Practical considerations, indications, and future perspectives for leadless and extravascular cardiac implantable electronic devices: a position paper by EHRA/HRS/LAHRS/APHRS

[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.

Systematic review of leadless pacemaker

Conventional pacing systems consist of a pacemaker and one or more leads threaded from the device pocket through veins into the heart conducting the pacing therapy to the desired pacing site. Although these devices are effective, approximately one in eight patients treated with these traditional pacing systems experiences a complication attributed to the pacemaker pocket or leads. With the technological advances in electronics, leadless pacemakers that small enough to implant within the heart were introduced. Leadless pacemakers have been developed to overcome many of the challenges of transvenous pacing including complications related to leads or pacemaker pockets. This review aims to provide an overview of advantages of leadless pacemaker, complications and limitations of leadless pacemaker, leadless pacemaker candidate, and future directions of this promising technology.

Leadless pacemakers at 5-year follow-up: the Micra transcatheter pacing system post-approval registry

BACKGROUND AND AIMS

Prior reports have demonstrated a favourable safety and efficacy profile of the Micra leadless pacemaker over mid-term follow-up; however, long-term outcomes in real-world clinical practice remain unknown. Updated performance of the Micra VR leadless pacemaker through five years from the worldwide post-approval registry (PAR) was assessed.

METHODS

All Micra PAR patients undergoing implant attempts were included. Endpoints included system- or procedure-related major complications and system revision rate for any cause through 60 months post-implant. Rates were compared through 36 months post-implant to a reference dataset of 2667 transvenous pacemaker patients using Fine-Gray competing risk models.

RESULTS

1809 patients were enrolled between July 2015 and March 2018 and underwent implant attempts from 179 centres in 23 countries with a median follow-up period of 51.1 months (IQR: 21.6-64.2). The major complication rate at 60 months was 4.5% [95% confidence interval (CI): 3.6%-5.5%] and was 4.1% at 36 months, which was significantly lower than the 8.5% rate observed for transvenous systems (HR: .47, 95% CI: .36-.61; P < .001). The all-cause system revision rate at 60 months was 4.9% (95% CI: 3.9%-6.1%). System revisions among Micra patients were mostly for device upgrades (41.2%) or elevated thresholds (30.6%). There were no Micra removals due to infection noted over the duration of follow-up. At 36 months, the system revision rate was significantly lower with Micra vs. transvenous systems (3.2% vs. 6.6%, P < .001).

CONCLUSIONS

Long-term outcomes with the Micra leadless pacemaker continue to demonstrate low rates of major complications and system revisions and an extremely low incidence of infection.

Strategies to improve atrioventricular synchrony in patients with a Micra AV leadless pacemaker

The second generation of transcatheter pacing systems, called Micra AV, can provide atrioventricular (AV) synchronous pacing via a new pacing algorithm relying on sensing mechanical atrial contraction. Several novel programming parameters were introduced to enable AV synchronous pacing, including an A3 window and A4 window as well as a conduction mode switch and an activity mode switch. In addition to several automated features, manual programming optimization of some of the novel parameters is key to improving AV synchrony. A solid knowledge of the features and their programming is essential for electrophysiologists implanting or following patients with Micra AV devices. Differences in programming optimization might partially explain the high variability of AV synchrony published in real-world data reports. This article reviews the key programming parameters of Micra AV. Subsequently, optimal programming recommendations for defined patient profiles are presented. Those were established by consensus within an expert panel comprised of 11 European electrophysiologists from high-volume Micra AV centres. The patient profiles were (1) high degree AV block and slow sinus rhythm; (2) high degree AV block and fast sinus rhythm; and (3) intermittent AV block. The panel recommended to evaluate the mechanical atrial activity on transthoracic echocardiography prior to implant. It was also agreed that Auto A3 Threshold and Tracking Check should be turned off in all patients, AV conduction mode switch should be turned off in all patients with high degree AV block, and the lower rate should be programmed to 50 bpm with exceptions based on individual clinical assessment. Future studies will be useful to evaluate the strength of those recommendations to improve the AV synchrony.

Update on Cardiovascular Implantable Electronic Device Infections and Their Prevention, Diagnosis, and Management: A Scientific Statement From the American Heart Association: Endorsed by the International Society for Cardiovascular Infectious Diseases

The American Heart Association sponsored the first iteration of a scientific statement that addressed all aspects of cardiovascular implantable electronic device infection in 2010. Major advances in the prevention, diagnosis, and management of these infections have occurred since then, necessitating a scientific statement update. An 11-member writing group was identified and included recognized experts in cardiology and infectious diseases, with a career focus on cardiovascular infections. The group initially met in October 2022 to develop a scientific statement that was drafted with front-line clinicians in mind and focused on providing updated clinical information to enhance outcomes of patients with cardiovascular implantable electronic device infection. The current scientific statement highlights recent advances in prevention, diagnosis, and management, and how they may be incorporated in the complex care of patients with cardiovascular implantable electronic device infection.

Left atrial strain is a good predictor of atrio-ventricular synchrony in leadless pacemaker pacing

INTRODUCTION

The importance of atrio-ventricular synchrony pacing in sinus rhythm patients is known. To identify patients in whom leadless pacemakers are able to guarantee this atrio-ventricular synchrony, we explored correlations among echocardiographic measures of left atrial (LA) size and function (doppler parameter and strain) with A4 amplitude in patients implanted with new generation Micra-AV device.

METHODS

After implantation with Micra-AV system, patients underwent device interrogation to evaluate AV synchrony based on the sensing of atrial mechanics and echocardiographic exam to assess LA morphology and LA function.

RESULTS

In the 21 studied patients (14 males, 72 ± 13 years), the A4 wave amplitude values inversely correlated with LA antero-posterior diameter, LA volume, LA contraction strain and LA conduit strain, while they were positively related with LA reservoir strain.

DISCUSSION

Our results indicate a statistically significant relationship between morphological echocardiographic LA parameters and atrial contraction signal (A4), detected by leadless pacemakers and used to synchronize ventricular pacing with the atrium. Instantaneous LA function assessment obtained with LA strain provides incremental information over morphological parameters. LA strain evaluates atrial myocardial deformation during the whole cardiac cycle. We found higher value of A4 in patients that have grater absolute value of LAsr, LAscd and LAsct, that are simple and measurable parameters of LA functional capacity.

CONCLUSION

Preimplant echocardiographic evaluation of the atrial contractility may be useful in predicting adequate A4 sensing and consequently a good atrio-ventricular synchrony pacing. Echocardiography LA strain study seems promising in Micra-AV patient selection.

Spanish pacemaker registry. 20th official report of the Heart Rhythm Association of the Spanish Society of Cardiology (2022)

INTRODUCTION AND OBJECTIVES

This article reports the cardiac pacing activity performed in 2022, including the total number of implants, adherence to remote monitoring, demographic and clinical factors, and the characteristics of the implanted devices.

METHODS

The information sources were the CardioDispositivos online platform, the European pacemaker patient identification card, and data provided by the manufacturers.

RESULTS

The rates of conventional pacemakers and low-energy resynchronizers were 866 and 34 units per million population, respectively. A total of 815 leadless pacemakers were implanted. In all, 16426 procedures performed in 82 hospitals were reported (9407 through CardioDispositivos), representing 40% of the activity. The mean age was 78.6 years, with a predominance of men (60.3%). The most frequent disorder was atrioventricular block, and 14.5% of the patients had atrial fibrillation. There was a predominance of the DDD/R pacing mode (55.6%), and pacing mode was influenced by age, such that more than one-third of patients older than 80 years in sinus rhythm received single-chamber ventricular pacing. The remote monitoring program included 35% of conventional pacemakers and 55% of low-energy resynchronization pacemakers.

CONCLUSIONS

The number of conventional pacemakers increased by 5.6%, low-energy resynchronizers by 16%, and leadless pacemakers by 25%. Adherence to remote monitoring was stable. The number of procedures included in CardioDispositivos increased by 11%, although the sample volume decreased. In the coming years, the widespread use of the platform will likely lead to a high-quality registry.

The Micra Transcatheter Pacing System: past, present and the future

Leadless permanent pacemakers represent an important innovation in cardiac device developments. Although transvenous permanent pacemakers have become indispensable in managing bradyarrhythmia and saving numerous lives, the use of transvenous systems comes with notable risks tied to intravascular leads and subcutaneous pockets. This drawback has spurred the creation of leadless cardiac pacemakers. Within this analysis, we compile existing clinical literature and proceed to evaluate the efficacy and safety of the Micra Transcatheter Pacing System. We also delve into the protocols for addressing a malfunctioning or end-of-life Micra as well as device extraction. Lastly, we explore prospects in this domain, such as the emergence of entirely leadless cardiac resynchronization therapy-defibrillator devices.

Case Report: A leadless and endovascular pacemaker teamwork

Background

Cardiac Implantable Electronic Device infections increase short- and long-term mortality, along with healthcare costs. Leadless pacemakers (PM) were developed to overcome pocket- and minimize lead-related complications in selected high-risk patients. Recent advancements enable leadless devices to mechanically detect atrial activity, facilitating atrioventricular (AV) synchronous stimulation.

Case summary

A 90-year-old woman, implanted with a dual-chamber pacemaker eight years ago due to sinus node dysfunction, presented with syncope. A diagnosis of complete AV block, in the setting of ventricular lead dysfunction was made. Due to a high risk of infection, the patient was implanted with a leadless PM capable of maintaining AV synchrony in VDD mode (MICRA™ model MC1AVR1). The transvenous PM was programmed to AAI-R mode to drive the atria, which, in turn, triggered the leadless PM to stimulate the ventricles. At six month follow-up, the AV synchrony rate was 85%.

Conclusion

The combination of classic atrial pacing with leadless ventricular stimulation can be used in high-risk patients to reduce the risk of complications, in the setting of ventricular lead dysfunction. In this manner, AV synchrony can be maintained, improving hemodynamic parameters and quality of life. Low sinus rate variability at rest is essential to achieve a high AV synchrony rate in such cases.

Worsening tricuspid regurgitation associated with permanent pacemaker and implantable cardioverter-defibrillator implantation: A systematic review and meta-analysis of more than 66,000 subjects

BACKGROUND

Worsening tricuspid regurgitation (TR) after either permanent pacemaker (PPM) or implantable cardioverter-defibrillator (ICD) implantation is an emerging clinical challenge. Early recognition of this entity is essential in guiding treatment.

OBJECTIVE

This meta-analysis was designed to identify the overall incidence and patient-specific predictors of TR post-device implantation.

METHODS

We searched electronic databases from inception to January 2023 for published studies that reported the incidence of TR worsening post-device implantation. The log odds ratio (OR) was used to summarize group differences.

RESULTS

Our analysis included 29 studies with 66,590 participants. Patients who underwent device implantation (n = 1008) were significantly more likely to develop worsening TR than controls who did not undergo device implantation (n = 58,605) (OR 3.18; P < .01). In a total of 7777 patients, the pooled incidence of at least 1-grade worsening of TR post-device implantation was 24%. Worsening TR post-device implantation significantly increases mortality (hazard ratio 1.42; P = .02). Larger right atrial area (OR 1.11; P < .01) is significantly associated with an increased risk of worsening TR post-device implantation, while male patients are less likely to develop this complication than female patients (OR 0.74; P < .01). Importantly, there is no statistically significant difference between the type of implanted device (ICD vs PPM) and post-device implantation TR. Further, right ventricular dysfunction, pulmonary artery pressure, baseline mitral regurgitation, left ventricular ejection fraction, baseline atrial fibrillation, and age have no association with worsening TR post-device implantation.

CONCLUSION

A substantial number of patients undergoing PPM or ICD implantation are at an increased risk of worsening TR. Importantly, in this largest review to date incorporating more than 66,000 subjects, worsening TR significantly increases mortality by greater than 140%, accordingly deserving more recognition and clinical attention in the current era.

Atrial mechanical contraction and ambulatory atrioventricular synchrony: Predictors from the OPTIVALL study

INTRODUCTION

The role that preprocedural factors have on atrioventricular synchrony (AVS) provided by leadless pacemakers requires investigation.

METHODS AND RESULTS

We aimed to assess the correlation between mitral inflow echocardiographic parameters and p-wave morphology with the accelerometer A4 signal amplitude. We also sought to identify clinical and echocardiographic predictors of optimal ambulatory AVS (≥85% of cardiac cycles). Forty-three patients undergoing Micra AV implant from June 2020 to March 2023 were prospectively enrolled. Baseline echocardiogram and 12-lead resting ECG were performed. Device follow-up was scheduled at 24 h, 1, 3, and 6 months and yearly after the implant. Ambulatory AVS was studied with a 24 h Holter monitor performed at 3 months follow-up in 35 patients who remained in VDD mode. A4 signal amplitude at 1 month correlated to peak A wave velocity (r = .376; p = .024) at echocardiogram, but no relationship was found with peak A' wave velocity, E/A, or E'/A' ratio. P-wave amplitude in lead I and aVF correlated to A4 signal amplitude at 1- and 3-months follow-up, respectively. Median AVS during 24 h of daily activities was 85.6 ± 7.6% and remained stable up to 100 bpm. Twenty-three out of 35 patients (65.7%) reached optimal ambulatory AVS. There was no association between mitral inflow echocardiographic parameters and optimal AVS. Diabetes (OR: 0.05, 95% CI: 0.01-0.47; p = .009) and chronic obstructive pulmonary disease (COPD) (OR: 0.06, 95% CI: 0.01-0.63; p = .019) strongly predicted ambulatory AVS <85%.

CONCLUSIONS

Diabetes and COPD should be considered when selecting candidates for Micra AV. Measurements of pulsed wave Doppler mitral inflow do not systematically reflect the behavior of the A4 signal amplitude.

Cardiac pacing and lead devices management: 25 years of research at EP Europace journal

AIMS

Cardiac pacing represents a key element in the field of electrophysiology and the treatment of conduction diseases. Since the first issue published in 1999, EP Europace has significantly contributed to the development and dissemination of the research in this area.

METHODS

In the last 25 years, there has been a continuous improvement of technologies and a great expansion of clinical indications making the field of cardiac pacing a fertile ground for research still today. Pacemaker technology has rapidly evolved, from the first external devices with limited longevity, passing through conventional transvenous pacemakers to leadless devices. Constant innovations in pacemaker size, longevity, pacing mode, algorithms, and remote monitoring highlight that the fascinating and exciting journey of cardiac pacing is not over yet.

CONCLUSION

The aim of the present review is to provide the current 'state of the art' on cardiac pacing highlighting the most important contributions from the Journal in the field.

Comparison of first- and second-generation leadless pacemakers in patients with sinus rhythm and complete atrioventricular block

INTRODUCTION

The efficacy and safety of leadless cardiac pacemakers (LPMs) as an alternative to conventional transvenous cardiac pacing have been largely reported. The first generation of the MicraTM transcatheter pacing system (VR; Medtronic) was able to provide single-chamber VVI(R) pacing mode only, with a potential risk of pacemaker syndrome in sinus rhythm patients. A second-generation system (AV) now provides atrioventricular synchrony through atrial mechanical (Am) sensing capability (VDD mode).

OBJECTIVE

We sought to compare VR and AV systems in sinus rhythm patients with chronic ventricular pacing (Vp) for complete atrioventricular block.

METHODS

All consecutive patients implanted with an LPM in our department for complete atrioventricular block were retrospectively screened. Patients with atrial fibrillation, sinus dysfunction, or Vp burden <20% at 1 month postimplantation were excluded. Patients were systematically followed with a visit at 1 month, and then at least once a year.

RESULTS

A total of 93 patients-45 VR (2015-2020) and 48 AV (2020-2021)-were included. VR and AV patients had similar baseline characteristics, except for VR patients being older (80 ± 8 vs. 77 ± 9 years, p = 0.049). The mean Vp burden was 77% in the VR and 82% in the AV group (p = 0.38). In AV patients, the median AV synchronous beats rate was 78%, with 65% having a >66% rate. An E/A ratio <1.2 as measured on echocardiography was the only independent predictor of accurate atrial mechanical tracking (p = 0.01). One-year survival rate was similar in both groups. Five patients in the VR and 0 in the AV group eventually developed pacemaker syndrome within 1 year post-implantation (p = 0.02).

CONCLUSION

In sinus rhythm patients with chronic Vp for complete atrioventricular block implanted with an LPM, the atrial mechanical sensing algorithm allowed significant atrioventricular synchrony in most patients and was associated with no occurrence of-otherwise rare-pacemaker syndrome.

Leadless cardiac pacing: Results from a large single-centre experience

BACKGROUND

The efficacy and safety of leadless cardiac pacing as an alternative to conventional transvenous cardiac pacing in selected patients have been widely reported.

AIM

To report the experience of a high-volume implantation centre with older and new generations of leadless pacemakers.

METHODS

This retrospective observational study included the first consecutive 400 patients who underwent implantation of a leadless pacemaker in our centre. Complications and electrical parameters were evaluated during follow-up, comparing patients implanted with first-generation (Micra™ VR) and second-generation (Micra™ AV) leadless pacemakers (Medtronic, Minneapolis, MN, USA). Data were collected by a review of medical files.

RESULTS

Among 400 procedures, there were 328 Micra™ VR pacemakers and 72 Micra™ AV pacemakers implanted, followed for a median of 16 months (694 patient-years). The mean age was 77 years and both groups had a high burden of co-morbidities. Implantation success rate was 99.5%. A total of 87.5% of patients were discharged the day after the procedure. The pacing threshold remained stable and<2V in 96.5% of all patients. The perioperative complication rate at 30 days was 3.5%. Outcomes were similar between the two groups.

CONCLUSION

Leadless cardiac pacing is a safe and efficient alternative to conventional transvenous cardiac pacing.

Effects of hyperbaric exposure on mechanical and electronic parameters of implantable cardioverter-defibrillators

AIMS

Hyperbaric oxygen therapy (HBOT) is the standard adjuvant treatment for life-threatening or disabling pathologies. Currently, mechanical and electronic variations of implantable cardioverter-defibrillators (ICD) in hyperbaric conditions have not been evaluated. As a result, many patients eligible for HBOT but ICD recipients cannot undergo this therapy, even in emergency situations.

METHODS AND RESULTS

Twenty-two explanted ICD of various brands and models were randomized in two groups: single hyperbaric exposure at an absolute pressure of 4000 hPa and 30 iterative hyperbaric exposures at an absolute pressure of 4000 hPa. Mechanical and electronic parameters of these ICD were blindly assessed before, during, and after hyperbaric exposures. Regardless of the hyperbaric exposure, we could not find any mechanical distortion, inappropriate occurrence of anti-tachycardia therapies, dysfunction of tachyarrhythmia therapeutic programming, or dysfunction of programmed pacing parameters.

CONCLUSION

Dry hyperbaric exposure seems harmless on ICD tested ex vivo. This result may lead to a reconsideration of the absolute contraindication of emergency HBOT to ICD recipients. A real-life study in these patients with an indication to HBOT should be performed to assess their tolerance to the treatment.

The VR leadless pacemaker: Results of an expert panel using the RAND/UCLA method

BACKGROUND

Leadless pacemakers were developed to reduce complications associated with transvenous pacemaker implantation and long-term follow-up. Existing international guidelines lack detailed instructions on patients suitable for leadless pacemaker implantation. Our aim was to develop a consensus document that provides medical guidance for all health professionals involved in the indication and implantation of Transcatheter Pacing System single-chamber device (VR leadless) pacemakers for patients with atrial fibrillation or in sinus rhythm.

METHODS

A panel of experts, including interventional and non-interventional cardiologists, used the Research ANd Development/University of California at Los Angeles (RAND/UCLA) method to rate the appropriateness of leadless pacemaker implantation for 64 scenarios in patients with atrial fibrillation and 192 scenarios in sinus rhythm. The scenarios were rated individually and again during a moderated group session. Median ratings and level of agreement were calculated to classify each scenario as appropriate, inappropriate, or questionable.

RESULTS

This consensus statement, based on available literature and the experts' opinions, summarizes recommendations for standardizing and optimizing leadless pacemaker implantation. The limitation for vascular access via the superior vena cava was the most influential variable when indicating leadless pacemaker implantation in both patients with atrial fibrillation and patients in sinus rhythm.

CONCLUSIONS

Life expectancy, risk of infection, prosthetic valve, left ventricular ejection fraction (LVEF), limitation for vascular access via the superior vena cava, and mobility and exercise capacity determine who is advised to undergo VR leadless pacemaker implantation. More prospective studies are needed to optimize existing recommendations.

NL-EVDR: Netherlands-ExtraVascular Device Registry

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

[Arrhythmias : Update on ablations and devices]

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

Leadless Micra pacemaker implantation in patient with previous Senning procedure for dextro-transposition of the great arteries

Leadless pacemakers have been developed with key advantages over traditional transvenous pacemakers by substantially mitigating the risks of device infection and lead related complications, and providing an alternative pacing strategy in patients with barriers to superior venous access. The Medtronic Micra leadless pacing system is designed for implantation through a femoral venous approach across the tricuspid valve, via Nitinol tine fixation into the trabeculated subpulmonic right ventricle. Patients with surgically corrected dextro-transposition of the great arteries (d-TGA) have an increased risk of pacing requirement. There is limited published experience of implantation of leadless Micra pacemakers in this population, with key challenges relating to trans-baffle access, and deployment of the device into the less trabeculated subpulmonic left ventricle. Here we describe a case report of leadless Micra implantation in a 49 year old male with d-TGA and Senning procedure in childhood, who required pacing for symptomatic sinus node disease, with anatomic barriers to transvenous pacing. Micra implantation was successfully performed following careful consideration of patient anatomy, including the utilisation of 3D modelling to guide the implantation procedure.