Long-term follow-up of subcutaneous ICD systems in patients with hypertrophic cardiomyopathy: a single-center experience

Long-Term Follow-Up of the S-ICD: A 10-Years Follow-Up Study of a Large Single Center Cohort

BACKGROUND

The subcutaneous implantable defibrillator (S-ICD) is an alternative to transvenous implantable defibrillators. The present analysis presents real-world data from patients with S-ICD and a follow-up duration of 10 years or more.

METHODS AND RESULTS

Between July 2010 and November 2013 76 S-ICD systems were implanted. After a follow-up duration of 10 years, data from 67 patients (88.1%) was available. Mean follow-up duration was 10.7 ± 1.3 years. Forty-seven patients (70.2%) were still alive with active S-ICD therapy. Eight patients (11.9%) died during follow-up. In eight patients (11.9%), conversion to a transvenous ICD system was necessary. This was either due to heart failure with indication for biventricular pacing (n = 2), bradycardia (n = 3), oversensing that could not be solved (n = 2), or pocket infection (n = 1). In four patients (6%), the S-ICD system was explanted without replacement for individual reasons. Sixteen patients already underwent two generator replacements, while one generator replacement was performed in the rest of the cohort. Therefore, generator longevity was documented to be within the predicted values. In 10 patients (14.9%), appropriate therapy delivery for ventricular arrhythmias was delivered. In 12 patients (17.9%), inappropriate shock delivery due to oversensing occurred. Of note, this could be resolved in all but two patients. Furthermore, the majority of these episodes occurred in the early years before the implementation of the Smart Pass algorithm.

CONCLUSION

S-ICD therapy can be successfully maintained over a long time. Incidence of oversensing significantly decreased with the implementation of novel algorithms and the new S-ICD generation. However, the present data also points out that in selected individuals conversion to transvenous systems is required.

Ventricular arrhythmias and the role of antitachycardia pacing in patients with electrical heart disease and hypertrophic cardiomyopathy

Background

Whether it is reasonable to program ATP in patients with electrical heart disease (EHD) or hypertrophic cardiomyopathy (HCM) is not thoroughly clarified. Aim of the study was to define the types of ventricular arrhythmias and evaluate the safety and efficacy of ATP activation in these patients.

Methods and results

A total of 154 patients (53.9 % male, 64.9 % secondary prevention) with EHD or HCM, who had an implanted cardioverter defibrillator (ICD) with ATP activated, were included in this retrospective analysis; comprising a median of 65.0 months of follow-up. In 39/154 (25.3 %) patients appropriate ICD therapy was delivered during the follow-up. Patients with HCM had a significantly higher incidence rate of monomorphic VTs than patients with EHD (0.21 versus 0.01 per month, 0 < 0.001). ATP terminated monomorphic VT with an efficacy of 88,2 % in 94.9 % of the occurring episodes. The incidence rate per month of torsade de pointes (TdP) tachycardia and VF was significantly higher in patients with EHD versus HCM (0.04 vs. 0.001, p=<0.001; 0.06 vs. 0.007, p=<0.001). The termination of TdP tachycardia and VF was associated with ATP in 14.0 % and 0 % (ATP efficacy of 28.3 % and 0 % respectively). The implantation for secondary prevention was associated with the occurrence of appropriate ICD therapy during the follow-up period (OR 3.94 [95%CI 1.53-10.14], p = 0.005).

Conclusion

Ventricular tachycardias in patients with HCM are primarily monomorphic and can be effectively terminated with ATP. In patients with EHD, TdP tachycardias and VF occur more frequently and are preferentially terminated by ICD shock.

Global and Temporal Trends in Utilization and Outcomes of Implantable Cardioverter Defibrillators in Hypertrophic Cardiomyopathy

BACKGROUND

Over the past decades, hypertrophic cardiomyopathy has become a contemporary treatable disease. However, limited data exist on the global trends of implantable cardioverter defibrillator (ICD) utilization and its impact on mortality/morbidity burden reduction.

METHODS

Electronic databases were systematically searched up to March 2024 for studies reporting on ICD utilization rates in hypertrophic cardiomyopathy. A random effects model was used to pool study estimates across time-era, geographic region, and age group. Primary outcome was global trends in ICD utilization. Secondary outcomes included trends of sudden cardiac death, appropriate/inappropriate shocks, and ICD-related complications.

RESULTS

In total, 234 studies (N=92 500, 514 748 patient-years) met inclusion criteria. Mean age was 46.2 (12.4) years and 37.49% were women. A total of 12 139 patients (16.43%) received an ICD over 429 766 person-years of follow-up, with an ICD implantation rate of 2.79%/y ([95% CI, 2.35%-3.32%] I²=97.80%). Rates of ICD implantation steadily increased over time from 1990 (1.09%) to 2021 (4.01%; P=0.002), with noticeable geographic variation (P=0.008). The overall rate of appropriate ICD discharges and ICD-related complications was 3.44%/y ([95% CI, 3.08%-3.84%] I²=88.40%) and 1.98%/y ([95% CI, 1.52%-2.59%] I²=90.44%), respectively, with no significant trend over time. The overall rate of inappropriate discharges was 3.58%/y ([95% CI, 3.08%-4.16%] I2=88.03%), and declined significantly over time (P=0.044). There was a significant decline in the rates of sudden cardiac death from 1990 (0.84%/y) to 2020 (0.31%/y).

CONCLUSIONS

Dramatic increases in ICD utilization have occurred, representing a 3.7-fold increase, with appropriate therapies occurring in 3.44%/y. In parallel a significant reduction in sudden cardiac death was observed, but there are insufficient data to demonstrate that a causative relationship exists. Geographic disparities in ICD utilization were evident, highlighting the need to improve access to specialized care for patients with hypertrophic cardiomyopathy. Geographic disparities in ICD utilization were evident, highlighting the need to improve access to specialized care for patients with hypertrophic cardiomyopathy.

REGISTRATION

URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42023407126.

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

BACKGROUND

To assess the risk of unsuccessful conversion of ventricular fibrillation during defibrillation testing (DFT) with the subcutaneous implantable cardioverter-defibrillator (S-ICD), the PRAETORIAN score has been proposed.

OBJECTIVE

The purpose of this study was to validate the PRAETORIAN score in a large S-ICD collective.

METHODS

A retrospective single-center analysis of S-ICD patients receiving intraoperative DFT was performed. DFT was performed using a stepwise protocol with 65-J standard polarity, change of polarity, increase to 80 J, and repositioning if necessary. If all DFTs failed, we switched to a transvenous ICD.

RESULTS

Overall, 398 patients were analyzed (268 male [67.3%]; mean age 42.4 ± 15.9 years; mean body mass index [BMI] 25.9 ± 4.8 kg/m2). Successful DFT with the first ICD shock was observed in 264 patients (66.3%). One hundred fourteen patients were defibrillated with the second (n = 104) or third (n = 10) DFT after changing shock polarity and/or shock energy. Overall, 20 patients needed at least 3 DFT (ie, 80 J and/or re-positioning). The majority (n = 88 [65.7%]) of DFT failures occurred before 2015 with the first-generation S-ICD. PRAETORIAN score was an independent predictor of DFT failure (odds ratio [OR] 1.007; 95% confidence interval [CI] 1.003-1.011 P ≤.001), while whereas BMI alone was not (P = .31). Presence of hypertrophic cardiomyopathy (HCM) (OR 2.6; 95% CI 1.3-4.4; P = .004) was predictive for at least 1 unsuccessful DFT in our multivariate regression analysis.

CONCLUSION

PRAETORIAN score proved to be a useful and valid predictive tool for successful DFT, whereas BMI only had a limited role. Patients with HCM were at increased risk for DFT failure or needed higher DFT energy.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy.

METHODS

A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate.

STRUCTURE

Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

The new European Society of Cardiology guideline for the management of cardiomyopathies: key messages for cardiac electrophysiologists

Electrocardiographic findings and arrhythmias are common in cardiomyopathies. Both may be an early indication of a specific diagnosis or may occur due to myocardial fibrosis and/or reduced contractility. Brady- and tachyarrhythmias significantly contribute to increased morbidity and mortality in patients with cardiomyopathies. Antiarrhythmic therapy including risk stratification is often challenging and plays a major role for these patients. Thus, an "electrophysiological" perspective on guidelines on cardiomyopathies may be warranted. As the European Society of Cardiology (ESC) has recently published a new guideline for the management of cardiomyopathies, this overview aims to present key messages of these guidelines. Innovations include a new phenotype-based classification system with emphasis on a multimodal imaging approach for diagnosis and risk stratification. The guideline includes detailed chapters on dilated and hypertrophic cardiomyopathy and their phenocopies, arrhythmogenic right ventricular cardiomyopathy, and restrictive cardiomyopathy as well as syndromic and metabolic cardiomyopathies. Patient pathways guide clinicians from the initial presentation to diagnosis. The role of cardiovascular magnetic resonance imaging and genetic testing during diagnostic work-up is stressed. Concepts of rhythm and rate control for atrial fibrillation have led to new recommendations, and the role of defibrillator therapy in primary prevention is discussed in detail. Whilst providing general guidelines for management, the primary objective of the guideline is to ascertain the disease etiology and disease-specific, individualized management.

Complications of Implantable Cardioverter Defibrillator and Their Potential Risk Factors in Patients with Hypertrophic Cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) has different complications such as cardiac arrhythmia and sudden cardiac death (SCD). Insertion of an implantable cardioverter defibrillator (ICD) is recommended for HCM patients who are at high risk of SCD and malignant arrhythmias, despite having their own potential complications. Hypothesis. We aimed to investigate the prevalence of different complications of ICD insertion and the impact of the potential influential baseline characteristics in a one-year follow-up period.

Methods

This was a retrospective study with a total of 71 HCM patients with ICD insertion. We evaluated the prevalence of different complications of ICD implantation and the impact of baseline characteristics on the occurrence of ICD complications using multivariate regression analysis in three 4-month periods.

Results

In a one-year follow-up, 13 patients (18.3%) experienced at least one of the complications including pneumothorax, lead failure, ICD infection, inappropriate shocks, perforation, and upper limb deep vein thrombosis (DVT) with no mortality. Inappropriate shocks were reported as the most common (11.3%) complication during this period, with a gradual increase in the second (4.2%) and third (5.6%) follow-up sessions. Among all of the baseline characteristics that were investigated in this study, a positive history of hypertension was the only risk factor with significant impact on the occurrence of complications (P = 0.01).

Conclusion

We demonstrated the occurrence of complications during a one-year follow-up as 18.3% in HCM patients with ICD insertion. A positive history of hypertension was the only baseline characteristic affecting the occurrence of complications, and inappropriate shocks were the most common complication.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases.

STRUCTURE

Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

Aim This executive summary of the hypertrophic cardiomyopathy clinical practice guideline provides recommendations and algorithms for clinicians to diagnose and manage hypertrophic cardiomyopathy in adult and pediatric patients as well as supporting documentation to encourage their use. Methods A comprehensive literature search was conducted from January 1, 2010, to April 30, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Structure Many recommendations from the earlier hypertrophic cardiomyopathy guidelines have been updated with new evidence or a better understanding of earlier evidence. This summary operationalizes the recommendations from the full guideline and presents a combination of diagnostic work-up, genetic and family screening, risk stratification approaches, lifestyle modifications, surgical and catheter interventions, and medications that constitute components of guideline directed medical therapy. For both guideline-directed medical therapy and other recommended drug treatment regimens, the reader is advised to follow dosing, contraindications and drug-drug interactions based on product insert materials.

Pitfalls of the S-ICD therapy: experiences from a large tertiary centre

Aim

The subcutaneous ICD (S-ICD) has evolved to a potential first option for many patients who have to be protected from sudden cardiac death. Many trials have underlined a similar performance regarding its effectiveness in relation to transvenous ICDs and have shown the expected benefits concerning infective endocarditis and lead failure. However, there have also been problems due to the peculiarities of the device, such as oversensing and myopotentials. In this study, we present patients from a large tertiary centre suffering from complications with an S-ICD and propose possible solutions.

Methods and results

All S-ICD patients who experienced complications related to the device (n = 40) of our large-scale single-centre S-ICD registry (n = 351 patients) were included in this study. Baseline characteristics, complications occurring and solutions to these problems were documented over a mean follow-up of 50 months. In most cases (n = 23), patients suffered from oversensing (18 cases with T wave or P wave oversensing, 5 due to myopotentials). Re-programming successfully prevented further oversensing episode in 13/23 patients. In 9 patients, generator or lead-related complications, mostly due to infectious reasons (5/9), occurred. Further problems consisted of ineffective shocks in one patient and need for antibradycardia stimulation in 2 patients and indication for CRT in 2 other patients. In total, the S-ICD had to be extracted in 10 patients. 7 of them received a tv-ICD subsequently, 3 patients refused re-implantation of any ICD. One other patient kept the ICD but had antitachycardic therapy deactivated due to inappropriate shocks for myopotential oversensing.

Conclusion

The S-ICD is a valuable option for many patients for the prevention of sudden cardiac death. Nonetheless, certain problems are immanent to the S-ICD (limited re-programming options, size of the generator) and should be addressed in future generations of the S-ICD.

Graphic abstract

Outcome differences and device performance of the subcutaneous ICD in patients with and without structural heart disease

BACKGROUND

The performance of the subcutaneous ICD (S-ICD™) has been described in different kinds of heart disease and has been proven to be an important advance in prevention of sudden cardiac death (SCD). While positive experiences with the S-ICD™ initially came from collectives of patients without structural heart diseases, positive results have also been collected from cohorts with structural heart disease.

MATERIALS AND METHODS

All S-ICD™ patients with either ischemic cardiomyopathy (ICM), dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) as the main indication for ICD implantation (n = 144 patients) or electrical heart disease/idiopathic ventricular fibrillation (n = 83 patients) in our large-scaled single-center S-ICD™ registry were included in this study. Baseline characteristics, appropriate and inappropriate shocks, and complications were documented in a mean follow-up of 18 ± 15 months.

RESULTS

Baseline characteristics were significantly different between the two groups in most categories. In contrast, there was no difference concerning neither appropriate nor inappropriate shock delivery between the two groups. Also other outcome parameters such as need for surgical revisions and all-cause mortality did not differ. There was a significant difference between the first- and second-generation S-ICDs™ in inadequate shocks mainly driven by patients with HCM.

CONCLUSION

In our study, S-ICD™ performance was similar in patients with and without structural heart disease. Decision pro- or contra-S-ICD™ should be made rather on the basis of expected shock rate and probability of the need for future anti-tachycardia or anti-bradycardia pacing than in dependence of the underlying heart disease.

Spotlight on S-ICD™ therapy: 10 years of clinical experience and innovation

Subcutaneous ICD (S-ICD™) therapy has been established in initial clinical trials and current international guideline recommendations for patients without demand for pacing, cardiac resynchronization, or antitachycardia pacing. The promising experience in ‘ideal’ S-ICD™ candidates increasingly encourages physicians to provide the benefits of S-ICD™ therapy to patients in clinical constellations beyond ‘classical’ indications of S-ICD™ therapy, which has led to a broadening of S-ICD™ indications in many centres. However, the decision for S-ICD™ implantation is still not covered by controlled randomized trials but rather relies on patient series or observational studies. Thus, this review intends to give a contemporary update on available empirical evidence data and technical advancements of S-ICD™ technology and sheds a spotlight on S-ICD™ therapy in recently discovered fields of indication beyond ideal preconditions. We discuss the eligibility for S-ICD™ therapy in Brugada syndrome as an example for an adverse and dynamic electrocardiographic pattern that challenges the S-ICD™ sensing and detection algorithms. Besides, the S-ICD™ performance and defibrillation efficacy in conditions of adverse structural remodelling as exemplified for hypertrophic cardiomyopathy is discussed. In addition, we review recent data on potential device interactions between S-ICD™ systems and other implantable cardio-active systems (e.g. pacemakers) including specific recommendations, how these could be prevented. Finally, we evaluate limitations of S-ICD™ therapy in adverse patient constitutions, like distinct obesity, and present contemporary strategies to assure proper S-ICD™ performance in these patients. Overall, the S-ICD™ performance is promising even for many patients, who may not be ‘classical’ candidates for this technology.

Prognostic impact of recurrences of ventricular tachyarrhythmias and appropriate ICD therapies in a high-risk ICD population

PURPOSE

The study sought to evaluate the prognostic impact of recurrences of ventricular tachyarrhythmias in consecutive ICD recipients with ventricular tachyarrhythmias on admission.

METHODS

All consecutive patients surviving at least one episode of ventricular tachyarrhythmias from 2002 to 2016 and discharged with an ICD (pre-existing ICD or ICD implantation at index hospitalization) were included. The primary endpoint was all-cause mortality according to the presence or absence of recurrences of ventricular tachyarrhythmias at 5 years. Secondary endpoints comprised the impact of different types of recurrences, appropriate ICD therapies, as well as predictors of recurrences and appropriate ICD therapies. Kaplan-Meier, multivariable Cox regression and propensity score matching analyses were applied.

RESULTS

A total of 592 consecutive ICD recipients was included (44% with recurrences of ventricular tachyarrhythmias and 56% without). Recurrences of ventricular tachyarrhythmias were associated with increased all-cause mortality at 5 years (HR = 1.498; 95% CI = 1.052-2.132; p = 0.025). Worst survival was observed in patients with sustained VT or VF as first recurrences compared to non-sustained VT, as well as in patients with cumulative recurrences of non-sustained or sustained VT plus VF, whereas mortality was not affected by the number of recurrences of ventricular tachyarrhythmias (> 4 vs. ≤ 4). Moreover, appropriate ICD therapies were associated with increased all-cause mortality (HR = 1.874; 95% CI = 1.318-2.666; p = 0.001), mainly attributed to secondary preventive ICDs. Finally, atrial fibrillation, LVEF < 35% and non-ischemic cardiomyopathy were identified as predictors of recurrences of ventricular tachyarrhythmias and appropriate ICD therapies.

CONCLUSIONS

Recurrences of ventricular tachyarrhythmias and recurrent appropriate ICD therapies are associated with increased long-term all-cause mortality in consecutive ICD recipients. Non-ischemic cardiomyopathy, AF and LVEF < 35% revealed to be significant predictors of both endpoints.

Device updates successfully reduce T‑wave oversensing and inappropriate shocks in subcutaneous ICD patients

Aims

To analyse the impact of device and software updates on the prevention of T‑wave oversensing (TWOS) and inappropriate shocks (IS) in subcutaneous ICD (S-ICD) patients.

Background

TWOS is a feared complication after implantation. It may lead to harmful IS. To date, specific strategies to reduce these events are lacking.

Methods

In this retrospective single-centre trial we analysed 146 S‑ICD patients who were implanted between 2010 and 2016. In all eligible consecutive patients (n = 139), follow-up of at least 6 weeks was studied. The incidence of TWOS/IS was analysed in patients receiving a 2^nd generation S‑ICD (Emblem-S-ICD) between 2014 and 2016 (Emblem). Their outcome was compared with a control group (SQ) treated with the SQ1010 device between 2010 and 2014, who were followed up for a maximum of 2 years. Furthermore, to test if the software update SMR8 reduces inappropriate shocks in the SQ1010-S-ICD population, the incidence of TWOS/IS was evaluated before and after update installation.

Results

Basic characteristics and indications for S‑ICD implantation were similar in both groups. However, the cumulative incidence of TWOS/IS was significantly decreased in Emblem vs. SQ (SQ: 15.4%, n = 14/91 vs. Emblem 4.2%, n = 2/48; p = 0.049). Furthermore, with regards to the SQ population we also observed a trend towards a significant reduction of TWOS/IS after installation of the software update SMR8 in 2014 (before update: 13.4%, n = 11/82 vs. after update: 4.6%, 3/65, p = 0.07).

Conclusion

2^nd generation devices but probably also the SMR8 software update reduce the incidence of TWOS/IS in S‑ICD 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.

[Management of inappropriate shocks/T-wave-oversensing in S-ICD®-patients]

Inappropriate shocks are a feared complication after implantable cardioverter-defibrillator (ICD) implantation and have a tremendous impact on quality of life. Inappropriate shocks in patients with subcutaneous ICD (S-ICD®, Boston Scientific, Marlborough, MA, USA) have various underlying causes. This review summarizes the current literature on this topic and lists possible treatment options.

The T-peak-to-T-end interval: a novel ECG marker for ventricular arrhythmia and appropriate ICD therapy in patients with hypertrophic cardiomyopathy

INTRODUCTION

Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of sudden cardiac death (SCD) primarily due to ventricular arrhythmia (VA). In patients (pts.) with a high risk of SCD, the implantation of an intracardiac cardioverter defibrillator (ICD) is thus indicated. Previous studies suggest that a prolonged interval between the peak and the end of the T wave, T-peak to T-end (TpTe), is associated with an elevated risk of VA and SCD in various clinical settings. The aim of our study was to evaluate the association between TpTe and VA in HCM pts. with a previously implanted ICD.

METHODS

In 40 HCM pts. (51.4 ± 16.4 years; 62.5% men), TpTe was measured using the baseline digital standard resting 12-lead ECG during sinus rhythm. VA was assessed by device follow-up.

RESULTS

Within 41.8 ± 35.1 months, 7 (17.5%) pts. had VA leading to appropriate therapy (AT), 7 pts. (17.5%) had non-sustained VA, and 26 pts. (65.0%) had no VA. The maximum TpTe was significantly prolonged in pts. with VA leading to AT compared to pts. without VA (101.3 ± 19.6 vs. 79.9 ± 15.3 ms; p = 0.004). Maximum TpTe was associated with an elevated risk of VA leading to AT (hazard ratio per 10 ms increase 1.63; 95% CI 1.04-2.54; p = 0.031) and pts. with a maximum TpTe ≤ 78 ms were without any VA leading to AT during follow-up. There was no correlation of maximum TpTe to other clinical parameters in our patient cohort.

CONCLUSION

A prolonged TpTe is associated with VA and AT in HCM. Our findings suggest that TpTe can possibly serve as a marker for ventricular arrhythmogenesis in pts. with HCM and assessment of TpTe might, therefore, optimize SCD risk stratification.

Analysis of Screening Electrocardiogram for the Subcutaneous Defibrillator in Adults with Congenital Heart Disease

Candidates for the subcutaneous implantable cardioverter-defibrillator (S-ICD) are screened using an electrocardiogram (S-ECG) tool to measure appropriate detection. We sought to define the S-ICD candidacy of congenital heart disease patients using the S-ECG tool. We also analyzed the reliability of the (S-ECG) tool between measurers in this population. Patients above the age of 12 and with a diagnosis associated with either a higher incidence of cardiac arrest or vascular access challenges were asked to undergo screening. S-ECGs were then analyzed by a pediatric electrophysiologist, an S-ICD device engineer, and an S-ICD clinical representative for candidacy. Results were compared for interobserver variability and S-ECGs were analyzed by t test to determine variables that differ among passing and failing leads. Thirty-one patients underwent screening. Two of the 31 (6.5%) patients failed S-ICD screening. Analysis of the screening leads demonstrated the highest passing rates using lead III at a 5 mm/mV amplitude setting with 71 and 62% pass rate in the supine and standing positions, respectively. Interobserver analysis correlated well among the three measurers. There was a higher amplitude difference between QRS and T waves among passing versus failing S-ECG. Congenital heart disease patients have acceptable passage rates utilizing the S-ECG algorithm. Interobserver measurements were well correlated and these data suggest that the proximal coil to device (lead III) vector would be best utilized in this patient population. A larger difference between QRS and T wave amplitudes was associated with a higher S-ECG passing rate.

Implantable cardioverter defibrillator therapy in hypertrophic cardiomyopathy: an updated systematic review and meta-analysis of outcomes and complications

BACKGROUND

Since the introduction of the implantable cardioverter-defibrillator (ICD) in patients with hypertrophic cardiomyopathy (HCM), the incidence of sudden cardiac death (SCD) has been significantly reduced. Given its widespread use, it is important to identify the outcomes associated with ICD use in patients with HCM. The present paper is a systematic review and meta-analysis of the rates of appropriate and inappropriate interventions, mortality, and device complications in HCM patients with an ICD.

METHODS

We conducted a systematic review and meta-analysis on 27 studies reporting outcomes and complications after ICD implantation in patients with HCM. ICD interventions, device complications, and mortality were extracted for analysis.

RESULTS

A total of 3,797 patients with HCM and ICD implantation were included (mean age, 44.5 years; 63% male), of which 83% of patients had an ICD for primary prevention of SCD. The cardiac mortality was 0.9% (95% CI: 0.7-1.3) per year and non-cardiac mortality was 0.8% (95% CI: 0.6-1.2) per year. Annualized appropriate intervention rate was 4.8% and annualized inappropriate intervention was 4.9%. The annual incidence of lead malfunction, lead displacement and infection was 1.4%, 1.3%, and 1.1%, respectively.

CONCLUSIONS

ICD use in patients with HCM produces low rates of cardiac and non-cardiac mortality, and an appropriate intervention rate of 4.8% per year. However, moderate rates of inappropriate intervention and device complications warrant careful patient selection in order to optimize the risk to benefit ratio in this select group of patients.

Posttraumatic stress and quality of life with the totally subcutaneous compared to conventional cardioverter-defibrillator systems

BACKGROUND

For prevention of sudden cardiac death, the transvenously implantable cardioverter-defibrillator therapy (tv-ICD) is well accepted. The subcutaneous system (S-ICD^®) is promising in terms of reducing ICD complications. Nevertheless, the impact of the novel generator position on patients' quality of life (QoL) is yet unknown.

OBJECTIVE

This study aimed at comparing QoL and posttraumatic stress with both systems.

METHODS

60 S-ICD^® and 60 case-controlled tv single-chamber ICD patients were asked to respond to three standardized questionnaires. PDS [screening for posttraumatic stress disorders (PTSD)] and PHQ-D (detection of the most predominant psychological disorders) were used to screen for potential mental comorbidities. The SF-12 questionnaire was used to evaluate physical and mental well-being. Groups were compared in terms of QoL and PTSD.

RESULTS

n = 42 (70%) pairs were analyzed (n = 30 male, mean age 44.6 ± 12.2 years). Prior appropriate (p = 0.06) or inappropriate episodes (p = 0.24), ejection fraction (p = 0.28), or underlying cardiac disease did not differ significantly between groups. PDS revealed a PTSD in n = 6 tv-ICD and n = 6 S-ICD^® patients (14.3%) equally. In the PHQ-D questionnaire, n = 4 tv-ICD and n = 2 S-ICD^® patients fulfilled criteria for a major depression (p = 0.68). Panic disorders (n = 2 tv, n = 0 S-ICD^®, p = 0.5), and anxiety disorders (n = 3 S-ICD^®, n = 0 tv-ICD, p = 0.24) did not differ between groups. The physical well-being score was 39.9 ± 12.5 in patients with a tv-ICD compared to 46.6 ± 9.9 in S-ICD^® patients (p = 0.01). The mental well-being score was comparable in both groups (tv-ICD 51.8 ± 10.8 vs. S-ICD^® 51.9 ± 10.4, p = 0.95).

CONCLUSIONS

Our case-control study revealed equal or even better physical well-being of patients with the S-ICD^®. PTSD occurred in almost 15% of ICD patients irrespective of the type of system.

Update on hypertrophic cardiomyopathy and a guide to the guidelines

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiovascular disorder, affecting 1 in 500 individuals worldwide. Existing epidemiological studies might have underestimated the prevalence of HCM, however, owing to limited inclusion of individuals with early, incomplete phenotypic expression. Clinical manifestations of HCM include diastolic dysfunction, left ventricular outflow tract obstruction, ischaemia, atrial fibrillation, abnormal vascular responses and, in 5% of patients, progression to a 'burnt-out' phase characterized by systolic impairment. Disease-related mortality is most often attributable to sudden cardiac death, heart failure, and embolic stroke. The majority of individuals with HCM, however, have normal or near-normal life expectancy, owing in part to contemporary management strategies including family screening, risk stratification, thromboembolic prophylaxis, and implantation of cardioverter-defibrillators. The clinical guidelines for HCM issued by the ACC Foundation/AHA and the ESC facilitate evaluation and management of the disease. In this Review, we aim to assist clinicians in navigating the guidelines by highlighting important updates, current gaps in knowledge, differences in the recommendations, and challenges in implementing them, including aids and pitfalls in clinical and pathological evaluation. We also discuss the advances in genetics, imaging, and molecular research that will underpin future developments in diagnosis and therapy for HCM.

[Updated ESC guideline: innovations for the treatment of ventricular arrhythmias and recommendations for prevention of sudden cardiac death]

The 2015 European Society of Cardiology Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death is an update of the former 2006 European/American guidelines. This new consensus document gives a detailed overview on prevention and therapy of ventricular arrhythmias and sudden cardiac death. This includes detailed discussion of channelopathies and various cardiomyopathies. Gaps in evidence are identified and also discussed. DNA analysis and postmortem assessment in sudden cardiac death victims is for the first time part of these new recommendations. In addition, for the first time recommendations on subcutaneous implantable cardioverter-defibrillator (ICD) and the wearable defibrillator are given. The guidelines strengthen the role of ICD therapy in primary and secondary prevention of sudden cardiac death although data used as the basis for these recommendations are 10-15 years old and patients' characteristics including therapeutic options have changed during that time. Systematic reassessment of left ventricular function 6-12 weeks after infarction is also included as a new recommendation. The role of catheter ablation in electrical storm and for those presenting with a first episode of sustained ventricular tachycardia has also been upgraded in the new guidelines. Hopefully, the new guidelines will reach not only cardiologists and help to improve patient care, but also contribute to reducing the high number sudden cardiac deaths in Europe.

Right Parasternal Lead Placement Increases Eligibility for Subcutaneous Implantable Cardioverter Defibrillator Therapy in Adults With Congenital Heart Disease

BACKGROUND

The subcutaneous implantable cardioverter defibrillator (S-ICD) provides an attractive option for patients with congenital heart disease (CHD) in whom a transvenous defibrillator is contraindicated. Given the unusual cardiac anatomy and repolarization strain, the surface electrocardiogram (ECG) is frequently abnormal, potentially increasing the screen failure rate.

METHODS AND RESULTS

We prospectively screened 100 adult CHD patients regardless of the presence of clinical indication for ICD utilizing a standard left sternal lead placement, as well as a right parasternal position. Baseline patient and 12-lead ECG characteristics were examined to assess for predictors of screen failure. Average patient age was 48±14 years, average QRS duration was 134±37 ms, and 13 patients were pacemaker dependent. Using the standard left parasternal electrode position, 21 patients failed screening. Of these 21 patients with screen failure, 9 passed screening with the use of right parasternal electrode positioning, reducing screening failure rate from 21% to 12%. QT interval and inverted T wave anywhere in V2-V6 leads were found to be independent predictors of left parasternal screening failure (P=0.01 and P=0.04, respectively).

CONCLUSIONS

Utilization of both left and right parasternal screening should be used in evaluation of CHD patients for S-ICD eligibility. ECG repolarization characteristics were also identified as novel predictors of screening failure in this group. (Circ J 2016; 80: 1328-1335).