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

BACKGROUND

Implantable cardioverter defibrillators (ICD) prevent sudden cardiac death (SCD). Patients with end-stage renal disease (ESRD) requiring dialysis are at a very high risk of infection from cardiac implantable electronic device (CIED) implantation as well as mortality. In the present study, we compared the long-term complications and outcomes between subcutaneous ICD (S-ICD) and transvenous ICD (TV-ICD) recipients.

METHODS

In this retrospective analysis, we analyzed a total of 43 patients with ESRD requiring dialysis who received either a prophylactic S-ICD (26 patients) or a single right ventricular lead TV-ICD (17 patients) at seven experienced centers in Germany. Follow-up was performed bi-annually, at the end of which the data concerning comorbidities and, if applicable, reason for death were checked and confirmed with patients' general practitioner, nephrologist and cardiologist.

RESULTS

The median follow up duration was 95.6 months (range 42.8-126.3 months). Baseline characteristics were without noteworthy significant differences between groups. During follow-up (FU), there were significantly more device-associated infections (HR 8.72, 95% confidence interval (CI), 1.18 to 12.85, p < 0.05) and device-associated hospitalizations (HR 10.20, 95% CI 1.22 to 84.61, p < 0.001), as well as a higher cardiovascular mortality (HR 9.17, 95% CI 1.12 to 8.33, p < 0.05), in the TV-ICD group. The number of patients requiring hospitalization for any reason was significantly higher in the TV-ICD group (HR 2.59, 95% CI 1.12 to 6.41, p < 0.05). There was no significant difference in overall mortality (HR 1.92, 95% CI 0.96 to 6.15, p = 0.274).

CONCLUSIONS

Our data suggest that, in this extended follow-up in seriously compromised renal patients on dialysis, the S-ICD patients have statistically fewer device infections and hospitalizations as well as lower cardiac mortality compared with the TV-ICD cohort.

Fifteen years of subcutaneous implantable cardioverter-defibrillator therapy: Where do we stand, and what will the future hold?

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has emerged as a feasible alternative to the transvenous ICD in the treatment of ventricular tachyarrhythmias in patients without indications for pacing or cardiac resynchronization therapy. Since its introduction, numerous innovations have been made and clinical experience has been gained, leading to its adoption in current practice and preference in certain populations. Moreover, emerging technologies like the extravascular ICD and the combination of the S-ICD with the leadless pacemaker offer new possibilities for the future. These advancements underscore the evolving role of the S-ICD in management of ventricular tachyarrhythmias. This review outlines implantation considerations, patient selection, and troubleshooting advancements in the last 15 years and provides insights into future perspectives.

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

Background

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.

Methods

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.

Results

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).

Conclusion

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.

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.

[History of the implantable cardioverter-defibrillator in Germany]

The implantable cardioverter-defibrillator (ICD) was a breakthrough in the prevention of sudden cardiac death. After years of technical development in the USA, Michel Mirowski succeeded in proving reliable automatic defibrillation of ventricular tachyarrhythmias through initial human implantations in 1980, despite many obstacles. Nearly 4 years later, the first patients received ICDs at multiple centers in Germany. Subsequently, outside the USA, Germany became the country with highest implantation rates. The absolute number of implantations remained small as long as implantations required epicardial defibrillation electrodes and therefore thoracotomy by cardiac surgeons. Pacemaker-like implantation using a transvenous defibrillation electrode with a pectoral ICD became feasible in the early 1990s pushing implantation rates to the next level. Technical advancements were accompanied by clinical research in Germany, and often, the first-in-human studies were conducted in Germany. In 1991, the first guidelines for indications were established in the USA and Germany. Several randomized studies on indications were published between 1996 and 2009, mostly led by American teams with German participation, but also under German leadership (CASH, CAT, DINAMIT, IRIS). The DANISH study in 2016 questioned the results of these long-standing studies. Instead of providing ICDs to patients using a broad indication, future efforts aim to identify patients who, despite optimal medical therapy, cardiac resynchronization therapy (CRT), and/or catheter ablation, need protection against sudden cardiac death. Risk scores incorporating myocardial scars in magnetic resonance imaging (MRI) and genetic information are expected to contribute to more individualized and effective indications.

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

BACKGROUND

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.

METHODS

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 6 months.

RESULTS

The mean ± standard deviation FU duration was 60.0 ± 11.4 months, with a range of 39 to 78 months. There were no deaths due to arrhythmia, or device-associated infections 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 ± 5.1 days and a hospitalization rate of 4.1 per 100 patient years.

CONCLUSIONS

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.

Procedure, management, and outcome of subcutaneous implantable cardioverter-defibrillator extraction in clinical practice

AIMS

Subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy is expanding rapidly. However, there are few data on the S-ICD extraction procedure and subsequent patient management. The aim of this analysis was to describe the procedure, management, and outcome of S-ICD extractions in clinical practice.

METHODS AND RESULTS

We enrolled consecutive patients who required complete S-ICD extraction at 66 Italian centres. From 2013 to 2022, 2718 patients undergoing de novo implantation of an S-ICD were enrolled. Of these, 71 required complete S-ICD system extraction (17 owing to infection). The S-ICD system was successfully extracted in all patients, and no complications were reported; the median procedure duration was 40 (25th-75th percentile: 20-55) min. Simple manual traction was sufficient to remove the lead in 59 (84%) patients, in whom lead-dwelling time was shorter [20 (9-32) months vs. 30 (22-41) months; P = 0.032]. Hospitalization time was short in the case of both non-infectious [2 (1-2) days] and infectious indications [3 (1-6) days]. In the case of infection, no patients required post-extraction intravenous antibiotics, the median duration of any antibiotic therapy was 10 (10-14) days, and the re-implantation was performed during the same procedure in 29% of cases. No complications arose over a median of 21 months.

CONCLUSION

The S-ICD extraction was safe and easy to perform, with no complications. Simple traction of the lead was successful in most patients, but specific tools could be needed for systems implanted for a longer time. The peri- and post-procedural management of S-ICD extraction was free from complications and not burdensome for patients and healthcare system.

CLINICAL TRIAL REGISTRATION

URL: http://clinicaltrials.gov/Identifier: NCT02275637.

Third-generation subcutaneous implantable cardioverter defibrillator and intermuscular two-incision implantation technique in patients with Arrhythmogenic cardiomyopathy: 3-year follow-up

BACKGROUND

Long-term data on the potential advantages of combining the third-generation subcutaneous implantable cardioverter defibrillator (S-ICD) with modern software upgrade including the "SMART Pass", modern programming strategies and the intermuscular (IM) two-incision implantation technique in arrhythmogenic cardiomyopathy (ACM) with different phenotypic variants are lacking. In this study we evaluated the long-term outcome of patients with ACM who underwent third-generation S-ICD (Emblem, Boston Scientific) and IM two-incision technique.

METHODS

The study population included 23 consecutive patients [70% male, median age 31 (24-46) years] diagnosed with ACM with different phenotypic variants who received third-generation S-ICD implantation with the IM two-incision technique.

RESULTS

During a median follow-up of 45.5 months [16-65], 4 patients (17.4%) received a at least one inappropriate shock (IS), with median annual event rate of 4.5%. Extra-cardiac oversensing (myopotential) during effort represented the only cause of IS. No IS due to T-wave oversensing (TWOS) were recorded. Only one patient (4.3%) experienced device-related complication consisting of premature cell battery depletion requiring device replacement. No device explantation because of need for anti-tachycardia pacing or ineffective therapy occurred. There was no significant difference between patients who did and did not experienced IS with regard to baseline clinical, ECG and technical characteristics. Five patients (21.7%) received appropriate shock on ventricular arrythmias.

CONCLUSIONS

According to our finding, although the third-generation S-ICD implanted with the IM two-incision technique appears to be associated with a low risk of complications and IS due to cardiac oversensing, the risk of IS due to myopotential mainly during effort should be considered.

Evaluating the magnet response in deep subcutaneous implanted cardioverter defibrillator implants

INTRODUCTION

The manufacturer of subcutaneous implantable cardioverter defibrillators (S-ICDs) acknowledges that 'deep implants' may fail to elicit a magnet response, however, does not define 'deep implant' or recommend a maximum implant depth. This study aims to systematically evaluate the effect of subcutaneous tissue depth and magnet types on evoked magnet response.

METHODS

Sunshine Coast University Hospital's S-ICD cohort underwent magnet response evaluation; where bar and donut magnets were compared and the evoked magnet response was recorded in three separate zones, guided by a template. Ordinal regression (OR) models assessed the relationship between the evoked magnet response and tissue depth (TD), measured via post-implant X-Ray. The patient's ability to hear the magnet response audible tone was recorded.

RESULTS

Patients (n = 39) with measurable TD (n = 30) were analyzed. The bar magnet evoked a magnet response in all zones in 53% of patients, compared with 73% of patients with the donut magnet (p = 0.18). The relationship between bar magnet response and TD showed the odds of an evoked magnet response decreased by 11% every 1 mm increase in TD (OR of 0.89, p < 0.01), whereas the donut magnet decreased by 16% per 1 mm (OR of 0.84, p < 0.01). Directly over the S-ICD was the most effective in evoking magnet response with the bar (85% of patients), and off-centre was most effective for the donut magnet (100%). BMI and Praetorian score were not significantly associated with magnet response. We found 23% of patients were unable to detect the audible tone.

CONCLUSION

We observed a statistically significant association between TD and ability to evoke magnet response. The bar magnet was less reliable than the donut magnet for therapy inhibition in deep implants.

Intermuscular two-incision technique for implantation of the subcutaneous implantable cardioverter defibrillator: a 3-year follow-up

PURPOSE

The aim of the present study was to evaluate the outcome of patients underwent subcutaneous implantable cardioverter defibrillator (S-ICD) implantation with the intermuscular (IM) two-incision technique during 3-year follow-up.

METHODS

the study population consisted of 105 consecutive patients (79 male; median 50 [13-77] years) underwent S-ICD implantation with the IM two-incision technique. The composite primary end point of the study consisted of device-related complications and inappropriate shocks (IAS). Secondary end points included the individual components of the primary end point, death from any cause, appropriate therapy, major adverse cardiac events, hospitalization for heart failure, and heart transplantation.

RESULTS

According to the PRAETORIAN score, the risk of conversion failure was classified as low in 99 patients (94.3%), intermediate in 6 (5.7%).Ventricular fibrillation was successfully converted at ≤65 J in 97.4% of patients. During a median follow-up of 39 (16-53) months, 10 patients (9.5%) experienced device-related complications, and 9 (8.5%) patients reported IAS. Lead-associated complications were the most common (5 patients, 4.7%), including 2 cases of lead failure (1.9%). Pocket complications were reported in 2 patients (1.9%). Extra-cardiac oversensing (3.8%) represented the leading cause of IAS. No T-wave oversensing episodes were recorded. Twelve patients (11.4%) experienced appropriate shocks. Eight patients (7.6%) died during follow-up. IAS or device-related complications did not impact on mortality.

CONCLUSIONS

The overall device-related complications and IAS rates over 3 years of follow-up were 9.5% and 8.5%, respectively. According to our findings, the IM two-incision technique allows for optimal positioning of the device achieving a low PRAETORIAN score with a high conversion rate. IM two-incision technique allows low incidence of pocket complications, shifting the type of complications towards lead-related complications, which represent the most common complications. The IM two-incision technique would not seem to impact the occurrence of IAS. Management of complications are safe without impact on the outcome.

Isolated subcutaneous implantable cardioverter-defibrillator generator displacement causing inappropriate shocks despite preserved lead tip and coil position: a case report

Background

Subcutaneous implantable cardioverter-defibrillators (S-ICDs) are increasingly used in patients without a pacing indication, and may reduce venous complications, endocarditis and extraction morbidity. Subcutaneous implantable cardioverter-defibrillator displacements may be less obvious than their transvenous counterparts.

Case summary

A 59-year-old man was found to have dilated cardiomyopathy associated with heavy alcohol intake following investigation for a stroke. Despite 2 years of alcohol cessation and optimal drug therapy, his ejection fraction remained severely impaired, and he received an S-ICD using the manufacturer recommended screening and implant method, and by an experienced operator. Ten months later, inappropriate shocks were delivered despite optimal programming. Device displacement was demonstrated by lateral chest radiography on the second instance of inappropriate therapy. On the first admission, a lateral film was not performed, and simple device programming was undertaken which failed to prevent the second occurrence. The patient requested an explant; as ventricular function had improved following initiation of sacubutril/valsartan, the clinical team opted to remove the device.

Discussion

Careful inspection of lateral chest films and review of device indication are needed to reduce the risk of inappropriate shocks. This is the first description of inappropriate device activity following lone generator displacement-lead displacement is well described.

Subcutaneous Implantable Cardioverter Defibrillators for the Prevention of Sudden Cardiac Death: Pediatric Single-Center Experience

BACKGROUND

The subcutaneous implantable cardioverter defibrillator (S-ICD) was developed as an alternative to the transvenous ICD, to prevent lead-related complications associated with the latter. The absence of intravascular or intracardiac components offers potential advantages to pediatric patients.

AIMS

The aim of the study is to present an overview of our experience with S-ICDs in the pediatric center that, currently, has performed the largest number of implantations in children in Poland.

METHODS

Retrospective analysis of data from medical history, qualification, implantation procedure, and S-ICD post-implantation observations in 11 pediatric patients were performed.

RESULTS

S-ICDs were implanted in 11 patients, 8 boys and 3 girls, aged 12-17 years. The S-ICD was implanted for primary prevention in seven patients: four with hypertrophic cardiomyopathy (HCM), two with dilated cardiomyopathy (DCM), and one with arrhythmogenic right ventricular cardiomyopathy (ARVC). It was implanted for secondary prevention in four patients: two with sudden cardiac arrest (SCA) in the course of idiopathic ventricular fibrillation (IVF), one with long QT syndrome (LQTS) after probable SCA, and one with Brugada syndrome after SCA. In all patients, the device was implanted intramuscularly. One patient did not have a defibrillation test performed due to the presence of an intracardiac thrombus. In one patient, during screening, it was decided to implant an electrode on the right side of the sternum. There were no early or late complications with any of the procedures. So far, no inadequate discharges have been observed.

CONCLUSIONS

Our results prove the efficacy of the S-ICD treatment option along with technically simple surgery, which supports its further and more widespread application in children.

"Shift and cover technique": conservative management of complications for the rescue of S-ICD subcutaneous implantable defibrillator systems

BACKGROUND

The risk of complications has been shown to be lower with subcutaneous implantable defibrillator (S-ICD) than with conventional ICDs. Given the low frequency of complications, experience of how to manage them is limited. In this paper, we describe generator- and lead-related complications recorded in a series of S-ICD patients, and we propose our conservative approach to managing them.

METHODS

The study cohort consisted of S-ICD patients who were referred to our institution owing to generator- or lead-related complications requiring surgical intervention. With our "shift and cover" approach, the system component involved is moved from its original position to an alternative, more protected location. In the case of the generator, this involves moving it to an intermuscular pocket. In the case of infections at the parasternal scar, the electrode sleeve is moved away from its original location, stitched, and then covered with the muscular fascia.

RESULTS

Fourteen S-ICD patients were referred to our institution owing to system-related complications. Complications involved the generator in 7 cases (deep pocket infections with erosion, extrusion, or pain), the lead in 5 cases (parasternal infections at the xyphoid incision site), and both the generator and the lead in 2 cases. Complications were managed without completely removing the device and resolved in a single surgical session with no intraoperative complications. During defibrillation testing, the first shock at 65 J was effective in all patients. The shock impedance after revision was significantly lower than that measured during first implantation (59 ± 10 Ohm versus 86 ± 24 Ohm, P = 0.013). In all cases, the cosmetic result was satisfactory. No complications or recurrent infections were reported at the 12-month follow-up visit.

CONCLUSIONS

The proposed conservative approach was successful in managing S-ICD complications. The revision procedure allowed to optimize the system configuration in terms of the defibrillation vector, resulting in lower shock impedance values and better device positioning.

Process Mapping Strategies to Prevent Subcutaneous Implantable Cardioverter-Defibrillator Infections

BACKGROUND

Infection remains a major complication of cardiac implantable electronic devices (CIEDs) and can lead to significant morbidity and mortality. Implantable devices that avoid transvenous leads, such as the subcutaneous implantable cardioverter-defibrillator (S-ICD), can reduce the risk of serious infection-related complications, such as bloodstream infection and infective endocarditis. While the 2017 AHA/ACC/HRS guidelines include recommendations for S-ICD use for patients at high risk of infection, currently, there are no clinical trial data that address best practices for the prevention of S-ICD infections. Therefore, an expert panel was convened to develop consensus on these topics.

METHODS

An expert process mapping methodology was used to achieve consensus on the appropriate steps to minimize or prevent S-ICD infections. Two face-to-face meetings of high-volume S-ICD implanters and an infectious diseases specialist, with expertise on cardiovascular implantable electronic device infections, were conducted to develop consensus on useful strategies pre-, peri-, and post-implant to reduce S-ICD infection risk.

RESULTS

Expert panel consensus of recommended steps for patient preparation, S-ICD implantation, and post-operative management were developed to provide guidance in individual patient management.

CONCLUSION

Achieving expert panel consensus by process mapping methodology for S-ICD infection prevention was attainable, and the results should be helpful to clinicians in adopting interventions to minimize risks of S-ICD infection. This article is protected by copyright. All rights reserved.

Subcutaneous ICD implantation under ultrasound-guided serratus anterior plane block: Single-center experience in the Netherlands

INTRODUCTION

To avoid general anesthesia (GA) and improve postoperative pain management for subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation there is a growing interest for alternative methods. We describe the first experience in the Netherlands of S-ICD implantation under Ultrasound-guided Serratus Anterior Plane Block (US-SAPB).

METHODS

US-SAPB was performed 1 hour before S-ICD implantation. The two-incision technique was used and a pocket beneath the latissimus dorsi muscle was surgically created. Lidocaine was used to provide anesthesia of the skin. Sedation during defibrillation testing (DFT) was induced by intravenous Propofol. Periprocedural pain experience was monitored using the Numerical Rating Scale for Pain (NRS-Pain). The results were compared with a control group of patients undergoing S-ICD implantation under GA.

RESULTS

Forty consecutive patients (29 Male/11 Female, median age 59 years (range 34-84 years), median body mass index 26 (range 17-41) underwent S-ICD implantation; Twenty patients under US-SAPB and twenty under GA. Median procedure time was 42 min. (range 28-60 min.) with no differences between both groups. In both groups implantations went successful and defibrillation was accomplished using 65 J. US-SAPB was successful in 19 of the 20 patients and GA was successful in all cases. Median NRS-Pain in the US-SAPB group was 2 (range 2-6) and in the GA group 4 (range 2-6). In the US-SAPB group 5 patients required additional opioids postoperatively compared to 10 patients in the GA group.

CONCLUSIONS

S-ICD implantation under US-SAPB is feasible, safe and reduces the need for postoperative opioids significantly. S-ICD implantation under US-SAPB seems a good alternative for GA.

ICD Outcome in Pediatric Cardiomyopathies

Background: Pediatric patients with cardiomyopathies are at risk of malignant arrhythmias and sudden cardiac death (SCD). An ICD may prevent SCD. The aim of this study was to evaluate ICD implantation outcomes, and to compare transvenous and subcutaneous ICDs (S-ICDs) implanted in pediatric patients with cardiomyopathies. Methods: The study is single center and retrospective, and includes pediatric patients with cardiomyopathies who required ICD implantation (2010–2021). Outcomes were recorded for appropriate/inappropriate ICD therapy and surgical complications. Transvenous ICD and S-ICD were compared. Data are presented as median values (25th–75th centiles). Results: Forty-four patients with cardiomyopathies (hypertrophic 39%, arrhythmogenic 32%, dilated 27%, and restrictive 2%) underwent transvenous (52%) and S-ICD (48%) implantation at 14 (12–17) years of age, mostly for primary prevention (73%). The follow-up period was 29 (14–60) months. Appropriate ICD therapies were delivered in 25% of patients, without defibrillation failures. Lower age at implantation and secondary prevention were significant risk factors for malignant ventricular arrhythmias that required appropriate ICD therapies. ICD-related complications were surgical complications (18%) and inappropriate shocks (7%). No significant differences in outcomes were recorded, either when comparing transvenous and S-ICD or comparing the different cardiomyopathies. Conclusions: In pediatric patients with cardiomyopathy, ICD therapy is effective, with a low rate of inappropriate shocks. Neither ICD type (transvenous and S-ICDs) nor the cardiomyopathies subgroup revealed divergent outcomes.

The Role of Subcutaneous ICDs in the Prevention of Sudden Cardiac Death

The ICD is an important therapy in the prevention of sudden cardiac death. The transvenous-ICD (TV-ICD) has been the primary device used for this purpose. However, mechanical and infectious complications occur with traditional TV-ICDs increasing morbidity and mortality. The subcutaneous-ICD (S-ICD) system was developed to circumvent some of these complications, but S-ICDs have their inherent set of limitations as well. These include inappropriate shock delivery, lack of bradycardia, antitachycardia or CRT pacing therapy and shorter device longevity. The S-ICD is now included in guidelines as an acceptable alternative to TV-ICDs among patients without pacing indications. This review discusses the rationale for S-ICDs by reviewing studies including the PRAETORIAN, PAS and UNTOUCHED trials.

A 10 J shock impedance in sinus rhythm correlates with a 65 J defibrillation impedance during subcutaneous defibrillator implantation using an intermuscular technique

INTRODUCTION

Defibrillation testing (DT) is recommended during the subcutaneous defibrillator (S-ICD) placement. We sought to compare 10 J shock impedance in sinus rhythm (SR) with 65 J defibrillation impedance and evaluate device position on a postimplant chest X-ray (CXR) using an intermuscular (IM) technique.

METHODS

Consecutive S-ICD implantations between 12/2019 and 12/2020 at The Ohio State University were reviewed. All implantations were performed using a two-incision IM technique. Standard DT with 65 J shock and 10 J shock in SR were performed unless contraindicated. The PRAETORIAN score was calculated based on CXR.

RESULTS

A total of 37 patients (age: 47.2 ± 15.8 years old, male: n = 26 [70.3%], body mass index: 30.1 ± 6.7 kg/m² ) underwent IM S-ICD implantation, and of those, 27 (73%) underwent both 65 J shock and 10 J shock in SR. The coefficient of determination (R² ) between 10 J shock impedance and 65 J shock impedance was 0.84. The mean of an impedance difference was 1.6 ± 4.8 Ω (minimum - 11 and maximum 8). Postimplant CXR was available for 33 out of 37 patients (89.2%). The PRAETORIAN score was less than 90 in all patients and the mean score was 32.7 ± 8.8.

CONCLUSION

We demonstrated that 10 J shock impedance in SR correlated well with 65 J defibrillation impedance during IM S-ICD implantation. An IM implantation technique provides excellent generator location on postimplant CXR. The IM technique combined with 10 J shock in SR may be sufficient to predict and ensure the defibrillation efficacy of the S-ICD.

Acute shock efficacy of the subcutaneous implantable cardioverter-defibrillator according to the implantation technique

BACKGROUND

The traditional technique for subcutaneous implantable cardioverter defibrillator (S-ICD) implantation involves three incisions and a subcutaneous (SC) pocket. An intermuscular (IM) 2-incision technique has been recently adopted.

AIMS

We assessed acute defibrillation efficacy (DE) of S-ICD (DE ≤65 J) according to the implantation technique.

METHODS

We analyzed consecutive patients who underwent S-ICD implantation and DE testing at 53 Italian centers. Regression analysis was used to determine the association between DFT and implantation technique.

RESULTS

A total of 805 patients were enrolled. Four groups were assessed: IM + 2 incisions (n = 546), SC + 2 incisions (n = 133), SC + 3 incisions (n = 111), and IM + 3 incisions (n = 15). DE was ≤65 J in 782 (97.1%) patients. Patients with DE ≤65 J showed a trend towards lower body mass index (25.1 vs. 26.5; p = .12), were less frequently on antiarrhythmic drugs (13% vs. 26%; p = .06) and more commonly underwent implantation with the 2-incision technique (85% vs. 70%; p = .04). The IM + 2-incision technique showed the lowest defibrillation failure rate (2.2%) and shock impedance (66 Ohm, interquartile range: 57-77). On multivariate analysis, the 2-incision technique was associated with a lower incidence of shock failure (hazard ratio: 0.305; 95% confidence interval: 0.102-0.907; p = .033). Shock impedance was lower with the IM than with the SC approach (66 vs. 70 Ohm p = .002) and with the 2-incision than the 3-incision technique (67 vs. 72 Ohm; p = .006).

CONCLUSIONS

In a large population of S-ICD patients, we observed a high defibrillation success rate. The IM + 2-incision technique provides lower shock impedance and a higher likelihood of successful defibrillation.

Pregnancy in patients with implantable cardiac defibrillators

The number of patients of reproductive age with inherited and congenital heart disease receiving implantable cardiac defibrillators (ICD) is steadily increasing. Safely and effectively coordinating pregnancy in this high-risk cohort is important to optimise maternal-foetal outcomes. As members of the multidisciplinary team caring for pregnant patients with indications for ICD, cardiologists and electrophysiologists should be aware of the considerations and nuances involved in managing these patients. This article reviews the pathophysiology of arrhythmias, ICD implantation considerations, novel minimal fluoroscopy techniques and subcutaneous ICD. In addition, antenatal and device management during pregnancy and delivery are discussed.

Pre-implant screening guided by cardiac silhouette fluoroscopy: a way to increase eligibility for the subcutaneous implantable cardioverter-defibrillator: a case report

BACKGROUND

Suitability for the subcutaneous implantable cardioverter-defibrillator (S-ICD) depends on a pre-implant electrocardiogram (ECG) screening to ensure appropriate sensing of electrical cardiac signals. Screening is performed positioning electrodes guided by chest surface anatomical landmarks.

CASE SUMMARY

We report a case of a patient with an initially negative conventional automatic screening for S-ICD, who underwent a modified screening guided by cardiac silhouette position, as seen under fluoroscopy, resulting in eligibility for the S-ICD.

DISCUSSION

The S-ICD reduces endovascular infection risk, providing therefore a potentially safer alternative in patients with prosthetic valves. It might be reasonable to perform a pre-implant ECG screening guided by fitting the cardiac silhouette in the shock vector, as this modified screening position could increase eligibility in patients who may benefit from S-ICD therapy such as the one presented.

Revision of subcutaneous implantable cardioverter defibrillator to intermuscular pocket to prevent inappropriate shocks

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

S-ICD lead dislodgement in a young isometric athlete: A rare complication

The subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to transvenous ICD in patients who do not need cardiac pacing. We report the case of a young isometric athlete who received S-ICD for primary prevention of sudden death. Lead dislodgement and myopotential noise oversensing during isometric training led to inappropriate shock, and a surgical revision was performed. During the procedure, strong fibrous adhesions were found, requiring polytetrafluoroethylene dilator sheaths. The S-ICD was finally reimplanted. Despite continued isometric training, no more myopotential oversensing occurred after 1-year follow-up. The present case highlights the possible higher risks of lead complication in an isometric athlete and the uncommon effort in removing an old-generation subcutaneous defibrillator lead.

Ultrasound-guided serratus anterior plane block for subcutaneous implantable cardioverter defibrillator implantation using the intermuscular two-incision technique

PURPOSE

Operative anaesthetic requirements and perioperative discomfort are barriers to wide adoption of the subcutaneous implantable cardioverter defibrillator (S-ICD) system, especially when the intermuscular technique is used because of the greater amount of tissue dissection. The procedure is most commonly performed under general anaesthesia (GA). There is growing interest in transitioning away from the routine use of GA and towards several alternative anaesthesia modalities for the S-ICD implant procedure without the involvement of an anaesthesiologist. We assessed the feasibility of ultrasound-guided serratus anterior plane block (US-SAPB) in patients undergoing S-ICD implantation with the intermuscular two-incision technique.

METHODS

The study population included 38 consecutive patients (84% male; median, 53 [46-62] years) who received S-ICD implantation using the intermuscular two-incision technique. All procedures were performed under US-SAPB and conscious sedation without the involvement of an anaesthesiologist.

RESULTS

The average procedure time was 67 ± 14 min. No patient experienced significant haemodynamic changes or oxygen desaturation during the period of the US-SAPB procedure and sedation; there was no need for pharmacological interventions. The entire procedure was well tolerated without discomfort or complications and with no need for GA, except in one (2.6%) patient who received GA with a laryngeal mask airway. Patients always remained able to respond appropriately to neurological monitoring during the S-ICD implantation procedure. There were no procedure-related complications.

CONCLUSIONS

US-SAPB and the intermuscular two-incision technique may be a promising safe and feasible combination for S-ICD implantation, overcoming the potential barrier to wider S-ICD adoption in clinical practice.

Multicentre early experience with totally subcutaneous cardioverter-defibrillators in Poland

INTRODUCTION

Implantable cardioverter-defibrillators (ICD) have a strong position in the prevention of sudden death. Nowadays, the most commonly used high-energy cardiac devices are transvenous ICDs. A new technology of totally subcutaneous ICDs (S-ICD) was invented and recently introduced into clinical practice in order to reduce lead-related complications of conventional ICDs. The aim of this paper is to present early experience with this new technology implemented in a few centres in Poland.

MATERIAL AND METHODS

Medical records of patients who had S-ICD-related interventions in Poland were retrospectively analysed.

RESULTS

During the first year of S-ICD introduction into the Polish health system 18 patients underwent surgery connected with S-ICDs. Majority of them (17 patients) were implanted de novo. In one patient surgical revision of a device implanted abroad was performed. Most of patients (78%) had S-ICDs implanted for secondary prevention. Inability of transvenous system implantation due to venous access obstruction or high risk of infection related with transvenous leads accounted for 83% of indications for S-ICD. Only in three patients were S-ICDs implanted due to young age and active mode of life. The implantations of S-ICDs were performed without important early or late complications. During follow-up one patient had episodes of ventricular arrhythmia successfully terminated with high-energy shocks. One patient died due to progression of heart failure.

CONCLUSIONS

S-ICD implantation procedure has been successfully and safely introduced in Polish clinical routine. Nevertheless, despite clear indications in recent ESC guidelines, this therapy is not directly reimbursed in Poland and needs individual application for refund.

Multicentre experience with the second-generation subcutaneous implantable cardioverter defibrillator and the intermuscular two-incision implantation technique

INTRODUCTION

The recently developed second-generation subcutaneous implantable cardioverter defibrillator (S-ICD) and the intermuscular two-incision implantation technique demonstrate potential favorable features that reduce inappropriate shocks and complications. However, data concerning large patient populations are lacking. The aim of this multicentre prospective study was to evaluate the safety and outcome of second-generation S-ICD using the intermuscular two-incision technique in a large population study.

METHODS AND RESULTS

The study population included 101 consecutive patients (75% male; mean age, 45 ± 13 years) who received second-generation S-ICD (EMBLEM; Boston Scientific, Marlborough, MA) implantation using the intermuscular two-incision technique as an alternative to the standard implantation technique. Twenty nine (29%) patients were implanted for secondary prevention. Twenty four (24%) patients had a previously implanted transvenous ICD. All patients were implanted without any procedure-related complications. Defibrillation testing was performed in 80 (79%) patients, and ventricular tachycardia was successfully converted at less than or equal to 65 J in 98.75% (79/80) of patients without pulse generator adjustments. During a median follow-up of 21 ± 10 months, no complications requiring surgical revision or local or systemic device-related infections were observed. Ten patients (9.9%) received appropriate and successful shocks for ventricular arrhythmias. Three (2.9%) patients experienced inappropriate shocks due to oversensing the cardiac signal (n = 1), noncardiac signal (n = 1), and a combination of both cardiac and noncardiac signals (n = 1), with one patient requiring device explantation. No patients required device explantation due to antitachycardia pacing indications.

CONCLUSIONS

According to our multicentre study, second-generation S-ICD implanted with the intermuscular two-incision technique is an available safe combination and appears to be associated with a low risk of complications, such as inappropriate shocks.

Fifteen years' experience of implantable cardioverter defibrillator in children and young adults: Mortality and complications study

BACKGROUND

Young implantable cardioverter defibrillator (ICD) recipients have a high rate of complications, some of which seem to be underestimated. We report our clinical experience with ICD therapy in children and young adults during a 15 year follow up.

METHODS

We reviewed the database of ICD recipients at the present institution and chose 73 consecutive patients who underwent implantation at age 6-21 years. We analyzed intervention rate, mortality, rate and characteristics of complications and treatment options.

RESULTS

A total of 20/73 patients (27.4%) received ≥1 episode of appropriate therapy (AT) for ventricular tachycardia/ventricular fibrillation (anti-tachycardia pacing or shock) and 24/73 patients (32.8%) had one or multiple episodes of inappropriate therapy (IT). Eight patients (11%) had both interventions: AT + IT. A total of 15/73 patients (20.5%) had ventricular lead dysfunction, with 13 re-implantations (17.8%) of a new system. Four of 73 patients (5.5%) had infection: endocarditis or device pocket infection. A total of 2/73 patients (2.7%) died due to ventricular lead dysfunction, while 22/73 patients (30.1%) needed elective device replacement, five of them twice (6.8%).

CONCLUSION

Endocardial ICD implantation in children and young adults is a feasible and life-saving procedure, according to the present 15 year follow up. The rate of complications including IT was high: 72.8% in the young ICD recipients. Re-implantation of a new system was often required due to ventricular lead dysfunction or infection in 25% of the patients.

The subcutaneous implantable cardioverter-defibrillator: A tertiary center experience

BACKGROUND

The aim of the study was to evaluate subcutaneous implantable cardioverter-defibrillator (S-ICD) patients with regard to underlying etiology, peri-procedural outcome, appropriate/inappropriate shocks, and complications during follow-up.

METHODS

All patients who underwent S-ICD implantation from February 2013 to March 2017 at an academic hospital in Vienna were included. Medical records were examined and follow-up interrogations of devices were conducted.

RESULTS

A total of 79 S-ICD patients (58.2% males) with a mean age of 44.5 ± 17.2 years were followed for a mean duration of 12.8 ± 13.7 months. A majority of patients (58.2%) had S-ICD for primary prevention of sudden cardiac death. The most common of the 16 underlying etiologies were ischemic cardiomyopathy, non-ischemic cardiomyopathy, and idiopathic ventricular fibrillation. The lead was implanted to the left sternal border in 96.2% of cases, between muscular layers in 72.2%. Mean implant time was 45 min, 3 patients were induced, and all patients except one were programmed to two zones. Six (7.6%) patients experienced at least one appropriate therapy for ventricular arrhythmias and the time to first event ranged from 1 to 52 months. Seven patients experienced inappropriate shocks due to T-wave oversensing, atrial tachycardia with rapid atrioventricular conduction, external electromagnetic interference, and/or baseline oversensing due to lead movement. Four patients underwent revision for lead repositioning (n = 1), loose device suture (n = 1), and infection (n = 2).

CONCLUSIONS

While S-ICDs are a feasible and effective treatment, issues remain with inappropriate shock and infection.

Intermuscular implantation technique for subcutaneous cardioverter-defibrillators

BACKGROUND

The conventional technique for subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation has been associated with pocket complications. The aim of this study was to evaluate the efficacy and safety of an alternative intermuscular technique for S‑ICD implantation.

METHODS

S-ICDs were implanted in ten consecutive patients (ten males, mean age: 46.8 ± 14.7 years). The pocket for the pulse generator was made above the serratus anterior muscular fascia and beneath the latissimus dorsi muscle by detaching the fibrous tissue between the muscles. Electrode implantation was performed using the three- (n = 4) or the two-incision technique (n = 6).

RESULTS

All S‑ICDs were successfully implanted in the absence of any procedure-related complications with a successful 65-J standard polarity defibrillation threshold testing, apart from one patient with Brugada syndrome who needed device repositioning more dorsally. During a mean follow-up of 16.5 ± 7.3 months, no major complications requiring surgical repair were encountered, while patients demonstrated high levels of comfort and satisfaction with the cosmetic result. One patient experienced an inappropriate shock due to noise detection, which was resolved after reprogramming to a different sensing vector.

CONCLUSION

The intermuscular technique is a safe and efficacious approach for S‑ICD implantation. This technique could lead to fewer pocket-related complications and better cosmetic results.