Specific indications and clinical outcome in patients with subcutaneous implantable cardioverter-defibrillator (ICD) - A nationwide multicentre registry

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.

Systematic Review on S-ICD Lead Extraction

BACKGROUND AND PURPOSE

Subcutaneous implantable cardioverter defibrillators (S-ICDs) have emerged in recent years as a valid alternative to traditional transvenous ICDs (TV-ICDs). Therefore, the number of S-ICD implantations is rising, leading to a consequent increase in S-ICD-related complications sometimes requiring complete device removal. Thus, the aim of this systematic review is to gather all the available literature on S-ICD lead extraction (SLE), with particular reference to the type of indication, techniques, complications and success rate.

METHODS

Studies were identified by searching electronic databases (Medline via PubMed, Scopus and Web of Science) from inception to 21 November 2022. The search strategy adopted was developed using the following key words: subcutaneous, S-ICD, defibrillator, ICD, extraction, explantation. Studies were included if they met both of the following criteria: (1) inclusion of patients with S-ICD; (2) inclusion of patients who underwent SLE.

RESULTS

Our literature search identified 238 references. Based on the abstract evaluation, 38 of these citations were considered potentially eligible for inclusion, and their full texts were analyzed. We excluded 8 of these studies because no SLE was performed. Eventually, 30 studies were included, with 207 patients who underwent SLE. Overall, the majority of SLEs were performed for non-infective causes (59.90%). Infection of the device (affecting either the lead or the pocket) was the cause of SLE in 38.65% of cases. Indication data were not available in 3/207 cases. The mean dwelling time was 14 months. SLEs were performed using manual traction or with the aid of a tool designed for transvenous lead extraction (TLE), including either a rotational or non-powered mechanical dilator sheath.

CONCLUSIONS

SLE is performed mainly for non-infective causes. Techniques vary greatly across different studies. Dedicated tools for SLE might be developed in the future and standard approaches should be defined. In the meantime, authors are encouraged to share their experience and data to further refine the existing variegated approaches.

Air entrapment as a potential cause of early subcutaneous implantable cardioverter defibrillator malfunction: a systematic review of the literature

AIMS

Air entrapment (AE) has been reported as a potential cause of early inappropriate shocks (ISs) following subcutaneous implantable cardioverter defibrillator (S-ICD) implantation, but a cause-effect relationship is not always evident. This systematic review aims to analyse this phenomenon concerning implantation techniques, electrogram (EGM) features, radiologic findings, and patient management.

METHODS AND RESULTS

A systematic search was conducted using PubMed, Embase, and Google Scholar databases following the PRISMA guidelines to obtain all available literature data since 2010 on S-ICD malfunctions possibly due to AE. The final analysis included 54 patients with AE as a potential cause of S-ICD malfunction. Overall, the aggregate incidence of this condition was 1.2%. Of ICD malfunctions possibly due to AE, 93% were ISs, and 95% were recorded within the first week following implantation. Radiologic diagnosis of AE was confirmed in 28% of the entire study cohort and in 68% of patients in whom this diagnostic examination was reported. At the time of device malfunction, EGMs showed artefacts, baseline drift, and QRS voltage reduction in 95, 76, and 67% of episodes, respectively. Management included ICD reprogramming or testing, no action (observation), and invasive implant revision in 57, 33, and 10% of patients, respectively. No recurrences occurred during follow-up, irrespective of management performed.

CONCLUSIONS

Device malfunction possibly due to AE may occur in ∼1% of S-ICD recipients. Diagnosis is strongly suggested by early occurrence, characteristic EGM features, and radiologic findings. Non-invasive management, principally device reprogramming, appears to be effective in most patients.

CE: Guideline-Directed Cardiac Devices for Patients with Heart Failure

ABSTRACT

Heart failure affects over 6.2 million adults in the United States and is expected to affect over 8 million by 2030. The U.S. one-year mortality rate is almost 30% among Medicare beneficiaries. Technological advances have produced several new cardiac devices that are available for therapy and symptom management. This article reviews current device therapies for heart failure and uses a composite case to demonstrate how bedside nurses can help patients understand treatment options related to their disease process and care for them through this experience.

State-of-the-art consensus on non-transvenous implantable cardioverter-defibrillator therapy

Within the last decade, implantable cardioverter-defibrillator (ICD) systems with non-transvenous leads were developed in order to minimize complications related to the cardiovascular position of transvenous ICD leads. This national expert consensus gives an overview of potential indications for the implantation of non-transvenous ICD systems, and provides specific recommendations for implantation, follow-up, and complication management in patients with subcutaneous ICD. Regarding particular issues like the necessity for shock efficacy testing, or the clinical outcome as compared to transvenous ICD, randomized data are expected in the near future.

Cardiac implantable electrical devices in patients with hypertrophic cardiomyopathy: single center implant data extracted from the Swedish pacemaker and ICD registry

Objectives: To investigate cardiac implantable electrical device (CIED) first implants in patients with hypertrophic cardiomyopathy (HCM) in a Swedish tertiary university hospital. Design: Clinical and technical data on pacemaker, implantable cardioverter defibrillator (ICD), and cardiac resynchronization therapy (CRT) first implants performed in HCM patients at the Karolinska University Hospital from 2005 to 2016 were extracted from the Swedish Pacemaker and ICD Registry. Echocardiographic data were obtained by review of hospital recordings. Results: The number of first pacemaker implants in HCM patients was 70 (1.5% of total pacemaker implants). The mean age of HCM pacemaker patients was 71 ± 10 years. Pacemaker implants were almost uniformly distributed between genders. Dual-chamber pacemakers with or without CRT properties were prevalent (6 and 93%, respectively). The number of first ICD implants in HCM patients was 99 (5.1% of total ICD implants). HCM patients receiving an ICD were 53 ± 15 years and prevalently men (70%). Sixty-five (66%) patients were implanted for primary prevention. Dual-chamber ICDs with or without CRT were 21 and 65%, respectively. Obstructive HCM was present in 47% pacemaker patients and 25% ICD patients with available pre-implant echo. Conclusions: This retrospective registry-based study provides a picture of CIED first implants in HCM patients in a Swedish tertiary university hospital. ICDs were the most commonly implanted devices, covering 59% of CIED implants. HCM patients receiving a pacemaker or an ICD had different epidemiological and clinical profiles.

The subcutaneous implantable cardioverter-defibrillator in review

The subcutaneous implantable cardioverter defibrillator (S-ICD) is a completely extrathoracic device that has recently been FDA approved for the prevention of sudden cardiac death in select populations. Although the transvenous implantable cardioverter defibrillator (TV-ICD) has a proven mortality benefit in multiple patient populations, there are significant risks both with implantation and years after its placement. The S-ICD may help prevent some of these complications. Currently, the S-ICD is typically implanted in patients with prior device infection or at an increased risk for an infection, younger patients with difficult venous access related to either hemodialysis or difficult cardiac anatomy, patients who live active lifestyles, and those who may outlive the TV-ICD leads. There is an absolute contraindication for S-ICD implantations for patients who need pacing either for ventricular tachycardia or bradycardia because this device cannot perform these functions. To date, there are no randomized controlled trial (RCT) data evaluating the safety and efficacy of this relatively new device. Observational studies of both the S-ICD alone and in comparison with the TV-ICD have showed promising results, including a decrease in lead-related and periprocedural complications as well as a high level of effectiveness at terminating ventricular arrhythmias. These analyses over time may have contributed to the evolution and comfortability with the S-ICD system, as physicians are more often referring for and/or implanting this device for patients with appropriate indications. Furthermore, inappropriate shock rates with the S-ICD have decreased over time especially with dual zone programming. This review summarizes the results of a multitude of observational studies with respect to patient selection for the S-ICD, complication rates, appropriate and inappropriate shock rates, and programming. This review also tackles current ongoing randomized trials. Although the results of ongoing trials will be helpful, there is still a continued need to evaluate the efficacy of the S-ICD in broader patient populations including patients with several comorbidities and older patients so that more patients can be considered for this potentially lifesaving device.

Lead failure in transvenous implantable cardioverter defibrillator: a new opportunity for an effective management

In case of transvenous defibrillator lead failure, a subcutaneous defibrillator may be implanted and the lead may be abandoned in order to avoid particular risk situations. For patients who require pacing and with an operational atrial lead, the transvenous ICD may be also maintained to ensure antibradycardia support.