Primary Results From the Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction (UNTOUCHED) Trial

NL-EVDR: Netherlands-ExtraVascular Device Registry

Cardiac implantable electronic device (CIED) therapy is an essential element in treating cardiac arrhythmias. Despite their benefits, conventional transvenous CIEDs are associated with a significant risk of mainly pocket- and lead-related complications. To overcome these complications, extravascular devices (EVDs), such as the subcutaneous implantable cardioverter-defibrillator and intracardiac leadless pacemaker, have been developed. In the near future, several other innovative EVDs will become available. However, it is difficult to evaluate EVDs in large studies because of high costs, lack of long-term follow-up, imprecise data or selected patient populations. To improve evaluation of these technologies, real-world, large-scale, long-term data are of utmost importance. A Dutch registry-based study seems to be a unique possibility for this goal due to early involvement of Dutch hospitals in novel CIEDs and an existing quality control infrastructure, the Netherlands Heart Registration (NHR). Therefore, we will soon start the Netherlands-ExtraVascular Device Registry (NL-EVDR), a Dutch nationwide registry with long-term follow-up of EVDs. The NL-EVDR will be incorporated in NHR's device registry. Additional EVD-specific variables will be collected both retrospectively and prospectively. Hence, combining Dutch EVD data will provide highly relevant information on safety and efficacy. As a first step, a pilot project has started in selected centres in October 2022 to optimise data collection.

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.

Opportunities and drawbacks of the subcutaneous defibrillator across different clinical settings

INTRODUCTION

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an established therapy for the prevention of sudden cardiac death (SCD) and an alternative to a transvenous implantable cardioverter-defibrillator system in selected patients. Beyond randomized clinical trials, many observational studies have described the clinical performance of S-ICD across different subgroups of patients.

AREAS COVERED

Our review aimed to describe the opportunities and drawbacks of the S-ICD, focusing on their use in special populations and across different clinical settings.

EXPERT OPINION

The choice to implant S-ICD should be based on the patient's tailored approach, which takes into account the adequate S-ICD screening at rest or during stress, the infective risk, the ventricular arrhythmia susceptibility, the progressive nature of the underlying disease, the work or sports activity, and the risk of lead-related complications.

Recent Developments in the Evaluation and Management of Cardiorenal Syndrome: A Comprehensive Review

Cardiorenal syndrome (CRS) is an increasingly recognized diagnostic entity associated with high morbidity and mortality among acutely ill heart failure (HF) patients with acute and/ or chronic kidney diseases (CKD). While traditionally viewed as a state of decline in glomerular filtration rate (GFR) due to decreased renal perfusion, mainly due to therapeutic interventions to relieve congestive in HF, recent insights into the underlying pathophysiologic mechanisms of CRS led to a broader definition and further classification of CRS into 5 distinct types. In this comprehensive review, we discuss the classification of CRS, highlighting the underlying common pathogenetic pathways of heart failure and kidney injury, including increased congestion, neurohormonal dysregulation, oxidative stress as well as inflammation, and cytokine storm that are particularly evident in COVID-19 patients with multiorgan failure and also in those with other disorders including sepsis, systemic lupus erythematosus and amyloidosis. In this review we also present the recent advances in the diagnostic strategies of CRS including cardiac and renal biomarkers as well as advanced cardiac and renal imaging techniques that are available to aid in the diagnosis as well as in the prognostication of this disorder. Finally, we discuss the various therapeutic options available to-date, including fluid optimization, hemofiltration, renal replacement therapy as well as the role of SGLT2 inhibitors in light of recent data from RCTs. It is important to note that, CRS population are either excluded or underrepresented, at best, in major RCTs and therefore, therapeutic recommendations are largely extrapolated from HF and CKD clinical trials.

Multicenter assessment of the outcomes of subcutaneous ICD implantation in patients with prior or future sternotomy

BACKGROUND

The subcutaneous ICD (S-ICD) is a viable alternative to transvenous ICD and avoids intravascular complications in patients without a pacing indication. The outcomes of S-ICD implantation are uncertain in patients with prior sternotomy.

OBJECTIVE

We aim to compare the implant techniques and outcomes with S-ICD implantation in patients with and without prior sternotomy.

METHODS

Multicenter retrospective cohort study including adult patients with an S-ICD implanted between January 2014 and June 2020. Outcomes were compared between patients with and without prior sternotomy.

RESULTS

Among the 212 patients (49 ± 15 years old, 43% women, BMI 30 ± 8 kg/m² , 68% primary prevention, 30% ischemic cardiomyopathy, LVEF median 30% IQR 25%-45%) who underwent S-ICD implantation, 47 (22%) had a prior sternotomy. There was no difference in the sensing vector (57% vs. 53% primary, p = 0.55), laterality of the S-ICD lead to the sternum (94% vs. 96% leftward, p = 0.54), or the defibrillation threshold (65 ± 1.4 J vs. 65 ± 0.8 J, p = 0.76) with versus without prior sternotomy. The frequency of 30-day complications was similar with and without prior sternotomy (n = 3/47 vs. n = 15/165, 6% vs. 9%, p = 0.56). Over a median follow-up of 28 months (IQR 10-49 months), the frequency of inappropriate shocks was similar between those with and without prior sternotomy (n = 3/47 and n = 16/165, 6% vs. 10%, p = 0.58).

CONCLUSION

Implantation of an S-ICD in patients with prior sternotomy is safe with a similar risk of 30-day complications and inappropriate ICD shocks as patients without prior sternotomy.

Lights and shadows of subcutaneous implantable cardioverter-defibrillator in Brugada syndrome

Currently the cornerstone of therapy for ventricular arrhythmic complications and sudden cardiac death prevention in Brugada syndrome (BrS) is an implantable cardioverter-defibrillator (ICD). BrS patient population differs from the majority of patients with an ICD implanted for structural heart disease, and as widely known, transvenous ICD (TV-ICD) systems have been associated with high complication rates in patients with BrS. Technological evolution of these devices has certainly reduced complications due to the device itself, but a careful preimplant screening of these patients is still essential. To date, criteria for an adequate screening process to select suitable candidates for a subcutaneous implantable cardioverter-defibrillator (S-ICD) from patients with BrS are sometimes nonstandardized and often lack important precautions that are instead fundamental to select the most suitable type of ICD for these patients. To better select suitable candidates for an S-ICD from patients with BrS, a full screening process should include screening during or immediately after an exercise test and after a drug provocation challenge test. We report an analysis of the "lights and shadows" of S-ICD for a correct use of this device in patients with BrS.

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.

Incidence of premature battery depletion in subcutaneous cardioverter-defibrillator patients: insights from a multicenter registry

BACKGROUND

The subcutaneous ICD established its role in the prevention of sudden cardiac death in recent years. The occurrence of premature battery depletion in a large subset of potentially affected devices has been a cause of concern. The incidence of premature battery depletion has not been studied systematically beyond manufacturer-reported data.

METHODS

Retrospective data and the most recent follow-up data on S-ICD devices from fourteen centers in Europe, the US, and Canada was studied. The incidence of generator removal or failure was reported to investigate the incidence of premature S-ICD battery depletion, defined as battery failure within 60 months or less.

RESULTS

Data from 1054 devices was analyzed. Premature battery depletion occurred in 3.5% of potentially affected devices over an observation period of 49 months.

CONCLUSIONS

The incidence of premature battery depletion of S-ICD potentially affected by a battery advisory was around 3.5% after 4 years in this study. Premature depletion occurred exclusively in devices under advisory. This is in line with the most recently published reports from the manufacturer.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04767516 .

Pre-implant predictors of inappropriate shocks with the third-generation subcutaneous implantable cardioverter defibrillator

AIMS

Despite recent improvements, inappropriate shocks emitted by implanted subcutaneous implantable cardioverter defibrillators (S-ICDs) remain a challenge in 'real-life' practice. We aimed to study the pre-implant factors associated with inappropriate shocks for the latest generation of S-ICDs.

METHODS AND RESULTS

Three-hundred patients implanted with the third-generation S-ICD system for primary or secondary prevention between January 2017 and March 2020 were included in this multicentre retrospective observational study. A follow-up of at least 6 months and pre-implant screening procedure data were mandatory for inclusion. During a mean follow-up of 22.8 (±11.4) months, 37 patients (12.3%) received appropriate S-ICD shock therapy, whereas 26 patients (8.7%) experienced inappropriate shocks (incidence 4.9 per 100 patient years). The total number of inappropriate shock episodes was 48, with nine patients experiencing multiple episodes. The causes of inappropriate shocks included supraventricular arrhythmias (34.6%) and cardiac (30.7%) or extra-cardiac noise (38.4%) oversensing. Using multivariate analysis, we explored the independent factors associated with inappropriate shocks. These were the availability of less than three sensing vectors during pre-implant screening [hazard ratio (HR), 0.33; 95% confidence interval (CI), 0.11-0.93; P = 0.035], low QRS/T wave ratio in Lead I (for a threshold <3; HR, 4.79; 95% CI, 2.00-11.49; P < 0.001), history of supraventricular tachycardia (HR, 8.67; 95% CI, 2.80-26.7; P < 0.001), and being overweight (body mass index > 25; HR, 2.66; 95% CI, 1.10-6.45; P = 0.03).

CONCLUSION

Automatic pre-implant screening data are a useful quantitative predictor of inappropriate shocks. Electrocardiogram features should be taken into consideration along with other clinical factors to identify patients at high risk of inappropriate shocks.

Infection in patients with subcutaneous implantable cardioverter-defibrillator: Results of the S-ICD Post Approval Study

BACKGROUND

Early subcutaneous implantable cardioverter-defibrillator (S-ICD) studies included atypical cohorts of patients who were younger with fewer comorbidities. Recent S-ICD studies included patient populations with more comorbidities.

OBJECTIVES

The goals of this study were to determine the incidence and predictors of S-ICD-related infection over a 3-year follow-up period and to use these results to develop an infection risk score.

METHODS

The S-ICD Post Approval Study is a US prospective registry of 1637 patients. Baseline demographic characteristics and outcomes with 3-year postimplantation follow-up were compared between patients with and without device-related infection. A risk score was derived from multivariable proportional hazards analysis of 22 variables.

RESULTS

Infection was observed in 55 patients (3.3%), with 69% of infections occurring within 90 days and a vast majority (92.7%) within 1 year of implantation. Late infections more likely involved device erosion; no infections occurred after year 2. The annual mortality rate postinfection was 0.6%/y. No lead extraction complications or bacteremia related to infection were observed. An infection risk score was created with diabetes, age, prior transvenous ICD implant, and ejection fraction as predictors. Patients with a risk score of ≥3 had an 8.8 hazard ratio (95% confidence interval 2.8-16.3) of infection compared with a 0 risk score.

CONCLUSION

Infection rates in the S-ICD Post Approval Study were similar to other S-ICD populations and not associated with systemic blood-borne infections. Late infection (>1 year) is uncommon and associated with system erosion. A high-risk infection cohort can be identified that may facilitate preventive measures.

Perioperative Safety and Early Patient and Device Outcomes Among Subcutaneous Versus Transvenous Implantable Cardioverter Defibrillator Implantations : A Randomized, Multicenter Trial

BACKGROUND

Implantable cardioverter defibrillators (ICDs) improve survival in patients at risk for cardiac arrest, but are associated with intravascular lead-related complications. The subcutaneous ICD (S-ICD), with no intravascular components, was developed to minimize lead-related complications.

OBJECTIVE

To assess key ICD performance measures related to delivery of ICD therapy, including inappropriate ICD shocks (delivered in absence of life-threatening arrhythmia) and failed ICD shocks (which did not terminate ventricular arrhythmia).

DESIGN

Randomized, multicenter trial. (ClinicalTrials.gov: NCT02881255).

SETTING

The ATLAS trial.

PATIENTS

544 eligible patients (141 female) with a primary or secondary prevention indication for an ICD who were younger than age 60 years, had a cardiogenetic phenotype, or had prespecified risk factors for lead complications were electrocardiographically screened and 503 randomly assigned to S-ICD (251 patients) or transvenous ICD (TV-ICD) (252 patients). Mean follow-up was 2.5 years (SD, 1.1). Mean age was 49.0 years (SD, 11.5).

MEASUREMENTS

The primary outcome was perioperative major lead-related complications.

RESULTS

There was a statistically significant reduction in perioperative, lead-related complications, which occurred in 1 patient (0.4%) with an S-ICD and in 12 patients (4.8%) with TV-ICD (-4.4%; 95% CI, -6.9 to -1.9; P = 0.001). There was a trend for more inappropriate shocks with the S-ICD (hazard ratio [HR], 2.37; 95% CI, 0.98 to 5.77), but no increase in failed appropriate ICD shocks (HR, 0.61 (0.15 to 2.57). Patients in the S-ICD group had more ICD site pain, measured on a 10-point numeric rating scale, on the day of implant (4.2 ± 2.8 vs. 2.9 ± 2.2; P < 0.001) and 1 month later (1.3 ± 1.8 vs. 0.9 ± 1.5; P = 0.035).

LIMITATION

At present, the ATLAS trial is underpowered to detect differences in clinical shock outcomes; however, extended follow-up is ongoing.

CONCLUSION

The S-ICD reduces perioperative, lead-related complications without significantly compromising the effectiveness of ICD shocks, but with more early postoperative pain and a trend for more inappropriate shocks.

PRIMARY FUNDING SOURCE

Boston Scientific.

Evolution of extravascular implantable cardioverter-defibrillator therapy for ventricular arrhythmias

Implantable cardioverter-defibrillators have become an established therapy for the prevention of sudden cardiac death due to life-threatening ventricular arrhythmias in the last decades. In all those years, the use of transvenous leads has proven to be the most vulnerable part of the system. The development of the completely subcutaneous implantable cardioverter-defibrillator opened a new era of device therapy outside of the vascular system. The next step, enabling extravascular devices with the option of antitachycardia pacing, is just around the corner. This may become an important option for all patients without a bradycardia pacing indication that are in need for antitachycardia pacing because of monomorphic ventricular tachycardia.

Sense-B-noise: an enigmatic cause for inappropriate shocks in subcutaneous implantable cardioverter defibrillators

AIMS

Subcutaneous implantable cardioverter defibrillators (S-ICDs) are well established. However, inappropriate shocks (IAS) remain a source of concern since S-ICDs offer very limited troubleshooting options. In our multicentre case series, we describe several patients who experienced IAS due to a previously unknown S-ICD system issue.

METHODS AND RESULTS

We observed six patients suffering from this novel IAS entity. The IAS occurred exclusively in primary or alternate S-ICD sensing vector configuration (therefore called 'Sense-B-noise'). IAS were caused by non-physiologic oversensing episodes characterized by intermittent signal saturation, diminished QRS amplitudes, and disappearance of the artefacts after the IAS. Noise/oversensing could not be provoked by manipulation, X-ray did not show evidence for lead/header issues and impedance measurements were within normal limits. The pooled experience of our centres implies that up to ∼5% of S-ICDs may be affected. The underlying root cause was discussed extensively with the manufacturer but remains unknown and is under further investigation.

CONCLUSION

Sense-B-noise is a novel cause for IAS due to non-physiologic signal oversensing, arising from a previously unknown S-ICD system issue. Sense-B-noise may be suspected if episodes of signal saturation in primary or alternate vector configuration are present, oversensing cannot be provoked, and X-ray and electrical measurements appear normal. The issue can be resolved by reprogramming the device to secondary sensing vector.

Spanish implantable cardioverter-defibrillator registry. 18th official report of the Heart Rhythm Association of the Spanish Society of Cardiology (2021)

INTRODUCTION AND OBJECTIVES

This article presents the data corresponding to implantable cardioverter-defibrillator (ICD) implantations in Spain in 2021.

METHODS

The data were drawn from implanting centers, which voluntarily completed a data collection sheet during the procedure.

RESULTS

In 2021, 7496 implant data sheets were received, compared with 7743 reported by Eucomed (European Confederation of Medical Suppliers Associations), indicating that data were collected from 96.8% of the devices implanted in Spain. Data completion ranged from 99.9% for "name of implanting hospital" to 8.9% for "implanting hospital". In 2021, 199 hospitals participated in the registry, exceeding the figures of previous years, with around 170 participating hospitals. The total rate of registered implants was 158/million inhabitants (163 according to Eucomed), making 2021 the year with the highest activity. However, the registry continues to show significant differences among the various autonomous communities and the lowest implantation rate of all the European countries participating in Eucomed.

CONCLUSIONS

The Spanish implantable cardioverter-defibrillator registry for 2021 recorded an increase in the number of ICD implantations, reflecting the recovery of hospital activity after the initial impact of the COVID-19 pandemic in 2020. Although the total number of implants has increased in Spain, figures are still much lower than the European Union average, with differences persisting among Spanish autonomous communities.

Clinical outcomes of subcutaneous vs. transvenous implantable defibrillator therapy in a polymorbid patient cohort

Background

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has been designed to overcome lead-related complications and device endocarditis. Lacking the ability for pacing or resynchronization therapy its usage is limited to selected patients at risk for sudden cardiac death (SCD).

Objective

The aim of this single-center study was to assess clinical outcomes of S-ICD and single-chamber transvenous (TV)-ICD in an all-comers population.

Methods

The study cohort comprised a total of 119 ICD patients who underwent either S-ICD (n = 35) or TV-ICD (n = 84) implantation at the University Hospital Frankfurt from 2009 to 2017. By applying an inverse probability-weighting (IPW) analysis based on the propensity score including the Charlson Comorbidity Index (CCI) to adjust for potential extracardiac comorbidities, we aimed for head-to-head comparison on the study composite endpoint: overall survival, hospitalization, and device-associated events (including appropriate and inappropriate shocks or system-related complications).

Results

The median age of the study population was 66.0 years, 22.7% of the patients were female. The underlying heart disease was ischemic cardiomyopathy (61.4%) with a median LVEF of 30%. Only 52.9% had received an ICD for primary prevention, most of the patients (67.3%) had advanced heart failure (NYHA class II–III) and 16.8% were in atrial fibrillation. CCI was 5 points in TV-ICD patients vs. 4 points for patients with S-ICD (p = 0.209) indicating increased morbidity. The composite endpoint occurred in 38 patients (31.9 %), revealing no significant difference between patients implanted with an S-ICD or TV-ICD (unweighted HR 1.50, 95 % confidence interval (CI) 0.78–2.90; p = 0.229, weighted HR 0.94, 95% CI, 0.61–1.50, p = 0.777). Furthermore, we observed no difference in any single clinical endpoint or device-associated outcome, neither in the unweighted cohort nor following inverse probability-weighting.

Conclusion

Clinical outcomes of the S-ICD and TV-ICD revealed no differences in the composite endpoint including survival, freedom of hospitalization and device-associated events, even after careful adjustment for potential confounders. Moreover, the CCI was evaluated in a S-ICD cohort demonstrating higher survival rates than predicted by the CCI in young, polymorbid (S-)ICD patients.

Device-related complications in subcutaneous versus transvenous ICD: a secondary analysis of the PRAETORIAN trial

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial.

METHODS AND RESULTS

The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047).

CONCLUSION

This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice.

Efficacy and Safety of an Extravascular Implantable Cardioverter-Defibrillator

BACKGROUND

The extravascular implantable cardioverter-defibrillator (ICD) has a single lead implanted substernally to enable pause-prevention pacing, antitachycardia pacing, and defibrillation energy similar to that of transvenous ICDs. The safety and efficacy of extravascular ICDs are not yet known.

METHODS

We conducted a prospective, single-group, nonrandomized, premarket global clinical study involving patients with a class I or IIa indication for an ICD, all of whom received an extravascular ICD system. The primary efficacy end point was successful defibrillation at implantation. The efficacy objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients with successful defibrillation was greater than 88%. The primary safety end point was freedom from major system- or procedure-related complications at 6 months. The safety objective would be met if the lower boundary of the one-sided 97.5% confidence interval for the percentage of patients free from such complications was greater than 79%.

RESULTS

A total of 356 patients were enrolled, 316 of whom had an implantation attempt. Among the 302 patients in whom ventricular arrhythmia could be induced and who completed the defibrillation testing protocol, the percentage of patients with successful defibrillation was 98.7% (lower boundary of the one-sided 97.5% confidence interval [CI], 96.6%; P<0.001 for the comparison with the performance goal of 88%); 299 of 316 patients (94.6%) were discharged with a working ICD system. The Kaplan-Meier estimate of the percentage of patients free from major system- or procedure-related complications at 6 months was 92.6% (lower boundary of the one-sided 97.5% CI, 89.0%; P<0.001 for the comparison with the performance goal of 79%). No major intraprocedural complications were reported. At 6 months, 25 major complications were observed, in 23 of 316 patients (7.3%). The success rate of antitachycardia pacing, as assessed with generalized estimating equations, was 50.8% (95% CI, 23.3 to 77.8). A total of 29 patients received 118 inappropriate shocks for 81 arrhythmic episodes. Eight systems were explanted without extravascular ICD replacement over the 10.6-month mean follow-up period.

CONCLUSIONS

In this prospective global study, we found that extravascular ICDs were implanted safely and were able to detect and terminate induced ventricular arrhythmias at the time of implantation. (Funded by Medtronic; ClinicalTrials.gov number, NCT04060680.).

Bradycardia in Patients with Subcutaneous Implantable Defibrillators-An Overestimated Problem? Experience from a Large Tertiary Centre and a Review of the Literature

Background

The subcutaneous ICD (S-ICD) has developed as a valuable alternative to transvenous implantable cardioverter defibrillator (ICD) systems. However there are certain peculiarities which are immanent to the S-ICD and may limit its use. Besides oversensing the main issue is the missing option for antibradycardia pacing. To evaluate the actual need for pacing during follow-up and changes to transvenous ICD we analyzed our large tertiary centre registry and compared it with data from other large cohorts and trials.

Methods and Results

We found out that in the 398 patients from our centre, there was a need for changing to a transvenous ICD in only 2 patients (0.5%) during a follow-up duration of almost 3 years. This rate was comparable to data obtained from other large data sets so that in the pooled analysis of almost 4000 patients the rate of bradycardia-associated complications was only 0.3%.

Conclusions

The use of the S-ICD is safe in a variety of heart diseases and the need for antibradycardia stimulation is a very rare complication throughout many different large studies. Clinicians may take these results into account when opting for a certain ICD system and the S-ICD may be chosen more often also in elderly patients, in whom the risk for bradycardia is deemed higher.

The SIDECAR project: S-IcD registry in European paediatriC and young Adult patients with congenital heaRt defects

AIMS

Subcutaneous-implantable cardiac defibrillators (S-ICDs) are used increasingly to prevent sudden cardiac death in young patients. This study was set up to gain insight in the indications for S-ICD, possible complications, and their predictors and follow-up results.

METHODS AND RESULTS

A multicentre, observational, retrospective, non-randomized, standard-of-care registry on S-ICD outcome in young patients with congenital heart diseases (CHDs), inherited arrhythmias (IAs), idiopathic ventricular fibrillation (IVF), and cardiomyopathies (CMPs). Anthropometry was registered as well as implantation technique, mid-term device-related complications, and incidence of appropriate/inappropriate shocks (IASs). Data are reported as median (interquartile range) or mean ± standard deviation. Eighty-one patients (47% CMPs, 20% CHD, 21% IVF, and 12% IA), aged 15 (14-17) years, with body mass index (BMI) 21.8 ± 3.8 kg/m2, underwent S-ICD implantation (primary prevention in 59%). This was performed with two-incision technique in 81% and with a subcutaneous pocket in 59%. Shock and conditional zones were programmed at 250 (200-250) and 210 (180-240) b.p.m., respectively. No intraoperative complications occurred. Follow up was 19 (6-35) months: no defibrillation failure occurred, 17% of patients received appropriate shocks, 13% of patients received IAS (supraventricular tachycardias 40%, T-wave oversensing 40%, and non-cardiac oversensing 20%). Reprogramming, proper drug therapy, and surgical revision avoided further IAS. Complications requiring surgical revision occurred in 9% of patients, with higher risks in patients with three-incision procedures [hazard ratio (HR) 4.3, 95% confidence interval (95% CI) 0.5-34, P = 0.038] and BMI < 20 (HR 5.1, 95% CI 1-24, P = 0.031).

CONCLUSION

This multicentre European paediatric registry showed good S-ICD efficacy and safety in young patients. Newer implantation techniques and BMI > 20 showed better outcome.

Safety and Tolerability of Implanted Subcutaneous Cardioverter-Defibrillator Systems

Aim. To study the safety and tolerability of the subcutaneous implantable cardioverter defibrillator (S-ICD) after implantation.

Material and methods. The results of 33 patients with implanted S-ICD 6 months follow-up. The criteria for inclusion in the observational study were: age over 18 years, indications for primary or secondary prevention of sudden cardiac death. The exclusion criteria were indications for implantation of transvenous ICD (patients with sustained monomorphic ventricular tachycardia, the need for anti-bradycardia or resynchronization therapy), as well as patients with a QRS complex of more than 130 msec. All patients underwent a standard preoperative examination (routine blood tests, chest X-ray, transthoracic echocardiography), quality-of-life questionnaires and transesophageal echocardiography. At follow-up, patients were examined after 6 months after implantation, the device was interrogated and a quality-of-life questionnaire was completed. All episodes of shock therapy and complications were documented.

Results. Male patients predominated (84%), with a mean age of 57 [43;62] years. Left ventricular ejection fraction was 30% [26;34]. The mean QRS duration was 100 [94;108] msec. According to the of 24-hour Holter ECG monitoring, episodes of unstable VT were recorded in 42.4% of patients. The most common indications for S-ICD implantation were dilated (33%) and ischemic cardiomyopathy (42%). Primary prevention was indicated in 97% of patients. At the end of the implantation of the S-ICD, the patients underwent a defibrillation test and device configuration. In 63.6% of cases, during automatic tuning, the device selected the primary perception vector. In 27.2% of patients, optimal recognition of the subcutaneous signal was observed in the secondary vector, and in 9.2% of patients, the alternative vector was favorable. All patients underwent two-zone programming. The conditional shock zone was programmed at an average rate of 192 beats/min (range 180-210 beats/min) and the shock zone was programmed at an average rate of 222 beats/min (range 220-240 beats/min). Perioperative complications occurred in two patients. During the follow-up period, no shocks were recorded in 27 patients. Adequate shocks for 6 months were recorded in two patients. During 6 months of observation, one lethal outcome was noted due to complications of viral pneumonia. During the observation period, there were no rehospitalizations for cardiovascular diseases.

Conclusion. The use of S-ICD, even in patients with structural myocardial disease who do not require antibradycardia pacing, is effective in preventing SCD. The number of inadequate discharges and the number of complications in clinical practice is comparable to the data of multicenter studies. S-ICD implantation was not accompanied by a decrease in quality of life. Careful selection of candidates, along with state-of-the-art device programming, is an important parameter for the selection and success of S-ICD application.

Inappropriate subcutaneous implantable cardioverter defibrillator shock due to incomplete sealing of the seal plug: a case report

Background

A subcutaneous implantable cardioverter defibrillator (S-ICD) has several advantages over the transvenous ICD, including a reduced risk of lead-related mechanical complications and infection. However, inappropriate shock therapy is one of the most common adverse events associated with S-ICDs. We herein report a case of inappropriate shock therapy of S-ICD due to incomplete sealing of the seal plug.

Case summary

A 60-year-old man, who had been on haemodialysis with a history of myocardial infarction, was transferred to the hospital after successfully being resuscitated from ventricular fibrillation (VF). An S-ICD was implanted for secondary prevention. On the third and the seventh post-operative days, S-ICD shock therapy was delivered without any tachyarrhythmias. As device interrogation revealed reproducible noises in both the secondary and alternate vectors by tapping at the generator, the sensing vector was fixed to the primary vector. Two months after discharge, the patient died of VF after receiving appropriate S-ICD shock delivery seven times. The S-ICD was retrieved from the body, and it was revealed that the seal plug had incompletely sealed and returned to its normal closed position after reinsertion of a torque wrench.

Discussion

Seal plug damage is a rare complication but should be considered if noise oversensing is provoked only at the secondary and/or alternate vectors. In the present case, the inappropriate shock therapy might have been prevented if we had checked the seal plug carefully. Therefore, we advocate confirming the seal plug routinely after the removal of the torque wrench.

Inappropriate shocks due to air entrapment in patients with subcutaneous implantable cardioverter-defibrillator: a meta-summary of case reports

Air entrapment has been recently described as a cause of inappropriate shock (IAS) among patients who underwent subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation. Data about this complication are lacking in the literature. This meta-summary aimed to collect the case reports describing IAS due to air entrapment, evaluate the possible promoting factors and elaborate a practical approach for prevention, diagnosis, and management of this complication. This article is protected by copyright. All rights reserved.

Characterization of the PRAETORIAN score in Japanese patients undergoing subcutaneous implantable cardioverter-defibrillator implantation

BACKGROUND

The PRAETORIAN score was developed to evaluate the implant position and predict defibrillation success in patients implanted with a subcutaneous implantable cardioverter-defibrillator (S-ICD). However, usefulness of the PRAETORIAN score for Japanese patients is unknown.

METHODS

We evaluated usefulness of this score, which was determined by width of sub-coil fat, sub-generator fat, and anterior positioning of the S-ICD generator by post-operative chest X-ray, in consecutive 100 Japanese S-ICD implanted patients [78 men, median age 59 (IQR 46.5-67.0) years, median body mass index (BMI) 24.2 (21.3-27.2) kg/m²].

RESULTS

The median PRAETORIAN score was 30 (30-45) and 93 patients were classified as a low risk of conversion failure. The remaining seven were at an intermediate risk. Almost all patients were classified as an optimal pulse-generator position in the second and third steps of the PRAETORIAN score. The only difference observed was in the width of sub-coil fat in the first step. To further evaluate its significance, patients were divided into the Thicker group (sub-coil fat >1 coil width, n = 19) and the Thinner group (sub-coil fat ≤1 coil width, n = 81). BMI and post-shock impedance were both higher in the Thicker group than in the Thinner group [27.1 (25.6-31.6) versus 23.1 (20.9-25.7) kg/m², p < 0.001, and 75 (68-88) versus 63 (55-74) Ω, p = 0.003, respectively]. During the median follow-up periods of 888 (523-1418) days, 7 patients experienced appropriate shock therapy for spontaneous ventricular tachyarrhythmias, who were all at a low risk. No conversion failure was observed. Inappropriate shock (IAS) occurred in 11 patients, and there was no difference in IAS rate between the Thicker group (n = 2) and the Thinner group (n = 9) (p = 0.747 by log-rank test).

CONCLUSIONS

Most Japanese patients were classified as at low risk of conversion failure. The PRAETORIAN score may be useful for the evaluation of conversion failure in Japanese S-ICD implanted patients.

Transvenous or subcutaneous implantable cardioverter defibrillator: a review to aid decision-making

The implantable cardioverter-defibrillator (ICD) is a proven treatment for preventing sudden cardiac death. Transvenous leads are associated with significant mortality and morbidity, and the subcutaneous ICD (S-ICD) addresses this. However, it is not without limitations, in particular the absence of anti-tachycardia pacing. The decision of which device is most suitable for an individual patient is often complex. Here, we review the relative merits and weaknesses of both the transvenous and S-ICD. We summarise the available evidence for each device in particular patient cohorts, namely: ischaemic and non-ischaemic cardiomyopathy, idiopathic ventricular fibrillation, Brugada syndrome, long QT syndrome, arrhythmogenic right ventricular cardiomyopathy, and hypertrophic cardiomyopathy.

Subcutaneous implantable cardioverter defibrillator after transvenous lead extraction: safety, efficacy and outcome

BACKGROUND

Subcutaneous implantable cardioverter defibrillator (S-ICD) is a suitable alternative for transvenous ICD (TV-ICD) patients who have undergone transvenous lead extraction (TLE). Limited data are available on the outcome of S-ICD patients implanted after TLE. We assessed the safety, efficacy, and outcome of S-ICD implantation after TLE of TV-ICD.

METHODS

The study population consisted of 36 consecutive patients with a median age of 52 (44-66) years who underwent S-ICD implantation after TLE of TV-ICD.

RESULTS

Indications for TLE were infection (63.9%) and lead malfunction (36.1%). During a median follow-up of 31 months, 3 patients (8.3%) experienced appropriate therapy and 7 patients (19.4%) experienced complications including inappropriate therapy (n = 4; 11.1%), isolated pocket erosion (n = 2; 5.5%), and ineffective therapy (n = 1; 2.8%). No lead/hardware dysfunction was reported. Premature device explantation occurred in 4 patients (11%). Eight patients (22.2%) died during follow-up, six of them (75%) because of refractory heart failure (HF). There were no S-ICD-related deaths. Predictors of mortality included NYHA class ≥ 2 (HR 5.05; 95% CI 1.00-26.38; p = 0.04), hypertension (HR 22.72; 95% CI 1.05-26.31; p = 0.02), diabetes (HR 10.64; 95% CI 2.05-55.60; p = 0.001) and ischemic heart disease (HR 5.92; 95% CI 1.17-30.30; p = 0.01).

CONCLUSION

Our study provides evidences on the use of S-ICD as an alternative after TV-ICD explantation for both infection and lead failure. Mortality of S-ICD patients who underwent TV-ICD explantation does not appear to be correlated with the presence of a prior infection, S-ICD therapy (appropriate or inappropriate), or S-ICD complications but rather to worsening of HF or other comorbidities.

Inappropriate Subcutaneous Implantable Cardioverter Defibrillator Shocks Secondary to Cardiac Remodeling: A Unique Case of T Wave Oversensing

Implantable cardioverter defibrillators (ICD) are used for the primary and secondary prevention of sudden cardiac death (SCD). Currently, two different modalities of ICDs are in use: transvenous (TV) and subcutaneous (S-ICD). The use of S-ICDs has been driven by several potential benefits of this technology: preservation of central venous vasculature, no risk of vascular or myocardial injury during implant, easier explanation, and lower risk of systemic infections. Inappropriate shocks are defined as shocks delivered for non-life-threatening arrhythmias or because of oversensing. Here, we present a case of a 58-year-old man who began experiencing inappropriate shocks three years after S-ICD placement. Careful analysis of the ICD showed T wave oversensing with no malfunction of the device. The shocks persisted even after reprogramming, leading to subsequent ICD removal and loop recorder implantation. The onset of shock episodes coincided with the improvement of left ventricular ejection fraction (LVEF). To the best of our knowledge, this is the first published report of cardiac remodeling leading to uncorrectable T wave oversensing that subsequently required S-ICD explant. This represents a potentially important limitation of S-ICD technology, especially as S-ICD use rises and medical therapy for cardiomyopathy continues to improve.

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 Versus Transvenous Implantable Defibrillator Therapy: A Systematic Review and Meta-Analysis of Randomized Trials and Propensity Score-Matched Studies

Background

Subcutaneous implantable cardioverter‐defibrillators (S‐ICDs) have been of great interest as an alternative to transvenous implantable cardioverter‐defibrillators (TV‐ICDs). No meta‐analyses synthesizing data from high‐quality studies have yet been published.

Methods and Results

An electronic literature search was conducted to retrieve randomized controlled trials or propensity score–matched studies comparing S‐ICD against TV‐ICD in patients with an implantable cardioverter‐defibrillator indication. The primary outcomes were device‐related complications and lead‐related complications. Secondary outcomes were inappropriate shocks, appropriate shock, all‐cause mortality, and infection. All outcomes were pooled under random‐effects meta‐analyses and reported as risk ratios (RRs) and 95% CIs. Kaplan–Meier curves of device‐related complications were digitized to retrieve individual patient data and pooled under a 1‐stage meta‐analysis using Cox models to determine hazard ratios (HRs) of patients undergoing S‐ICD versus TV‐ICD. A total of 5 studies (2387 patients) were retrieved. S‐ICD had a similar rate of device‐related complications compared with TV‐ICD (RR, 0.59 [95% CI, 0.33–1.04]; P=0.070), but a significantly lower lead‐related complication rate (RR, 0.14 [95% CI, 0.07–0.29]; P<0.0001). The individual patient data–based 1‐stage stratified Cox model for device‐related complications across 4 studies yielded no significant difference (shared‐frailty HR, 0.82 [95% CI, 0.61–1.09]; P=0.167), but visual inspection of pooled Kaplan–Meier curves suggested a divergence favoring S‐ICD. Secondary outcomes did not differ significantly between both modalities.

Conclusions

S‐ICD is clinically superior to TV‐ICD in terms of lead‐related complications while demonstrating comparable efficacy and safety. For device‐related complications, S‐ICD may be beneficial over TV‐ICD in the long term. These indicate that S‐ICD is likely a suitable substitute for TV‐ICD in patients requiring implantable cardioverter‐defibrillator implantation without a pacing indication.

The development of the extravascular defibrillator with substernal lead placement: A new Frontier for device-based treatment of sudden cardiac arrest

INTRODUCTION

The extravascular implantable cardioverter-defibrillato (EV ICD) system with substernal lead placement is a novel nontransvenous alternative to current commercially available ICD systems. The EV ICD provides defibrillation and pacing therapies without the potential long-term complications of endovascular lead placement but requires a new procedure for implantation with a safety profile under evaluation.

METHODS

This paper summarizes the development of the EV ICD, including the preclinical and clinical evaluations that have contributed to the system and procedural refinements to date.

RESULTS

Extensive preclinical research evaluations and four human clinical studies with >140 combined acute and chronic implants have enabled the development and refinement of the EV ICD system, currently in worldwide pivotal study.

CONCLUSION

The EV ICD may represent a clinically valuable solution in protecting patients from sudden cardiac death while avoiding the long-term consequences of transvenous hardware. The EV ICD offers advantages over transvenous and subcutaneous systems by avoiding placement in the heart and vasculature; relative to subcutaneous systems, EV ICD requires less energy for defibrillation, enabling a smaller device, and provides pacing features such as antitachycardia and asystole pacing in a single system.

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.

Impact of SMART Pass filter in patients with ajmaline-induced Brugada syndrome and subcutaneous implantable cardioverter-defibrillator eligibility failure: results from a prospective multicentre study

AIMS

Ajmaline challenge can unmask subcutaneous implantable cardioverter-defibrillator (S-ICD) screening failure in patients with Brugada syndrome (BrS) and non-diagnostic baseline electrocardiogram (ECG). The efficacy of the SMART Pass (SP) filter, a high-pass filter designed to reduce cardiac oversensing (while maintaining an appropriate sensing margin), has not yet been assessed in patients with BrS. The aim of this prospective multicentre study was to investigate the effect of the SP filter on dynamic Brugada ECG changes evoked by ajmaline and to assess its value in reducing S-ICD screening failure in patients with drug-induced Brugada ECGs.

METHODS AND RESULTS

The S-ICD screening with conventional automated screening tool (AST) was performed during ajmaline challenge in subjects with suspected BrS. The S-ICD recordings were obtained before, during and after ajmaline administration and evaluated by the means of a simulation model that emulates the AST behaviour with and without SP filter. A patient was considered suitable for S-ICD if at least one sensing vector was acceptable in all tested postures. A sensing vector was considered acceptable in the presence of QRS amplitude >0.5 mV, QRS/T-wave ratio >3.5, and sense vector score >100. Of the 126 subjects (mean age: 42 ± 14 years, males: 61%, sensing vectors: 6786), 46 (36%) presented with an ajmaline-induced Brugada type 1 ECG. Up to 30% of subjects and 40% of vectors failed the screening during the appearance of Brugada type 1 ECG evoked by ajmaline. The S-ICD screening failure rate was not significantly reduced in patients with Brugada ECGs when SP filter was enabled (30% vs. 24%). Similarly, there was only a trend in reduction of vector-failure rate attributable to the SP filter (from 40% to 36%). The most frequent reason for screening failure was low QRS amplitude or low QRS/T-wave ratio. None of these patients was implanted with an S-ICD.

CONCLUSION

Patients who pass the sensing screening during ajmaline can be considered good candidates for S-ICD implantation, while those who fail might be susceptible to sensing issues. Although there was a trend towards reduction of vector sensing failure rate when SP filter was enabled, the reduction in S-ICD screening failure in patients with Brugada ECGs did not reach statistical significance.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov Unique Identifier NCT04504591.

Subcutaneous Implantable Cardioverter-defibrillator Explantation-A Single Tertiary Center Experience

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. The objective of this study was to assess the incidence and indications for S-ICD explantation at a large tertiary referral center. We conducted a retrospective study of all S-ICD explantations performed from 2014–2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation were collected. A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution, of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7 ± 20.1 months. The mean age of the patients at explantation was 44.8 ± 15.3 years, and 42% (n = 27) were women. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of patients, respectively. The most common reason for explantation was infection (32.8%), followed by abnormal sensing (25%) and the need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7 ± 13.6 vs. 42.3 ± 14.6 years, P = 0.005) with a wider QRS duration (111 ± 19 vs. 98 ± 19 ms, P = 0.03) at device implantation compared to patients who underwent explantation for other indications. The incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for one-third of the explantations, a significant number of explantations were due to sensing abnormalities and the need for pacing. These data may have implications for patient selection for S-ICD implantation.

Primary results from the Japanese Heart Failure and Sudden Cardiac Death Prevention Trial (HINODE)

Aims

The HINODE study aimed to analyse rates of mortality, appropriately treated ventricular arrhythmias (VA), and heart failure in Japanese patients and compared with those in Western patients.

Methods and results

After treatment decisions following contemporary practice in Japan, patients were prospectively enrolled into four cohorts: (i) internal cardioverter‐defibrillator (ICD), (ii) cardiac resynchronization therapy (CRT) defibrillator (CRT‐D), (iii) standard medical therapy (‘non‐device’: ND), or (iv) pacing (indicated for CRT; received pacemaker or CRT pacing). Cohorts 1–3 required a left ventricular ejection fraction ≤35%, a history of heart failure, and a need for primary prevention of sudden cardiac death based on two to five previously identified risk factors. Endpoint outcomes were adjudicated by the independent committees. ICD and CRT‐D cohorts, considered as high‐voltage (HV) cohorts, were pooled for Kaplan–Meier analysis and propensity‐matched to Multicenter Automatic Defibrillator Implantation Trial‐Reduce Inappropriate Therapy (MADIT‐RIT) arm B and C patients. The study enrolled 354 patients followed for 19.6 ± 6.5 months, with a minimum of 12 months. Propensity‐matched HV cohorts showed comparable VA (P = 0.61) and mortality rates (P = 0.29) for HINODE and MADIT‐RIT. The ND cohort presented a high crossover rate to ICD therapy (6.1%, n = 7/115), and the CRT‐D cohort showed elevated mortality rates. The pacing cohort revealed that patients implanted with pacemakers had higher mortality (26.0%) than those with CRT‐Pacing (8.4%, P = 0.05).

Conclusions

The mortality and VA event rates of landmark trials are applicable to patients with primary prevention in Japan. Patients who did not receive guideline‐indicated CRT devices had poor outcomes.

A real-world experience of subcutaneous and transvenous implantable cardiac defibrillators-comparison with the PRAETORIAN study

Background

PRAETORIAN is the first randomized controlled trial that demonstrated the noninferiority of subcutaneous ICD (S-ICD) in comparison with transvenous ICD (TV-ICD). We retrospectively reviewed electronic records of patients with ICD implanted over the past 6 years, with the primary objective to compare our real-world single tertiary center experience with the randomized data from the PRAETORIAN study.

Methods

Seventy S-ICD patients were compared with 197 TV-ICD patients, from July 2014 to June 2020 retrospectively, over a median period of 1304 days (296-2451 days). Primary composite endpoints included inappropriate shocks and device-related malfunctions.

Results

Patients with S-ICD implantation were younger than those who received TV-ICD (mean, 49.7 years vs 63.9 years, p < .001). About 31.4% of S-ICDs were implanted for secondary prevention, and 58.6% of S-ICD patients had ischemic cardiomyopathy (ICM) with a median left ventricular ejection fraction of 32.5% (range: 10-67%). S-ICDs and TV-ICD had statistically similar inappropriate shocks (4.3% vs 4.6%, p = .78), device-related complications (11.4% vs 9.1%, p = .93), and the overall primary endpoints (15.7% vs 13.7%, p = .68). The findings remained the same even after age and gender adjustments and time-dependent analysis.

Conclusion

Although single-center experience with a small number of S-ICD patients, results of the PRAETORIAN study has been replicated in our real-world experience of S-ICD and TV-ICD implantations across diverse etiologies, indications, and age groups confirming the comparable performance of S-ICD and TV-ICD when implanted in selected patients.

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.

Longitudinal Outcomes of Subcutaneous or Transvenous Implantable Cardioverter-Defibrillators in Older Patients

BACKGROUND

The subcutaneous (S-) implantable cardioverter-defibrillator (ICD) is an alternative to the transvenous (TV-) ICD that is increasingly implanted in younger patients; data on the safety and effectiveness of the S-ICD in older patients are lacking.

OBJECTIVES

The purpose of this study was to compare outcomes among older patients who received an S- or TV-ICD.

METHODS

The authors compared S-ICD and single-chamber TV-ICD implants in Fee-For-Service Medicare beneficiaries using the National Cardiovascular Data Registry ICD Registry. Outcomes were ascertained from Medicare claims data. Cox regression or competing-risk models (with TV-ICD as reference) with overlap weights were used to compare death and nonfatal outcomes (device reoperation, device removal for infection, device reoperation without infection, and cardiovascular admission), respectively. Recurrent all-cause readmissions were compared using Anderson-Gill models.

RESULTS

A total of 16,063 patients were studied (age 72.6 ± 5.9 years, 28.4% women, ejection fraction 28.3 ± 8.9%). Compared with TV-ICD patients (n = 15,072), S-ICD patients (n = 991, 6.2% overall) were more often Black, younger, and dialysis dependent and less likely to have history of atrial fibrillation or flutter. In adjusted analyses, there were no differences between device type and risk of all-cause mortality (HR: 1.020; 95% CI: 0.819-1.270), device reoperation (subdistribution [s] HR: 0.976; 95% CI: 0.645-1.479), device removal for infection (sHR: 0.614; 95% CI: 0.138-2.736), device reoperation without infection (sHR: 0.975; 95% CI: 0.632-1.506), cardiovascular readmission (sHR: 1.087; 95% CI: 0.912-1.295), or recurrent all-cause readmission (HR: 1.072; 95% CI: 0.990-1.161).

CONCLUSIONS

In a large representative national cohort of older patients undergoing ICD implantation, risk of death, device reoperation, device removal for infection, device reoperation without infection, and cardiovascular and all-cause readmission were similar among S- and TV-ICD recipients.

S-ICDs: advantages and opportunities for improvement

INTRODUCTION

The subcutaneous implantable cardioverter defibrillator (S-ICD) is currently in its third generation and has been adopted in guidelines and in mainstream clinical practice. Considerable improvements have been made since the introduction of this device over a decade ago.

AREAS COVERED

A literature search was undertaken in Pubmed on articles relating to the S-ICD.

EXPERT OPINION

The therapy has been proven to be safe and effective and is a valuable option in selected patients. Nevertheless, there remain many shortcomings of the S-ICD which are discussed in this review, and which hopefully will be addressed by future generations of the device.