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

Leadless pacemaker implantation in real-world clinical practice: An Italian survey promoted by the AIAC (Italian Association of Arrhythmology and Cardiac Pacing)

Backgrounds

After a decade since the introduction of leadless pacemaker (L-PM), its use is still limited. The aim of this survey is to evaluate how this technology is perceived by electrophysiologist members of a National scientific society in clinical practice.

Methods

A questionnaire with 22 questions was posted in the reserved area of the society website. The multiple-choice questions concerned the center's characteristics, patient selection criteria, limitations to the L-PM use, implant procedures, and follow-up. Additionally, non-implanting centers were also allowed to participate by completing the initial nine questions.

Results

Ninety-two responders participated in this survey: 59% implanted <20 L-PM yearly and 31% did not implant L-PM. The three main reasons to choose an L-PM were anatomic contraindications to a transvenous pacemaker, the patient's high infective risk, and previous lead extraction, accounting for 78%, 74%, and 64% of the responses, respectively. Age >60 years was indicated as more suitable by most of the responders. Among the implanting centers, the main limitation to a wider adoption was cost (49%), the lack of atrial pacing (28%), the absence of a dedicated extraction tool, and data on replacement (22%). The L-PM implant was performed with only local anesthesia in 77% of the centers and was associated with limited procedure duration and fluoroscopy time even in low-volume centers.

Conclusions

Although the L-PM implant is not a particularly complex procedure, these data confirm that its use is currently limited to selected patients of older age. Cost decreases and new developments might increase the adoption of this technology.

ACC/AHA/ASE/HFSA/HRS/SCAI/SCCT/SCMR 2025 Appropriate Use Criteria for Implantable Cardioverter-Defibrillators, Cardiac Resynchronization Therapy, and Pacing

This appropriate use criteria (AUC) document is developed by the American College of Cardiology along with key specialty and subspecialty societies. It provides a comprehensive review of common clinical scenarios where implantable cardioverter-defibrillator (ICD), cardiac resynchronization therapy (CRT), cardiac contractility modulation, leadless pacing, and conduction system pacing therapies are frequently considered. The 335 clinical scenarios covered in this document address ICD indications including those related to secondary prevention, primary prevention, comorbidities, generator replacement at elective replacement indicator, dual-chamber, and totally subcutaneous ICDs, as well as device indications related to CRT, conduction system pacing, leadless pacing, cardiac contractility modulation, and ICD therapy in the setting of left ventricular assist devices (LVADs).

The indications (clinical scenarios) were derived from common applications or anticipated uses, as well as from current clinical practice guidelines and results of studies examining device implantation. The indications in this document were developed by a multidisciplinary writing group and scored by a separate independent rating panel on a scale of 1 to 9 to designate care that is considered “Appropriate” (median 7 to 9), “May Be Appropriate” (median 4 to 6), and “Rarely Appropriate” (median 1 to 3). The final ratings reflect the median score of the 17 rating panel members.

In general, Appropriate designations were assigned to scenarios for which clinical trial evidence and/or clinical experience was available that supported device implantation. In contrast, scenarios for which clinical trial evidence was limited or device implantation seemed reasonable for extenuating or practical reasons were categorized as May Be Appropriate. Scenarios for which there were data showing harm, or no data were available, and medical judgment deemed device therapy was illadvised were categorized as Rarely Appropriate. For example, comorbidities including reduced life expectancy related to noncardiac conditions or severe cognitive dysfunction would negatively impact appropriateness ratings.

The appropriate use criteria for ICD, CRT, and pacing have the potential to enhance clinician decision making, healthcare delivery, and payment policy. Furthermore, recognition of clinical scenarios rated as May Be Appropriate facilitates the identification of areas where there may be gaps in evidence that would benefit from future research.

The American College of Cardiology (ACC) has a long history of developing documents (eg, expert consensus decision pathways, health policy statements, AUC documents) to provide members with guidance on both clinical and nonclinical topics relevant to cardiovascular care. In most circumstances, these documents have been created to complement clinical practice guidelines and to inform clinicians about areas where evidence is new and evolving or where sufficient data are more limited. Despite this, numerous gaps persist, highlighting the need for more streamlined and efficient processes to implement best practices in patient care.

Central to the ACC’s strategic plan is the generation of actionable knowledge —a concept that places emphasis on making clinical information easier to consume, share, integrate, and update. To this end, the ACC has shifted from developing isolated documents to creating integrated “solution sets.” These are groups of closely related activities, policy, mobile applications, decision-support tools, and other resources necessary to transform care and/or improve heart health. Solution sets address key questions facing care teams and attempt to provide practical guidance to be applied at the point of care. They use both established and emerging methods to disseminate information for cardiovascular conditions and their related management. The success of solution sets rests firmly on their ability to have a measurable impact on the delivery of care. Because solution sets reflect current evidence and ongoing gaps in care, the associated tools will be refined across time to match changing evidence and member needs.

AUC represent a key component of solution sets. They consist of common clinical scenarios associated with given disease states and ratings that define when it is reasonable to perform testing or provide therapies and, importantly, when it is not. AUC methodology relies on content development work groups, which create patient scenarios, and independent rating panels that employ a modified Delphi process to rate the relevant options for testing and intervention as Appropriate, May Be Appropriate, or Rarely Appropriate. AUC should not replace clinician judgment and practice experience but should function as tools to improve patient care and health outcomes in a cost-effective manner.

I extend sincere gratitude to the writing group for their invaluable contributions to the development of this document’s structure and clinical scenarios; to the rating panelists—a distinguished group of professionals with diverse expertise—for their thoughtful deliberation of the merits of device implantation across various clinical contexts; and to the reviewers for their thoughtful evaluation of the clinical scenarios and evidence mapping. Additionally, I am grateful to the members of the Solution Set Oversight Committee, which provided insight and guidance, and to ACC staff members María Velásquez and Lara Gold, for their support in bringing this document to fruition.

Long-term management of leadless pacemakers

Leadless pacemakers (LPs) are increasingly being used to treat bradyarrhythmias, and end of service (EOS) management decisions are becoming increasingly important given finite battery lifespans. Two strategies have been adopted for device EOS: LP abandonment and LP removal. Certain scenarios including high degree of LP encapsulation and 'last expected' pacing devices favour LP abandonment, while other LP complications may necessitate device removal. When abandoning LP, clinicians must understand design, performance, and safety considerations for devices left in place. When removing LP, specialized tools and techniques have been developed, each varying by device manufacturer and model. Case reports and series on LP removal have elucidated how to overcome challenges that may arise during removal. Despite best practice techniques, complications can arise before and after removal. Current studies on LP EOS management are limited, and further studies are needed to help understand predictors of successful device removal and long-term sequelae of both strategies. The aim of this state-of-the-art review is to help clinicians understand current strategies and considerations for both LP abandonment and removal.

A leadless pericardial pacemaker

BACKGROUND

Cardiac pacemakers have complications related to long pacemaker leads, subcutaneous pockets, and endovascular hardware.

OBJECTIVE

We report on the development of a leadless micropacemaker for percutaneous implantation into the pericardial space.

METHODS

Percutaneous implantations of a micropacemaker system were performed in 15 pigs through subxiphoid access to the pericardial space. In our concept phase, 10 implants were performed with iterative changes to the design and implantation techniques until a design was reached for a viable device. In the study phase, a viable device was implanted in 5 pigs and observed during 8 weeks.

RESULTS

At the completion of the concept phase, a prototype micropacemaker device was fabricated that met 3 mandatory system requirements: can be safely and reproducibly implanted percutaneously into the pericardial space; does not migrate after implantation; and successfully captures the myocardium at implantation and during long-term follow-up (up to 8 weeks). The prototype device was successfully and safely implanted into all 5 pigs in the study phase. These 5 animals survived to the 8-week end point without complications. Ventricular capture threshold calculations at implantation were a median 0.43 V at 0.4 ms (range, 0.05-0.75 V at 0.4 ms). At 8 weeks of follow-up, median capture thresholds were 2.8 V at 0.4 ms (total range, 2.2-7.1 V).

CONCLUSION

A novel pericardial micropacemaker system allows minimally invasive implantation of a leadless cardiac pacemaker without entering the vascular space. We provide proof of concept of this design with encouraging follow-up data.

A case report of pre-implantation feasibility test for combining leadless pacemaker and subcutaneous implantable cardioverter-defibrillator in adult congenital heart disease

New cardiac implantable electronic devices (CIEDs), such as leadless pacemakers and subcutaneous implantable cardioverter defibrillators (S-ICDs), are being used in patients with adult congenital heart disease. The selection of CIEDs often requires careful consideration due to technical challenges posed by a unique heart structure. A 27-year-old man following a surgical tetralogy of Fallot (TOF) repair developed non-sustained ventricular tachycardia, sick sinus syndrome, and complete atrioventricular block. He had a history of recurrent bacteremia. We discussed the use of a combination of leadless pacemaker and S-ICD as a non-transvenous CIED after considering the infection risk and decided to select the appropriate CIED after a pre-implantation test. Ventricular tachycardia was not induced in the electrophysiological study. Although he did not need an ICD at that point, patients after TOF repair are at a high risk for ventricular tachycardia later in life. We measured the local pacing threshold and R-wave amplitude and performed an S-ICD screening for paced-QRS. Finally, we implanted a leadless pacemaker safely with the option to add an S-ICD if needed. A pre-implantation test could help future decisions regarding combinations of leadless pacemakers with S-ICDs in patients with adult congenital heart disease.

Learning objectives

The appropriate selection of a cardiac implantable electronic device (CIED) in patients with adult congenital heart disease requires careful consideration. The pre-implantation feasibility test for combining a leadless pacemaker (LP) and a subcutaneous implantable cardioverter defibrillator aided decision-making in CIED selection and safe LP implantation procedure in the unique heart structure.

Life-Saving Cooperative Function of a Subcutaneous Cardioverter-Defibrillator and a Pacemaker in Dextrocardia With Heart Failure

A 47-year-old man with congenitally corrected transposition of the great arteries, dextrocardia, heart failure, and pacemaker-dependency presented with nonsustained ventricular tachycardia. He underwent a right-sided transmuscular cardioverter-defibrillator insertion after appropriate testing. One year later, life-saving antiarrhythmic therapy was applied by the subcutaneous defibrillator while the appropriate pacemaker functioning supported heart rhythm.

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.).

Decision-making regarding subcutaneous implantable cardioverter defibrillator as primary prevention in patients with low ejection fraction

BACKGROUND

Conventional transvenous implantable cardioverter-defibrillator (TV-ICD) is the standard device used for primary prevention of sudden cardiac death (SCD) in patients with reduced left ventricular ejection fraction (LVEF). Nonetheless its use is associated with lead-related complications including infection and malfunction. A subcutaneous implantable cardioverter-defibrillator (S-ICD) offers an alternative option without the need for a transvenous lead but has limitations. The decision to implant a TV-ICD or S-ICD in patients with impaired LVEF for primary prevention of SCD is controversial. Several randomised controlled trials and large observational studies have confirmed similar safety and efficacy of S-ICDs and TV-ICDs in such population.

METHODS

A literature review was conducted to compare the outcomes of subcutaneous (S-ICD) versus transvenous (TV-ICD) implantable cardioverter-defibrillators. Databases including PubMed, MEDLINE, and Cochrane were searched for relevant peer-reviewed articles. Studies were selected based on relevance and quality. Key outcomes like complication rates, efficacy, and patient survival were summarized in a comparative table.

RESULTS

Different factors that influence the choice between an TV-ICD and S-ICD for primary prevention of SCD in patients with LVEF are highlighted to guide selection of the appropriate device in different patient populations. Moreover, future perspective on the combination of SICD with leadless pacemaker, and the latest development of the extravascular implantable cardioverter defibrillator are also discussed.

CONCLUSIONS

S-ICD offers a safe and efficacious option to primary prevention in reduced ejection fraction. Future development including incorporation of leadless pacemaker will add to the arsenal of choice to protect patients from sudden cardiac death.

Case Report: Leadless and left bundle branch area pacemakers, complementary advantages require a personalized approach

Traditional transvenous pacemakers consist of a pacemaker generator usually positioned surgically in the upper left chest on the pectoral muscle fascia and one or more leads positioned through the veins to the right atrium and across the tricuspid valve to the right ventricular apex. While these devices reduce symptoms and improve survival among patients with symptomatic bradycardia, they are associated with an increased risk of infection, venous occlusion, heart failure, and tricuspid valve regurgitation. Although new pacemaker designs minimize these risks, none of the current-generation pacemaker designs effectively eliminate all of them. A personalized approach to selecting the appropriate pacemaker for each patient is needed to optimize outcomes.

Subcutaneous versus transvenous implantable cardioverter defibrillator in hypertrophic cardiomyopathy: a systematic review and meta-analysis

Background

A subcutaneous implantable cardioverter-defibrillator (S-ICD) is an alternative to a transvenous implantable cardio defibrillator (TV-ICD). An S-ICD reduces the risk of transvenous lead placement. However, further research is required to determine how S-ICDs affect patients with hypertrophic cardiomyopathy (HCM). In this study, we investigated the comparative efficacy and safety of S-ICDs versus TV-ICDs in HCM.

Methods

On December 6th, 2023, we performed a comprehensive search of the PubMed, Embase, Scopus, and Cochrane databases to identify randomized clinical trials (RCTs) and observational studies comparing S-ICDs with TV-ICDs in HCM patients published from 2004 until 2023. No language restrictions were applied. The primary outcome was appropriate shocks (AS), with inappropriate shocks (IAS), and device-related complications considered as secondary outcomes. Odds ratios (ORs) and 95% confidence intervals (CIs) were pooled using a random effects model. The ROBINS-I tool was used to assess the risk of bias of the studies.

Results

The search yielded 1,114 records. Seven studies comprising 4,347 HCM patients were included, of whom 3,325 (76.0%) had TV-ICDs, and 1,022 (22.6%) had S-ICDs. There were 2,564 males (58.9%). The age range was from 39.1 to 49.4 years. Compared with the TV-ICD group, the S-ICD cohort had a significantly lower incidence of device-related complications (OR 0.52; 95% CI: 0.30-0.89; P=0.02; I2=4%). Contrastingly, there were no statistically significant differences in the occurrences of AS (OR 0.49; 95% CI: 0.22-1.08; P=0.08; I2=75%) and IAS (OR 1.03; 95% CI: 0.57-1.84; P=0.93; I2=65%) between the two device modalities. In the analysis of the overall risk of bias in the studies, we found 42% of them with several, 28% with moderate, and 14% with low risk of bias.

Conclusions

In HCM patients, S-ICDs were associated with a lower incidence of device-associated problems than TV-ICDs. AS and IAS incidence rates were similar between groups. These findings may assist clinicians in determining the most suitable device for treating patients with HCM.

Beyond Medical Therapy-An Update on Heart Failure Devices

Heart failure (HF) is a complex and progressive disease marked by substantial morbidity and mortality rates, frequent episodes of decompensation, and a reduced quality of life (QoL), with severe financial burden on healthcare systems. In recent years, several large-scale randomized clinical trials (RCTs) have widely expanded the therapeutic armamentarium, underlining additional benefits and the feasibility of rapid titration regimens. This notwithstanding, mortality is not declining, and hospitalizations are constantly increasing. It is widely acknowledged that even with guideline-directed medical therapy (GDMT) on board, HF patients have a prohibitive residual risk, which highlights the need for innovative treatment options. In this scenario, groundbreaking devices targeting valvular, structural, and autonomic abnormalities have become crucial tools in HF management. This has led to a full-fledged translational boost with several novel devices in development. Thus, the aim of this review is to provide an update on both approved and investigated devices.

[Treatment with cardiac electronic implantable devices]

Cardiac device therapy provides not only treatment options for bradyarrhythmia but also advanced treatment for heart failure and preventive measures against sudden cardiac death. In heart failure treatment it enables synergistic reverse remodelling and reduces pharmacological side effects. Cardiac resynchronization therapy (CRT) has revolutionized the treatment of reduced left ventricular ejection fraction (LVEF) and left bundle branch block by decreasing the mortality and morbidity with improvement of the quality of life and resilience. Conduction system pacing (CSP) as an alternative method of physiological stimulation can improve heart function and reduce the risk of pacemaker-induced cardiomyopathy. Leadless pacers and subcutaneous/extravascular defibrillators offer less invasive options with lower complication rates. The prevention of infections through preoperative and postoperative strategies enhances the safety of these therapies.

Implantable Cardiac Devices in Patients with Brady- and Tachy-Arrhythmias: An Update of the Literature

Implantable cardiac devices are a vital treatment option in the management of tachy/brady-arrhythmias and heart failure with conduction disease. In the recent years, these devices have become increasingly sophisticated, with high implantation success rates and longevity. However, these devices are not without risks and complications, which need to be carefully considered before implantation. In an era of rapidly evolving cardiac device therapies, this review article will provide an update on the literature and outline some of the emerging technologies that aim to maximise the efficiency of implantable devices and reduce complications. We discuss novel pacing techniques, including alternative pacing sites in anti-bradycardia and biventricular pacing, as well as the latest evidence surrounding leadless device technologies and patient selection for implantable device therapies.

Pacing and Defibrillation Consideration in the Era of Transcatheter Tricuspid Valve Replacement

PURPOSE OF REVIEW

Tricuspid regurgitation is a commonly encountered valvular pathology in patients with trans-tricuspid pacing or implantable cardioverter-defibrillator leads. Transcatheter tricuspid valve interventions are increasingly performed in patients at high surgical risk. Implantation of these valves can lead to the "jailing" of a trans-tricuspid lead. This practice carries both short- and long-term risks of lead failure and subsequent infection without the ability to perform traditional transvenous lead extraction. Herein, this manuscript reviews available therapeutic options for lead management in patients undergoing transcatheter tricuspid valve interventions.

RECENT FINDINGS

The decision to jail a lead may be appropriate in certain high-risk cases, though extraction may be a better option in most cases given the variety of options for re-implant, including leadless pacemakers, valve-sparing systems, epicardial leads, leads placed directly through prosthetic valves, and the completely subcutaneous implantable-defibrillator. A growing number of patients meet the requirement for CIED implantation in the United States. A significant proportion of these patients will have tricuspid valve dysfunction, either related to or independent of their transvenous lead. As with any percutaneous intervention that has shown efficacy, the role of TTVI is also likely to increase as this therapy advances beyond the investigational phase. As such, the role of the heart team in the management of these patients will be increasingly critical in the years to come, and in those patients that have pre-existing CIED leads, we advocate for the involvement of an electrophysiologist in the heart team.

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.