A Leadless Intracardiac Transcatheter Pacing System

Expert opinion on a safe same day discharge strategy as standard of care after leadless pacemaker implantation

Introduction

Leadless pacemaker (LPs) is a safe and effective alternative to conventional transvenous pacing. There is currently no guidance on which patients could be safely discharged the same day post-procedure.

Purpose

To provide guidance to medical teams regarding safe same day discharge (SDD) after LP implantation.

Methods

An Advisory Board (AB) of 6 expert Micra™ implanters was formed. Interviews were conducted with each member to understand their experience on patient selection, care pathway, complications, and follow-up of Micra™ implanted patients. This information was used to develop a patient pathway for safe SDD after Micra™ implantation. A further survey was conducted to obtain consensus regarding decision points within the pathway.

Results

The SDD after Micra™ Implantation Patient Pathway consists of four phases:Pre-procedure assessment: Social factors are key in deciding suitability of SDD (6/6 AB members agreed, 100%). Patient's comorbidities, frailty status and timing of procedure are also important in decision-making for SDD.Micra™ implant: Ultrasound-guidance reduces vascular access-related complications, increasing the likelihood for SDD (100%).Post-procedure observation: Peri-procedural complications such as pericardial effusion, severe vascular complications, bleeding from access site and device complications would prevent SDD (100%). Patients should complete 6 h of observation prior to discharge (100%).Follow-up: First follow-up should be in-person, 1-4 weeks post-procedure (84 %). Long-term follow-up should be organised as per Micra™ standard of care at each centre (100 %).

Conclusions

SDD after Micra™ Implantation Patient Pathway was developed via expert consensus. Adoption of the pathway in clinical practice may facilitate safe SDD after Micra™ Implantation.

Instantaneous Piezoelectric Nanogenerator for Pacemaker Applications

Implantable nanogenerators (NG) are a promising solution to the self-sustainable power source for cardiovascular implantable electronic devices (CIEDs), such as pacemakers, by harvesting biomechanical energy from heartbeats. Nevertheless, the conversion efficiency of mechanical energy into electrical energy has long been a significant challenge, limiting the practical application of NGs to effectively charge a power storage component. In this work, we report an instantaneous piezoelectric NG (i-PENG) design that converted the wave-like output of a regular PENG into output spikes with ~7 times higher amplitude. Due to the largely raised electrical energy, the i-PENG exhibited a substantially faster charging rate on a capacitor. The i-PENG was further integrated with a rectifier and a micro capacitor, serving as both the contact electrodes and an electrical regulating circuit. When implanted on a pig's heart surface, this integrated power system was able to charge a capacitance of 100 μF to 4 V in 13 minutes. This level of electrical power was able to operate a commercial pacemaker to provide regular stimulation signals. This study provides a design principle that can raise the electrical energy of the piezoelectricity, leading toward practical applications of PENG for powering implantable biomedical devices.

Leadless Micra pacemakers: Estimating long-term longevity. A real word data analysis

BACKGROUND

Although leadless pacemakers have demonstrated satisfactory safety and efficacy, there is limited published data regarding the estimated lifespan in real word clinical scenarios.

METHODS

Between May 2015 and September 2023, all consecutive patients who underwent implantation of a single-chamber leadless Micra pacemaker were included in the One Hospital ClinicalService project and systematically tracked through remote monitoring at 15 Italian cardiology sites. Data on procedures, complications, electrical parameters, and estimated battery longevity were collected at baseline and annually during follow-up (FU). Additionally, virtual battery longevity (VBL) was calculated as the sum of the actual battery life consumed and the predicted remaining longevity (VBL = months consumed + months predicted), providing an estimate of the device's total battery lifespan.

RESULTS

Patient and device data were gathered from 391 patients. Over a median follow-up period of 33.9 months (with interquartile range from 17.5 to 52.0 months), one patient experienced battery depletion. When examining VBL across all patients, the median VBL at baseline was 172 months (with a I-III interquartile range of 146 to 200 months), and VBL remained consistent or greater from the time of implantation up to seven years post-implant. The strongest predictor of VBL depletion within 8 years was capture threshold at implant greater than 1 V @ 0.24 ms.

CONCLUSION

In clinical practice, leadless pacemakers appear to have a median expected longevity ranging from 14 to 17 years. Having a stimulation threshold less than or equal to 1 V @ 0.24 ms seems to be an excellent predictor of increased longevity.

Outcomes of Micra Leadless Pacemaker Implants in Centers With and Without Cardiac Surgery

BACKGROUND

Micra leadless pacemaker offers an alternative to traditional transvenous pacemakers by eliminating the risks associated with leads and device pockets. Due to the technical demands of a leadless transcatheter pacemaker, concerns initially limited the procedure to centers with on-site cardiac surgery (CS) capabilities. However, growing evidence supports its safe implementation in noncardiac surgical centers, though data comparing outcomes in these settings remain limited.

AIMS

This analysis aims to evaluate the safety and feasibility of Micra leadless pacemaker implantation in centers with and without CS, assessing acute complications, device performance, and patient follow-up.

METHODS

A retrospective analysis was conducted on 1899 patients who received a Micra pacemaker from May 2015 to September 2024 at 23 centers. Patients were divided into two groups: those implanted in centers with CS (CS, n = 1025) and those without (No-CS, n = 874). The primary endpoint was acute complications within 15 days postimplant, while secondary endpoints included device performance and clinical follow-up at 12 months.

RESULTS

The overall acute complication rate was low at 0.6%, with no significant difference between the CS (0.5%) and No-CS groups (0.8%; p = 0.391). Procedural times were slightly shorter in No-CS centers (41.2 ± 19.8 vs. 46.1 ± 19.3 min; p < 0.001), and both groups showed comparable device performance and patient outcomes over the follow-up period.

CONCLUSION

The Micra leadless pacemaker can be safely and effectively implanted in centers without CS capabilities, broadening access to this technology across diverse clinical settings.

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.

Behavior of leadless atrioventricular synchronous pacing during exercise

BACKGROUND

The leadless Micra AV pacemaker is designed to provide atrioventricular (AV) synchronous tracking by detecting atrial contraction. Detection of the mechanical atrial signals can become challenging at a fast sinus rate.

OBJECTIVE

The purpose of the study was to evaluate the AV synchronous performance during exercise in outpatients implanted with a Micra AV pacemaker.

METHODS

Patients were enrolled at least 1 month after Micra AV implantation and underwent a cycle test protocol. Serial device interrogations (each minute) and continuous electrocardiograms were collected to measure AV synchrony and determine maximum achieved sinus and ventricular rates for each patient. In addition, the A1, A2, A3, and A4 accelerometer signal amplitudes were measured at the start and peak of exercise.

RESULTS

Thirty-five patients (mean age 75.6 ± 13.4 years; 28 (80%) male) were enrolled in the study; 22 (64%) were predominantly ventricular paced (>90%) during exercise. Mean AV synchrony was 90.4% in the entire cohort and 84.7% in patients with high-degree AV block. The mean amplitude of the accelerometer signals increased significantly from the start to the peak of exercise: A1, 4.1-6.3 m/s2; A2, 2.4-3.8 m/s2; and A4, 4.5-7.6 m/s2 (P < .01 for all). The time from the ventricular ecvent (VS/VP) to A2 showed a decrease of 25 ms for each 100 ms decrease of the R-R interval.

CONCLUSION

Maintaining AV synchrony during maximal exercise in elderly patients is achievable by adequate detection of atrial contraction at fast sinus rates by the leadless Micra AV pacemaker. All components of the accelerometer signal increased, likely because of increased contractility related to exercise.

One-Year Safety and Performance of a Dual-Chamber Leadless Pacemaker

BACKGROUND

A dual-chamber leadless pacemaker can provide bradycardia therapy to most patients with pacemaker indications without the complications associated with a lead or pulse generator. We sought to confirm whether previously reported 3-month safety and performance outcomes were sustained through 12 months by determining whether 12-month complication-free and performance success rates exceeded their prespecified performance goals.

METHODS

Patients were enrolled in the prospective, single-group Aveir DR i2i Study if they had a standard indication for dual-chamber pacing. Enrolled patients were implanted with an Aveir DR dual-chamber leadless pacemaker system, which comprised 2 communicating leadless pacemakers (1 in the right atrium and 1 in the right ventricle). The primary safety outcome evaluated whether freedom from serious device- or procedure-related events through 365 days exceeded the predetermined performance goal of 76.5%. The primary performance outcome determined whether the composite of atrial capture threshold (≤3.0 V at 0.4 ms) and sensing amplitude (P-wave ≥1.0 mV) at the 12-month visit exceeded the predetermined performance goal of 80.0%.

RESULTS

Sites attempted implantation in 300 subjects, where 63.3% had sinus-node dysfunction and 33.3% had atrioventricular block as their primary pacing indication. The primary safety end point was achieved, with a Kaplan-Meier 12-month complication-free rate of 88.6% (95% CI, 84.5-91.8; P<0.001). The primary performance end point was achieved in 92.8% of patients (95% CI, 89.7-95.8; P<0.001).

CONCLUSIONS

Both primary safety and performance end points were met after 1 year, demonstrating consistency with previously reported 3-month outcomes of a dual-chamber leadless pacemaker.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT05252702.

Worldwide Chronic Retrieval Experience of Helix-Fixation Leadless Cardiac Pacemakers

BACKGROUND

The growing use of leadless pacemaker (LP) technology requires safe and effective solutions for retrieving and removing these devices over the long term.

OBJECTIVES

This study sought to evaluate retrieval and removal of an active helix-fixation LP studied in worldwide regulatory clinical trials.

METHODS

Subjects enrolled in the LEADLESS II phase 1 investigational device exemption, LEADLESS Observational, or LEADLESS Japan trials with an attempted LP retrieval at least 6 weeks postimplantation were included. The retrieval success rate was evaluated for all attempted retrievals. Site-reported complications associated with LP retrievals were quantified, with the severity and relationship adjudicated by an independent clinical events committee.

RESULTS

There were 1,423 successful LP implants and 234 chronic LP retrieval attempts in 233 subjects. The overall retrieval success rate was 87.6% (205 of 234 attempts). The most common reason for failed retrieval (86.2%, 25 of 29 attempts) was inability to access the LP docking button. The mean time from implantation to attempted retrieval was 3.2 years (range 0.2-9.0 years) and did not significantly influence the retrieval success (P = 0.71). The clinical events committee adjudicated 11 complications in 9 subjects as being retrieval related (3.9%, 9 of 233 subjects).

CONCLUSIONS

The safety and efficacy of chronic LP retrieval of an active helix-fixation device was demonstrated in an international clinical trial setting, with implant durations up to 9 years.

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.

Leadless pacing: a comprehensive review

Over the past decade, leadless pacing has undergone a rapid evolution, resulting in multiple leadless pacemaker (LPM) devices that offer advancements such as atrioventricular synchronized pacing in VDD mode, atrial stimulation, dual-chamber pacing, and longer battery longevity. Studies comparing LPMs with transvenous pacemakers (TVPMs) show a lower rate of device-related complications with LPMs. In the near future, LPMs could be combined with other devices such as non-transvenous implantable cardioverter-defibrillators to provide anti-tachycardia pacing or bradycardia pacing. Future prospectives for leadless cardiac resynchronization therapy and leadless conduction system pacing are being investigated. As LPMs continue to improve, their applications are anticipated to expand further improving patient outcome, promising a bright future for leadless pacing. In this review, the past, present, and future of leadless pacing are discussed with a focus on cutting-edge implantation techniques, clinical outcomes, and modern advancements of LPMs.

Long-Term Complications Related to Cardiac Implantable Electronic Devices

Cardiac implantable electronic devices (CIEDs) are commonly used for a number of cardiac-related conditions, and it is estimated that over 300,000 CIEDs are placed annually in the US. With advances in technology surrounding these devices and expanding indications, CIEDs can remain implanted in patients for long periods of time. Although the safety profile of these devices has improved over time, both the incidence and prevalence of long-term complications are expected to increase. This review highlights pertinent long-term complications of CIEDs, including lead-related issues, device-related arrhythmias, inappropriate device therapies, and device-related infections. We also explore key clinical aspects of each complication, including common presentations, patient-specific and non-modifiable risk factors, diagnostic evaluation, and recommended management strategies. Our goal is to help spread awareness of CIED-related complications and to empower physicians to manage them effectively.

Comparison of 30-day complications between a tine-based and a screw-in helix fixation single-chamber ventricular leadless pacemaker: Results of a propensity score-matched analysis from a multicenter, nationwide registry

BACKGROUND

Medtronic Micra VR and Abbott Aveir VR are 2 single-chamber ventricular leadless pacemakers (L-PMs) currently available in clinical practice. They differ in their design, fixation mechanism (tine-based fixation for Micra VR, screw-in helix fixation for Aveir VR), and implantation technique. Few comparative safety data are available for these L-PMs.

OBJECTIVE

We aimed to compare the rate of acute procedure-related complications of patients undergoing Aveir VR vs Micra VR implantation.

METHODS

A prospective, multicenter, observational registry enrolled consecutive patients who underwent Aveir VR or Micra VR implantation. The rate and nature of device-related complications at 30-day follow-up were analyzed and compared between the groups. Individual 1:1 propensity score matching of baseline characteristics was performed.

RESULTS

A total of 1141 patients (75.9 ± 14.8 years; 60.2% male) were enrolled: 211 Aveir VR and 930 Micra VR. Propensity score matching yielded 189 matched pairs. In the matched cohort, the risk of device-related complications at 30 days of follow-up of the 2 L-PMs was similar (2.1% vs 2.1%; P = 1). Device migration (1.6% vs 0.5%; P = .315) and vascular complications (0.5% vs 1.1%; P = .562) were the most frequent complications, with no significant differences between the groups. Cardiac perforation was rare (1 case in the Micra VR group, no cases in the Aveir VR group).

CONCLUSION

The risk of acute device-related complications associated with Aveir VR and Micra VR L-PM implantation was similar. These findings suggest that despite differences in design, fixation mechanism, and implantation technique, these 2 devices appear to have a similar short-term safety profile.

Leadless Pacemaker Pitfalls: Navigating Implantation and Postprocedure Challenges

BACKGROUND

Leadless pacemakers (LPs) are implanted into the right ventricular septum, eliminating intravascular complications associated with traditional pacemakers. They attach to the myocardium using 4 curved, self-expanding nitinol tines.

CASE SUMMARY

Our case highlights the rare occurrence of LP dislodgement into the pulmonary artery and the delayed development of a traumatic right ventricular apical pseudoaneurysm.

DISCUSSION

LPs were designed to reduce the lead- and pocket-related complications that can be seen with conventional pacemakers. However, LPs carry a risk of dislodgement and embolization into the pulmonary artery compared with conventional pacemakers.

TAKE-HOME MESSAGES

This case explores the complexities and risks involved in both the implantation and retrieval of LPs in high-risk patient populations and highlights the importance of meticulous technique in retrieving an acutely embolized LP from the right PA.

Leadless pacemaker 5-year outcomes: good news?

In the last 10 years, leadless pacemaker (PM) therapy has moved beyond the experimental phase and has become an established therapeutic option. A substantial body of data are now available, even with medium-length follow-ups, suggesting that leadless PMs are associated with fewer infections and fewer overall complications, particularly in the long term, compared with transvenous PMs. The introduction of VDD(R) pacing and, more recently, DDD(R), has expanded the indication area of these devices to a significantly larger number of patients. High costs, limited experience with replacement and the lack of randomized studies still limit their widespread adoption. However, for many patients, the leadless PM already represents the first therapeutic choice.

Risk of infections related to endovascular catheters and cardiac implantable devices in hemodialysis patients

Patients requiring dialysis are extremely vulnerable to infectious diseases. The high burden of comorbidities and weakened immune system due to uremia and previous immunosuppressive therapy expose the patient on dialysis to more infectious events than the general population. The infectious risk is further increased by the presence of endovascular catheters and implantable cardiologic devices. The former is generally placed as urgent vascular access for dialysis and in subjects requiring hemodialysis treatments without autogenous arteriovenous fistula. The high frequency of cardiovascular events also increases the likelihood of implanting indwelling implantable cardiac devices (CIED) such as pacemakers (PMs) and defibrillators (ICDs). The simultaneous presence of CVC and CIED yields an increased risk of developing severe prosthetic device-associated bloodstream infections often progressing to septicemia. Although, antibiotic therapy is the mainstay of prosthetic device-related infections, antibiotic resistance of biofilm-residing bacteria reduces the choice of infection eradication. In these cases, the resolution of the infection process relies on the removal of the prosthetic device. Compared to CVC removal, the extraction of leads is a more complex procedure and poses an increased risk of vessel tearing. As a result, the prevention of prosthetic device-related infection is of utmost importance in hemodialysis (HD) patients and relies principally on avoiding CVC as vascular access for HD and placement of a new class of wireless implantable medical devices. When the combination of CVC and CIED is inevitable, prevention of infection, mainly due translocation of skin bacteria, should be a mandatory priority for healthcare workers.

Leadless Pacemaker Implantation in an Adolescent with Durable LVAD Support

Left ventricular assist device (LVAD) utilization is increasing in pediatrics. These patients are often complex and may require treatment of AV block. Leadless pacing has been associated with a lower risk of device-related adverse events, but there are no reports of a leadless pacemaker implant in a pediatric patient with LVAD support. This report describes the use of a leadless pacemaker implantation in a 17-year-old patient with dilated cardiomyopathy and continuous flow LVAD support which facilitated transition to outpatient care.

Safety and Performance of the Micra VR Leadless Pacemaker in a South Korean Cohort: A Comparison to Global Studies

BACKGROUND AND OBJECTIVES

The Micra leadless pacemaker demonstrated a favorable safety and efficacy profile in global trials, but its performance and safety in a South Korean-specific population are unknown.

METHODS

The prospective, single-arm Micra Acute Performance South Korean registry was designed to study the performance of the Micra VR leadless pacemaker in patients from South Korea. The primary objectives were to characterize the rate of acute (30 days) and longer-term (12 months) major complications. Electrical performance and quality of life at baseline and follow-up were also characterized.

RESULTS

A total of 100 enrolled patients underwent Micra VR implant at 8 centers in South Korea between July 2021 and February 2022 with 99% successfully implanted. Mean pacing capture threshold was 0.57±0.46 V at implant and remained stable through 12 months (0.65±0.44 V). Korean valuation of health status significantly increased from baseline (0.78±0.24) to 12 months (0.84±0.21) (p=0.016). Compared with global patients, South Korean patients were younger, had a lower body mass index, and fewer had a prior cardiovascular implantable electronic device (all p<0.01). During the follow-up period 1 major complication was reported (implant site hematoma) at 26 days post-implant. No pericardial effusion or tamponade events were observed. Through 12 months post-implant the major complication rate was 1.0% (95% confidence interval, 0.03%, 5.45%).

CONCLUSIONS

In a South Korean cohort, the Micra VR leadless pacemaker was implanted with a high success rate and low major complication rate.

Leadless pacemakers in patients with different stages of chronic kidney disease: Real-world data from the updated i-LEAPER registry

BACKGROUND

Limited data are available on leadless pacemaker (LPM) outcomes according to different stages of chronic kidney disease (CKD).

OBJECTIVE

The purpose of this study was to investigate differences in the safety and efficacy of LPMs among patients stratified per different stages of renal function.

METHODS

Consecutive patients enrolled in the multicenter international i-LEAPER registry (International LEAdless PacemakEr Registry) were analyzed. Patients were divided into 3 groups according to CKD stage. The primary end point was the comparison of LPM-related major complication rate at implantation and during follow-up. Differences in electrical performance were deemed secondary outcomes.

RESULTS

Of the 1748 patients enrolled, 33% were in CKD stage G3a/G3b and 9.4% were in CKD stage G4/G5. Patients with CKD presented cardiovascular comorbidities more frequently. During a median follow-up of 39 months (interquartile range [IQR] 18-59 months), major complication rate did not differ between groups (normal kidney function [NKF] group 1.8% vs CKD stage G3a/G3b group 2.9% vs CKD stage G4/G5 group 2.4%; P = .418). All-cause mortality resulted higher in the CKD stage G4/G5 group than in the NKF group (19.5% vs 9.8%; adjusted hazard ratio 1.9; 95% confidence interval 1.25-2.89; P = .003). LPM electrical performance was comparable between groups, except for patients with CKD who showed a slightly higher pacing threshold during 1-month follow-up (NKF group 0.50 V [IQR 0.35-0.70 V] vs G3a/G3b group 0.56 V [IQR 0.38-0.81 V] vs G4/G5 group 0.51 V [0.38-0.84 V] @ 0.24 ms; P < .001).

CONCLUSION

In a real-world setting, patients with advanced CKD who underwent LPM implantation were underrepresented. Although all-cause mortality was higher in end-stage CKD, periprocedural complications and LPM performance were overall comparable between NKF and different stages of CKD, except for higher values of pacing threshold in patients with CKD up to first-month follow-up.

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.

Leadless Pacing: Current Status and Ongoing Developments

Although significant strides have been made in cardiac pacing, the field is still evolving. While transvenous permanent pacing is highly effective in the management of bradyarrhythmias, it is not risk free and may result in significant morbidity and, rarely, mortality. Transvenous leads are often the weakest link in a pacing system. They may dislodge, fracture, or suffer breaches in their insulation. This review was undertaken to clarify leadless risks, benefits, and alternatives to transvenous cardiac pacing for bradyarrhythmias and heart failure management. In order to clarify the role(s) of leadless pacing, this narrative review was undertaken by searching MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and review articles, as well as other clinically relevant reports and studies. The search was limited to English-language reports published between 1932 and 2024. Leadless pacing was searched using the terms Micra™, Nanostim™, AVEIR™, single-chamber leadless pacemaker, dual-chamber leadless pacemaker, cardiac resynchronization therapy (CRT), cardiac physiological pacing (CPP) and biventricular pacing (BiV). Google and Google Scholar, as well as bibliographies of identified articles were also reviewed for additional references. The advantages and limitations of leadless pacing as well as options that are under investigation are discussed in detail.

Leadless Pacemaker vs. Transvenous Pacemaker in End Stage Kidney Disease: Insights from the Nationwide Readmission Database

Background: Leadless pacemakers offer a safe and effective alternative pacing strategy. However, limited data are available for patients with end stage renal disease (ESRD), a population of significant relevance. Methods: Using the Nationwide Readmission Database, we extracted data from all adult patients with ESRD who underwent traditional transvenous or leadless pacemaker implantation between 2016 and 2021. We compared in-hospital mortality, 30-day readmission rates, complication rates, and healthcare resource utilization between the two cohorts. Results: A total of 6384 (81.2%) patients were included in the transvenous pacemaker cohort, and 1481(18.8%) patients were included in the leadless pacemaker cohort. In patients with ESRD, leadless pacemaker implantation was linked to higher in-hospital complications when compared to transvenous pacemakers. These included the need for blood transfusion (aOR 1.85, 95% CI 1.32-2.60, p < 0.01), vascular complications (aOR 3.6, CI 1.40-9.26, p = 0.01), and cardiac complications (aOR 4.12, CI 1.70-9.98, p < 0.01). However, there were no differences between the two groups in terms of in-hospital mortality and 30-day readmission rates. The median length of stay was longer for leadless pacemaker implantation than transvenous pacemaker implantation (5 days vs. 4 days, p < 0.01). The total hospitalization charges were also higher ($139,826 vs. $93,919, p < 0.01). Conclusions: Although previous studies have demonstrated lower long-term complication rates with leadless pacemakers than transvenous pacemakers, our analysis shows a higher risk of short-term in-hospital complications in ESRD patients, though no differences in in-hospital mortality and 30-day readmissions.

Leadless pacemaker implantation in challenging scenarios: A case report series of patients with mechanical tricuspid valves

INTRODUCTION

The advancement of medical technology has introduced leadless pacemakers (LPMs) as a significant innovation in cardiac pacing, offering potential advantages over traditional ventricular transvenous pacemakers. This report explores the application of LPMs in two patients with complex valvular histories, particularly those with mechanical tricuspid valves.

CASE REPORTS

The first case involves a 60-year-old male with a history of rheumatic heart disease and triple valve replacement who developed a high-grade AV block. Due to significant RV pacing, a single-chamber VVI pacemaker using the Micra Transcatheter Pacing System was successfully implanted, navigating the mechanical tricuspid valve with stable pacing parameters. The second case describes a 70-year-old female with HIV, diabetes, hypothyroidism, and multiple valve surgeries presenting with syncope and dyspnea. Given her complex medical history and recurrent conduction issues, the Micra pacemaker was chosen. Despite initial resistance, successful deployment was achieved at the lower septum with acceptable pacing thresholds.

DISCUSSION

LPMs offer a promising alternative for patients with mechanical tricuspid valves, eliminating the risks associated with transvenous leads. The Micra system's minimally invasive approach and stable performance in these challenging cases suggest its potential viability in high-risk patients with complex valvular conditions.

CONCLUSION

These cases demonstrate the feasibility of LPM implantation through mechanical tricuspid valves; however, given the associated risks, careful evaluation and meticulous procedural planning are essential before considering this approach.

Is day-case surgical procedure safe for MICRA leadless pacemaker implantation?

BACKGROUND

MICRA implantation is not commonly done as a day-case procedure. Elective leadless pacemakers are implanted routinely in our centre.

OBJECTIVE

To assess whether the day-case MICRA procedure is safe.

METHODS

We retrospectively collected data from all patients undergoing elective MICRA implantation at our centre between May 2014 and Nov 2022 (n = 81). Two patient groups were stratified: those planned to be discharged on the same day (SD, n = 52) and those planned to be observed overnight after the procedure (ON, n = 29). Patient demographics, size of the sheath used, type of MICRA device, and rate of complications were recorded. In patients with successful implants (n = 80), device function at discharge and first routine follow-up were evaluated.

RESULTS

There were 58% males in the SD group and 45% in the ON group. Median age was 49 years in the SD and 67 years in the ON. Among patients who were planned as a day case, 8 patients had to stay in the hospital but for < 48 h: 2 due to minor groin bleeding, 1 due to patient's request despite fit to discharge, 4 due to the procedure carried out later in the day, and 1 for observation due to procedural complexity. MICRA implantation was successful in 80 patients. The rate of the major complications was 2% in the SD group and 7% in the ON group (p = 0.223), and none of the co-morbidities assessed showed an association with any complications. Device parameters at the follow-up were available in 76 patients. The rate of patients with low and stable PCT at follow-up was also 98% in the SD group and 96% in the ON group.

CONCLUSIONS

Day case MICRA procedure can be performed safely in an appropriately selected patient population.

Micra Leadless and Transvenous Pacemaker: A Single-Center Comparative Study of QRS Wave Duration Resulting From Different Pacing Sites

OBJECTIVE

To compare the paced QRS duration on different sites in age-, gender-, and indication-matched patients implanted with Micra leadless pacemakers and conventional transvenous pacemakers (TV-PM).

METHOD

A total of 82 patients from Xinhua Hospital, Shanghai Jiaotong University, were enrolled, including two groups of 41 patients matched according to gender, age, and pacemaker indications, who underwent Micra and TV-PM implantations, respectively. The baseline data of the patients, the pacing site described using three- and nine-partition methods, and the paced QRS duration on 12-lead electrocardiogram were then analyzed.

RESULTS

Overall, patients in our population were on average 79.2 years of age and mostly male (75.6%). Atrioventricular node dysfunction was the most common indication (56.1%) for pacemaker therapy. Mid-septum, especially Site 5, is the implantation site for most patients in both groups. Micra (145 ms) and TV-PM (133 ms) both had the narrowest-paced QRS at high septum, but Micra may exhibit significantly more reduced QRS duration than TV-PM at low septum (Micra vs. TV-PM: 143.0 [142.8-156.5] ms vs. 163.5 ± 17.5 ms, p = 0.044).

CONCLUSION

The narrowest-paced QRS complex for Micra leadless pacemakers is achieved at high septum, and pacing at low septum by Micra may acquire shorter QRS duration than conventional TV-PM.

Impact of right ventricular pacing site on the subcutaneous ICD sensing-a step towards personalised device therapy?

BACKGROUND

Patients with an existing subcutaneous implantable cardiac defibrillator (S-ICD) may develop a pacing indication. When transvenous pacing is not feasible, combining an S-ICD and a leadless pacemaker (LP) can be a reasonable option. There are reports of concomitant use of both devices. However, the effect of pacing on the S-ICD sensing is not well studied. We hypothesise that pacing changes R and T-wave amplitudes, causing changes in R:T ratios as perceived by a S-ICD, increasing the risk for T wave oversensing (TWO) during paced rhythm with a subsequent risk of inappropriate shocks.

METHODS

This is a prospective study in patients undergoing electrophysiological studies. Participants were fitted with a Holter®, and the leads were placed to correspond to the vectors of an S-ICD. The right ventricle was paced at four positions for 10 beats each at 8 mA/2 ms. The Holter® traces were analysed, using two-way analysis of variance (ANOVA) to assess the effect of pacing on the R:T ratio.

RESULTS

Forty-seven patients (age 56.02 ± 16.02, 72% male) were enrolled (81% structurally normal heart, 15% dilated cardiomyopathy, 2% ischaemic cardiomyopathy, and 2% adult congenital heart disease). Age, sex, and aetiology had no effect on the R:T ratio. Pacing caused significant changes in the R:T ratio. There was no significant difference in the R:T ratios between the pacing sites (p < 0.001).

CONCLUSIONS

Pacing alters the R:T ratio significantly in most patients, theoretically increasing the risk for TWO and inappropriate shocks. Tailored programming for both devices is important for concomitant use of LPs and S-ICDs.

Impact of left atrial strain on clinical outcomes in patients with permanent pacemaker implantation

AIMS

This study aimed to investigate the clinical impact of pre-procedural left atrial strain (LAS) in patients undergoing permanent pacemaker implantation (PPI).

METHODS AND RESULTS

This single-centre retrospective study enrolled 434 patients who were admitted for transvenous PPI between 2010 and 2020. After excluding patients with persistent atrial fibrillation, PPI for complete atrioventricular block, severe valvular disease, history of open-heart surgery and those without LAS data, 172 patients were analysed. The LAS was measured using commercially available software to calculate the average strain value of the apical four- and two-chamber views before PPI. The primary composite endpoint was hospitalization due to heart failure or cardiovascular death. Cox proportional hazard models were used to evaluate risk factors for the primary composite endpoint. The mean patient age was 78 ± 8 years, and 42% of the patients were men. PPI was performed for sick sinus syndrome in 64% and second-degree atrioventricular block in 36% of the patients. The pre-procedure left atrial reservoir strain (LASr) was 28 ± 11%. The median follow-up period was 4.7 years, and the primary endpoint was observed in 23 (13%) patients. In multivariate Cox proportional risk analysis, LASr was independently associated with the primary composite endpoint (hazard ratio, 1.08 per 1% decrease; 95% confidence interval, 1.02-1.15; P = 0.007). The receiver operating characteristic curve of the LASr for the primary composite endpoint showed a cutoff value of 21% (area under the curve 0.657, P = 0.004). The prognostic impact of LASr was consistent with that of sick sinus syndrome and atrioventricular block.

CONCLUSIONS

A decreased pre-procedure LASr was associated with long-term adverse outcomes after PPI use.

Device dislodgement and embolization associated with a new leadless pacemaker

INTRODUCTION

Currently, there are two approved single chamber leadless pacemakers (LP) in the United States (US), Micra VR™; approved since 2016 and AVEIR VR™; approved in 2022. A potential complication of LPs is dislodgement and/or embolization (D/E) during or after implant. According to the IDE trials, there appears to be a significant difference in D/E rates between the two LPs that have different fixation mechanisms; Micra uses nitinol tines, while AVEIR uses an active screw helix. The aim of this study was to determine if the AVEIR VR LP has continued to exhibit D/E in the United States since it was approved by the Food and Drug Administration (FDA) in April 2022.

METHODS

The FDA Manufacturer and User Facility Device Experience (MAUDE) database was searched for US D/E reports communicated by the manufacturers of both LP devices. For AVEIR VR we reviewed reports from approval till December 2023, and for Micra VR we looked at reports from approval to April 2024. Excluded were reports based on information indirectly obtained from registries, journals, social media, or volunteers. Total number of US implants was acquired from the manufacturers' product performance reports.

RESULTS

During a period of 21 months, 5990 AVEIR VR implants had been registered in the United States, of which 53 (0.88%) encountered D/E both during and after the procedure. More D/E (32; 60.4%) occurred during the implantation procedure, with device release problems being the most prominent procedural issue involved with these events. Within a 8-year period, 72 237 Micra VR implants have been registered in the United States, of which 211 (0.29%) showed D/E. The rate of D/E since the US approval of both devices was significantly higher for AVEIR VR compared to Micra VR (0.88% vs 0.29%; p < .0001).

CONCLUSION

AVEIR VR implants may be complicated by dislodgement with or without embolization. Currently, the estimated incidence is about 0.9%, which is significantly higher than Micra VR. Fixation issues and separation problems of the device from the delivery catheter appear to be responsible for most of these D/E events.

Cost-effectiveness of Micra™ VR leadless pacemaker in patients with bradycardia and atrial fibrillation in Australia

Background

Micra™ VR Transcatheter Pacing System (Micra VR) is a single-chamber transcatheter leadless pacemaker. Absence of leads and subcutaneous pocket reduces or completely eliminates the risk of complications associated with the conventional transvenous pacemakers (TVPM). When compared with TVPM, the leadless technology provides a quicker postimplantation recovery and causes less cosmetic concerns/discomfort providing better patient experiences in the long run. We performed a modeled cost-utility analysis of Micra VR versus TVPM for the management of patients with bradycardia.

Methods

We developed a Markov model comparing Micra VR to TVPM over the device battery life of 17 years. Key data inputs were drawn from the MICRA Coverage with Evidence Development (CED) study. Costs were obtained from Australian sources. The analysis is from the perspective of the Australian healthcare system.

Results

The risks of complications, including device-related events, in real-world clinical practice were relatively low for TVPM. The magnitude of cost savings arising from risk reductions provided by Micra VR was however sizable, offsetting roughly a quarter of its additional device cost. Over the 17-year model period, Micra VR was associated with an estimated incremental cost of A$4277 and an incremental quality-adjusted life years (QALYs) of 0.09 when compared with TVPM, yielding an incremental cost-effectiveness ratio of A$47 379 per QALY gain.

Conclusions

Micra VR is likely to offer a cost-effective alternative to the conventional TVPM technology for the management of patients with bradycardia.

A comparison of procedure-related adverse events between two right ventricular leadless pacemakers

INTRODUCTION

The Medtronic Micra VR and Abbott AVEIR VR are the leadless pacemakers (LPM) currently available in the United States (US). Micra VR employs fixation tines and the AVEIR VR uses an active fixation helix. Micra VR requires fixation before electrical measurements are obtained, while R-waves may be mapped by AVEIR VR without fixation. Little comparative data is available for these LPMs. Accordingly, we compared the incidences of procedure-related major adverse clinical events (MACE) and device problems in the US for Micra VR and AVEIR VR during 2022-2024.

METHODS

We searched the FDA's Manufacturer and User Facility Device Experience (MAUDE) database for US reports of MACE and device problems that were filed from April 2022 to December 2023 for AVEIR VR, and from June 2022 to April 2024 for Micra VR. Totals for US-registered LPM implants were obtained from the manufacturers' product performance reports.

RESULTS

During the study period, 5990 AVEIR VR and 10 940 Micra VR implants were registered in the US. We found 305 MAUDE reports for AVEIR VR (5.1%), versus 541 MAUDE reports for Micra VR (4.9%) (p = .702). The incidence of MACE was 0.72% (43/5990) for AVEIR VR versus 0.59% (65/10 940) for Micra VR, (p = .387). The incidences of procedure-related death, cardiac perforation. cardiac arrest, emergency pericardial drainage or reparative surgery were similar for both LPMs (p > .05). Micra VR had more unacceptable thresholds requiring LPM replacement compared to AVEIR VR (95;0.9% vs. 24;0.4%; p = .001). AVEIR VR had a statistically higher incidence of device dislodgement during (32) and after (21) implant compared to Micra VR (53 (0.9%) vs. 46 (0.4%), p < .001).

CONCLUSIONS

Micra VR and AVEIR VR have similar procedural safety profiles, including the incidences of death and perforation. However, device problems differed significantly, possibly related to their design differences. Compared to Micra VR, AVEIR VR appears to have an advantageous threshold measurement capability but is more prone to device dislodgement.

A Direct-Digital 40 A 100 kb/s Intracardiac Communication Receiver With 250 s Startup Time for Low Duty-Cycle Leadless Pacemaker Synchronization

The first commercial dual-chamber leadless pacemaker (LLPM) was introduced recently. The system combines two separate implants situated in the right atrium and the right ventricle of the heart. Implant synchronization is accomplished with conductive intracardiac communication (CIC) using the myocardium and blood as transmission channel. Successful implant synchronization of this dual-chamber LLPM has been demonstrated. However, the continuously active synchronization transceivers, consuming about 800 nA, cause a 25-45 reduction in the projected device longevity. This work proposes an alternative strategy for power-optimized LLPM synchronization, which is based on synchronous duty-cycling of the transceivers and direct-digital CIC (DD-CIC). In line with this strategy, a novel low-power DD-CIC receiver for short-packet communication based on Manchester-encoded data and with fast startup time is presented. The circuit was fabricated in 180 nm CMOS technology and analyzed with respect to sensitivity, current consumption and startup time under highly duty-cycled operation. The receiver achieves a sensitivity of 81.67.4 V at a data rate of 100 kb/s, with an active current consumption of 39.10.6 A and a startup time below 250 s. Operating the receiver as specified by the proposed LLPM synchronization strategy reduces the current consumption to a measured average value of 73 nA. In conclusion, this work suggests synchronous duty-cycling for CIC-based implant synchronization as a promising concept to severely reduce the current consumption of contemporary dual-chamber LLPMs. Consequently, device longevity may be increased significantly, potentially reducing the frequency of costly and complication-prone re-interventions.

An Approach to Cardiac Implantable Electronic Device Pocket Infections: From Prevention to Diagnosis and Management

Cardiac implantable electronic device (CIED) infections are a highly morbid and potentially fatal complication of CIED implantation. Prompt diagnosis is paramount to the proper management of such infections. This review seeks to highlight the pathophysiology, risk factors, diagnostic approach, and prevention strategies for CIED infection, with an emphasis on pocket infection. Management will be discussed in detail, with complete device removal representing the standard of case, but with conservative management representing a potential alternative for patients at high risk for extraction. The high prevalence of CIED in the cardiac population renders understanding of this subject essential for the practicing clinician.

Ten Years of Leadless Cardiac Pacing

Leadless pacemakers (LPs) are self-contained pacemakers implanted inside the heart, providing a clinical strategy of pacing without pacemaker leads or a subcutaneous pocket. From an experimental therapy first used clinically in 2012, a decade later this technology is an established treatment option. Because of technologic advances and growing evidence, LPs are increasingly being used. Herein, the experience gained from a decade of leadless pacing is reviewed. We cover the safety and efficacy of single-chamber LPs, including comparisons with transvenous pacemakers and various models, and the initial clinical results of the first dual-chamber LP system. Furthermore, evidence and considerations regarding the optimal replacement strategy will be covered. Finally, we discuss future device developments that may broaden indications, such as LPs communicating with subcutaneous implantable cardiac defibrillators and energy-harvesting LPs.

Outcomes of a 24/7 service for urgent permanent pacemaker implantation

INTRODUCTION AND OBJECTIVES

Most of the complications associated with acute and symptomatic bradyarrhythmia (ASB) occur in the time from diagnosis to permanent pacemaker implantation (PPI). We aimed to evaluate the outcomes of an urgent 24/7 PPI service (PPI-24/7) for patients with ASB.

METHODS

A total of 664 patients undergoing first-time PPI for ASB were prospectively assessed during 2 periods of identical length (18 months): 341 patients who underwent the procedure during working hours only (PPI-WH), and 323 patients who underwent the procedure after the implementation of the PPI-24/7 service. The primary safety endpoint was established as the cumulative 180-day incidence of complications related to the index arrhythmia and device implant. The primary efficacy endpoint was determined as the average number of hospital stays per patient.

RESULTS

The PPI-24/7 period was associated with a significant shortening of the time from diagnosis to implantation (median [interquartile range]): 3hours [2-6] vs 16 [5-21]). The cumulative incidence of patients with complications at 180 days was lower in the PPI-24/7 period: 9% vs 17% (adjusted odds ratio, 0.5; P=.002), due to a significant reduction in preimplant complications: 2.5% vs 12% (P <.001). The average number of hospital stays was reduced by 2 per patient in the PPI-24/7 period (nonparametric P <.001). PPI-24/7 implants performed outside working hours (n=178) were safe, with a 180-day cumulative incidence in procedure-related complications of 3.9%.

CONCLUSIONS

Among patients with ASB, PPI-24/7 was associated with a significant reduction in patient morbidity and efficient hospital resource use.

A rate-responsive duty-cycling protocol for leadless pacemaker synchronization

Dual-chamber leadless pacemakers (LLPMs) consist of two implants, one in the right atrium and one in the right ventricle. Inter-device communication, required for atrioventricular (AV) synchrony, however, reduces the projected longevity of commercial dual-chamber LLPMs by 35-45%. This work analyzes the power-saving potential and the resulting impact on AV-synchrony for a novel LLPM synchronization protocol. Relevant parameters of the proposed window scheduling algorithm were optimized with system-level simulations investigating the resulting trade-off between transceiver current consumption and AV-synchrony. The parameter set included the algorithm's setpoint for the target number of windows per cardiac cycle and the number of averaging cycles used in the window update calculation. The sensing inputs for the LLPM model were derived from human electrocardiogram recordings in the MIT-BIH Arrhythmia Database. Transceiver current consumption was estimated by combining the simulation results on the required communication resources with electrical measurements of a receiver microchip developed for LLPM synchronization in previous work. The performance ratio given by AV-synchrony divided by current consumption was maximized for a target of one window per cardiac cycle and three averaging cycles. Median transceiver current of both LLPMs combined was 166 nA (interquartile range: 152-183 nA) and median AV-synchrony was 92.5%. This corresponded to median reduction of 18.3% and 3.2% in current consumption and AV-synchrony, respectively, compared to a non-rate-responsive implementation of the same protocol, which prioritized maximum AV-synchrony. In conclusion, adopting a rate-responsive communication protocol may significantly increase device longevity of dual-chamber LLPMs without compromising AV-synchrony, potentially reducing the frequency of device replacements.

Improved outcomes with leadless vs. single-chamber transvenous pacemaker in haemodialysis patients

AIMS

Cardiac conduction disorders are common in haemodialysis patients, with a relatively high rate of pacemaker implantations. Pacemaker-related complications, especially lead infections and central venous stenosis, pose significant challenges in this population. This study aims to compare single-chamber leadless pacemaker to single-chamber transvenous pacemakers in terms of survival and related complications in haemodialysis patients.

METHODS AND RESULTS

This retrospective study included adult haemodialysis patients who received a first single-chamber transvenous or leadless pacemaker between January 2017 and December 2020. Data were obtained from the French national REIN registry matched to the national health databases (Système National des Données de Santé). Propensity score matching was used to balance baseline characteristics. Survival and complications were compared between groups by Cox regression and by competitive risk models, respectively. One hundred and seventy-eight patients were included after propensity score matching, with 89 patients in each group. The median follow-up time was 24 (range 7-37) months. Leadless pacemakers were associated with significantly lower all-cause mortality rates compared to transvenous pacemakers [hazard ratio (HR) = 0.68, 95% confidence interval (CI) (0.47-0.99)]. Device-related infections are significantly lower with leadless pacemakers throughout the follow-up period (HR 0.43, 95% CI 0.21-0.86). Leadless pacemaker recipients also required fewer vascular access interventions [odds ratio 0.53, 95% CI (0.33-0.68)] on arteriovenous fistula.

CONCLUSION

With the limitations of its observational design, this study suggests that leadless pacemakers are associated with a lower rate of complications and better survival as compared with transvenous VVI pacemakers in haemodialysis patients, supporting to consider their preferential use in this population.

Leadless pacemakers: Where are we?

Pacemakers have been the cornerstone of brady-arrhythmia management since the mid-20th century. Despite the widespread use and success of traditional transvenous pacemakers, they are associated with an estimated 15 % complication rate at three years. Driven by the advantages over traditional transvenous pacemakers including a lack of transvenous leads, resistance to infection, and ease of implantation, the number of leadless pacemakers placed annually in the United States has dramatically increased since their initial approval. While current iterations of leadless pacemakers lack the versatility offered by transvenous devices, recent advances in leadless pacing offer an increasingly diverse range of therapeutic options. This review will discuss the past, present, and future emerging technologies, and strategies in leadless pacing.

Outcomes of leadless pacemaker implantation in the United States based on sex

BACKGROUND

To determine differences in baseline characteristics and outcomes of leadless pacemaker implantation based on sex.

METHODS

For the purpose of this study, data were extracted from the National Inpatient Sample database for years 2016-2020. The study group was then stratified based on sex. Baseline characteristics and in-hospital outcomes including complications were then analyzed in each group. Multivariable logistic regression models were created to analyze the association of sex with important outcomes of mortality, major complications (defined as pericardial effusion requiring intervention and any vascular complication), prolonged length of stay (defined as > 6 days), and increased cost of hospitalization (defined as median cost > 34,098$) after leadless pacemaker implantation.

RESULTS

A total of 29,000 leadless pacemakers (n in women = 12,960, 44.7%) were implanted during our study period. Women were found to have an increased burden of co-morbidities as compared to men. In the adjusted analysis, the likelihood of mortality (aOR 1.27, 95% CI 1.14-1.43), major complications (aOR 1.07, 95% CI 0.98-1.18), prolonged length of stay (aOR 1.09, 95% CI 1.04-1.15), and increased hospitalization cost (aOR 1.14, 95% CI 1.08-1.20) were higher in women as compared to men after leadless pacemaker implantation.

CONCLUSION

Important and significant differences exist in leadless pacemaker implantation in women as compared to men. These findings highlight the need for evaluating etiologies behind such differences with a goal of improving outcomes in all patients after leadless pacemaker implantation.

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.).

Transcatheter non-acute retrieval of the tine-based leadless ventricular pacemaker

AIMS

We report our single-centre experience of mid-term to long-term retrieval and reimplantation of a tine-based leadless pacemaker [Micra transcatheter pacing system (TPS)]. The TPS is a clinically effective alternative to transvenous single-chamber ventricular pacemakers. Whereas it is currently recommended to abandon the TPS at the end of device life, catheter-based retrieval may be favourable in specific scenarios.

METHODS AND RESULTS

We report on nine consecutive patients with the implanted TPS who subsequently underwent transcatheter retrieval attempts. The retrieval system consists of the original TPS delivery catheter and an off-the-shelf single-loop 7 mm snare. The procedure was guided by fluoroscopy and intracardiac echocardiography. After an implantation duration of 3.1 ± 2.8 years (range 0.4-9.0), the overall retrieval success rate was 88.9% (8 of 9 patients). The mean procedure time was 89 ± 16 min, and the fluoroscopy time was 18.0 ± 6.6 min. No procedure-related adverse device events occurred. In the one unsuccessful retrieval, intracardiac echocardiography revealed that the TPS was partially embedded in the ventricular tissue surrounding the leadless pacemaker body in the right ventricle. After retrieval, three patients were reimplanted with a new TPS device. All implantations were successful without complications.

CONCLUSION

A series of transvenous late retrievals of implanted TPS devices demonstrated safety and feasibility, followed by elective replacement with a new leadless pacing device or conventional transvenous pacing system. This provides a viable end-of-life management alternative to simple abandonment of this leadless pacemaker.

First long-term outcome data for the MicraVR™ transcatheter pacing system: data from the largest prospective German cohort

AIMS

The MicraVR™ transcatheter pacing system (TPS) has been implemented into clinical routine for several years. The primary recipients are patients in need for VVI pacing due to bradycardia in the setting of atrial fibrillation (AF). Implantation safety and acute success have been proven in controlled studies and registries. So far only few long-term real-life data on TPS exist. We report indication, procedure and outcome data from two high-volume implanting German centers.

METHODS

Between 2016 and 2019, 188 (of 303) patients were included. During follow-up (FU), TPS interrogation was performed after 4 weeks and thereafter every 6 months.

RESULTS

Indication for TPS implantation in 159/188 (85%) patients was permanent or intermittent AV block III° in the setting of atrial fibrillation. The mean procedure duration was 50 min [35.0-70.0]. The average acute values after system release were: thresholds: 0.5V [0.38-0.74]/0.24ms; R-wave sensing: 10.0mV [8.1-13.5]; impedance: 650 Ohm [550-783]; RV-pacing demand: 16.9% [0.9-75.9]; and battery status: 3.15 V [3.12-3.16]. During FU of 723.4 ± 597.9 days, neither pacemaker failure nor infections were reported. Long-term FU revealed: thresholds: 0.5V [0.38-0.63]/0.24 ms; sensing: 12.3mV [8.9-17.2]; impedance: 570 Ohm [488-633]; RV-pacing demand: 87.1% [29.5-98.6]; and battery status 3.02 V [3.0-3.1]. Forty-three patients died from not-device-related causes.

CONCLUSION

This to date largest German long-term dataset for MicraVR™ TPS implantation revealed stable device parameter. Foremost, battery longevity seems to fulfill predicted values despite a significant increase in RV-pacing demand over time and even in patients with consecutive AV-node ablation. Of note, no infections or system failure were observed.

Six-month electrical performance of the first dual-chamber leadless pacemaker

BACKGROUND

The first dual-chamber leadless pacemaker (DC-LP) system consists of 2 separate atrial and ventricular devices that communicate to maintain synchronous atrioventricular pacing and sensing. The initial safety and efficacy were previously reported.

OBJECTIVE

The purpose of this study was to evaluate the chronic electrical performance of the DC-LP system.

METHODS

Patients meeting standard dual-chamber pacing indications were enrolled and implanted with the DC-LP system (Aveir DR, Abbott), including right atrial and ventricular helix-fixation LPs (atrial leadless pacemaker [ALP], ventricular leadless pacemaker [VLP]). Pacing capture threshold, sensed amplitude, and pacing impedance were collected using the device programmer at prespecified timepoints from 0-6 months postimplant.

RESULTS

De novo devices were successfully implanted in 381 patients with complete 6-month data (62% male; age 69 ± 14 years; weight 82 ± 20 kg; 65% sinus nodal dysfunction, 30% atrioventricular block). ALPs were implanted predominantly in the right atrial appendage anterior base and VLPs primarily at the mid-to-apical right ventricular septum. From implant to 1 month, pacing capture thresholds (0.4-ms pulse width) improved in both ALPs (2.4 ± 1.5 V to 0.8 ± 0.8 V; P <.001) and VLPs (0.8 ± 0.6 V to 0.6 ± 0.4 V; P <.001). Sensed amplitudes improved in both ALPs (1.8 ± 1.3 mV to 3.4 ± 1.9 mV; P <.001) and VLPs (8.8 ± 4.0 mV to 11.7 ± 4.2 mV; P <.001). Impedances were stable in ALPs (334 ± 68 Ω to 329 ± 52 Ω; P = .17) and reduced in VLPs (789 ± 351 Ω to 646 ± 190 Ω; P <.001). Electrical measurements remained relatively stable from 1-6 months postimplant. No differences in electrical metrics were observed among ALP or VLP implant locations.

CONCLUSION

This first in-human evaluation of the new dual-chamber leadless pacemaker system demonstrated reliable electrical performance throughout the initial 6-month evaluation period.

Ventricular lead malfunction in a patient with complete atrioventricular block and corrected transposition of the great arteries: Is leadless pacemaker the best solution?

Corrected transposition of the great arteries (c-TGA) is a congenital abnormality characterized by atrioventricular (AV) and ventriculoarterial discordance, associated with early and late-onset conduction disturbances. We report the case of a c-TGA patient affected by congenital complete AV block, with right ventricular lead malfunction with prolonged dwell time and two abandoned leads. He underwent leadless VDD pacemaker implantation at an unusual site (i.e. the anterior wall of subpulmonic left ventricle), with an optimal electrical performance, a good AV synchrony, and QRS narrowing.

Learning objective

Leadless VDD pacing is safe and feasible in patients affected by corrected transposition of the great arteries, even with an unusual implant site such as the anterior wall of subpulmonic left ventricle.