Incidence of Atrial Tachyarrhythmias in Pacemaker Patients: Results from the Balanced Evaluation of Atrial Tachyarrhythmias in Stimulated Patients (BEATS) Study

Long-term risk of cardiovascular implantable electronic device reinterventions following external cardioversion of atrial fibrillation and flutter: A nationwide cohort study

BACKGROUND

External cardioversion (ECV) is an essential part of rhythm control of atrial fibrillation and flutter in patients with and without cardiovascular implantable electronic devices (CIEDs). Long-term follow-up data on ECV-related CIED dysfunctions are limited.

OBJECTIVE

The purpose of this study was to investigate the risk of CIED reintervention following ECV in a nationwide cohort.

METHODS

We identified CIED implants and surgical reinterventions from 2005 to 2021 in the Danish Pacemaker and ICD Register. We included CIED patients undergoing ECV from 2010 to 2019 from the Danish National Patient Registry. For each ECV-exposed generator, 5 matched generators without ECV were identified, and for each ECV-exposed lead, 3 matched leads were identified. The primary endpoints were generator replacement and lead reintervention.

RESULTS

We compared 2582 ECV-exposed patients with 12,910 matched patients with a pacemaker (47%), implantable cardioverter-defibrillator (ICD) (29%), cardiac resynchronization therapy-pacemaker (6%), or cardiac resynchronization therapy-defibrillator (18%). During 2 years of follow-up, 210 ECV-exposed generators (8.1%) vs 670 matched generators (5.2%) underwent replacements, and 247 ECV-exposed leads (5.6%) vs 306 matched leads (2.3%) underwent reintervention. Unadjusted hazard ratios were 1.61 (95% confidence interval [CI] 1.37-1.91; P <.001) for generator replacement and 2.39 (95% CI 2.01-2.85; P <.001) for lead reintervention. One-year relative risks were 1.73 (95% CI 1.41-2.12; P <.001) for generator replacement and 2.85 (95% CI 2.32-3.51; P <.001) for lead reintervention, and 2-year relative risks were 1.39 (95% CI 1.19-1.63; P <.001) and 2.18 (95% CI 1.84-2.57; P <.001), respectively.

CONCLUSION

ECV in patients with a CIED is associated with a higher risk of generator replacement and lead reintervention. The risks of reinterventions were more pronounced within the first year after cardioversion.

External cardioversion of atrial fibrillation and flutter in patients with cardiac implantable electrical devices

BACKGROUND

Atrial fibrillation and flutter are often treated with external electrical cardioversion (ECV) in patients with potentially electrically sensitive cardiovascular implantable electronic devices (CIED). Long-term follow-up data on contemporary CIED undergoing ECV is sparse. The aim is to investigate shock-related complications and impact on CIEDs.

METHODS

All ECV procedures from 2010 to 2020 in patients with CIED performed at a tertiary university hospital were identified in the Danish National Patient Registry. Changes in device measurements after ECV were retrospectively studied and procedure-related complications were identified by review of medical records.

RESULTS

We analyzed 763 ECV procedures in 372 patients, median device implant time 1.9 years. The mean age of patients was 69.9 ± 9.9 years of which 73.4% were men. We identified two cases of device programming changes and four cases of premature battery depletion (≤3 years after device implant). Minor changes in device measurements were found for impedances, sensing, and pacing thresholds. No patients died due to ECV-related device dysfunctions within the first 12 months after cardioversions.

CONCLUSION

External cardioversion in patients with contemporary pacemakers and implantable cardioverter-defibrillators seems safe in the majority of patients. Clinically important changes in device function following cardioversion were rarely observed but may be critical for device function. In an observational study, causality between cardioversion and device dysfunction cannot be established. For patient safety, we suggest that routine device interrogation after cardioversion still should be part of standard care.

What to do with device-detected atrial high-rate episodes: Summary of the evidences

Cardiac implanted electronic devices (CIEDs), that perform atrial sensing via an atrial electrode, commonly detect self-terminating atrial arrhythmias. Nomenclature of these arrhythmias is defined as atrial high-rate episodes (AHREs) and subclinical atrial fibrillation (SCAF). We have provided a comprehensive summation of the trials regarding the incidence and adverse outcomes of AHREs. The reported incidence of AHRE varies considerably (approximately 10% to %70) between studies depending on the definition of AHRE, duration of follow-up and the clinical profile of the population. There is increasing evidence related with the association between AHREs' and stroke and/or systemic embolism. However, risk of stroke and/or systemic embolism seems to be less than the risk associated with clinical AF. There is still lack of sufficient evidence related with oral anticoagulation (OAC) in patients with AHRE to reduce thromboembolic risk. Although, the strongest association of OAC treatment with reduction in stroke has been reported to be observed among patients with device detected SCAF episodes of >24 hours; it is still questionable whether AHRE is a direct cause of thromboembolic event or just a marker of increased risk. Results of ongoing randomized clinical trials (NOAH-AFNET 6 and ARTESIA) will provide robust evidence on effect of OAC therapy on AHREs. This article is protected by copyright. All rights reserved.

[Pifalls in the interpretation of pacemaker ECGs]

The analysis of the pacemaker ECG is usually regarded as difficult and may generate rather mediocre interpretations. It is a common opinion that a pacemaker ECG can only be analyzed if the type of pacemaker (single-, dual-, triple-chamber, manufacturer, model) and its programming are known. The following pitfalls illustrate how to achieve a clinically meaningful ECG interpretation in daily practice, even if these details are not known. A systematic approach to ECG interpretation is particularly crucial in this context: Basic rhythm (P waves, intrinsic or paced rhythm), paced QRS complex (axis, width, bundle branch block morphology), signs of pacemaker malfunction (under‑/oversensing, loss of capture), arrhythmia to which the pacemaker reacts, or activity of any pacemaker algorithm. Many small details should not be overlooked and many questions can be answered if a few principles are applied. Understanding of the pacemaker ECG can improve the life of a device patient at the touch of a button.

Pacemaker detected prolonged atrial high rate episodes - Incidence, predictors and implications; a retrospective observational study

Introduction

Atrial tachyarrhythmias especially atrial fibrillation are the most commonly encountered arrhythmias in clinical practice. Most atrial tachyarrhythmia episodes are subclinical. Cardiac implantable electronic devices with atrial sensing function enable detection of atrial tachyarrhythmias through means of atrial high rate event algorithms. Prolonged atrial high rate episodes(AHRE) above a defined rate and duration threshold represent episodes of atrial fibrillation, atrial flutter, and longer atrial tachycardias that correlate strongly with risk for thromboembolic events.

Objective

1. To examine the occurrence of prolonged AHRE in dual-chamber pacemaker recipients over the study period. 2. To examine the factors which influence the occurrence of prolonged AHRE in these patients.

Methods

In this study, we analyzed data of 398 patients without valvular heart disease or history of atrial fibrillation who underwent dual chamber permanent pacemaker implantation at our center from January 2013 to June 2018. Patient demographics, cardiovascular comorbidities, medications, echocardiographic parameters such as ejection fraction and left atrial(LA) dimension were obtained. Also, we collected pacing characteristics such as paced QRS duration(QRSd), ventricular pacing site and cumulative percentage ventricular paced beats.

Results

Prolonged AHRE occurred in 59 patients(14.8%). Baseline LA dimension was greater in patients with prolonged AHRE(median 35 mm, IQR 33-37 vs median 35 mm, IQR 34-38, P = 0.004) compared to those without. Paced QRSd was significantly longer in patients with prolonged AHRE (median of 147 ms, IQR 139-160 ms vs 140 ms, IQR 132-150 ms; P < 0.001). On multivariable logistic regression, paced QRSd(OR 1.04, 95%CI 1.02-1.06; P = 0.001) and baseline LA dimension(OR 1.14, 95%CI 1.03-1.27; P = 0.01) significantly co-predicted AHRE. On Kaplan Meier analysis, patients with paced QRSd≥142 ms had more likelihood of developing prolonged AHRE during follow up (HR 2.46, CI 1.40-4.3, P = 0.001). After adjusting for baseline values, patients with paced QRSd≥142 ms had significant decline in left ventricular ejection fraction (adjusted mean difference -1.27%; P = 0.02) and significant LA dilation (adjusted mean difference 0.62 mm; P = 0.05).

Conclusion

In our study, paced QRSd and LA dimension were the strongest predictors for prolonged AHRE. The incidence of AHRE may be reduced by achieving the narrowest possible paced QRSd during device implantation.

Risk Assessment of Stroke in Patients with Atrial Fibrillation: Current Shortcomings and Future Directions

Atrial fibrillation is a well-known risk factor for cardioembolic stroke; a number of risk stratification scoring systems have been developed to help differentiate which patients would stand to benefit from anticoagulation. However, these scoring systems cannot be utilized in patients whose atrial fibrillation has not been diagnosed. As implantable cardiac monitors become more prevalent, it becomes possible to identify occult, subclinical atrial fibrillation. With this data, it is also possible to examine the relationship between episodes of paroxysmal atrial fibrillation and thromboembolism and the total burden of paroxysmal atrial fibrillation and thromboembolic risk. The data gleaned from these devices provides insight and raises questions regarding the underlying mechanism of thromboembolism in atrial fibrillation, and in doing so, exposes shortcomings in the present clinical use of current risk scoring systems, specifically, the inability to account for atrial fibrillation burden and to apply scores at all in subclinical atrial fibrillation.

Subclinical atrial fibrillation - what is the risk of stroke?

Atrial fibrillation is the most common arrhythmia and as such, it has become a significant public health issue due to its impact on patient morbidity and mortality. The prevalence of atrial fibrillation (AF) almost doubled in the last decade, being currently 2% in unselected patient populations. Its occurrence varies with age (present in almost 20% of octogenarians) and concomitant diseases. The most prevalent concomitant diseases are hypertension, diabetes, heart failure, renal failure, and cognitive decline. Cognitive decline or stroke may be actually the first manifestation of undiagnosed atrial fibrillation. In the majority of cases, atrial fibrillation is more of a syndrome than a disease in itself, with a multitude of etiologic factors and mechanisms. The risk of cardioembolic stroke increases with the number of comorbidities and age. The overall age-adjusted risk of stroke in patients with atrial fibrillation is 5 times higher than in the general population. Nowadays, the detection of asymptomatic episodes of atrial fibrillation by cardiac electronic implantable devices (CIED), referred to as device detected or subclinical atrial fibrillation, has opened new frontiers in AF management. The risk of stroke and subsequent need for anticoagulation treatment in this group of patients with device detected AF is however not clear. Here, we will review the literature to determine the association of subclinical atrial fibrillation with the risk of stroke.

Role of cardiac electronic implantable device in the stratification and management of embolic risk of silent atrial fibrillation: are all atrial fibrillations created equal?

INTRODUCTION

Ischemic strokes may be associated with atrial fibrillation (AF). AF detection is critical in ischemic stroke survivors, often recommending a switch from antiplatelet therapy to oral anticoagulants for secondary prevention. Areas covered: Cardiac implantable electronic devices (CIED) with their long-term recording capability allows to document AF and to quantify the arrhythmia burden. Recent series in pacemaker and implantable cardioverter-defibrillator (ICD) recipients with no prior stroke showed that short episodes of AF increased stroke risk compared with those without AF recorded. Detection of AF by CIEDs represent a unique opportunity for promp prevention of embolic risk in silent AF. It will be attractive to identify AF before a stroke occurs. Expert commentary: The purpose of this article is to review the role of CIED to detect AF, to quantify the role of AF burden, and to guide primary and secondary stroke prevention.

Electrical cardioversion of patients with implanted pacemaker or cardioverter-defibrillator: results of a survey of german centers and systematic review of the literature

AIMS

A relevant number of patients presenting for electrical cardioversion carry a pacemaker (PM) or ICD. Case reports suggest a potential hazard of external cardioversion/defibrillation. The incidence of shock related device complications is unknown. No guidelines or recommendations by international medical societies for a cardioversion protocol of cardiovascular implantable electronic device (CIED) patients exist. We conducted a nationwide survey to gather real-world clinical data on the current clinical approach towards these patients during electrical cardioversion and to estimate the incidence of shock-related complications.

METHODS AND RESULTS

Ninety hospitals with > 380 ECV in 2014 were identified from mandatory hospital quality reports and 60 were randomly selected. All centers were provided with a standardized questionnaire on the general proceedings and complications during electrical cardioversion of pacemaker, ICD and CRT patients (CIED patients). Thirty-two centers (53%) participated in the survey. In total, 16,554 ECV were reported (534 ± 314 per center). Biphasic cardioversion with a first shock energy of ≥ 150 J via adhesive patches in antero-posterior orientation was preferred by most centers (78%). Eleven percent (n = 1809) of pts were reported to carry a PM/ICD. The ECV protocol was heterogeneous among centers. Complications associated with electrical cardioversion were reported in 11/1809 patients (0.6%), all were transitory elevations of pacing thresholds.

CONCLUSIONS

In this nationwide snapshot survey of cardioversion procedures in Germany, approximately 11% of patients presenting for elective electrical cardioversion were pacemaker or ICD carriers. Cardioversion protocols in these patients are heterogeneous throughout centers and mostly not in accordance with recommendation of the German Cardiac Society. Complications associated with external electrical cardioversion are rare. Controlled trials and large registries are necessary to provide evidence for future recommendations.

Clinical Implications of Brief Device-Detected Atrial Tachyarrhythmias in a Cardiac Rhythm Management Device Population

Background:

The RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) is a prospective, outcomes-oriented registry designed to document the prevalence of atrial tachycardia and/or fibrillation (AT/AF) of any duration in patients with pacemakers and implantable cardioverter defibrillators (ICDs) and evaluate associations between rigorously adjudicated AT/AF and predefined clinical events, including stroke. The appropriate clinical response to brief episodes of AT/AF remains unclear.

Methods:

Rigorously adjudicated electrogram (EGM) data were correlated with adjudicated clinical events with logistic regression and Cox models. Long episodes of AT/AF were defined as episodes in which the onset and/or offset of AT/AF was not present within a single EGM recording. Short episodes of AT/AF were defined as episodes in which both the onset and offset of AT/AF were present within a single EGM recording.

Results:

We enrolled 5379 patients with pacemakers (N=3141) or ICDs (N=2238) at 225 US sites (median follow-up 22.9 months). There were 359 deaths. There were 478 hospitalizations among 342 patients for clinical events. We adjudicated 37 531 EGMs; 50% of patients had at least one episode of AT/AF. Patients with clinical events were more likely than those without to have long AT/AF (31.9% vs. 22.1% for pacemaker patients and 28.7% vs. 20.2% for ICD patients; P <0.05 for both groups). Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF (5.1% vs. 7.9% for pacemaker patients and 11.5% vs. 10.4% for ICD patients; P =0.21 and 0.66, respectively).

Conclusions:

In the RATE Registry, rigorously adjudicated short episodes of AT/AF, as defined, were not associated with increased risk of clinical events compared with patients without documented AT/AF.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00837798.

Relevance of Monitoring Atrial Fibrillation in Clinical Practice

The monitoring of atrial fibrillation (AF) is performed using a variety of tools, ranging from the conventional Holter electrocardiogram to modern implantable loop recording with remote data exchange. The main clinical areas in AF where monitoring is crucial for decision-making are catheter and surgical ablation, as well as anticoagulation to prevent strokes. Identifying the patient cohort at risk - e.g., those with subclinical silent AF - is a challenge. In addition, the interaction of AF with implanted devices - e.g. AF-triggered inadequate shock therapy - should be the object of continuous monitoring. The prevention of inadequate shock delivery in particular is of major clinical importance.

Usefulness of continuous electrocardiographic monitoring for atrial fibrillation

The problem of early recognition of atrial fibrillation (AF) is greatly aggravated by the often silent nature of the rhythm disturbance. In about 1/3 of patients with this arrhythmia, patients are not aware of the so-called asymptomatic AF. In the past 15 years, the diagnostic data provided by implanted pacemakers and defibrillators have dramatically increased knowledge about silent AF. The unreliability of symptoms to estimate AF burden and to identify patients with and without AF has been pointed out not only by pacemaker trials but also in patients without implanted devices. The technology for continuous monitoring of AF has been largely validated. It is a powerful tool to detect silent paroxysmal AF in patients without previously documented arrhythmic episodes, such as those with cryptogenic stroke or other risk factors. Early diagnosis triggers earlier treatment for primary or secondary stroke prevention. Today, new devices are also available for pure electrocardiographic monitoring, implanted subcutaneously using a minimally invasive technique. In conclusion, this recent and promising technology adds relevant clinical and scientific information to improve risk stratification for stroke and may play an important role in testing and tailoring the therapies for rhythm and rate control.

Current and emerging indications for implantable cardiac monitors

Implantable cardiac monitors (ICMs) continuously monitor the patient's electrocardiogram and perform real-time analysis of the heart rhythm, for up to 36 months. The current clinical use of ICMs involves the evaluation of transitory symptoms of possible arrhythmic origin, such as unexplained syncope and palpitations. Moreover, ICMs can also be used for the evaluation of difficult cases of epilepsy and unexplained falls, though current indications for their application in these sectors are less clearly defined. Finally, the ability of new-generation ICMs to automatically record arrhythmic episodes suggests that these devices could also be used to study asymptomatic arrhythmias, and thus could be proposed for the long-term evaluation of the total (symptomatic and asymptomatic) arrhythmic burden in patients at risk of arrhythmic events. In particular, ICMs may have an emerging role in the management of patients with atrial fibrillation and in those at risk of ventricular arrhythmias.

[Stored electrograms in pacemakers and ICDs]

Stored electrograms (EGMs) represent an important development in pacemaker and ICD therapy. The most important issue in pacemaker EGMs is the confirmation of the detection of atrial tachyarrhythmias, especially atrial fibrillation. In ICD therapy, the discrimination between ventricular and supraventricular tachycardia (i.e., detection of inadequate therapy) is of central interest. Unfortunately, systematic"instructions" for interpreting stored EGMs in systems by different manufacturers are not available and the knowledge on this topic is limited to (too) few experts. The contributions in this issue aim at explaining the interpretation of stored EGMs in systems by different manufacturers, providing an understanding of marker annotations and EGM registrations in clinical examples. With the aim of improving pacemaker and ICD therapy, a broad distribution of knowledge on the usefulness and the practical use of stored EGMs is highly desirable.

Reliability of an external loop recorder for automatic recognition and transtelephonic ECG transmission of atrial fibrillation

In order to test a newly developed algorithm for detecting atrial fibrillation in clinical practice, we carried out parallel recordings using a conventional 24-h electrocardiogram (ECG) monitor and telemonitoring with an external loop recorder. Recordings were made in 24 patients with persistent atrial fibrillation and in another 24 patients with sinus rhythm. Atrial fibrillation was detected immediately in 23 of 24 patients with persistent atrial fibrillation and 20 min after fitting the single-channel loop recorder in the 24th patient (sensitivity 100%). On average, 3.1 false positives (i.e. detection of an episode, including the end or beginning of atrial fibrillation) were transmitted per patient. The sensitivity of the algorithms for automatically detecting bradycardiac and tachycardiac atrial fibrillation was also high. In 12 of 24 patients with sinus rhythm, false-positive tele-ECGs were transmitted. These were caused by supraventricular or ventricular extrasystoles and by sinus arrhythmias or sinoatrial (SA) blocks. The external loop recorder was very effective at detecting paroxysmal atrial fibrillation. Possible indications for the clinical use of this recorder include, in addition to diagnosis, monitoring patients for atrial fibrillation recurrence after cardioversion or catheter ablation.

Registry of Atrial Tachycardia and Atrial Fibrillation Episodes in the cardiac rhythm management device population: the RATE Registry design

Most atrial fibrillation is asymptomatic. In patients with implanted pacemakers and defibrillators, accurate documentation of asymptomatic episodes provides the opportunity to better understand atrial fibrillation burden and its clinical consequences. The Registry of Atrial Tachycardia and Atrial Fibrillation Episodes in the cardiac rhythm management device population (RATE) is designed to follow 5,000 patients with pacemakers, defibrillators, and resynchronization devices for 2 years. Demographic and initial clinical data will be correlated with atrial fibrillation burden and with other outcome measures relating to therapies and adverse events. The hypothesis of the RATE Registry is that there exists a definable burden of atrial fibrillation episodes in the RATE population that will be predictive of important clinical outcomes, including progression from asymptomatic to symptomatic atrial fibrillation (if any) or to sustained atrial fibrillation, heart failure, and risk of stroke.

Stroke in atrial fibrillation: update on pathophysiology, new antithrombotic therapies, and evolution of procedures and devices

Atrial fibrillation (AF) is said to be an epidemic, affecting 1%-1.5% of the population in the developed world. The clinical significance of AF lies predominantly in a 5-fold increased risk of stroke. Strokes associated with AF are usually more severe and confer increased risk of morbidity, mortality, and poor functional outcome. Despite the advent of promising experimental therapies for selected patients with acute stroke, pharmacological primary prevention remains the best approach to reducing the burden of stroke. New antithrombotic drugs include both parenteral agents (e.g. a long-acting factor Xa inhibitor idraparinux) and oral anticoagulants, such as oral factor Xa inhibitors and direct oral thrombin inhibitors (ximelagatran, dabigatran). Ximelagatran had shown significant potential as a possible replacement to warfarin therapy, but has been withdrawn because of potential liver toxicity. Its congener dabigatran appears to have a better safety profile and has recently entered a phase III randomized clinical trial in AF. Oral factor Xa inhibitors (rivaroxaban, apixaban, YM150) inhibit factor Xa directly, without antithrombin III mediation, and may prove to be more potent and safe. Selective inhibitors of specific coagulation factors involved in the initiation and propagation of the coagulation cascade (factor IXa, factor VIIa, circulating tissue factor) are at an early stage of development. Additional new agents with hypothetical, although not yet proven, anticoagulation benefits include nematode anticoagulant peptide (NAPc2), protein C derivatives, and soluble thrombomodulin. A battery of novel mechanical approaches for the prevention of cardioembolic stroke has recently been evaluated, including various models of percutaneous left atrial appendage occluders which block the connection between the left atrium and the left atrial appendage, minimally invasive surgical isolation of the left atrial appendage, and implantation of the carotid filtering devices which divert large emboli from the internal to the external carotid artery, preventing the embolic material from reaching intracranial circulation. Despite recent advances and promising new approaches, prevention of recurrent AF may be one of the best protections against AF-related stroke and may reduce the prevalence of stroke by almost 25%. Improved pharmacological and nonpharmacological rhythm control strategies for AF as well as primary prevention of AF with 'upstream' therapy and risk factor modification are likely to produce a larger effect on the reduction of stroke rates in the general population than will specific interventions.

Pharmacotherapy changes following pacemaker implantation in patients with bradycardia-tachycardia syndrome

The management of bradycardia-tachycardia syndrome (BTS) includes bradycardia and tachyarrhythmia therapy. At present, the treatment for symptomatic bradycardia in BTS patients is permanent cardiac pacing. The pharmacological treatment of atrial tachyarrhythmias comprises of rhythm and rate control, and prevention of thromboembolism. Patients with BTS often require both pacemaker and drug therapy. This article reviews the interactions of pacing and drug therapies in BTS. Drugs that alter cardiac electrophysiological properties may influence pacemaker indications, pacing mode selection, efficacy of pacing algorithms and pacing performance. Pacing by preventing drug-induced bradycardia increases the safety of pharmacotherapy and, thus, allows the intensification of those treatments. Pacing therapy and antiarrhythmic drugs used together as a hybrid therapy have a synergistic effect in the prevention of atrial tachyarrhythmias. Atrial-based pacing may reduce atrial tachyarrhythmia burden, allowing reduction of rhythm and rate control. Contemporary pacemakers' memory functions may help guide rhythm and rate control, as well as anticoagulation pharmacotherapy.