the option for pacing therapy and may therefore be extracted in patients who later develop an indication for bradycardia pacing, antitachycardia pacing or resynchronization therapy. In this analysis, we aim to evaluate occurrence and reasons for S-ICD replacement and extraction. Methods In this retrospective analysis, we collected data on S-ICD generator replacement and extraction from consecutive patients who were implanted with an S-ICD in our tertiary center between February 2009 and December 2021. Results A total of 408 patients received an S-ICD, with a median follow-up duration of 4.0 (IQR 1.5-6.8) years. Of the 168 implanted first generation S-ICDs, 123 (73.2%) were replaced after a mean of 5.9 ± 0.8 years, all due to battery depletion. A second generation S-ICD was replaced in 2/40 (5%) patients and a third generation S-ICD in 11/200 patients (5.5%), after a mean of 4.8 ± 0.12 and 3.6 ± 1.6 years, respectively. Two third generation S-ICDs were replaced due to device malfunction, all other replacements (134/136, 98.5%) were due to battery depletion. The S-ICD was extracted in 38/408 (9.3%) patients. The mean time from initial implantation to extraction was 3.7 ± 2.5 years. Reasons for extraction were a newly developed indication for pacing or resynchronization therapy (N = 14), an expired indication for ICD therapy (N = 8), heart transplantation or implantation of left ventricular assist device (N = 4), repeated inappropriate shocks (N = 4), pocket infection (N = 3), pocket erosion (N = 2), lead defect (N = 1), Twiddler syndrome (N = 1) and patient preference (N = 1). A new S-ICD could be re-implanted in 7 patients (18.4%), a cardiac resynchronization therapy defibrillator was implanted in 7 patients (18.4%) and there was a need for a transvenous ICD in 10 patients (26.3%). The remaining 14 patients (36.8%) were not re-implanted with any type of ICD. Reasons for end of S-ICD therapy are presented in the figure. Conclusion In this large cohort, a battery longevity of the first generation S-ICD of 5.9 years was reached. After a median follow-up duration of 4.0 years, 17/408 patients received a transvenous device, due to the need for bradycardia or antitachycardia pacing or resynchronization therapy. Importantly, 14/408 patients underwent an S-ICD extraction and were not re-implanted with any type of ICD. These patients may especially benefit from S-ICD therapy, as this device is less complicated to extract compared to a transvenous ICD.

Safety and Efficacy of Magnet Use to Temporarily Inhibit Inappropriate Subcutaneous Implantable Cardioverter Defibrillator Therapy in Emergency Situations: A Case Report

Abstract Introduction: The subcutaneous implantable cardioverter defibrillator (S-ICD) represents a major advancement in ICD technology. Inappropriate shocks (IAS) occur in more than 3.1% of the population with S-ICD each year and are usually followed by admission to the emergency department (ED). In this setting, the disabling of IAS is mandatory during a pseudo-electrical storm (ES). This report describes the strategies that can be followed in order to temporarily inhibit IAS in critical care settings with the use of magnets. Case presentation: An S-ICD was implanted more than 6 weeks prior to presentation in a 68-year-old man with hypertrophic cardiomyopathy. In the ED, the patient experienced 3 IAS in the last hour. A Medtronic magnet was applied to stop IAS, as the specific programmer was not available. The maneuver interrupted the IAS. In order to verify the universal magnetic response of the S-ICD, six different magnets and one smartphone with MagSafe technology were tested. All magnet models suspended arrhythmia detection and IAS, while the smartphone did not cause magnet interferences. Conclusions: This report demonstrates the safety and efficacy of all clinical magnet models in inhibiting IAS. In case of pseudo-ES, any type of magnet allows ED providers to easily and rapidly disable the functionality of the devices when appropriate.

Comparative Assessment of Transvenous versus Subcutaneous Implantable Cardioverter-defibrillator Therapy Outcomes: An Updated Systematic Review and Meta-analysis

BackgroundSubcutaneous (S-ICD) and transvenous (TV-ICD) implantable cardioverter-defibrillator devices effectively reduce the incidence of sudden cardiac death in patients at a high risk of ventricular arrhythmias. This study aimed to evaluate the safe replacement of TV-ICD with S-ICD based on updated recent evidence. MethodsWe systematically searched EMBASE, JSTOR, PubMed/MEDLINE, and Cochrane Library on 30 July 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. ResultsWe identified 26 studies that examined 7542 (58.27%) patients with S-ICD and 5400 (41.72%) with TV-ICD. The findings indicated that, compared to patients with TV-ICD, patients with S-ICD had a lower incidence of defibrillation lead failure (odds ratio [OR], 0.12; 95% confidence interval [CI], 0.01–0.98; p = 0.05), lead displacement or fracture (OR, 0.25; 95% CI, 0.12–0.86; p = 0.0003), pneumothorax and/or hemothorax (OR: 0.22, 95% CI 0.05, 0.97, p = 0.05), device failure (OR: 0.70, 95% CI 0.51, 0.95, p = 0.02), all-cause mortality (OR: 0.44 [95% CI 0.32, 0.60], p < 0.001), and lead erosion (OR: 0.01, 95% CI 0.00, 0.05, p < 0.001). Patients with TV-ICD had a higher incidence of pocket complications than patients with S-ICD (OR, 2.13; 95% CI, 1.23–3.69; p = 0.007) and a higher but insignificant incidence of inappropriate sensing (OR, 3.53; 95% CI, 0.97–12.86; p = 0.06). ConclusionsThe S-ICD algorithm was safer and more effective than the TV-ICD system as it minimized the incidence of pocket complications, lead displacement or fracture, inappropriate sensing, defibrillation lead failure, pneumothorax/hemothorax, device failure, lead erosion, and all-cause mortality. Future studies should explore the scope of integrating novel algorithms with the current S-ICD systems to improve cardiovascular outcomes.

Eligibility for subcutaneous implantable cardioverter-defibrillator in adults with congenital heart disease.

AimsPatients with adult congenital heart disease (ACHD) carry an increased risk for sudden cardiac death. Implantable cardioverter‐defibrillator (ICD) therapy may be challenging in these patients due to anatomical barriers, repeated cardiac surgery, or complicated transvenous access. Thus, the subcutaneous ICD (S‐ICD) can be a promising alternative in this patient population. Patients with ACHD show significant electrocardiogram (ECG) abnormalities, which could affect S‐ICD sensing because it depends on surface ECG.Methods and resultsOne hundred patients with ACHD were screened for S‐ICD eligibility. Standard ECG‐based screening test and automated S‐ICD screening test were performed in all patients. Sixty‐six patients (66%) were male. Underlying congenital heart disease (CHD) was mainly CHD of great complexity (71%) and moderate complexity (29%), including repaired tetralogy of Fallot (20%), which was the most common entity. Thirty‐seven patients (37%) already had a pacemaker (23%) or ICD (14%) implanted. Automated screening test identified 83 patients (83%) eligible for S‐ICD implantation in either left parasternal position (78%) or right parasternal position (75%). Absence of sinus rhythm, QRS duration, and a paced QRS complex were associated with S‐ICD screening failure in univariate analysis. Receiver operating characteristic curve and multivariate analysis revealed a QRS duration ≥148 ms as the only independent predictor for S‐ICD screening failure.ConclusionsPatients with ACHD show satisfactory eligibility rates (83%) for S‐ICD implantation utilizing the automated screening test, including patients with CHD of high complexity. S‐ICD therapy should be considered with caution in ACHD patients with a QRS duration ≥148 ms and/or need for ventricular pacing.

A novel screening tool to unmask potential interference between S-ICD and left ventricular assist device.

In patients with a left ventricular assist device (LVAD), the subcutaneous implantable cardioverter-defibrillator (S-ICD) can be an alternative to transvenous ICD systems due to reduced risk of systemic infection, which could lead to extraction of the ICD as well as the LVAD. S-ICD eligibility is lower in patients with LVAD than in patients with end-stage heart failure without LVAD. Several reports have shown inappropriate S-ICD therapy in the coexistence of LVAD and S-ICD. The aim of the present study was to evaluate S-ICD eligibility in patients with LVAD using the established electrocardiogram (ECG)-based screening test as well as a novel device-based screening test to identify potentially inappropriate S-ICD sensing in this specific patient cohort. The present study included 115 patients implanted with an LVAD. The standard ECG-based screening test and a novel device-based screening test were performed in all patients. Eighty patients (70%) were eligible for S-ICD therapy with the standard ECG-based screening test. Performance of the novel device-based screening test identified device-device interference in 14 of these 80 patients (12%). Using a novel extended device-based S-ICD screening method, a small number of patients with LVAD deemed eligible for S-ICD with the standard ECG-based screening test exhibit device-device interference. Careful S-ICD screening should be performed in patients with LVAD, who are candidates for S-ICD therapy, to prevent inappropriate sensing or ICD therapy.

Usefulness of subcutaneous implantable cardioverter-defibrillator therapy in patients with Brugada syndrome.

Implantable cardioverter-defibrillators (ICDs) are the main therapy to prevent sudden cardiac death in patients with Brugada syndrome (BrS). The subcutaneous ICD (S-ICD) can eliminate lead-associated complications compared with transvenous ICD (TV-ICD). However, S-ICD is susceptible to T-wave oversensing (TWOS) and may result in more frequent inappropriate shocks in patients with BrS. This study aimed to compare inappropriate shocks between TV-ICD and S-ICD in patients with BrS. We enrolled 32 patients with BrS (including one woman; mean age 52 ± 18years) who were implanted with ICD (23 TV-ICDs and 9 S-ICDs) between January 2002 and November 2018 in Oita University Hospital. We carried out a standard surface electrocardiogram (ECG) screening tests in both supine and standing positions prior to S-ICD implantation. The patients received routine clinical review every month and device monitoring every 4months. The period of follow-up was 129 ± 51months. Six patients with BrS and TV-ICDs experienced inappropriate shocks (26%) with their ICD therapy. In contrast, two patients with BrS and S-ICDs experienced inappropriate shocks (22%). There was no significant difference between the two groups (P = 0.82). Although one case in the S-ICD group experienced TWOS-induced inappropriate shock, SMART Pass (new high-pass filter) prevented the subsequent recurrence of inappropriate shocks during ICD therapy. Our results suggest that S-ICD is not inferior to TV-ICD in the incidence of inappropriate shocks. SMART Pass may be a useful tool to prevent inappropriate ICD shocks by TWOS in patients with BrS.

Eligibility for subcutaneous implantable cardioverter-defibrillator in patients with left ventricular assist device

PurposeThe subcutaneous implantable cardioverter-defibrillator (S-ICD) could be a promising alternative to the conventional transvenous ICD in patients with LVAD due to its reduced risk of infection. However, surface ECG is altered following LVAD implantation and, since S-ICD detection is based on surface ECG, S-ICD could be potentially affected. The aim of the present study was to analyze S-ICD eligibility in patients with LVAD.MethodsSeventy-five patients implanted with an LVAD were included in this prospective single-center study. The ECG-based screening test and the automated screening test were performed in all patients.ResultsFifty-five (73.3%) patients had either a positive ECG-based or automated screening test. Out of these, 28 (37.3%) patients were found eligible for S-ICD implantation with both screening tests performed. ECG-based screening test was positive in 50 (66.6%) patients; automated screening test was positive in 33 (44.0%) patients. Three ECG-based screening tests could not be evaluated due to artifacts. With the automated screening test, in 9 (12.0%) patients, the test yielded no result.ConclusionsPatients implanted with an LVAD showed lower S-ICD eligibility rates compared with patients without LVAD. With an S-ICD eligibility rate of maximal 73.3%, S-ICD therapy may be a feasible option in these patients. Nevertheless, S-ICD implantation should be carefully weighed against potential device-device interference. Prospective studies regarding S-ICD eligibility before and after LVAD implantation are required to further elucidate the role of S-ICD therapy in this population.

INAPPROPRIATE S-ICD PATIENT RECEIVES FALSE POSITIVE SHOCKS

Subcutaneous implantable cardioverter defibrillator (S-ICD) protects the patients at risk for sudden cardiac death while leaving the heart and vasculature untouched. It provides life-saving therapy, but may also deliver inappropriate therapy. Presented case demonstrates a possibility of S-ICD therapy induction due to double-counting. It was original caused by lack of suitable sensing vectors and the solution was possible just particularly. As the inter-individual variability of subcutaneous cardiac signal is considerable, the patient screening should be necessary for identification of such patients, which have an unsuitable subcutaneous sensing signals.

Incidence of myopotential induction in subcutaneous implantable cardioverter-defibrillator patients: Is the oversensing issue really solved?

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has established its role in the prevention of sudden cardiac death in a defined population. Inappropriate shocks and device malfunction in S-ICD therapy may be caused by myopotential (MP) oversensing. The purpose of this study was to systematically evaluate a cohort of consecutive S-ICD patients for MP inducibility. After S-ICD implantation, all vectors (primary [PrimV], secondary [SecV], alternative [AltV]) were analyzed during isometric chest press (ICP), lifting and holding a 20-kg weight, and side plank exercise (SPE), supporting the body weight on the left arm. When MPs were induced, signal classification was assessed: adequate noise detection, induced undersensing (R waves classified as noise), and oversensing (noise annotated as R waves). In case of noise induction in the current vector, device reprogramming to a noise-free vector was done. We systematically assessed 41 patients. In nearly all patients (90.2%), MPs were inducible. ICP was the most potent inductor of MPs. Whereas SecV (70.7%) and AltV (75.6%) were most vulnerable during ICP, PrimV was most affected during SPE (51.2%). In only a few cases did the S-ICD software distinguish correctly between MPs and QRS. MPs predominantly led to undersensing (up to 65.9%), but in up to 22% of patients MP-induced oversensing occurred but did not lead to tachycardia detection. No relation was seen between S-ICD lead and generator position and MP inducibility. Induction of MPs during physical exercise was observed frequently. Although in most cases MP noise led to undersensing, oversensing events were commonly observed.

Understanding Outcomes with the EMBLEM S-ICD in Primary Prevention Patients with Low EF Study (UNTOUCHED): Clinical characteristics and perioperative results

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has shown favorable outcomes in large registries with broad inclusion criteria. The cohorts reported had less heart disease and fewer comorbidities than standard ICD populations. The purpose of this study is to characterize acute performance for primary prevention patients with a left ventricular ejection fraction (LVEF) ≤35% (primary prevention ≤35%). Primary prevention ≤35% patients with no prior documented sustained ventricular tachycardia (VT), pacing indication, end-stage heart failure, or advanced renal failure were prospectively enrolled. Analyses included descriptive statistics, Kaplan-Meier time to event, and multivariable linear and logistic regression. In 1112 of 1116 patients, an S-ICD was successfully implanted (99.6%). Predictors for longer procedure time included 3-incision technique, higher body mass index (BMI), performing defibrillation testing (DFT), imaging, younger age, black race, and European vs North American centers. Patients undergoing DFT (82%) were successfully converted (99.2%; 93.5% converting at ≤65 J). Higher BMI was predictive of failing DFT at ≤65 J. The rate of 30-day freedom from complications was 95.8%. Most complications involved postoperative healing (45%) or interventions after DFT or impedance check (19%). The procedural outcome data of UNTOUCHED reinforce that S-ICD therapy has low perioperative complication rates and high conversion efficacy of induced ventricular fibrillation, even in a higher-risk cohort with low LVEF and more comorbidities than previous S-ICD studies. Higher BMI warrants more careful attention to implant technique.

Subcutaneous implantable cardioverter defibrillator in cardiomyopathies and channelopathies.

: Cardiomyopathies and channelopathies are heterogeneous disorders that increase the risk of sudden cardiac death (SCD). Implantable cardioverter-defibrillator (ICD) therapy is safe and effective for preventing SCD in patients at risk for malignant ventricular arrhythmias. Because of the poor positive predictive value of current risk stratification tools, the majority of patients implanted with an ICD will never receive a life-saving therapy but will be exposed to the risk of complications such as device infection, lead failure and inappropriate therapy. Subcutaneous ICD (S-ICD) now constitutes a valuable alternative to conventional transvenous ICD in patients with cardiomyopathies and channelopathies as it provides protection from SCD while avoiding the risks of intravascular lead infection or failure. This may be particularly advantageous for young patients with a very long life expectancy. On the other hand, S-ICD cannot deliver antitachycardia pacing or antibradycardia pacing. The purpose of this article is to review the available evidence and the future perspectives of S-ICD therapy in patients with cardiomyopathies or channelopathies.