Efficacy and Safety of an Extravascular Implantable Cardioverter-Defibrillator

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

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

A Modular Communicative Leadless Pacing-Defibrillator System

BACKGROUND

The subcutaneous implantable cardioverter-defibrillator (ICD) is associated with fewer lead-related complications than a transvenous ICD; however, the subcutaneous ICD cannot provide bradycardia and antitachycardia pacing. Whether a modular pacing-defibrillator system comprising a leadless pacemaker in wireless communication with a subcutaneous ICD to provide antitachycardia and bradycardia pacing is safe remains unknown.

METHODS

We conducted a multinational, single-group study that enrolled patients at risk for sudden death from ventricular arrhythmias and followed them for 6 months after implantation of a modular pacemaker-defibrillator system. The safety end point was freedom from leadless pacemaker-related major complications, evaluated against a performance goal of 86%. The two primary performance end points were successful communication between the pacemaker and the ICD (performance goal, 88%) and a pacing threshold of up to 2.0 V at a 0.4-msec pulse width (performance goal, 80%).

RESULTS

We enrolled 293 patients, 162 of whom were in the 6-month end-point cohort and 151 of whom completed the 6-month follow-up period. The mean age of the patients was 60 years, 16.7% were women, and the mean (±SD) left ventricular ejection fraction was 33.1±12.6%. The percentage of patients who were free from leadless pacemaker-related major complications was 97.5%, which exceeded the prespecified performance goal. Wireless-device communication was successful in 98.8% of communication tests, which exceeded the prespecified goal. Of 151 patients, 147 (97.4%) had pacing thresholds of 2.0 V or less, which exceeded the prespecified goal. The percentage of episodes of arrhythmia that were successfully terminated by antitachycardia pacing was 61.3%, and there were no episodes for which antitachycardia pacing was not delivered owing to communication failure. Of 162 patients, 8 died (4.9%); none of the deaths were deemed to be related to arrhythmias or the implantation procedure.

CONCLUSIONS

The leadless pacemaker in wireless communication with a subcutaneous ICD exceeded performance goals for freedom from major complications related to the leadless pacemaker, for communication between the leadless pacemaker and subcutaneous ICD, and for the percentage of patients with a pacing threshold up to 2.0 V at a 0.4-msec pulse width at 6 months. (Funded by Boston Scientific; MODULAR ATP ClinicalTrials.gov NCT04798768.).

Atrioventricular optimization improves cardiac resynchronization response in patients with long interventricular electrical delays: A pooled analysis of the SMART-AV and SMART-CRT trials

BACKGROUND

The utility of atrioventricular (AV) optimization (AVO) algorithms remains in question. A substudy of the SMART-AV trial found that patients with prolonged interventricular delays ≥70 ms were more likely to benefit from cardiac resynchronization therapy (CRT) with AVO. The SMART-CRT trial evaluated AVO on the basis of these results, but the study was underpowered.

OBJECTIVE

To increase statistical power, data from SMART-AV patients meeting the inclusion criterion of interventricular delay ≥70 ms were pooled with data from SMART-CRT to reassess AVO.

METHODS

SMART-CRT and SMART-AV were prospective, randomized, multicenter clinical trials. Patients in both studies were randomized to be programmed with an AVO algorithm (SmartDelay) or fixed AV delay (120 ms). Paired echocardiograms obtained at baseline and 6 months were compared, with CRT response defined as ≥15% reduction in left ventricular end-systolic volume.

RESULTS

A total of 451 complete patient data sets were pooled and analyzed. The baseline demographics between studies did not differ statistically in terms of age, sex, left ventricular ejection fraction, or left ventricular end-systolic volume. The AVO group had a greater proportion of CRT responders (SmartDelay, 73.9%; fixed, 63.1%; P = .014) and greater changes in measures of reverse remodeling. SmartDelay patients with a recommended sensed AV delay outside the nominal range (100-120 ms) had 2.3 greater odds of CRT response than fixed AV delay patients.

CONCLUSION

Greater CRT response and measures of reverse remodeling were observed in patients with SmartDelay enabled vs a fixed AV delay. This study supports the use of SmartDelay in patients with a CRT indication and interventricular delay ≥70 ms.

CLINICALTRIALS

GOV REGISTRATION

NCT00677014 and NCT03089281.

The Year in Electrophysiology: Selected Highlights From 2023

This special article is a continuation of an annual series for the Journal of Cardiothoracic and Vascular Anesthesia, highlighting the latest developments in the field of electrophysiology, particularly concerning cardiac anesthesiologists. The selected topics in the specialty for 2023 include consensus statements on left atrial appendage closure, outcomes in patients with atrial fibrillation and heart failure after ablation, further developments in the field of pulse field ablation, alternate defibrillation strategies for refractory ventricular fibrillation, updates on conduction system pacing, new devices such as the Aurora EV system and AVEIR leadless pacemaker system, artificial intelligence and its use in electrocardiogram-based diagnosis and latest evidence regarding the impact of anesthetic techniques on patient outcomes undergoing electrophysiology procedures.

Inappropriate Extravascular ICD Shock Due to Wet Car Seat

Inappropriate shocks from an Intracardiac defibrillator are associated with increased mortality and may be caused by external electromagnetic interference. This case illustrates that water is an excellent conductor of electricity and that determined investigation may reveal the cause of inappropriate shocks.

New Guidelines of Pediatric Cardiac Implantable Electronic Devices: What Is Changing in Clinical Practice?

Guidelines are important tools to guide the diagnosis and treatment of patients to improve the decision-making process of health professionals. They are periodically updated according to new evidence. Four new Guidelines in 2021, 2022 and 2023 referred to pediatric pacing and defibrillation. There are some relevant changes in permanent pacing. In patients with atrioventricular block, the heart rate limit in which pacemaker implantation is recommended was decreased to reduce too-early device implantation. However, it was underlined that the heart rate criterion is not absolute, as signs or symptoms of hemodynamically not tolerated bradycardia may even occur at higher rates. In sinus node dysfunction, symptomatic bradycardia is the most relevant recommendation for pacing. Physiological pacing is increasingly used and recommended when the amount of ventricular pacing is presumed to be high. New recommendations suggest that loop recorders may guide the management of inherited arrhythmia syndromes and may be useful for severe but not frequent palpitations. Regarding defibrillator implantation, the main changes are in primary prevention recommendations. In hypertrophic cardiomyopathy, pediatric risk calculators have been included in the Guidelines. In dilated cardiomyopathy, due to the rarity of sudden cardiac death in pediatric age, low ejection fraction criteria were demoted to class II. In long QT syndrome, new criteria included severely prolonged QTc with different limits according to genotype, and some specific mutations. In arrhythmogenic cardiomyopathy, hemodynamically tolerated ventricular tachycardia and arrhythmic syncope were downgraded to class II recommendation. In conclusion, these new Guidelines aim to assess all aspects of cardiac implantable electronic devices and improve treatment strategies.

Ten years of subcutaneous defibrillator therapy: Consolidated clinical evidence and future perspectives

The subcutaneous implantable cardioverter defibrillator (S-ICD) was developed as an alternative to the traditional transvenous implantable cardioverter defibrillator (TV-ICD), aiming to provide easier implantation, simplified detection algorithm of malignant ventricular arrhythmias and prevention from placing components in the cardiovascular system. The S-ICD is implanted subcutaneously or intramuscularly with the generator placed in the left midaxillary line and the lead tunneled subcutaneously in the left para-sternal region. Preimplant electrocardiogram screening is recommended to prevent implantation in patients at high risk of T wave over-sensing. Currently, the S-ICD is unsuitable for patients requiring pacing or cardiac resynchronization. Since the beginning, the S-ICD underwent extensive preclinical investigation until the first prospective multicentre trial demonstrating high efficacy and safety led to market release. While earlier studies focused on younger patients with higher ejection fraction, more recent studies showed favorable outcomes even in patients with comorbidities similar to those typically observed in patients receiving TV-ICD. The development of second and third generation devices has contributed to reduce inappropriate shocks and overcome previous limitations. The aim of this paper is to review the evidence in the literature over the past decade supporting S-ICD as a valid alternative to TV-ICD in terms of safety and efficacy, highlighting the improvements in technology, as well as outcomes.

Defibrillation threshold in elective subcutaneous implantable defibrillator generator replacements: Time to reduce the size of the pulse generator?

INTRODUCTION

The first step-down defibrillation studies in the subcutaneous implantable cardioverter-defibrillator (S-ICD) described a defibrillation threshold (DFT) of 32.5 ± 17.0 J and 36.6 ± 19.8 J. Therefore, the default shock output of the S-ICD was set at 80 J. In de novo implants, the DFT is lower in optimally positioned S-ICDs. However, a retrospective analysis raised concerns about a high DFT in S-ICD replacements, possibly related to fibrosis.

OBJECTIVE

We aimed to find the DFT in patients undergoing S-ICD generator replacement.

METHODS

This prospective study enrolled patients who underwent S-ICD generator replacement with subsequent defibrillation testing. A pre-specified defibrillation testing protocol was used to determine the DFT, defined as the lowest shock output that effectively terminated the induced ventricular arrhythmia.

RESULTS

A total of 45 patients were enrolled, 6.0 ± 2.1 years after initial implant. Mean DFT during replacement in the total cohort was 27.4 ± 14.3 J. In patients with a body mass index (BMI) 18.5-25 kg/m2 (N = 22, BMI 22.5 ± 1.6), median DFT was 20 J (IQR 17.5-30). In 18/22 patients, the DFT was ≤30 J and 5/22 patients were successfully defibrillated at 10 J. One patient with hypertrophic cardiomyopathy had a DFT of 65 J. In patients with a BMI >25 kg/m2 (N = 23, BMI 29.5 ± 4.2), median DFT was 30 J (IQR 20-40). In 15/23 patients, the DFT was ≤30 J and 4/23 patients had a successful defibrillation test at 10 J.

CONCLUSIONS

This study eases concerns about a high DFT after S-ICD generator replacement. The majority of patients had a DFT ≤30 J, regardless of BMI, suggesting that the shock output of the S-ICD could be safely reduced.

[History of the implantable cardioverter-defibrillator in Germany]

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

Patients with a high defibrillation threshold: Approaches to management

Implantable cardioverter-defibrillators (ICDs) have revolutionized the prognosis for patients at elevated risk of ventricular tachyarrhythmias. For safety, defibrillation should be effective with a minimum of 10 J below the device's maximum energy. While modern ICDs rarely deliver ineffective shocks in primary prevention, the surge in managing severe heart failure patients has led to an increased number of patients with high defibrillation thresholds (DFTs). This article elucidates the potential causes of high DFT, including clinical factors, lead and device placement, the presence of a Left Ventricular Assist Device (LVAD), prolonged ventricular arrhythmias, shock vectors, waveform tilt, medications, and manufacturer-specific options. We also detail management strategies, highlighting alternative shock coil placements, practical recommendations, and case studies from our institution. Our management algorithm suggests addressing preventable causes, re-evaluating coil positions, considering non-invasive system modifications, upgrading to a higher-capacity device, and adding extra coil(s).

Patient-reported quality of life and acceptance of the extravascular implantable cardioverter-defibrillator: Results from pivotal study

INTRODUCTION

The pivotal study of the extravascular implantable cardioverter-defibrillator (EV ICD) recently demonstrated primary efficacy and safety endpoints comparable to previous ICD systems. Patient experience with this novel device has not been reported. The current study examined the standardized patient-reported outcome (PRO) metrics of quality of life (QOL) and patient acceptance of the device.

METHODS

The EV ICD Pivotal Study was a prospective, single-arm, nonrandomized, global, premarket approval trial. Patients completed the 12-Item Short Form Survey (SF-12) QOL surveys at baseline and at 6 months following implant. Additionally, patients completed the Florida Patient Acceptance Survey (FPAS) QOL survey at 6 months.

RESULTS

From baseline to 6 months, patients within the EV ICD Pivotal Study (n = 247) reported statistically significant SF-12 improvements in physical QOL (45.4 ± 9.4 vs. 46.8 ± 9.1 respectively, p = .020) and no changes in mental QOL (49.3 ± 10.4 vs. 50.5 ± 9.7, p = .061). No differences were noted by sex, atrial fibrillation, or the experience of ICD shock. EV ICD patients reported better total FPAS patient acceptance of their ICD than TV-ICD or S-ICD patients using historical norms comparisons (80.4 ± 15.7 vs. 70.2 ± 17.8, p < .0001 for S-ICD and 73.0 ± 17.4, p = .004 for TV-ICD).

CONCLUSION

The initial PROs for EV ICD patients indicated that patients had improvements in physical QOL from baseline to 6-month follow-up and markedly better overall acceptance of their ICD compared to a previous study with S-ICD and TV-ICD data. These initial results suggest that the EV ICD is evaluated positively by patients.

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

INTRODUCTION

The extravascular implantable cardioverter defibrillator (EV ICD) has extended projected battery longevity compared to the subcutaneous implantable cardioverter defibrillator (S-ICD). This study used modeling to characterize the need for generator changes, long-term complications, and overall costs for both the EV ICD and S-ICD in healthcare systems of various countries.

METHODS

Battery longevity data were modeled using a Markov model from averages reported in device labeling for the S-ICD and with engineering estimates based on real life usage from EV ICD Pivotal Study patient data to introduce variability. Clinical demographic data were derived from published literature. The primary outcomes were defined as the number of generator replacement surgeries, complications, and total healthcare system costs due to battery depletion over the expected lifetime of patients receiving EV ICD or S-ICD therapy.

RESULTS

Average modeled battery longevity was determined to be 7.3 years for the S-ICD versus 11.8 years for the EV ICD. The probability of a complication after a replacement procedure was 1.4%, with an operative mortality rate of 0.02%. The use of EV ICD was associated with 1.4-1.6 fewer replacements on average over an expected patient lifetime as compared to S-ICD and a 24.3%-26.0% reduction in cost. A one-way sensitivity analysis of the model for the US healthcare system found that use of an EV ICD resulted in a reduction in replacement surgeries of greater than 1 (1.1-1.6) along with five-figure cost savings in all scenarios ($18 602-$40 948).

CONCLUSION

The longer projected battery life of the EV ICD has the potential to meaningfully reduce long-term morbidity and healthcare resources related to generator changes from the perspective of multiple diverse healthcare systems.

Topological Data Analysis in Cardiovascular Signals: An Overview

Topological data analysis (TDA) is a recent approach for analyzing and interpreting complex data sets based on ideas a branch of mathematics called algebraic topology. TDA has proven useful to disentangle non-trivial data structures in a broad range of data analytics problems including the study of cardiovascular signals. Here, we aim to provide an overview of the application of TDA to cardiovascular signals and its potential to enhance the understanding of cardiovascular diseases and their treatment in the form of a literature or narrative review. We first introduce the concept of TDA and its key techniques, including persistent homology, Mapper, and multidimensional scaling. We then discuss the use of TDA in analyzing various cardiovascular signals, including electrocardiography, photoplethysmography, and arterial stiffness. We also discuss the potential of TDA to improve the diagnosis and prognosis of cardiovascular diseases, as well as its limitations and challenges. Finally, we outline future directions for the use of TDA in cardiovascular signal analysis and its potential impact on clinical practice. Overall, TDA shows great promise as a powerful tool for the analysis of complex cardiovascular signals and may offer significant insights into the understanding and management of cardiovascular diseases.

Emerging Technologies for the Smallest Patients

Pediatric and congenital heart disease patients may require cardiac implantable electronic device implantation, inclusive of pacemaker, ICD, and implantable cardiac monitor, for a variety of etiologies. While leads, generators, and monitors have decreased in size over the years, they remain less ideal for the smallest patients. The potential for a miniature pacemaker, fetal micropacemaker, improving leadless technology, and rechargeable devices creates hope that the development of pediatric-focused devices will increase. Further, alternative approaches that avoid the need for a transvenous or surgical approach may add more options to the toolbox for the pediatric and congenital electrophysiologist.

Prediction of Sudden Death Risk in Patients with Congenital Heart Diseases

Risk stratification for sudden death should be discussed with patients with congenital heart disease at each stage of personal and cardiac development. For most patients, risk is low through teenage years and the critical factors to consider are anatomy, ventricular function, and symptoms. By adulthood, these are supplemented by screening for atrial arrhythmias, ventricular arrhythmias, and pulmonary hypertension. Therapies include medication, ablation, and defibrillator placement.

Ultrasound utilization for implantation of cardiac implantable electronic devices

Ultrasound (US) guidance for implantation of cardiac implantable electronic devices (CIED) is currently not routine practice. This article sought to review published data on the use of ultrasound in each of the major surgical steps involved in implantation of CIEDs, including achieving anesthesia, obtaining venous access and implantation of leads. A literature review was performed, revealing a total of 20 peer-reviewed studies that assessed US guidance for CIED implantation; 3 of these were randomized trials while the remainder were mostly feasibility studies. The available data suggest that ultrasound can be useful in guiding implantation of CIEDs, with a trend towards less complication rates; however, more high-quality studies that compare US guidance to traditional techniques in CIED implantation are required.

Simultaneous subcutaneous implantable cardioverter-defibrillator and leadless pacemaker implantation for patients at high risk of infection: a retrospective case series report

BACKGROUND

The subcutaneous implantable cardioverter defibrillator (S-ICD) and leadless pacemaker (LP) are alternative options for patients at high risk of infection requiring ICD and pacing therapy. In this analysis, we described the simultaneous implantation of S-ICD and LP in patients with high infectious risk.

METHODS

The study cohort comprised patients referred to our institution for ICD implantation due to high-risk factors of infection.

RESULTS

Between 2018 and 2022, 13 patients were referred, including 11 with infected ICD and 2 for first ICD implantation in the presence of high-risk factors. In cases of infected ICD, successful extraction was performed using a mechanical dilatation technique. Reimplantation was delayed until resolution of infection with antibiotic therapy. The devices were implanted during a single procedure, with S-ICD implantation following LP placement for verification of sensing adequacy through surface ECG screening. Suitable vectors for sensing during inhibited and ventricular pacing were identified in all patients. Defibrillation testing was effective, and no issues with double counting or undersensing were observed. The postoperative period was uneventful, and during a median follow-up of 35 months, no complications or infections were reported. The median ventricular pacing percentage was 5%, and a single inappropriate shock episode due to myopotential interference was reported and resolved by reprogramming the sensing vector.

CONCLUSION

Simultaneous implantation of S-ICD and LP is feasible and safe in patients at high risk of infection requiring both ICD and pacing therapy. This combined approach provides an effective solution for these patients.

Lead management in patients undergoing percutaneous tricuspid valve replacement or repair: a 'heart team' approach

Clinically significant tricuspid regurgitation (TR) has historically been managed with either medical therapy or surgical interventions. More recently, percutaneous trans-catheter tricuspid valve (TV) replacement and tricuspid trans-catheter edge-to-edge repair have emerged as alternative treatment modalities. Patients with cardiac implantable electronic devices (CIEDs) have an increased incidence of TR. Severe TR in this population can occur for multiple reasons but most often results from the interactions between the CIED lead and the TV apparatus. Management decisions in patients with CIED leads and clinically significant TR, who are undergoing evaluation for a percutaneous TV intervention, need careful consideration as a trans-venous lead extraction (TLE) may both worsen and improve TR severity. Furthermore, given the potential risks of 'jailing' a CIED lead at the time of a percutaneous TV intervention (lead fracture and risk of subsequent infections), consideration should be given to performing a TLE prior to a percutaneous TV intervention. The purpose of this 'state-of-the-art' review is to provide an overview of the causes of TR in patients with CIEDs, discuss the available therapeutic options for patients with TR and CIED leads, and advocate for including a lead management specialist as a member of the 'heart team' when making treatment decisions in patients TR and CIED leads.

Current and novel percutaneous epicardial access techniques for electrophysiological interventions: A comparison of procedural success and safety

Accessing the pericardial space safely and efficiently is an important skill for interventional cardiac electrophysiologist. With the increased recognition of the complexity of the 3-dimensional arrhythmogenic substrate due to advances in imaging and mapping technologies there has been an expansion of epicardial procedures in recent years. Equally, minimally invasive implantation of epicardial pacing, cardiac resynchronization, or defibrillation leads is expanding in specific patients where transvenous systems are contraindicated or their long term sequelae should be ideally avoided. Selective delivery of intrapericardial pharmacological antiarrhythmic therapy is yet another potential indication, albeit still investigational. The expanding indications for percutaneous epicardial procedures is contrasted by the still substantial risk and challenges associated with accessing the pericardial space. Myocardial perforation, coronary artery laceration, and damage to the surrounding organs are all recognized and feared complications. A number of innovative epicardial access techniques have been proposed to overcome the difficulties and risks of traditional dry subxiphoid punctures and may allow for more widespread use of epicardial access in the future. We review 10 different established and novel subxiphoidal epicardial access techniques describing procedural success rates, safety profile and overall experience. The technical aspects as well as access times and costs for extra equipment will be reviewed. Finally, an outlook of reported preclinical techniques awaiting in-human feasibility studies is provided.

Transvenous versus subcutaneous implantable cardioverter defibrillators in young cardiac arrest survivors

Secondary prevention implantable cardioverter defibrillators (ICDs) are indicated in young patients presenting with aborted sudden cardiac death (SCD) because of ventricular arrhythmias. Transvenous-ICDs (TV-ICDs) are effective, established therapies supported by evidence. The significant morbidity associated with transvenous leads led to the development of the newer subcutaneous-ICD (S-ICD). This review discusses the clinical considerations when selecting an ICD for the young patient presenting with out-of-hospital cardiac arrest. The major benefits of TV-ICDs are their ability to pace (antitachycardia pacing [ATP], bradycardia support and cardiac resynchronisation therapy [CRT]) and the robust evidence base supporting their use. Other benefits include a longer battery life. Significant complications associated with transvenous leads include pneumothorax and tamponade during insertion and infection and lead failure in the long term. Comparatively, S-ICDs, by virtue of having no intravascular leads, prevent these complications. S-ICDs have been associated with a higher incidence of inappropriate shocks. Patients with an indication for bradycardia pacing, CRT or ATP (documented ventricular tachycardia) are seen as unsuitable for a S-ICD. If venous access is unsuitable or undesirable, S-ICDs should be considered given the patient is appropriately screened. There is a need for further randomised controlled trials to directly compare the two devices. TV-ICDs are an effective therapy for preventing SCD limited by significant lead-related complications. S-ICDs are an important development hindered largely by an inability to pace. Young patients stand to gain the most from a S-ICD as the cumulative risk of lead-related complications is high. A clinical framework to aid decision-making is presented.

Spanish implantable cardioverter-defibrillator registry. 19th official report of Heart Rhythm Association of the Spanish Society of Cardiology (2022)

INTRODUCTION AND OBJECTIVES

This article presents data on implantable cardioverter-defibrillator implants in Spain in 2022.

METHODS

The data were collected from implantation centers, which voluntarily completed a data collection sheet during the implantation process, either manually or through a web page.

RESULTS

In 2022, 170 hospitals participated in the registry. A total of 7693 forms were received compared with the 7970 reported by Eucomed (European Confederation of Medical Suppliers Associations), representing 96.5% of the devices. The total rate of registered implants was 162/million inhabitants (168 according to Eucomed), showing a slight increase compared with previous years. Disparities persisted among autonomous communities and Spain continued to have the lowest implantation rate among countries participating in Eucomed.

CONCLUSIONS

The data from the registry for 2022 reflect the complete recovery of activity after the impact of the COVID-19 pandemic in 2020. Despite a slight improvement, there was no significant change in our position in Europe or in the substantial differences among autonomous communities.

The Lancet Commission to reduce the global burden of sudden cardiac death: a call for multidisciplinary action

Despite major advancements in cardiovascular medicine, sudden cardiac death (SCD) continues to be an enormous medical and societal challenge, claiming millions of lives every year. Efforts to prevent SCD are hampered by imperfect risk prediction and inadequate solutions to specifically address arrhythmogenesis. Although resuscitation strategies have witnessed substantial evolution, there is a need to strengthen the organisation of community interventions and emergency medical systems across varied locations and health-care structures. With all the technological and medical advances of the 21st century, the fact that survival from sudden cardiac arrest (SCA) remains lower than 10% in most parts of the world is unacceptable. Recognising this urgent need, the Lancet Commission on SCD was constituted, bringing together 30 international experts in varied disciplines. Consistent progress in tackling SCD will require a completely revamped approach to SCD prevention, with wide-sweeping policy changes that will empower the development of both governmental and community-based programmes to maximise survival from SCA, and to comprehensively attend to survivors and decedents' families after the event. International collaborative efforts that maximally leverage and connect the expertise of various research organisations will need to be prioritised to properly address identified gaps. The Commission places substantial emphasis on the need to develop a multidisciplinary strategy that encompasses all aspects of SCD prevention and treatment. The Commission provides a critical assessment of the current scientific efforts in the field, and puts forth key recommendations to challenge, activate, and intensify efforts by both the scientific and global community with new directions, research, and innovation to reduce the burden of SCD worldwide.

Utilization of Regional Anesthesia in the Electrophysiology Lab: A Narrative Review

PURPOSE OF REVIEW

The electrophysiology lab is an important source of growth of anesthetic volume as the indications and evidence for catheter ablations and various cardiac implantable electronic devices improve. Paired with this increase in volume is an increasing number of patients with substantial comorbid conditions presenting for their EP procedures. For these patients, the interaction between their comorbidities and traditional anesthesia practices may create the risk of hemodynamic instability, cardiovascular or respiratory complications, and potential need for prolonged post-operative monitoring negatively impacting length of hospital stay.

RECENT FINDINGS

Regional anesthetic techniques, including pectoralis, serratus, and erector spinae plane blocks, offer options for both regional analgesia and surgical anesthesia for a variety of EP procedures. Existing case reports and extrapolations from other areas support these techniques as viable, safe, and effective components of an anesthetic plan. In this article, we will review the development and challenges of various EP procedures and how different regional anesthetic techniques can function as a component of the anesthesia plan.

Art and science of risk stratification of sudden cardiac death in hypertrophic cardiomyopathy: Current state, unknowns, and future directions

The progress in the management of hypertrophic cardiomyopathy (HCM) over the last several decades has resulted in great improvements in quality of life and overall survival for HCM patients. Yet, sudden cardiac death (SCD) due to ventricular tachyarrhythmias is among the common causes of HCM-related mortality. SCD risk stratification is a central and often challenging domain in the care of the HCM patient. Distinguishing the individuals most likely to benefit from a primary prevention implantable-cardioverter defibrillator (ICD) from those truly at a low risk of SCD in whom an ICD is not necessary is a nuanced process. Clinicians need to carefully balance the potential benefit and risks of ICDs, particularly in young patients. Because of intense investigations in diverse HCM cohorts globally, two main approaches to SCD risk stratification in HCM have emerged, one based on major SCD risk factors and one based on a mathematically derived risk score. In this overview, we discuss the current state, latest advances and remaining unknowns about established and novel markers of risk of SCD in HCM. We also review how the risk factor- and risk score-based assessments can and should be used in conjunction to enhance rather than contradict each other in facilitating informed ICD decision-making in contemporary clinical practice.

Substernal Extravascular Implantable Cardioverter-Defibrillator System Infections in Large Animals

The extravascular implantable cardioverter-defibrillator (EV ICD) with lead implantation in the substernal space may provide clinical advantages over transvenous and subcutaneous systems. This is the first reported examination of substernal infection in large animals implanted with the EV ICD system.The system was implanted in 13 large animals (canine, porcine, and ovine). The porcine were co-implanted with a transvenous cardiac resynchronization therapy with defibrillator (CRT-D) system. Infection was promoted through a cadence of immunosuppressive monitors and study interventions. The animals were monitored for clinical presentation of infection over 12-18 weeks, and cultures were collected to confirm infection. Treatment was bifurcated: 1) some infections were treated only with antibiotics ( "antibiotics only" ), whereas 2) some infections were treated with system removal and antibiotics ( "antibiotics + explant" ). Histopathology was conducted at the study closure.Five infections were confirmed over the course of the study, four of which involved infection of the EV ICD system and one infection of only the concomitantly implanted transvenous CRT-D system without EV ICD-related infection. Among the four EV ICD infections, two of two infections treated with antibiotics only did not resolve whereas two of two infections treated with antibiotics + explant resolved, as shown by histology. The transvenous CRT-D system infection progressed to septicemia and endocarditis, requiring early study discontinuation. No EV ICD-related infection progressed to blood stream infection, and the sternal bone did not become infected when infection was present in the substernal tissues.The study findings suggest that EV ICD-related infections are treatable with system removal and antibiotic therapy.

Development of the Implantable Cardioverter-Defibrillator: JACC Historical Breakthroughs in Perspective

Implantable cardioverter-defibrillators (ICDs) represent transformational technology, arguably the most significant advance in cardiovascular medicine in 50 years. The vision and determination of pioneers Mirowski and Mower was fundamental to this monumental achievement, working with limited resources and confronted by skepticism/criticism from medical establishment. The inventors were followed >35 years in which a multitude of innovative clinical scientists and engineers introduced technological advances leading to the sophisticated devices in practice today. A pivotal patient experiment with automated termination of ventricular fibrillation (1980) led to U.S. Food and Drug Administration approval. Transvenous lead systems converted ICDs from thoracotomy-based secondary prevention to primary prevention of sudden death devices in countless patients worldwide. ICD acceptance was solidified by prospective randomized controlled trials showing reduced mortality superior to antiarrhythmic drugs. ICDs eventually expanded from coronary disease to inherited arrhythmia conditions (eg, hypertrophic cardiomyopathy). The ICD breakthrough story demonstrates how significant progress is possible in medicine against all odds, given fearless imagination to pursue novel ideas that conflict with accepted wisdom.

Design and rationale of the MODULAR ATP global clinical trial: A novel intercommunicative leadless pacing system and the subcutaneous implantable cardioverter-defibrillator

Background

The subcutaneous implantable cardioverter-defibrillator (S-ICD) has demonstrated safety and efficacy for the treatment of malignant ventricular arrhythmias. However, a limitation of the S-ICD lies in the inability to either pace-terminate ventricular tachycardia or provide prolonged bradycardia pacing support.

Objective

The rationale and design of a prospective, single-arm, multinational trial of an intercommunicative leadless pacing system integrated with the S-ICD will be presented.

Methods

A technical description of the modular cardiac rhythm management (mCRM) system (EMPOWER leadless pacemaker and EMBLEM S-ICD) and the implantation procedure is provided. MODULAR ATP (Effectiveness of the EMPOWER™ Modular Pacing System and EMBLEM™ Subcutaneous ICD to Communicate Antitachycardia Pacing) is a multicenter, international trial enrolling up to 300 patients at risk of sudden cardiac death at up to 60 centers trial design. The safety endpoint of freedom from major complications related to the mCRM system or implantation procedure at 6 months and 2 years are significantly higher than 86% and 81%, respectively, and all-cause survival is significantly >85% at 2 years.

Results

Efficacy endpoints are that at 6 months mCRM communication success is significantly higher than 88% and the percentage of subjects with low and stable thresholds is significantly higher than 80%. Substudies to evaluate rate-responsive features and performance of the pacing module are also described.

Conclusion

The MODULAR ATP global clinical trial will prospectively test the safety and efficacy of the first intercommunicating leadless pacing system with the S-ICD. This trial will allow for robust validation of device-device communication, pacing performance, rate responsiveness, and system safety.

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.

[Arrhythmias : Update on ablations and devices]

The field of invasive electrophysiology is technically evolving and especially the catheter ablation treatment of symptomatic atrial fibrillation (AF). The technically innovative method of so-called electroporation (pulsed field ablation, PFA) is characterized by a rapid and effective treatment of AF. The current study data confirm a high success rate for ablation and a good safety profile in the treatment of paroxysmal and persistent AF. In the field of radiofrequency ablation (RF) of AF the modified form of energy transfer, the very high-power short-duration (vHPSD) protocols, show good results and can reduce the procedural time. There are also technical innovations in other single-shot devices. There is a device based on the RF technique that could show good clinical results in an initial study and can combine the targeted delivery of RF energy with the advantages of a single-shot device. For ventricular tachycardia (VT) there are innovations in the diagnostics and clarification in the new European guidelines that were presented in August 2022. These make individual recommendations for different types of cardiomyopathy. There are also technical developments in the field of active rhythm implants. In cardiac pacemaker treatment and specifically for conduction system pacing (CSP) there is evidence for a targeted stimulation of the bundle of His or left bundle branch pacing (LBBP). This form of stimulation is particularly advantageous for patients with heart failure and a broad QRS complex. For leadless pacemakers (leadless pacing) there are now good long-term results and also a two-chamber approach.

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.