HRS/ACCF Expert Consensus Statement on Pacemaker Device and Mode Selection

Predictors of complications and mortality among patients undergoing pacemaker implantation in resource-limited settings: a 10-year retrospective follow-up study

INTRODUCTION

Pacemakers (PMs) are used to treat patients with severe bradycardia symptoms. They do, however, pose several complications. Even with these risks, there are only a few studies assessing PM implantation outcomes in resource-limited settings like Ethiopia and other sub-Saharan countries in general. Therefore, this study aims to assess the mid-term outcome of PM implantation in patients who have undergone PM implantation in the Cardiac Center of Ethiopia by identifying the rate and predictors of complications and death.

METHODOLOGY

This retrospective study was conducted at the Cardiac Center of Ethiopia from October 2023 to January 2024 on patients who had PM implantation from September 2012 to August 2023 to assess the midterm outcome of the patients. Complication rate and all-cause mortality rate were the outcomes of our study. Multivariable logistic regression was used to identify factors associated with complications and death. To analyze survival times, a Kaplan-Meier analysis was performed.

RESULTS

This retrospective follow-up study included 182 patients who underwent PM implantation between September 2012 and August 2023 and were at least 18 years old. The patients' median follow-up duration was 72 months (Interquartile range (IQR): 36-96 months). At the end of the study, 26.4% of patients experienced complications. The three most frequent complications were lead dislodgement, which affected 6.6% of patients, PM-induced tachycardia, which affected 5.5% of patients, and early battery depletion, which affected 5.5% of patients. Older age (Adjusted Odds Ratio (AOR) 1.1, 95% CI 1.04-1.1, p value < 0.001), being female (AOR 4.5, 95%CI 2-9.9, p value < 0.001), having dual chamber PM (AOR 2.95, 95%CI 1.14-7.6, p value = 0.006) were predictors of complications. Thirty-one (17%) patients died during the follow-up period. The survival rates of our patients at 3, 5, and 10 years were 94.4%, 92.1%, and 65.5% respectively with a median survival time of 11 years. Patients with a higher Charlson comorbidity index before PM implantation (AOR 1.2, 95% CI 1.1-1.8, p = 0.04), presence of complications (AOR 3.5, 95% CI 1.2-10.6, p < 0.03), and New York Heart Association (NYHA) class III or IV (AOR 3.3, 95% CI 1.05-10.1, p = 0.04) were associated with mortality.

CONCLUSION

Many complications were experienced by patients who had PMs implanted, and several factors affected their prognosis. Thus, it is essential to identify predictors of both complications and mortality to prioritize and address the manageable factors associated with both mortality and complications.

Physiologic Pacing Targeting the His Bundle and Left Bundle Branch: a Review of the Literature

PURPOSE OF REVIEW

Conduction system pacing (CSP) has emerged as a means to preserve or restore physiological ventricular activation via pacing at the His bundle or at more distal targets in the conduction system, including the left bundle branch area. This review examines strengths, weaknesses, and clinical applications of CSP performed via these approaches.

RECENT FINDINGS

His bundle pacing (HBP) has been successfully utilized for standard bradyarrhythmia indications and for QRS correction among patients receiving devices for cardiac resynchronization therapy (CRT). Limitations of HBP pacing have included implant complexity and rising pacing thresholds over time. Left bundle branch area pacing (LBBAP) appears to deliver similar physiological benefits with shorter implant times and more stable thresholds. More recently, hybrid systems utilizing HBP or LBBAP in combination with left ventricular leads have been used to treat heart failure (HF) patients, and may be useful in multilevel or mixed conduction blocks. There is growing interest in CSP for bradycardia and HF indications, although high quality data with randomized controlled trials are needed to help guide future treatment paradigms.

Personalized pacing for diastolic dysfunction and heart failure with preserved ejection fraction: Design and rationale for the myPACE randomized controlled trial

Background

Patients with pacemakers and heart failure with preserved ejection fraction (HFpEF) or isolated diastolic dysfunction (DD) may benefit from a higher backup heart rate (HR) setting compared with the standard setting of 60 bpm.

Objective

The purpose of this study was to assess the effects of a personalized backup HR setting (myPACE group) compared with 60 bpm (control group).

Methods

In this prospective, blinded, randomized controlled study, pacemaker patients with DD or HFpEF and atrial pacing with intrinsic ventricular conduction or conduction system or biventricular pacing are randomized to the myPACE group or control group for 1 year. The primary outcome is the change in Minnesota Living with Heart Failure Questionnaire (MLHFQ) scores. Secondary endpoints include changes in N-terminal pro–brain natriuretic peptide levels, physical and emotional MLHFQ subscores, and pacemaker-detected atrial arrhythmia burden, patient activity levels, and thoracic impedance; hospitalization for heart failure, atrial fibrillation, cerebrovascular accident, or myocardial infarction; and loop diuretic or antiarrhythmic medication initiation or up-titration. A sample size of 118 subjects is expected to allow detection of a 5-point change in MLHFQ score in an intention-to-treat analysis and allow initial assessment of clinical outcomes and subgroup analyses.

Results

Enrollment began in July 2019. As of November 2020, 107 subjects have been enrolled. It is projected that the 1-year follow-up will be completed by December 2021.

Conclusion

Atrial pacing with intrinsic ventricular conduction or advanced ventricular pacing at a higher, personalized backup HR may be a therapeutic target for patients with isolated DD or HFpEF. The myPACE trial is designed to test this hypothesis.

Inducible cardiomyocyte injury within the atrioventricular conduction system uncovers latent regenerative capacity in mice

The cardiac conduction system (CCS) ensures regular contractile function, and injury to any of its components can cause cardiac dysrhythmia. Although all cardiomyocytes (CMs) originate from common progenitors, the CCS is composed of biologically distinct cell types with unique functional and developmental characteristics. In contrast to ventricular cardiomyocytes, which continue to proliferate after birth, most CCS cells terminally exit the cell cycle during fetal development. Although the CCS should thus provide a poor substrate for postnatal injury repair, its regenerative capacity remains untested. Here, we describe a genetic system for ablating CMs that reside within the atrioventricular conduction system (AVCS). Adult mouse AVCS ablation resulted in regenerative failure characterized by persistent atrioventricular conduction defects and contractile dysfunction. In contrast, AVCS injury in neonatal mice led to recovery in a subset of these mice, thus providing evidence for CCS plasticity. Furthermore, CM proliferation did not appear to completely account for the observed functional recovery, suggesting that mechanisms regulating recovery from dysrhythmia are likely to be distinct from cardiac regeneration associated with ventricular injury. Taken together, we anticipate that our results will motivate further mechanistic studies of CCS plasticity and enable the exploration of rhythm restoration as an alternative therapeutic strategy.

Patient selection, pacing indications, and subsequent outcomes with de novo leadless single-chamber VVI pacing

AIMS

Patient selection is a key component of securing optimal patient outcomes with leadless pacing. We sought to describe and compare patient characteristics and outcomes of Micra patients with and without a primary pacing indication associated with atrial fibrillation (AF) in the Micra IDE trial.

METHODS AND RESULTS

The primary outcome (risk of cardiac failure, pacemaker syndrome, or syncope related to the Micra system or procedure) was compared between successfully implanted patients from the Micra IDE trial with a primary pacing indication associated with AF or history of AF (AF group) and those without (non-AF group). Among 720 patients successfully implanted with Micra, 228 (31.7%) were in the non-AF group. Reasons for selecting VVI pacing in non-AF patients included an expectation for infrequent pacing (66.2%) and advanced age (27.2%). More patients in the non-AF group had a condition that precluded the use of a transvenous pacemaker (9.6% vs. 4.7%, P = 0.013). Atrial fibrillation patients programmed to VVI received significantly more ventricular pacing compared to non-AF patients (median 67.8% vs. 12.6%; P < 0.001). The overall occurrence of the composite outcome at 24 months was 1.8% with no difference between the AF and non-AF groups (hazard ratio 1.36, 95% confidence interval 0.45-4.2; P = 0.59).

CONCLUSION

Nearly one-third of patients selected to receive Micra VVI therapy were for indications not associated with AF. Non-AF VVI patients required less frequent pacing compared to patients with AF. Risks associated with VVI therapy were low and did not differ in those with and without AF.

Basic Principles of Cardiac Electrophysiology

This article represents an overview of the basic concepts of cardiac electrophysiology. This relatively new field became a subspecialty of cardiology in the mid-1990s due to the rapid development of equipment that allowed the study and cure of cardiac arrhythmias percutaneously. Simultaneously, technology provided the field with percutaneous cardiac implantable electronic devices designed to protect patients from life-threatening bradyarrhythmias and tachyarrhythmias. Recently, the field has focused on the ablative treatment of atrial fibrillation, the most common arrhythmia facing an aging population, and the diagnosis and management of many inherited arrhythmias through advances in understanding of their genetic cause.

Bradyarrhythmias for the Internist

In this article, the authors review the different types of sinus node and atrioventricular node diseases that lead to bradyarrhythmias with their associated symptoms, the diagnostic investigations needed to assess the degree of disease, and the therapeutic management, including the indications for permanent pacing.

Rehospitalizations for complications and mortality following pacemaker implantation: A retrospective cohort study in an older population

INTRODUCTION

A large number of older people receive pacemakers each year but broad population-based studies that describe complications following pacemaker implantation in this population are lacking.

METHODS

We conducted a retrospective cohort study using data from the Australian Government Department of Veterans' Affairs database. The cohort consisted of patients who received a pacemaker from 2005 to 2014. The outcomes were subsequent rehospitalizations for infections, procedure-related complications, thromboembolism, cardiovascular events (heart failure, myocardial infarction, and atrial fibrillation), and reoperation of pacemaker, and mortality.

RESULTS

There were 10 883 pacemakers recipients, the median age was 86 years (interquartile range 83-89), 61% were males, and 74% received a dual-chamber pacemaker. Within 90 days postdischarge, rehospitalizations were occasioned by pacemaker infection in 0.5%, device-related complications in 1.5%, cerebral infarction in 0.7%, and heart failure in 6% of single-chamber pacemaker recipients. In dual-chamber pacemaker recipients rehospitalizations were occasioned by pacemaker infection in 0.4%, septicemia in 0.4%, device-related complications in 1.2%, cerebral infarction in 0.3%, and heart failure in 3%. Rehospitalizations for pacemaker adjustment occurred in 1.5% of patients. The 90-day postdischarge mortality was 5% and 3% in patients with single- and dual-chamber pacemaker, respectively.

CONCLUSION

Rehospitalizations for infection, procedure-related complications, or thromboembolism occurred in 1% to 2% of patients within 90 days postdischarge, while 10% of single chamber and 7% of dual-chamber recipients experienced a rehospitalization for a cardiovascular event.

Sick Sinus Syndrome and Takotsubo Cardiomyopathy

Background. Takotsubo cardiomyopathy is associated with increased risk of ventricular arrhythmias, atrial fibrillation, and bradyarrhythmias. However, sinus node dysfunction is relatively infrequent in the setting of takotsubo cardiomyopathy. Case Report. We are reporting a case of a 73-year-old woman with a history of asymptomatic sinus bradycardia who developed sick sinus syndrome complicated by takotsubo cardiomyopathy. Conclusion. Acute symptomatic sick sinus syndrome in patients with preexisting silent sinus node dysfunction can trigger takotsubo cardiomyopathy. Understanding precipitating factors of takotsubo cardiomyopathy and identifying the patients at risk of life-threatening arrhythmia can help in refining risk stratification and therapy planning. Patients with sick sinus syndrome complicated by takotsubo cardiomyopathy may benefit from pacemaker implantation. However, evaluation on a case-by-case basis is mandatory.

Association between paced QRS duration and atrial fibrillation after permanent pacemaker implantation: A retrospective observational cohort study

Right ventricular pacing often results in prolonged QRS duration (QRSd) as the result of right ventricular stimulation, and atrial fibrillation (AF) may result. The association of pacing-induced prolonged QRSd and AF in patients with permanent pacemakers is unknown.We selected 180 consecutive patients who underwent pacemaker implantation for complete/advanced atrioventricular block. All of the patients were paced from the right ventricular septum. Electrocardiography recordings were obtained at the beginning and the end of pacemaker implantation. QRSd was measured in all 12 leads. The QRSd variation was calculated by subtracting the preimplantation QRSd from the postimplantation QRSd.The occurrence of AF was observed in 64 (35.56%) patients (follow-up 33.62 ± 21.47 mo). No significant differences in preimplantation QRSd were observed between the AF occurrence and nonoccurrence groups. The QRSd variation in leads V4 (54.22 ± 29.03 vs 42.66 ± 33.79 ms, P = .022), and V6 (64.62 ± 23.16 vs 48.45 ± 34.40 ms, P = .001) differed significantly between the occurrence and nonoccurrence groups. More QRSd variation in lead V6 (P = .005, HR = 1.822, 95% CI 1.174-2.718, interval scale of QRSd was 40 ms) and left atrial diameter (P = .045, HR = 1.042, 95% CI 1.001-1.086) were independent risk factors for AF occurrence. Receiver operating characteristic curve suggested that QRSd variation in lead V6 could predict AF occurrence, especially for patients with long preimplantation QRSd (≥120 ms, area under the curve was 0.826, 95% CI 0.685-0.967).QRSd variation in lead V6 might be positively correlated with postimplantation AF occurrence. In patients with pacemaker implantation, QRSd could be a complementary criterion for optimizing the right ventricular septal pacing site, and smallest QRSd might be worth pursuing.

Under-utilization of pacemaker therapy for sinus node dysfunction - Real world data from South Asia

OBJECTIVE

Chronic symptomatic sinus node dysfunction (SND), the most common bradyarrhythmia, can be effectively managed by permanent cardiac pacing. Yet the care pathway and barriers to adoption of pacing therapy are not well understood - particularly in low volume implanting countries. The IMPROVE Brady study is a quality improvement initiative being conducted at centers in South Asia, Latin America, and Russia. We assessed the rates of SND diagnosis and pacemaker treatment for SND in the South Asia cohort.

METHODS

The prospective study enrolled patients with heart rate of  ≤50 beats per minute presenting with symptoms including syncope, dizziness, and/or dyspnea from ten centers in India and Bangladesh. Patients were followed to identify the proportion diagnosed with SND and subsequently treated with pacemaker therapy.

RESULTS

A total of 508 patients meeting criteria were enrolled and followed on average for 8.3±8.0months. Patients were on average 58 years of age, 77% were male, and 91% had completed at least primary education. An SND diagnosis was made in 368 (72%) of patients, with the majority (80%) of diagnoses occurring within 1 month of enrollment. Of the patients with an SND diagnosis, 63 (17%) were treated with a pacemaker. Reasons for not receiving treatment were: subject refusal or deferred decision (45%), unaffordability (34%), physician determined - not-indicated (20%), and other (1%). Older age, female gender, history of hypertension, lower resting heart rate, and syncopal or pre-syncopal symptoms were associated with a higher probability of implant.

CONCLUSIONS

In a care pathway assessment for the diagnosis and treatment of symptomatic SND in South Asia only 1 in 6 patients received pacemaker indicated therapy, largely due to patient refusal and physician decision. Phase II of the study will be aimed to improve this treatment rate.

Heart Rhythm Society: expert consensus statements-part 1

One of the most important roles for professional societies in medicine is assembling multiple stakeholders and experts to develop documents that can help guide and define policies and strategies for best medical care. Each year the Heart Rhythm Society (HRS) develops several consensus documents that address critical clinical subjects that have been identified by input from HRS members and HRS committees. Over the past 5 years, HRS has produced documents with multiple professional societies from around the world, and although the topics chosen for exploration center around arrhythmia management, the reviews and recommendations made in the documents are important for clinical cardiologists and generalists who are not arrhythmia specialists. When an internist or other primary care provider identifies a patient who may be having symptoms from an arrhythmia, the referral first is made to the clinical cardiologist and only later, if necessary, does an arrhythmia specialist become involved. These expert consensus statements are developed for specific clinical questions regarding arrhythmia management where there is controversy or uncertainty, often with less data from randomized controlled trials to help guide recommendations, which must then be made by extrapolation of existing data, observational data, and expert opinion. In this 2-part review, the consensus statements developed by the HRS over the past 5 years that pertain to adults are discussed in part 1; part 2 focuses on consensus statements that HRS has developed in conjunction with the Pediatric and Congenital Electrophysiology Society that address arrhythmia issues in children and adults with congenital heart disease.

Cardiac Evaluation and Monitoring of Patients Undergoing Noncardiac Surgery

Surgical management of disease has a tremendous impact on our health system. Millions of people worldwide undergo surgeries every year. Cardiovascular complications in the perioperative period are one of the most common events leading to increased morbidity and mortality. Although such events are very small in number, they are associated with a high mortality rate making it essential for physicians to understand the importance of perioperative cardiovascular risk assessment and evaluation. Its involves a detailed process of history taking, patient's medical profile, medications being used, functional status of the patient, and knowledge about the surgical procedure and its inherent risks. Different risk assessment tools and calculators have also been developed to aid in this process, each with their own advantages and limitations. After such a comprehensive evaluation, a physician will be able to provide a risk assessment or it may all lead to further testing if it is believed that a change in management after such testing will help to reduce perioperative morbidity and mortality. There is extensive literature on the significance of multiple perioperative testing modalities and how they can change management. The purpose of our review is to provide a concise but comprehensive analysis on all such aspects of perioperative cardiovascular risk assessment for noncardiac surgeries and provide a basic methodology toward such assessment and decision making.

"Two for the Price of One": A Single-Lead Implantable Cardioverter-Defibrillator System with a Floating Atrial Dipole

In patients known to be a high risk for sudden cardiac arrest, implantable cardioverter defibrillators (ICD) are a proven therapy to reduce risk of death. However, in patients without conventional indications for pacing, the optimal strategy for type of device, dual- versus single-chamber, remains debatable. The benefit of prophylactic pacing in this category of patients has never been documented. Although available atrial electrograms in a dual chamber system improve interpretation of stored arrhythmia events, allow monitoring of atrial fibrillation and may potentially reduce the risk of inappropriate shocks by enhancing automated arrhythmia discrimination, the use of dual-chamber ICDs has a number of disadvantages. The addition of an atrial lead adds complexity to implantation and extraction procedures, increases procedural cost and is associated with a higher risk of periprocedural complications. The single lead pacing system with ability to sense atrial signals via floating atrial electrodes (VDD) clinically became available in early 1980's but did not gain much popularity due to inconsistent atrial sensing and concerns about the potential need for an atrial lead if sinus node fails. Most ICD patients do not have indications for pacing at implantation and subsequent risk of symptomatic bradycardia seems to be low. The concept of atrial sensing via floating electrodes has recently been revitalized in the Biotronik DX ICD system (Biotronik, SE & Co., Berlin, Germany) aiming to provide all of the potential advantages of available atrial electrograms without the risks and incremental cost of an additional atrial lead. Compared to a traditional VDD pacing system, the DX ICD system uses an optimized (15 mm) atrial dipole spacing and improved atrial signal processing to offer more reliable atrial sensing. The initial experience with the DX system indicates that the clinically useful atrial signal amplitude in sinus rhythm remains stable over time. Future studies are needed to determine reliability of atrial sensing during tachyarrhythmias, particularly atrial fibrillation as well as clinical utility and cost-effectiveness of this technology in different populations of patients.

Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study

AIMS

Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker.

METHODS AND RESULTS

Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms.

CONCLUSION

Early assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov ID NCT02004873.

Successful implantation of a dual-chamber pacemaker in an ELBW infant for long QT syndrome

Long QT syndromes encompass the most prevalent group of ion channelopathies. Long QT syndromes are predominantly familial and predispose the affected individual to ventricular arrhythmias and sudden death. Permanent pacemaker insertion for long QT syndrome is discouraged apart from younger patients exhibiting 2:1 atrioventricular block. However, permanent pacemaker insertion is a relatively common procedure in neonates with atrioventricular block, and dual-chamber permanent pacemaker insertion in low birth weight infants is challenging. We describe the management of long QT syndrome - type 2 - presenting in an extremely preterm neonate including epicardial, dual-chamber permanent pacemaker insertion.

Permanent leadless cardiac pacing: results of the LEADLESS trial

BACKGROUND

Conventional cardiac pacemakers are associated with several potential short- and long-term complications related to either the transvenous lead or subcutaneous pulse generator. We tested the safety and clinical performance of a novel, completely self-contained leadless cardiac pacemaker.

METHODS AND RESULTS

The primary safety end point was freedom from complications at 90 days. Secondary performance end points included implant success rate, implant time, and measures of device performance (pacing/sensing thresholds and rate-responsive performance). The mean age of the patient cohort (n=33) was 77±8 years, and 67% of the patients were male (n=22/33). The most common indication for cardiac pacing was permanent atrial fibrillation with atrioventricular block (n=22, 67%). The implant success rate was 97% (n=32). Five patients (15%) required the use of >1 leadless cardiac pacemaker during the procedure. One patient developed right ventricular perforation and cardiac tamponade during the implant procedure, and eventually died as the result of a stroke. The overall complication-free rate was 94% (31/33). After 3 months of follow-up, the measures of pacing performance (sensing, impedance, and pacing threshold) either improved or were stable within the accepted range.

CONCLUSIONS

In a prospective nonrandomized study, a completely self-contained, single-chamber leadless cardiac pacemaker has shown to be safe and feasible. The absence of a transvenous lead and subcutaneous pulse generator could represent a paradigm shift in cardiac pacing.

CLINICAL TRIAL REGISTRATION URL

http://clinicaltrials.gov. Unique identifier: NCT01700244.

Mechanical dyssynchrony precedes QRS widening in ATP-sensitive K⁺ channel-deficient dilated cardiomyopathy

Background

Contractile discordance exacerbates cardiac dysfunction, aggravating heart failure outcome. Dissecting the genesis of mechanical dyssynchrony would enable an early diagnosis before advanced disease.

Methods and Results

High‐resolution speckle‐tracking echocardiography was applied in a knockout murine surrogate of adult‐onset human cardiomyopathy caused by mutations in cardioprotective ATP‐sensitive K⁺ (K_ATP) channels. Preceding the established criteria of cardiac dyssynchrony, multiparametric speckle‐based strain resolved nascent erosion of dysfunctional regions within cardiomyopathic ventricles of the K_ATP channel–null mutant exposed to hemodynamic stress. Not observed in wild‐type counterparts, intraventricular disparity in wall motion, validated by the degree, direction, and delay of myocardial speckle patterns, unmasked the disease substrate from asymptomatic to overt heart failure. Mechanical dyssynchrony preceded widening of the QRS complex and exercise intolerance and progressed into global myocardial discoordination and decompensated cardiac pump function, precipitating a low output syndrome.

Conclusions

The present study, with the use of high‐resolution imaging, prospectively resolved the origin and extent of intraventricular motion disparity in a K_ATP channel–knockout model of dilated cardiomyopathy. Mechanical dyssynchrony established as an early marker of cardiomyopathic disease offers novel insight into the pathodynamics of dyssynchronous heart failure.