Performance of a New Leadless Implantable Cardiac Monitor in Detecting and Quantifying Atrial Fibrillation Results of the XPECT Trial

2021 ISHNE / HRS / EHRA / APHRS Collaborative Statement on mHealth in Arrhythmia Management: Digital Medical Tools for Heart Rhythm Professionals: From the International Society for Holter and Noninvasive Electrocardiology / Heart Rhythm Society / European Heart Rhythm Association / Asia Pacific Heart Rhythm Society

This collaborative statement from the International Society for Holter and Noninvasive Electrocardiology / Heart Rhythm Society / European Heart Rhythm Association / Asia Pacific Heart Rhythm Society describes the current status of mobile health ("mHealth") technologies in arrhythmia management. The range of digital medical tools and heart rhythm disorders that they may be applied to and clinical decisions that may be enabled are discussed. The facilitation of comorbidity and lifestyle management (increasingly recognized to play a role in heart rhythm disorders) and patient self-management are novel aspects of mHealth. The promises of predictive analytics but also operational challenges in embedding mHealth into routine clinical care are explored.

Leadless and Wireless Cardiac Devices: The Next Frontier in Remote Patient Monitoring

In the last decade, advances in wireless and sensor technologies, and the implementation of telemedicine, have led to innovative digital health care for cardiac patients. Continuous monitoring of patients' biomedical signals, and acute changes in these signals, may result in timely, accurate diagnoses and implementation of early interventions. In this review, we discuss commonly used wireless and leadless cardiac devices including pulmonary artery pressure sensors, implantable loop recorders, leadless pacemakers and subcutaneous implantable cardioverter-defibrillators. We discuss the concept and function of each device, indications, methods of delivery, potential complications, consideration for implantation, and cost-effectiveness.

Atrial Fibrillation in Patients with Embolic Stroke of Undetermined Source during 3 Years of Prolonged Monitoring with an Implantable Loop Recorder

BACKGROUND

 Undocumented atrial fibrillation (AF) is suspected as a main stroke cause in patients with embolic stroke of undetermined source (ESUS), but its prevalence is largely unknown. This prospective study therefore aimed at delineating the prevalence of AF in patients with ESUS using continuous cardiac monitoring by implantable loop recorder (ILR) with daily remote interrogation over a period of 3 years and its clinical consequences, including recurrent stroke.

METHODS

 In consecutive patients with an ESUS diagnosis after complete work-up, an ILR was implanted and followed by daily remote monitoring until AF was detected or a follow-up of at least 3 years was completed. Additionally, the ILR was interrogated in-hospital in 6-month intervals.

RESULTS

 A total of 123 patients (74 male, mean age 65 ± 9 years) were enrolled and completed the 3 years study period. AF was detected in 51 patients (41.4%). In 43 of the 51 AF positive patients (84%) oral anticoagulation was established. Recurrent strokes occurred in 18 patients (14.6%) of this ESUS population, 9 of these patients being AF positive (17.6% of the AF-positive patients) and 9 being AF negative (12.5% of AF-negative patients). Patients with AF were slightly older than patients without AF (63.1 ± 8.8 vs. 67.5 ± 9.6 years, p = 0.12). Other parameters such as CHA₂DS₂-VASc score, infarct localization, micro- and macroangiopathy, carotid or aortic plaques, or stroke recurrence were not significantly different between groups.

CONCLUSION

 In ESUS patients, early implantation of an ILR with cardiac monitoring and remote transmission over a 3-year period detected AF in 41.4% and resulted in oral anticoagulation in 84% of these patients.

The Importance of Arrhythmia Burden for Outcomes and Management Related to Catheter Ablation of Atrial Fibrillation

Atrial fibrillation (AF) ablation has been shown to be an effective treatment for AF, although our understanding of AF ablation outcomes until now, has been based on AF recurrence as a dichotomous variable. Reduction in AF burden, defined as the proportion of time that an individual is in AF during a monitoring period, has been already correlated to an improvement in quality of life and is likely a better assessment of success. Clinically, many patients may still have a few short recurrences of AF but feel much better. In addition, several studies have related higher AF burden with poorer health outcomes and a higher risk of stroke. Despite the growing understanding of AF burden, it is not clear yet which threshold of AF burden would be considered an appropriate outcome measure for AF ablation. Further investigations are needed to address that question. However, the reduction of AF burden seems to be a more accurate reflection of procedural success and a better predictor of prognosis and stroke risk than a single measure of AF.

Cost-effectiveness of an insertable cardiac monitor to detect atrial fibrillation in patients with cryptogenic stroke

Background: We assessed cost-effectiveness of insertable cardiac monitors (ICMs) in a US cryptogenic stroke population. Materials & methods: We modelled lifetime costs and quality-adjusted life years for three monitoring strategies post cryptogenic stroke: ICM starting immediately, ICM starting after Holter monitoring (delayed ICM) and standard of care involving intermittent ECG and Holter monitoring. Patient characteristics and detection efficacy were based on the CRYSTAL-AF trial. AF detection altered the modelled anticoagulation therapy and subsequent stroke and bleed risks. Results & conclusion: Immediate ICM was found to be cost-effective versus standard of care and cost-saving versus delayed ICM. Results were robust to sensitivity analyses. ICMs are a cost-effective diagnostic tool for the prevention of recurrent stroke in a US cryptogenic stroke population.

Recommendations on the utilization of telemedicine in cardiology

The enormous progress made in recent years in the field of information and communication technology and also in sensor and computer technology has affected numerous fields of medicine and is capable of inducing even radical changes in diagnostic and therapeutic processes. This is particularly true for cardiology, where, for example, telemetric monitoring of cardiac and circulatory functions has been in use for many years. Nevertheless, broad application of newer telemedical processes has not yet been achieved to the extent one would expect from the encouraging results of numerous clinical studies in this field and the state of the art of the underlying technology. In the present paper, the Working Group on Rhythmology of the Austrian Cardiological Society aims to provoke a critical discussion of the digital change in cardiology and to make recommendations for the implementation of those telemedical processes that have been shown to exert positive effects on a wide variety of medical and economic parameters. The greatest benefit of telecardiological applications is certainly to be found in the long-term care of patients with chronic cardiovascular diseases. Accordingly, follow-up care of patients with cardiological rhythm implants, management of chronic heart failure and secondary prevention following an acute cardiac event during rehabilitation are currently the most important fields of application. Telemedicine is intended to enable high-quality and cost-efficient care for an increasing number of patients, whose care poses one of the greatest challenges to our healthcare system. Not least of all, telemedicine should make a decisive contribution to improving the quality of life of this segment of the population by favorably influencing mortality, morbidity and hospitalization as well as the patient's contribution to treatment.

Implantable loop recorders can detect paroxysmal atrial fibrillation in Standardbred racehorses with intermittent poor performance

Background

Limited information is available on paroxysmal atrial fibrillation (PAF) in the horse. Indeed, undiagnosed PAF could result in poor performance. Due to the intermittent occurrence, PAF is difficult to diagnose. However, implanting a small ECG device (implantable loop recorder, ILR) subcutaneously, allows the continuous and automatic detection of PAF.

Objectives

The aim was to investigate the potential of ILRs as a tool for diagnosing PAF in horses with poor performance.

Study design

Prospective field study.

Methods

Twelve racing Standardbred trotters with intermittent reduced performance (mean age: six years) were enrolled prospectively. The ILR was implanted subcutaneously at the fifth or sixth left intercostal space and data from the ILR was collected during the study period in which the horses were followed for a median duration of 7.5 month (range 6‐28).

Results

The ILR was able to detect PAF in four out of twelve racehorses. The ILR also detected sustained atrial fibrillation (AF) in one horse during the study. The ILRs rely on RR detection and R waves were correctly identified in 96%. One hundred episodes were categorised as AF by the ILRs and subsequently visual ECG inspection categorised 12 as sinus rhythm (SR), 28 as sinus arrhythmia (SA), 14 as other arrhythmias and 46 as AF episodes. The Root Mean Square of the Successive Differences (RMSSD) values were significantly increased for AF compared to SR and SA.

Main limitations

Few horses included and duration of study period varied among the horses. Further it was not possible to assess the sensitivity of the device in the current study and the ILRs proved to have a high rate of false positive misclassifications.

Conclusions

This study indicates that ILRs can be used for detection of PAF episodes and could be a useful ECG tool for horses presenting with poor performance. This methodology provides a platform to facilitate the long‐term assessment of AF development and quantification of AF burden in horses. Further studies including both healthy and poor performing horses are needed in order to learn more about PAF prevalence in racehorses.

Real-world experience with implantable loop recorder monitoring to detect subclinical atrial fibrillation in patients with cryptogenic stroke: The value of p wave dispersion in predicting arrhythmia occurrence

PURPOSE

We hypothesized patients implanted with ILRs for cryptogenic stroke in "real life" clinical practice will show an AF detection rate comparable to prior clinical studies, and that clinical or imaging features may help to identify those at higher risk of AF detection.

METHODS

A retrospective chart review was conducted of all patients who presented with cryptogenic stroke and received an ILR at an academic medical center from 2015 to 2017 with an active inpatient stroke service. The electronic health record and remote monitoring were used to identify occurrence of AF.

RESULTS

A total of 178 patients who received ILRs for cryptogenic stroke were included. Overall, after a thorough evaluation for other etiologies of stroke, 35 (19.6%) were found to have AF detected. Mean follow-up was 365 days with a median time to detection of 131 days. Advanced age (p = 0.001), diastolic dysfunction on echo (p = 0.03), as well as ECG findings of premature atrial contractions (PACs) and p wave dispersion (PWD) > 40 ms were found to be predictive of AF detection (p = 0.04, p < 0.001, respectively). On multiple regression analysis, the only independent predictor of AF detection was PWD > 40 ms.

CONCLUSION

After a thorough evaluation to exclude other etiologies for stroke, approximately 20% of patients of our cryptogenic stroke population were found to have AF with ILR surveillance. Advanced age, diastolic dysfunction, as well as ECG findings of PACs and increased PWD may help to predict those at higher risk of AF detection, while PWD was the only independent predictor. This has important clinical implications, as better prediction of AF may help identify those at highest risk and might subsequently aid in guiding therapy.

Atrial fibrillation detection by the subcutaneous defibrillator: real-world clinical performances and implications from a multicentre study

AIMS

No data exist concerning the clinical performances of the subcutaneous implantable cardioverter-defibrillator (S-ICD) atrial fibrillation (AF) detection algorithm. We aimed to study the performances and implications of the latter in a 'real-world' setting.

METHODS AND RESULTS

Between July 2017 and August 2019, 155 consecutive S-ICD recipients were included. Endpoint of the study was the incidence of de novo or recurrent AF using a combined on-site and remote-monitoring follow-up approach. After a mean follow-up of 13 ± 8 months, 2531 AF alerts were generated for 55 patients. A blinded analysis of the 1950 subcutaneous electrocardiograms available was performed. Among them 47% were true AF, 23% were premature atrial contractions or non-sustained AF, 29% were premature ventricular contractions or non-sustained ventricular tachycardia, and 1% were misdetection. Fourteen percent (21/155) patients had at least one correct diagnosis of AF by the S-ICD algorithm. One patient presented symptomatic paroxysmal AF not diagnosed by the S-ICD algorithm (false negative patient). Patient-based sensitivity, specificity, positive, and negative predictive values were respectively 95%, 74%, 38%, and 99%. Among patients with at least one correct diagnosis of AF, 38% (8/21) had subsequent clinical implications (anticoagulation initiation or rhythm control therapies).

CONCLUSION

The S-ICD AF detection algorithm yields a high sensitivity for AF diagnosis. Low specificity and positive predictive value contribute to a high remote monitoring-notification workload and underline the necessity of a manual analysis. Atrial fibrillation diagnosis by the S-ICD AF detection algorithm might lead to significant therapeutic adjustments.

Clinical classification and the subclinical atrial fibrillation challenge: a position paper of the European Cardiac Arrhythmia Society

Symptomatic atrial fibrillation (AF) or clinical AF is associated with impaired quality of life, higher risk of stroke, heart failure, and increased mortality. Current clinical classification of AF is based on the duration of AF episodes and the recurrence over time. Appropriate management strategy should follow guidelines of Scientific Societies. The last decades have been marked by the advances in mechanism comprehension, better management of symptomatic AF, particularly regarding stroke prevention with the use of direct oral anticoagulants and a wider use of AF catheter or surgical ablations. The advent of new tools for detection of asymptomatic AF including continuous monitoring with implanted electronic devices and the use of implantable cardiac monitors and recently wearable devices or garments have identified what is called "subclinical AF" encompassing atrial high-rate episodes (AHREs). New concepts such as "AF burden" have resulted in new management challenges. Oral anticoagulation has proven to reduce substantially stroke risk in patients with symptomatic clinical AF but carries the risk of bleeding. Management of detected asymptomatic atrial arrhythmias and their relation to clinical AF and stroke risk is currently under evaluation. Based on a review of recent literature, the validity of current clinical classification has been reassessed and appropriate updates are proposed. Current evidence supporting the inclusion of subclinical AF within current clinical classification is discussed as well as the need for controlled trials which may provide responses to current therapeutic challenges particularly regarding the subsets of asymptomatic AF patients that might benefit from oral anticoagulation.

Integration of novel monitoring devices with machine learning technology for scalable cardiovascular management

Ambulatory monitoring is increasingly important for cardiovascular care but is often limited by the unpredictability of cardiovascular events, the intermittent nature of ambulatory monitors and the variable clinical significance of recorded data in patients. Technological advances in computing have led to the introduction of novel physiological biosignals that can increase the frequency at which abnormalities in cardiovascular parameters can be detected, making expert-level, automated diagnosis a reality. However, use of these biosignals for diagnosis also raises numerous concerns related to accuracy and actionability within clinical guidelines, in addition to medico-legal and ethical issues. Analytical methods such as machine learning can potentially increase the accuracy and improve the actionability of device-based diagnoses. Coupled with interoperability of data to widen access to all stakeholders, seamless connectivity (an internet of things) and maintenance of anonymity, this approach could ultimately facilitate near-real-time diagnosis and therapy. These tools are increasingly recognized by regulatory agencies and professional medical societies, but several technical and ethical issues remain. In this Review, we describe the current state of cardiovascular monitoring along the continuum from biosignal acquisition to the identification of novel biosensors and the development of analytical techniques and ultimately to regulatory and ethical issues. Furthermore, we outline new paradigms for cardiovascular monitoring.

Advances in cardiovascular monitoring technologies have resulted in an influx of consumer-targeted wearable sensors that have the potential to detect numerous heart conditions. In this Review, Krittanawong and colleagues describe processes involved in biosignal acquisition and analysis of cardiovascular monitors, as well as their associated ethical, regulatory and legal challenges.

Advances in the use of cardiovascular monitoring technologies, such as the development of novel portable sensors and machine learning algorithms that can provide near-real-time diagnosis, have the potential to provide personalized care.

Wearable sensor technologies can detect numerous biosignals, such as cardiac output, blood-pressure levels and heart rhythm, and can integrate multiple modalities.

The use of novel biosignals for diagnosis raises concerns regarding accuracy and actionability within clinical guidelines, in addition to medical, legal and ethical issues.

Machine learning-based interpretation of biosensor data can facilitate rapid evaluation of the haemodynamic consequences of heart failure or arrhythmias, but is limited by the presence of noise and training data that might not be representative of the real-world clinical setting.

The use of data derived from cardiovascular monitoring devices is associated with numerous challenges, such as data security, accessibility and ownership, in addition to other ethical and regulatory concerns.

Unsupervised Classification of Atrial Fibrillation Triggers Using Heart Rate Variability Features Extracted from Implantable Cardiac Monitor Data

Catheter ablation is a common treatment of atrial fibrillation (AF), but its success rate is around 60%. It is believed that the success rate can be improved if the procedure were to be guided by the specific AF triggers found in the "Flashback", i.e. the trend of around 500 ventricular beats preceding the AF onset stored in an implantable cardiac monitor (ICM). The need to automatically classify these different triggers: atrial tachycardia (AT), atrial flutter, premature atrial contractions (PAC) or Spontaneous AF has motivated the design in this paper of an unsupervised classification method evaluating statistical and geometrical Heart Rate Variability (HRV) features extracted from the Flashback. From a cohort of 132 patients (57± 12 years, male 67%), 528 Flashbacks were extracted and classified into 5 different clusters after the Principal Component Analysis (PCA) was computed on the HRV features. 2 principal components explained more than 95% of the variance and were a combination of the mean R-R interval, Square root of the mean squared differences of successive R-R intervals (RMSSD), Standard deviation of the R-R intervals (SDNN) and Poincare descriptors, SD1 and SD2. RMSSD and SD1 were significantly different among all clusters (p-value < 0.05, with Holm's correction) showing that distinct patterns can be found using this method.Clinical Relevance-Preliminary step towards ablation strategy guidance using the AF trigger patterns to improve catheter ablation success rates.

Accuracy of arrhythmia detection in implantable cardiac monitors: A prospective randomized clinical trial comparing Reveal LINQ and Confirm Rx

BACKGROUND

Implantable cardiac monitors (ICMs) are increasingly used to detect arrhythmias in various clinical situations. However, the data transmission time and accuracy of detecting cardiac arrhythmias are unclear.

OBJECTIVE

The objective of this study was to compare the efficiency of data transmission and arrhythmia detection accuracy of the Reveal LINQ with TruRhythm Detection with the Confirm Rx with SharpSense Technology.

METHODS

In this prospective study, 142 patients were randomized 1:1 to receive Reveal LINQ or Confirm Rx ICM system. Arrhythmic events include atrial fibrillation (AF), pauses, and bradycardia. Data transmission time is defined as the time from event occurrence to physician notification. All the arrhythmic events are adjudicated for accuracy.

RESULTS

A total of 3510 events were transmitted in 61 patients over 7.1 ± 3.5 months. The transmission time both for all events (448 ± 271 vs 610 ± 515 minutes, P = .02) and for patient activated triggers (24 ± 103 vs 475 ± 426 minutes, P < .0001) was significantly shorter in the Confirm Rx group. The total number of events was also higher in the Confirm Rx group (25.5 ± 45.6 vs 0.9 ± 1.1 events per patient-month, P < .01), which is likely due to event transmission setting differences between the two groups. Kaplan-Meier analysis showed that the Confirm Rx group detected true arrhythmic episodes sooner with higher percentage of diagnosed patients during 6-month follow-up (P = .006). Patient-averaged true positive detection rates were not statistically significant in the two groups (Reveal LINQ vs Confirm Rx, AF: 52% vs 38%; bradycardia: 67% vs 59%; pause: 24% vs 20%; tachycardia: 81% vs 94%).

CONCLUSION

Compared to the Reveal LINQ, Confirm Rx has shorter event transmission time, more frequent event detections, shorter duration to diagnose true arrhythmic events, and higher percentage of diagnosed patients. The accuracy of arrhythmia detection in both ICMs remains suboptimal.

Predictors of atrial fibrillation detection and features of recurrent strokes in patients after cryptogenic stroke

BACKGROUND AND PURPOSE

Use of implantable cardiac monitors (ICMs) has increased diagnosis of atrial fibrillation (AF) in cryptogenic stroke (CS) patients. Identifying AF predictors may enhance the yield of AF detection. Recurrent strokes after CS are not well described. We aimed to assess the predictors for AF detection and the characteristics of recurrent strokes in patients after CS.

METHODS

We reviewed electronic medical records of CS patients who were admitted between February 2014 and September 2017 and underwent ICM placement with minimum one-year follow-up. Patient demographics, stroke characteristics, pre-defined risk factors as well as recurrent strokes were compared between patients with and without AF detection.

RESULTS

389 patients with median follow-up of 548 days were studied. AF was detected in 102 patients (26.2%). Age (per decade increase, OR 2.10, CI 1.64-2.68, with vs. without AF) and left atrium diameter (per 5 mm increase, OR 1.91, CI 1.33-2.74) were identified as AF predictors. Intracranial large vessel stenosis >50% irrelevant to the index strokes was associated with AF detection within 30 days (OR 0.24, CI 0.09-0.69, >30 vs. <30 days). Recurrent strokes occurred in 14% patients with median follow-up about 2.5 years. Topography of these strokes resembled embolic pattern and was comparable between patients with and without AF. Among recurrent strokes in patients with AF, the median time to AF detection was much shorter (90 vs. 251 days), and the median time to first stroke recurrence was much longer (422 vs. 76 days) in patients whose strokes recurred after AF detection than those before AF detection.

CONCLUSIONS

Older age and enlarged left atrium are predictors for AF detection in CS patients. Intracranial atherosclerosis is more prevalent in patients with early AF detection within 30 days. Recurrent strokes follow the embolic pattern, and early AF detection could delay the stroke recurrence.

Over- and undersensing-pitfalls of arrhythmia detection with implantable devices and wearables

Cardiac implantable electronic devices (CIEDs) are a cornerstone of arrhythmia and heart failure detection as well as management. In recent years new kinds of devices have emerged which can be used subcutaneously or worn on the skin. In particular for large-scale arrhythmia monitoring, small, unobtrusive gadgets seem positioned to upend paradigms and care delivery. However, the performance of CIEDs and wearables is only as good as their sensing and detection capacities. Whether for pacing, defibrillation or diagnostic monitoring, the device must be able to process and filter the sensed signal to reduce noise and to exclude irrelevant physiological signals. The demands on sensing and detection quality will differ depending on how the information is applied. With a pacemaker or implantable cardioverter/defibrillator, withheld or erroneous therapy can have severe consequences and accurate and reliable detection of cardiac function is crucial. Monitoring devices are usually used in risk assessment and management, with greater tolerance for isolated artefacts or lower quality of readings. This review discusses sensing and detection and the performance to date by CIEDs as well as subcutaneous and wearable devices.

Antithrombotic Treatment after Atrial Fibrillation Ablation

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Atrial fibrillation is a major cause of debilitating strokes and anticoagulation is an established and indispensable therapy for reducing their rate. Ablation of the arrhythmia has emerged as a putative means of disrupting its natural course by isolating its triggers and modifying its substrate, dependent on the chosen method. An important dilemma lies in the need for continuation of anticoagulation therapy in those previously receiving it following an, apparently, successful intervention, purportedly preventing arrhythmia recurrence with considerably high rates. Current guidance, given scarcity of high-quality data from randomized trials, focuses on established knowledge and recommends anticoagulation continuation based solely on estimated thromboembolic risk. In the present review, it will be attempted to summarize the pathophysiological rationale for maintaining anticoagulation post-successful ablation, along with the latter’s definition, including the two-fold effects of the procedure per se on thrombogenicity. Available evidence pointing to an overall clinical benefit of anticoagulation withdrawal following careful patient assessment will be discussed, including ongoing randomized trials aiming to offer definitive answers. Finally, the proposed mode of post-ablation anticoagulation will be presented, including the emerging, guideline-endorsed, role of direct oral anticoagulants in the field, altering cost/benefit ratio of anticoagulation and potentially affecting the very decision regarding its discontinuation.

Detection of atrial fibrillation with implantable loop recorders in horses

Background

Cardiac arrhythmias in horses are diagnosed by auscultation or electrocardiogram (ECG), which results in a low sensitivity for detecting arrhythmias that occur sporadically. Implantable loop recorders (ILRs) are small ECG devices placed subcutaneously, to automatically detect arrhythmias in human patients.

Objectives

To test ILRs ability to detect atrial fibrillation (AF) in horses. Furthermore, we hypothesised that anatomical location of the implant site might influence signal quality. Signal quality was evaluated both during exercise and over time.

Study design

Experimental study.

Methods

In five Standardbred mares, eleven ILRs were implanted subcutaneously in up to three different positions (Front: pectoral region, Left‐6: sixth left intercostal space and Ventral: xiphoid region) and AF induced. The R‐ and T‐wave amplitudes were measured in all positions over time during AF. AF burden automatically registered by the ILRs over a 2‐month period was compared with selected Holter ECG recordings.

Results

All three positions had stable R‐ and T‐wave amplitudes during the study period and were of sufficient quality to allow AF detection at rest. The position Left‐6 showed significantly higher R‐ and T‐wave amplitudes compared with the other positions. During submaximal exercise only the Left‐6 position was able to record ECG signals of diagnostic quality. No position yielded diagnostic signals at maximum exercise due to artefacts.

Main limitations

Few horses and ILRs included and no spontaneous AF episodes were studied.

Conclusions

This preliminary study indicates that ILRs can be used for AF detection in horses, but the anatomical location is important for optimal ECG quality. Despite insufficient quality during exercise, ILRs were suitable for AF detection at rest. Therefore, the ILR may be a valuable diagnostic tool for detecting paroxysmal AF in horses.

Implantable loop recorders for cardiac dysrhythmia monitoring

Incorporation of technological advances in healthcare delivery has played a foundational role in development of modern healthcare. With the use of wireless transmission in conjunction with digitization of electrocardiography, continuous monitoring strategies have redefined our approach to dysrhythmia. These devices show promising results in evolving implantable loop recorder technology. In this review, we summarize the history of remote monitoring, indications for loop recorders, devices available, evidence for specific devices and anticipated studies.

The Role of Antithrombotic Therapy in Heart Failure

Heart failure is a major contributor to global morbidity and mortality burden affecting approximately 1-2% of adults in developed countries, mounting to over 10% in individuals aged >70 years old. Heart failure is characterized by a prothrombotic state and increased rates of stroke and thromboembolism have been reported in heart failure patients compared with the general population. However, the impact of antithrombotic therapy on heart failure remains controversial. Administration of antiplatelet or anticoagulant therapy is the obvious (and well-established) choice in heart failure patients with cardiovascular comorbidity that necessitates their use, such as coronary artery disease or atrial fibrillation. In contrast, antithrombotic therapy has not demonstrated any clear benefit when administered for heart failure per se, i.e. with heart failure being the sole indication. Randomized studies have reported decreased stroke rates with warfarin use in patients with heart failure with reduced left ventricular ejection fraction, but at the expense of excessive bleeding. Non-vitamin K oral anticoagulants have shown a better safety profile in heart failure patients with atrial fibrillation compared with warfarin, however, current evidence about their role in heart failure with sinus rhythm is inconclusive and further research is needed. In the present review, we discuss the role of antithrombotic therapy in heart failure (beyond coronary artery disease), aiming to summarize evidence regarding the thrombotic risk and the role of antiplatelet and anticoagulant agents in patients with heart failure.

Accuracy of implantable loop recorders for detecting atrial tachyarrhythmias after atrial fibrillation catheter ablation

Background

Implantable loop recorders (ILRs) can provide an enhanced possibility to detect atrial fibrillation (AF), but the accuracy, especially the positive predictive value (PPV), is controversial. This study aimed to evaluate the accuracy of ILRs for detecting AF through a comparison with Holter.

Method and results

Thirteen patients who underwent AF ablation were enrolled. ILRs were implanted in all patients, who were scheduled to have Holter monitorings after the procedure. The incidence of AF was compared between the two modalities and analyzed for any correlations. A total of 51 Holters (67,985.5 min) and concomitant ILRs were available for the comparison. The judgment of the presence of AF did not perfectly correlate between the ILR and Holter (Kappa = 0.866, P < 0.001). In the ILR data, the sensitivity of detecting AF on the Holter was 81.6% (95% confidence interval [CI] 0.812–0.820; P < 0.001). The specificity was 99.9% (95% CI 0.998–0.999; P < 0.001). When the ILR detected AF, the PPV was 99.5% (95% CI 0.994–0.995), but the ILR did not detect AF, and the negative predictive value was 94.2% (95% CI 0.941–0.944). A separate analysis of AF/atrial tachycardia (AT) showed that the AT detection rate of the ILR was 2.3%.

Conclusion

The ILR had a low false positive value and high PPV for AF events. However, it was limited in identifying AT.

Un-LINQed: Spontaneous extrusion of newer generation implantable loop recorders

Background

Insertable cardiac monitors (ICMs) are often used for long-term monitoring of cardiac rhythm. The Medtronic’s LINQ Reveal ™ is a new generation wireless, automated, and patient responsive subcutaneous ECG monitoring device. Despite several advantages to its small size we have noted an unusually high incidence of extrusion at our center.

Methods

& Results: We conducted a retrospective case analysis to review Reveal LINQs implanted at our center. All devices were inserted using the provided insertion tools. Patients with extruded devices were identified and details regarding the site and technique of insertion, incision closure, use of peri-operative antibiotics, and follow-up details were collected. 81 patients underwent 85 Reveal LINQ implants at a tertiary care University Hospital referral center. The most common reason for implant was suspected arrhythmia with or without structural heart disease or unexplained syncope. There were 4 spontaneous extrusions occurring within 7–24 days after insertion with an incidence rate of 4.7%. One extruded device was anchored to subcutaneous tissue, and no pocket/device infections or hematomas were noted.

Conclusions

Device migration and erosion through skin are important potential adverse events for the Reveal LINQ implantable loop recorder. This study reports an unexpectedly high rate of extrusion without infection. The authors suggest that the depth of the incision is the main factor impacting extrusions. Larger studies are recommended, however, and a proposed measure to avoid spontaneous extrusion is the design of a longer manufacturer’s blade in order to increase the depth of the incision and insertion.

Silent atrial fibrillation: clinical management and perspectives

Silent atrial fibrillation (AF) is an asymptomatic atrial arrhythmia that can be diagnosed by chance during a systematic electrocardiogram, an external Holter, or from implanted cardiac devices. There is a significant body of the literature around silent AF, yet it remains largely underdiagnosed in everyday clinical practice. Meanwhile, new diagnostic tools have significantly improved the detection of silent AF, creating a potential for mass screening via new technologies and the promise of a major step forward in e-health progress. However, it is not yet known whether silent AF is associated with the same thromboembolic risk as symptomatic AF, and whether these asymptomatic and often short-lasting episodes therefore require anticoagulation therapy and rhythm management.

Are implantable cardiac monitors reliable tools for cardiac arrhythmias detection? An intra-patient comparison with permanent pacemakers

INTRODUCTION

Implantable cardiac monitor (ICM) is an established tool for the management of unexplained syncope and atrial fibrillation (AF) even if its accuracy of arrhythmia detection may be suboptimal. The aim of this study was to perform an intra-patient comparison of the diagnostic capability of ICM with a dual-chamber PM as a gold standard.

METHODS

We included 19 patients with a previously implanted ICM (BioMonitor 2 Biotronik, Berlin, Germany), who received a dual-chamber PM for standard indications. ICM-detected arrhythmic events in a 6-month follow-up were compared with those detected by the PM and classified by visual inspection of intracardiac electrograms.

RESULTS

During follow up, ICMs generated 15 false asystole and 39 false bradycardia detections in 5 patients (26.3%) due to recurrent premature ventricular contractions. A total of 34 true high ventricular rate (HVR) episodes were detected by the PM. Of them, 30 (88%) events were also recorded by the ICM, which further detected 14 false HVR snapshots, leading to a sensitivity and positive predictive value of 88% and 68%, respectively. In addition, PM identified 234 true AF episodes. Of them, 225 (96%) events were also detected by the ICM, while 8 (42%) ICMs stored 50 AF episodes classified as false positives. The ICM sensitivity for AF was 96% with a positive predictive value of 82%.

CONCLUSION

Our intra-patient comparison with permanent PM confirmed that ICM is an effective tool for cardiac arrhythmias detection. ICM algorithms for AF and HVR detection were highly sensitive with an acceptable rate of false positive episodes.

Detection of Atrial Fibrillation Episodes in Long-Term Heart Rhythm Signals Using a Support Vector Machine

Atrial fibrillation (AF) is a serious heart arrhythmia leading to a significant increase of the risk for occurrence of ischemic stroke. Clinically, the AF episode is recognized in an electrocardiogram. However, detection of asymptomatic AF, which requires a long-term monitoring, is more efficient when based on irregularity of beat-to-beat intervals estimated by the heart rate (HR) features. Automated classification of heartbeats into AF and non-AF by means of the Lagrangian Support Vector Machine has been proposed. The classifier input vector consisted of sixteen features, including four coefficients very sensitive to beat-to-beat heart changes, taken from the fetal heart rate analysis in perinatal medicine. Effectiveness of the proposed classifier has been verified on the MIT-BIH Atrial Fibrillation Database. Designing of the LSVM classifier using very large number of feature vectors requires extreme computational efforts. Therefore, an original approach has been proposed to determine a training set of the smallest possible size that still would guarantee a high quality of AF detection. It enables to obtain satisfactory results using only 1.39% of all heartbeats as the training data. Post-processing stage based on aggregation of classified heartbeats into AF episodes has been applied to provide more reliable information on patient risk. Results obtained during the testing phase showed the sensitivity of 98.94%, positive predictive value of 98.39%, and classification accuracy of 98.86%.

Rhythm monitoring strategies in patients at high risk for atrial fibrillation and stroke: A comparative analysis from the REVEAL AF study

BACKGROUND

Reducing atrial fibrillation (AF)-related stroke requires timely AF diagnosis, but the optimal monitoring strategy is unknown.

OBJECTIVE

We used insertable cardiac monitor (ICM) data from the REVEAL AF study to compare AF detection rates by various short-term continuous monitoring (STM) strategies.

METHODS AND RESULTS

Patients without known AF, but with CHADS₂ scores ≥3 (or = 2 with ≥1 additional AF risk factor) received an ICM for AF detection. One-time STM strategies were assessed by computing AF incidence at 1, 2, 7, 14, and 30 days post-ICM insertion. Repeated STM strategies (quarterly 24-hour, 48-hour, 7-day, or monthly 24-hour monitoring) were modeled by randomly selecting day(s) within a 30-day window around each nominal evaluation date over a 1-year period (simulated 10,000 times). Endpoints included AF ≥6 minutes, AF ≥1 hour, and daily AF burden ≥1 and ≥ 5.5 hours. The impact of compliance on AF detection was evaluated using daily compliance rates of 85%, 75%, 65% and 55% during follow-up months 1-3, 4-6, 7-9, and 9-12, respectively. Based on data from 385 patients (71.5 ± 9.9 years; CHADS₂ score 3.0 ± 1.0) the incidence of AF ≥6 minutes via ICM at 12 months was 27.1% (95% CI, 22.5-31.5%). This exceeded the range of estimated rates from all modeled one-time and repeated STM strategies (0.8% for 24-hour Holter monitoring to 10.6% for quarterly 7-day monitoring). Findings were similar for all AF endpoints. Modeled non-compliance reduced AF detection by 4.5% to 22.9%.

CONCLUSIONS

Most AF episodes detected via ICMs would go undetected via conventional STM strategies, thus preventing optimal prophylaxis for adverse consequences.

Diagnostic value of implantable loop recorder in patients undergoing cryoballoon ablation of atrial fibrillation

BACKGROUND

Due to limited data, implantable loop recorders (ILR) are not currently recommended by the guidelines to routinely monitor patients after atrial fibrillation (AF) ablation.

AIMS

To validate the diagnostic value of ILR after AF ablation, modern generation ILRs (LINQ) were implanted in patients scheduled for cryoballoon ablation of AF (CBA).

METHODS

We included 29 patients with frequent and symptomatic episodes of paroxysmal AF. ILR was implanted 3 months prior to CBA, and data were collected before and for 6 months after the procedure. The device was programmed to maximize sensitivity of AF/ atrial tachycardia (AT) detection. All EGM recordings were "manually" assessed and annotated as true AF, pseudo AF, unrecognized AF, and episodes with no EGM available. Duration and episode-based standard performance metrics were evaluated.

RESULTS

A total number of 5,842 episodes were recorded. A total of 4,403 episodes were true AF, 453 episodes were pseudo AF, and 986 episodes had no EGM available. The device did not recognize 144 episodes of AF. Duration-based sensitivity was 95.2%, duration-based specificity 99.9%, duration-based PPV 99.2%, duration-based NPV 99.9%, episode-based sensitivity 98.0%, and episode-based PPV 91.0%. Misdiagnosis happened in 1 in 10 episodes. Total data review time was 166 hr.

CONCLUSIONS

Implantable loop recorders is a valuable tool in evaluation of AF episodes in patients undergoing CBA. However, for high precision all recorded episodes need to be evaluated "manually." The memory storage space is too low for frequent AF episodes, resulting in overwriting of stored EGMs and data loss.

Smartwatch for the Detection of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia and poses a substantial economic burden due to associated thromboembolic complications. Screening for AF may theoretically be effective, but there is no consensus regarding the optimal screening method because the available tools are either invasive or not cost-effective. Recently, smartwatch industry has received a surge of interest for this purpose by introducing technologies such as photoplethysmography, artificial intelligence, and actual electrodes taking an electrocardiogram to measure and analyze heart rate and rhythm with relatively acceptable accuracy. Combined with other features such as ease of use and connectivity, smartwatches can potentially be used for large-scale AF screening and might eventually replace the current gold standards. In this review, we discuss the feasibility of this approach and summarize the current evidence on AF detection with smartwatches.

Postablation Atrial Fibrillation Burden and Patient Activity Level: Insights From the DISCERN AF Study

Background Recent evidence shows an association between the level of physical activity and cardiovascular mortality and morbidity in patients with atrial fibrillation ( AF ). We sought to assess the impact of AF daily burden on the activity level of the patient who underwent pulmonary vein isolation. Methods and Results Patients enrolled in the DISCERN AF (Discerning Symptomatic and Asymptomatic Episodes Pre and Post Radiofrequency Ablation of Atrial Fibrillation) study all had insertable cardiac monitors, which provided the daily burden of atrial tachycardia and atrial fibrillation ( AT / AF ) and a corresponding activity level. A total of 44 341 daily AT / AF burden points were collected from 50 patients with an average of 887 observations for every patient, with <5 minutes of AT / AF reported on 82.6% of days. The daily burden of AT / AF after ablation ranged between 0 and 1440 minutes. The minimum and maximum daily activity was 0 and 600 minutes per day, respectively. A significant inverse association was detected between activity levels and AF burden ( P<0.001; 95% confidence interval, 0.01-0.04). The daily activity starts progressively decreasing after 500 minutes of AF and considerably drops after 1000 minutes. The association between activity level and burden of AT / AF was still statistically significant after adjustment for clinical variables ( P =0.02; 95% confidence interval, -003 to 0.04). Conclusions Daily activity level correlates with daily AT / AF burden in patients who underwent AF ablation. The daily activity started decreasing after a daily burden of 500 minutes of AF and greatly drops after 1000 minutes. Therefore, the amount of AT / AF burden that may impact the activity level seems to be related to hours and not minutes of arrhythmias. Clinical Trial Registration URL : https://www.clinicaltrials.gov . Unique identifier: NCT 00745706.

Atrial high-rate episodes: prevalence, stroke risk, implications for management, and clinical gaps in evidence

Self-terminating atrial arrhythmias are commonly detected on continuous rhythm monitoring, e.g. by pacemakers or defibrillators. It is unclear whether the presence of these arrhythmias has therapeutic consequences. We sought to summarize evidence on the prevalence of atrial high-rate episodes (AHREs) and their impact on risk of stroke. We performed a comprehensive, tabulated review of published literature on the prevalence of AHRE. In patients with AHRE, but without atrial fibrillation (AF), we reviewed the stroke risk and the potential risk/benefit of oral anticoagulation. Atrial high-rate episodes are found in 10-30% of AF-free patients. Presence of AHRE slightly increases stroke risk (0.8% to 1%/year) compared with patients without AHRE. Atrial high-rate episode of longer duration (e.g. those >24 h) could be associated with a higher stroke risk. Oral anticoagulation has the potential to reduce stroke risk in patients with AHRE but is associated with a rate of major bleeding of 2%/year. Oral anticoagulation is not effective in patients with heart failure or survivors of a stroke without AF. It remains unclear whether anticoagulation is effective and safe in patients with AHRE. Atrial high-rate episodes are common and confer a slight increase in stroke risk. There is true equipoise on the best way to reduce stroke risk in patients with AHRE. Two ongoing trials (NOAH-AFNET 6 and ARTESiA) will provide much-needed information on the effectiveness and safety of oral anticoagulation using non-vitamin K antagonist oral anticoagulants in patients with AHRE.

Adapting detection sensitivity based on evidence of irregular sinus arrhythmia to improve atrial fibrillation detection in insertable cardiac monitors

Aims

Intermittent change in p-wave discernibility during periods of ectopy and sinus arrhythmia is a cause of inappropriate atrial fibrillation (AF) detection in insertable cardiac monitors (ICM). To address this, we developed and validated an enhanced AF detection algorithm.

Methods and results

Atrial fibrillation detection in Reveal LINQ ICM uses patterns of incoherence in RR intervals and absence of P-wave evidence over a 2-min period. The enhanced algorithm includes P-wave evidence during RR irregularity as evidence of sinus arrhythmia or ectopy to adaptively optimize sensitivity for AF detection. The algorithm was developed and validated using Holter data from the XPECT and LINQ Usability studies which collected surface electrocardiogram (ECG) and continuous ICM ECG over a 24–48 h period. The algorithm detections were compared with Holter annotations, performed by multiple reviewers, to compute episode and duration detection performance. The validation dataset comprised of 3187 h of valid Holter and LINQ recordings from 138 patients, with true AF in 37 patients yielding 108 true AF episodes ≥2-min and 449 h of AF. The enhanced algorithm reduced inappropriately detected episodes by 49% and duration by 66% with <1% loss in true episodes or duration. The algorithm correctly identified 98.9% of total AF duration and 99.8% of total sinus or non-AF rhythm duration. The algorithm detected 97.2% (99.7% per-patient average) of all AF episodes ≥2-min, and 84.9% (95.3% per-patient average) of detected episodes involved AF.

Conclusion

An enhancement that adapts sensitivity for AF detection reduced inappropriately detected episodes and duration with minimal reduction in sensitivity.

Continuous monitoring after atrial fibrillation ablation: the LINQ AF study

Aims

To study device performance, arrhythmia recurrence characteristics, and methods of outcome assessment using a novel implantable cardiac monitor (ICM) in patients undergoing ablation for atrial fibrillation (AF).

Methods and results

In 419 consecutive patients undergoing first-time catheter ablation for symptomatic paroxysmal (n = 224) or persistent (n = 195) AF an ICM was injected at the end of the procedure. Telemedicine staff ensured full episode transmission coverage and manually evaluated all automatic arrhythmia episodes. Device detection metrics were calculated for ≥2, ≥6, and ≥10 min AF detection durations. Four methods of outcome assessment were studied: continuous recurrence analysis, discontinuous recurrence analysis, AF-burden analysis, and analysis of individual rhythm profiles. A total of 43 673 automatic AF episodes were transmitted over a follow-up of 15 ± 6 months. Episode-based positive predictive values changed significantly with longer AF detection durations (70.5% for ≥2 min, 81.8% for ≥6 min, and 85.9% for ≥10 min). Patients with exclusive short episode recurrences (≥2 to <6 min) were rare and their arrhythmia detection was clinically irrelevant. Different methods of outcome assessment showed a large variation (46–79%) in ablation success. Individual rhythm characteristics and subclinical AF added to this inconsistency. Analysis of AF-burden and individual rhythm profiles were least influenced and showed successful treatment in 60–70% of the patients.

Conclusion

We suggest AF detection duration >6 min and AF burden >0.1% as a standardized outcome definition for AF studies to come in the future.

Noninvasive long-term ECG monitoring vs. loop recorder implantation for the atrial fibrillation management

OBJECTIVE

The objective of the study was to estimate the efficacy of a noninvasive ambulatory ECG monitoring (NIAM) in comparison with implantable loop recorder (ILR) in patients with atrial fibrillation (AF).

METHODS

Thirty-two patients 58 [47; 73] years of age with AF were included in the study. Patients were randomized into two groups: in group I (n = 15), "Reveal XT" ILR was used for invasive ECG monitoring up to 3 months; in group II (n = 17), "Spyder" device was used for NIAM up to 14 days.

RESULTS

In both groups, at least one AF episode was detected during 14 days of monitoring. The overall count of AF episodes was 25 in NIAM group and 28 in ILR group. The mean time between AF start and its registration by a physician was 8 hr in NIAM group and 20 hr in ILR group (p = .005). The diagnostic value parameters of NIAM were as follows: sensitivity-80.1%, specificity-73.1%; positive predictive value-74.1%; and negative predictive value-79.2%. The same parameters in ILR group were comparable with NIAM: sensitivity-78.6%; specificity-69%; positive predictive value-71%; and negative predictive value-77%. At the same time, continued monitoring with ILR for longer than two weeks did not lead to a significant change in the sensitivity and specificity of the method.

CONCLUSION

In patients with paroxysmal AF, the diagnostic value of both NIAM and ILR is comparable. An increase in the duration of ECG monitoring for longer than two weeks does not provide additional diagnostic information.

Cost-effectiveness of an insertable cardiac monitor in a high-risk population in the UK

Objective

To evaluate the cost-effectiveness of insertable cardiac monitors (ICMs) compared with standard of care (SoC) for detecting atrial fibrillation (AF) in patients at high risk of stroke (CHADS₂ >2), using a UK National Health Service (NHS) perspective.

Methods

Using patient characteristics and clinical data from the REVEAL AF trial, a Markov model assessed the cost-effectiveness of detecting AF with an ICM compared with SoC. Costs and benefits were extrapolated across modelled patient lifetime. Ischaemic and haemorrhagic strokes, intracranial and extracranial haemorrhages and minor bleeds were modelled. Diagnostic and device costs were included, plus costs of treating stroke and bleeding events and costs of oral anticoagulants (OACs). Costs and health outcomes, measured as quality-adjusted life years (QALYs), were discounted at 3.5% per annum. One-way deterministic and probabilistic sensitivity analyses (PSA) were undertaken.

Results

The total per-patient cost for ICM was £13 360 versus £11 936 for SoC (namely, annual 24 hours Holter monitoring). ICMs generated a total of 6.50 QALYs versus 6.30 for SoC. The incremental cost-effectiveness ratio (ICER) was £7140/QALY gained, below the £20 000/QALY acceptability threshold. ICMs were cost-effective in 77.4% of PSA simulations. The number of ICMs needed to prevent one stroke was 21 and to cause a major bleed was 37. ICERs were sensitive to assumed proportions of patients initiating or discontinuing OAC after AF diagnosis, type of OAC used and how intense the traditional monitoring was assumed to be under SoC.

Conclusions

The use of ICMs to identify AF in a high-risk population is cost-effective for the UK NHS.

Clinical evaluation of a small implantable cardiac monitor with a long sensing vector

Introduction

We conducted this study to show the safety and efficacy of a new implantable cardiac monitor (ICM), the BioMonitor 2 (Biotronik SE & Co. KG; Berlin, Germany), and to describe the arrhythmia detection performance.

Methods

The BioMonitor 2 has an extended sensing vector and is implanted close to the heart. It can transmit up to six subcutaneous electrocardiogram strips by Home Monitoring each day. We enrolled 92 patients with a standard device indication for an ICM in a single‐arm, multicenter prospective trial. Patients were followed for 3 months, and 48‐h Holter recordings were used to evaluate the arrhythmia detection performance.

Results

One patient withdrew consent and in one patient, the implantation failed. Two study device‐related serious adverse events were reported, satisfying the primary safety hypothesis. Implantations took 7.4 ± 4.4 min from skin cut to suture. At 1 week, the R‐wave amplitude was 0.75 ± 0.53 mV. In the 82 patients with completed Holter recordings, all patients with arrhythmias were correctly identified. False positive detections of arrhythmia were mostly irregular rhythms wrongly detected as atrial fibrillation (episode‐based positive predictive value 72.5%). Daily Home Monitoring transmission was 94.9% successful.

Conclusion

Safety and efficacy of the new device has been demonstrated. The detected R‐wave amplitudes are large, leading to a low level of inappropriate detections due to over‐ or undersensing.

Incidence of Previously Undiagnosed Atrial Fibrillation Using Insertable Cardiac Monitors in a High-Risk Population: The REVEAL AF Study

Importance

In approximately 20% of atrial fibrillation (AF)-related ischemic strokes, stroke is the first clinical manifestation of AF. Strategies are needed to identify and therapeutically address previously undetected AF.

Objective

To quantify the incidence of AF in patients at high risk for but without previously known AF using an insertable cardiac monitor.

Design, Setting, and Participants

This prospective, single-arm, multicenter study was conducted from November 2012 to January 2017. Visits took place at 57 centers in the United States and Europe. Patients with a CHADS2 score of 3 or greater (or 2 with at least 1 additional risk factor) were enrolled. Approximately 90% had nonspecific symptoms potentially compatible with AF, such as fatigue, dyspnea, and/or palpitations.

Exposures

Patients underwent monitoring with an insertable cardiac monitor for 18 to 30 months.

Main Outcomes and Measures

The primary end point was adjudicated AF lasting 6 or more minutes and was assessed at 18 months. Other analyses included detection rates at points from 30 days to 30 months and among CHADS2 score subgroups. Median time from insertion to detection and the percentage of patients subsequently prescribed oral anticoagulation therapy was also determined.

Results

A total of 446 patients were enrolled; 233 (52.2%) were male, and the mean (SD) age was 71.5 (9.9) years. A total of 385 patients (86.3%) received an insertable cardiac monitor, met the primary analysis cohort definition, and were observed for a mean (SD) period of 22.5 (7.7) months. The detection rate of AF lasting 6 or more minutes at 18 months was 29.3%. Detection rates at 30 days and 6, 12, 24, and 30 months were 6.2%, 20.4%, 27.1%, 33.6%, and 40.0%, respectively. At 18 months, AF incidence was similar among patients with CHADS2 scores of 2 (24.7%; 95% CI, 17.3-31.4), 3 (32.7%; 95% CI, 23.8-40.7), and 4 or greater (31.7%; 95% CI, 22.0-40.3) (P = .23). Median (interquartile) time from device insertion to first AF episode detection was 123 (41-330) days. Of patients meeting the primary end point, 13 (10.2%) had 1 or more episodes lasting 24 hours or longer, and oral anticoagulation therapy was prescribed for 72 patients (56.3%).

Conclusions and Relevance

The incidence of previously undiagnosed AF may be substantial in patients with risk factors for AF and stroke. Atrial fibrillation would have gone undetected in most patients had monitoring been limited to 30 days. Further trials regarding the value of detecting subclinical AF and of prophylactic therapies are warranted.

Trial Registration

clinicaltrials.gov Identifier: NCT01727297.

External continuous ECG versus loop recording for atrial fibrillation detection in patients who had a stroke

BACKGROUND

Detection of atrial fibrillation (AF) in patients who had ischaemic stroke and transient ischaemic attack (IS/TIA) is recommended. We aimed to compare external loop recording (ELR) against simultaneous continuous ECG recording for AF detection in patients who had acute IS/TIA and determine sensitivity, specificity and positive predictive value of AF detection using ELR. We hypothesised ELR to detect 15% fewer patients with AF than continuous ECG recording.

METHODS

In this prospective cohort study, we included 1412 patients who had acute IS/TIA without prior AF. Monitoring was 48 hours. Primary outcome was AF >30 s. Cardiologist verified AF in continuous ECG was gold standard.

RESULTS

In continuous ECG, 38 (2.7%) patients had AF. ELR automatically categorised 219/1412 patients (15.5%) with AF, including 32/38 (85%) patients with AF in continuous ECG. After cardiologist adjudication of ELR recordings, AF was diagnosed in 57/219 patients, of which 32 (56%) had AF in continuous ECG. For adjudicated AF detection by ELR, sensitivity was 84%, 95% CI (69% to 94%), specificity was 98%, 95% CI (97% to 99%) and positive predictive value was 56%, 95% CI (42% to 69%).

CONCLUSION

Automatic AF detection with ELR results in an AF diagnosis in more than five patients without AF for each patient with AF as verified in continuous ECG. For adjudicated AF detection by ELR, sensitivity was confirmed to 84% and specificity 98%. Automatic ELR as investigated in this study may be considered to rule out AF, but it is not suitable as a single monitoring device for AF screening in patients early after stroke.

TRIAL REGISTRATION NUMBER

NCT02155907.

Apical hypertrophic cardiomyopathy with preexcitation presenting as a myocardial infarction and ischemic stroke with a history of recurrent syncope: A case report

Contrast-enhanced echocardiography or cardiac magnetic resonance imaging is of value in the diagnosis of apical hypertrophic cardiomyopathy. Apical hypertrophic cardiomyopathy is rare in Caucasians, and gene negativity does not rule out the diagnosis. Risk stratification for sudden cardiac death and decisions about anticoagulation in cases with atrial fibrillation should be based on guidelines.

Effect of Catheter Ablation vs Antiarrhythmic Medication on Quality of Life in Patients With Atrial Fibrillation: The CAPTAF Randomized Clinical Trial

IMPORTANCE

Quality of life is not a standard primary outcome in ablation trials, even though symptoms drive the indication.

OBJECTIVE

To assess quality of life with catheter ablation vs antiarrhythmic medication at 12 months in patients with atrial fibrillation.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial at 4 university hospitals in Sweden and 1 in Finland of 155 patients aged 30-70 years with more than 6 months of atrial fibrillation and treatment failure with 1 antiarrhythmic drug or β-blocker, with 4-year follow-up. Study dates were July 2008-September 2017. Major exclusions were ejection fraction <35%, left atrial diameter >60 mm, ventricular pacing dependency, and previous ablation.

INTERVENTIONS

Pulmonary vein isolation ablation (n = 79) or previously untested antiarrhythmic drugs (n = 76).

MAIN OUTCOMES AND MEASURES

Primary outcome was the General Health subscale score (Medical Outcomes Study 36-Item Short-Form Health Survey) at baseline and 12 months, assessed unblinded (range, 0 [worst] to 100 [best]). There were 26 secondary outcomes, including atrial fibrillation burden (% of time) from baseline to 12 months, measured by implantable cardiac monitors. The first 3 months were excluded from rhythm analysis.

RESULTS

Among 155 randomized patients (mean age, 56.1 years; 22.6% women), 97% completed the trial. Of 79 patients randomized to receive ablation, 75 underwent ablation, including 2 who crossed over to medication and 14 who underwent repeated ablation procedures. Of 76 patients randomized to receive antiarrhythmic medication, 74 received it, including 8 who crossed over to ablation and 43 for whom the first drug used failed. General Health score increased from 61.8 to 73.9 points in the ablation group vs 62.7 to 65.4 points in the medication group (between-group difference, 8.9 points; 95% CI, 3.1-14.7; P = .003). Of 26 secondary end points, 5 were analyzed; 2 were null and 2 were statistically significant, including decrease in atrial fibrillation burden (from 24.9% to 5.5% in the ablation group vs 23.3% to 11.5% in the medication group; difference -6.8% [95% CI, -12.9% to -0.7%]; P = .03). Of the Health Survey subscales, 5 of 7 improved significantly. Most common adverse events were urosepsis (5.1%) in the ablation group and atrial tachycardia (3.9%) in the medication group.

CONCLUSIONS AND RELEVANCE

Among patients with symptomatic atrial fibrillation despite use of antiarrhythmic medication, the improvement in quality of life at 12 months was greater for those treated with catheter ablation compared with antiarrhythmic medication. Although the study was limited by absence of blinding, catheter ablation may offer an advantage for quality of life.

TRIAL REGISTRATION

clinicaltrialsregister.eu Identifier: 2008-001384-11.

Long-term rhythm monitoring with an implantable loop recorder in patients after the first clinical atrial fibrillation episode. Towards an individualized management

Although atrial fibrillation (AF) is an arrhythmia with a variable clinical profile (symptomatic and asymptomatic episodes), the first symptomatic episode leads to its initial diagnosis in most cases. Nowadays, continuous and remote long-term cardiac rhythm monitoring is feasible by the use of implantable loop recorders. The data concerning the AF recurrences and progression after the first electrocardiographic-documented clinical AF episode demonstrates that a high percentage of patients may not suffer any other AF recurrence, or may present a low recurrence rate of the arrhythmia in the future. The AF burden may play a key role in the management of the arrhythmia as far as the decision-making for anticoagulation, rate and/or rhythm control therapy is concerned. There is evidence that a higher AF burden is associated with a higher risk of ischemic stroke. Non-vitamin K antagonists (NOACs) anticoagulants are increasingly used in the management of AF, providing a more predictable effect with rapid onset and offset of their action. The use of these agents in combination with devices that provide a continuous remote rhythm monitoring capability has encouraged anticoagulation strategies based on the AF burden. Data from tailored anticoagulation studies in AF are in favor of the long-term rhythm monitoring, ensuring a patient-centered approach with a better evaluation and more individualized management of AF, especially in patients with intermediate thromboembolic risk and high bleeding risk. Further large randomized trials are needed, not only to evaluate such strategies but also to elucidate the long-term cardiac rhythm monitoring in the AF management.

Implantable loop recorder in clinical practice

The implantable loop recorder (ILR), also known as insertable cardiac monitor (ICM) is a subcutaneous device used for diagnosing heart rhythm disorders. These devices have been strongly improved and miniaturized during the last years showing several reliable features along with the availability of remote monitoring which improves the diagnostic timing and the follow-up strategy with a potential reduction of costs for health care. The recent advent of injectable ILRs makes the procedure even easier and more tolerated by patients. ILR allows the investigation of unexplained recurrent syncope with uncertain diagnosis, revealing a possible relationship with cardiac arrhythmias. In addition, it has recently been equipped with sophisticated algorithms able to detect atrial fibrillation episodes. This new opportunity may provide to the physicians systematic heart rhythm screening with possible effects on patient antiarrhythmic and anticoagulant therapy management. The use of such devices will surely increase, since they may be helpful to diagnose a wide range of disorders and pathologies. Indeed, further studies should be performed in order to identify all the potentialities of these tools.

Treatment of sleep apnea in patients with paroxysmal atrial fibrillation: design and rationale of a randomized controlled trial

RATIONALE

Atrial fibrillation is associated with increased mortality as well as morbidity. There is strong evidence for an association between atrial fibrillation and sleep apnea. It is not known whether treatment of sleep apnea with continuous positive airway pressure (CPAP) will reduce the burden of atrial fibrillation.

OBJECTIVE

The Treatment of Sleep Apnea in Patients with Paroxysmal Atrial Fibrillation study will investigate the effects of CPAP in patients with paroxysmal atrial fibrillation and sleep apnea.

DESIGN

The trial has a dual center, randomized, controlled, open-label, parallel design.

METHODS

Two centers will enroll a total of 100 patients with both paroxysmal atrial fibrillation and sleep apnea (apnea-hypopnea index [AHI] ≥ 15 events/h) who are scheduled for catheter ablation. Patients will be randomized in a 1:1 ratio to CPAP or control group (50 patients in each arm). The effects of CPAP treatment on atrial fibrillation will be determined using an implanted loop recorder (Reveal LINQ™, Medtronic) that detects all arrhythmia episodes. The primary endpoint is a reduction of the total burden of atrial fibrillation in the intervention group, after 5 months' follow-up (preablation). Reduction in the arrhythmia recurrence rate after ablation is the main secondary endpoint. All patients will be followed up for 12 months after ablation.

CONCLUSION

This study is the first randomized controlled trial that will provide data on the effects of CPAP therapy in patients with paroxysmal atrial fibrillation and sleep apnea. The results are expected to improve our understanding of the interaction between paroxysmal atrial fibrillation and sleep apnea. ClinicalTrials.gov Identifier. NCT02727192.

Relations between baseline burden, maximum duration, and relative reduction of atrial fibrillation: Insights from continuous monitoring in rhythm control

INTRODUCTION

Cardiac implantable electronic devices (CIEDs) can measure atrial fibrillation (AF) early; however, the timing for administering antiarrhythmic drugs (AADs) to suppress AF remains unclear. This study aimed to investigate the association between baseline values and changes after AAD in terms of relative reduction of AF burden (RRAB) and maximum AF duration (RRMD).

METHODS

This multicenter retrospective study screened all patients with nonpermanent AF who had dual-chamber pacemakers and only enrolled those receiving a naive AAD between September 2009 and December 2014. AF burden and maximum duration were calculated using CIED at 0 and 3 to 6 months after starting rhythm control. All the enrolled patients were divided into four groups according to baseline AF burden. RRAB and RRMD were monitored using CIEDs.

RESULTS

Overall, 145 eligible subjects received a naive AAD for nonpermanent AF. The mean RRAB in the four groups (AF burden <1%, 1%-4%, 4%-18%, and ≥18%) were -65.3%, -46.4%, -34.7%, and -27.9% (P = 0.005), respectively. Mean RRMD were -26.8%, -12.4%, 4.2%, and 6.0%, respectively ( P = 0.006). Multivariate analysis revealed that the lowest baseline AF burden (<1%) was significantly associated with greater RRAB, which was not observed in the RRMD model.

CONCLUSIONS

Lower baseline AF burden was associated with greater RRAB by AADs. Our finding suggests that rhythm control should be started in the early stage to achieve better responses to AADs.

2018 Korean Guideline of Atrial Fibrillation Management

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in the general population. The Korean Heart Rhythm Society organized a Korean AF Management Guideline Committee and analyzed all available studies regarding the management of AF, including studies on Korean patients. This guideline is based on recent data of the Korean population and the recent guidelines of the European Society of Cardiology, European Association for Cardio-Thoracic Surgery, American Heart Association, and Asia Pacific Heart Rhythm Society. Expert consensus or guidelines for the optimal management of Korean patients with AF were achieved after a systematic review with intensive discussion. This article provides general principles for appropriate risk stratification and selection of anticoagulation therapy in Korean patients with AF. This guideline deals with optimal stroke prevention, screening, rate and rhythm control, risk factor management, and integrated management of AF.

Incidence and Predictive Factors of Hidden Atrial Fibrillation Detected by Implantable Loop Recorder After an Embolic Stroke of Undetermined Source

Background

The term embolic stroke of undetermined source (ESUS) has been defined for patients with ischemic strokes, where neither a cardioembolic nor a non-cardiac source can be detected. These patients may have asymptomatic episodes of atrial fibrillation (AF). Prolonged monitoring with implantable loop recorder (ILR) and daily remote interrogation in patients after an ESUS has shown an incidence of AF of about 25%.

Aims

The main objective of this study was to analyze the incidence and predictive factors of atrial fibrillation in patients with ESUS who underwent an ILR implantation.

Methods

It was a single center study. From June 2013 to January 2017 all consecutive patients with an ESUS, who underwent an ILR implantation searching for hidden AF, were included. Possible predictive factors of AF were also analyzed.

Results

65 patients were included (mean age 65.4±13.8 years, 55.4% males, mean CHA2DS2VASc score 2.3± 1.5). After a median follow-up of 17.1±10.7 months, AF was detected in 19 (29.2%) of patients. Variables associated with AF were: age > 65 years (HR 9.45 (CI 95% 1.25-71.34); p= 0.02), CHA2DS2VASC score≥2 (HR 4.09 (CI 95% 0.93-17.87); p=0,06), left atrial enlargement (HR 2.29 (CI 95% 0.89-5.91); p=0.08) and presence of Supraventricular premature complex(SVC) on 24-hour Holter (HR 4.05 (CI 95% 1.55-10.57); p = 0.004) A cut-point of 0.15% for SVC was identified to predict AF with a sensitivity and specificity of 88.9 and 90%, respectively. A CHA2DS2VASc score<2 and age<65 years showed a negative predictive value to exclude AF of 91.3% and 96%, respectively.

Conclusion

A high incidence of AF was detected in this population. Age >65 years, LA enlargement, CHA2DS2VASC score≥2 and presence of SVC on 24-hour Holter are predictive factors of AF in patients with ESUS.