Prevalence of markers of atrial cardiomyopathy in embolic stroke of undetermined source: A systematic review

BACKGROUND

Emerging evidence suggests the potential role of atrial cardiomyopathy (AC) as a direct thromboembolic determinant in embolic stroke of undetermined source (ESUS).

OBJECTIVE

We aimed to quantify the prevalence of potential AC markers among ESUS, non-cardioembolic (NCE) and cardioembolic (CE) stroke patients.

METHODS

PubMed and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for publications from inception to October 2021, with duplicate data extraction and risk of bias assessment. The Newcastle-Ottawa assessment scale was used to evaluate study quality.

RESULTS

Among 398 screened studies, 11 observational studies with 2009 ESUS patients (mean age 66.5 years) fulfilled the inclusion criteria. Of electrocardiographic markers, increased P-wave terminal force in lead V1 was more prevalent in ESUS vs NCE (OR=2.26, 95%CI: 1.40-3.66). Of imaging markers, left atrial volume index (LAVI) and left atrial diameter (LAd) were higher in ESUS vs NCE (OR=1.04, 95%CI: 1.02-1.06 and OR=3.41, 95%CI: 1.35-8.61 respectively). Non-chicken wing morphology of the left atrial appendage was more frequent in ESUS compared to NCE patients in the majority of studies. Of serum biomarkers, the prevalence of NT-proBNP >250 pg/ml did not differ among ESUS vs NCE (OR=0.73, 95%CI: 0.39 -1.35).

CONCLUSIONS

Electrocardiographic, echocardiographic markers and advanced imaging modalities able to assess the morphologic characteristics of left atrial appendage and left atrial function may be important tools to discriminate AC among ESUS vs NCE stroke patients. Prospective studies exploring the association of potential AC markers with ESUS occurrence are warranted to validate their clinical utility.

Atrial CARdiac Magnetic resonance imaging in patients with embolic stroke of unknown source without documented Atrial Fibrillation (CARM-AF): Study design and clinical protocol

Background

Initiation of anticoagulation therapy in ischemic stroke patients is contingent on a clinical diagnosis of atrial fibrillation (AF). Results from previous studies suggest thromboembolic risk may predate clinical manifestations of AF. Early identification of this cohort of patients may allow early initiation of anticoagulation and reduce the risk of secondary stroke.

Objective

This study aims to produce a substrate-based predictive model using cardiac magnetic resonance imaging (CMR) and baseline noninvasive electrocardiographic investigations to improve the identification of patients at risk of future thromboembolism.

Methods

CARM-AF is a prospective, multicenter, observational cohort study. Ninety-two patients will be recruited following an embolic stroke of unknown source (ESUS) and undergo atrial CMR followed by insertion of an implantable loop recorder (ILR) as per routine clinical care within 3 months of index stroke. Remote ILR follow-up will be used to allocate patients to a study or control group determined by the presence or absence of AF as defined by ILR monitoring.

Results

Baseline data collection, noninvasive electrocardiographic data analysis, and imaging postprocessing will be performed at the time of enrollment. Primary analysis will be performed following 12 months of continuous ILR monitoring, with interim and delayed analyses performed at 6 months and 2 and 3 years, respectively.

Conclusion

The CARM-AF Study will use atrial structural and electrocardiographic metrics to identify patients with AF, or at high risk of developing AF, who may benefit from early initiation of anticoagulation.

Atrial High-Rate Episodes Detected by Cardiac Implantable Electronic Devices: Dynamic Changes in Episodes and Predictors of Incident Atrial Fibrillation

Simple Summary

Atrial high rate episodes (AHRE) detected by cardiac implantable electronic devices (CIEDs) may be associated with a risk of progression towards long-lasting episodes (≥24 h) and clinical atrial fibrillation (AF). Identification of this subset of patients is key to promptly starting oral anticoagulant therapy and possibly avoiding stroke and systemic thromboembolism. In the present study, we describe the clinical characteristics of 104 retrospectively enrolled patients with AHRE episodes lasting 5 min–23 h 59 min, no AF at 12-lead ECG, and no history of prior clinical AF. Moreover, we define predictors of the composite outcome of clinical AF and/or AHRE episodes lasting ≥24 h. Over a median follow-up of 24.3 (10.6–40.3) months, 31/104 (29.8%) patients experienced the composite outcome. Baseline CHA₂DS₂-VASc score and the longest AHRE episode at enrollment lasting 12 h–23 h 59 min were independently associated with the composite outcome and with incident clinical AF as well. To conclude, in patients with AHRE, the incidence of clinical AF or AHRE episodes lasting ≥24 h is high. Baseline patients’ characteristics (CHA₂DS₂-VASc score) and AHRE duration may help to intensify monitoring and decision-making, being independently associated with clinical AF in a two-year follow-up.

Abstract

Background. Atrial high rate episodes (AHRE) detected by cardiac implantable electronic devices (CIEDs) may be associated with a risk of progression towards long-lasting episodes (≥24 h) and clinical atrial fibrillation (AF). Methods. Consecutive CIED patients presenting AHRE (with confirmation of an arrhythmia lasting 5 min–23 h 59 min, atrial rate ≥175/min, with no AF at 12-lead ECG and no prior clinical AF) were retrospectively enrolled. The aims of this study were to describe patients’ characteristics and the incidence of adverse events, and second, to identify potential predictors of the composite outcome of clinical AF and/or AHRE episodes lasting ≥24 h. Results. 104/107 (97.2%) patients (median age 79.7 (74.0–84.2), 33.7% female) had available follow-up data. Over a median follow-up of 24.3 (10.6–40.3) months, 31/104 (29.8%) patients experienced the composite outcome of clinical AF or AHRE episodes lasting ≥24 h. Baseline CHA₂DS₂-VASc score and the longest AHRE episode at enrollment lasting 12 h–23 h 59 min were independently associated with the composite outcome (Hazard ratio (HR); 95% CI: 1.40; 1.07–1.83 and HR: 8.15; 95% CI 2.32–28.65, respectively). Baseline CHA₂DS₂-VASc score and the longest AHRE episode at enrollment lasting 12 h–23 h 59 min were the only independent predictors of incident clinical AF (HR: 1.45; 95% CI 1.06–2.00 and HR: 4.25; 95% CI 1.05–17.20, respectively). Conclusions. In patients with AHRE, the incidence of clinical AF or AHRE episodes lasting ≥24 h is high in a two-year follow-up. Baseline patients’ characteristics (CHA₂DS₂-VASc score) and AHRE duration may help to intensify monitoring and decision-making, being independently associated with clinical AF at follow-up.

The Heart Brain Team and Patient-Centered Management of Ischemic Stroke

The multifaceted connections between the heart and the brain have been extensively studied at the anatomy, pathophysiology, and clinical levels. Studies have suggested a vital role for both cardiologists and neurologists in the management of various cardiovascular and neurological disorders. However, a true heart-brain team-based approach remained confined to large, specialized centers. In this paper, we review the various intersection areas of cardiology and neurology with regard to ischemic stroke. We focus our discussion on the challenges and opportunity for a heart-team approach to stroke in the context of atrial fibrillation, carotid disease, and patent foramen ovale, and in the setting of strokes complicating transcatheter endovascular interventions.

Use of Prolonged Cardiac Rhythm Monitoring to Identify Atrial Fibrillation After Cryptogenic Stroke

PURPOSE OF REVIEW

Prolonged cardiac monitoring (PCM) improves detection of atrial fibrillation (AF) after cryptogenic stroke. We summarize current research supporting the use of PCM as part of the cryptogenic stroke evaluation, while highlighting areas that require more investigation.

RECENT FINDINGS

Despite increased AF detection with longer durations of PCM, more definitive research is needed to demonstrate how PCM improves clinical outcomes. The optimal type, timing, and length of cardiac monitoring after cryptogenic stoke remains unknown. Clinical calculators will be important to risk stratify which cryptogenic stroke patients are most likely to benefit from PCM. Currently, AF detection after cryptogenic stroke should prompt consideration of anticoagulation, but it is unclear if all durations and timing of AF after stroke should be treated the same. PCM remains an important part of the cryptogenic stroke work up, and detection of AF allows for anticoagulation initiation. Additional research is needed to further refine our application of PCM to cryptogenic stroke.

Early evaluation of atrial high rate episodes using remote monitoring in pacemaker patients: Results from the RAPID study

Aim

Remote monitoring (RM) of implantable cardiac devices has enabled continuous surveillance of atrial high rate episodes (AHREs) with well‐recognized clinical benefits. We aimed to add evidence on the role of the RM as compared to conventional follow‐up by investigating the interval from AHRE onset to physician’s evaluation and reaction time in actionable episodes.

Methods and Results

A total of 97 dual‐chamber pacemaker recipients were followed with RM (RM‐ON group; N = 64) or conventional in‐office visits (RM‐OFF group; N = 33) for 18 months. In‐office visits were scheduled at 1, 6, 12, and 18 months in the RM‐OFF group and at 1 and 18 months in the RM‐ON group. The overall AHRE rate was 1.98 per patient‐year (95% confidence interval [CI], 1.76–2.20) with no difference between the two groups (RM‐ON vs. RM‐OFF weighted‐HR, 0.88; CI, 0.36–2.13; p = .78). In the RM‐ON group, 100% AHREs evaluated within 11 days from onset, and within 202 days in the RM‐OFF group, with a median evaluation delay 79 days shorter in the RM‐ON group versus the RM‐OFF group (p < .0001). Therapy adjustment in actionable AHREs occurred 77 days earlier in the RM‐ON group versus the control group (p < .001). In the RM‐ON group, there were 50% less in‐office visits as compared to the RM‐OFF group (p < .001).

Conclusions

In our pacemaker population with no history of atrial fibrillation, RM allowed significant reduction of AHRE evaluation delay and prompted treatment of actionable episodes as compared to biannual in‐office visit schedule.

Atrial Fibrillation Detected After Stroke and Transient Ischemic Attack: A Novel Clinical Concept Challenging Current Views

Atrial fibrillation (AF) can be newly detected in approximately one-fourth of patients with ischemic stroke and transient ischemic attack without previously recognized AF. We present updated evidence supporting that AF detected after stroke or transient ischemic attack (AFDAS) may be a distinct clinical entity from AF known before stroke occurrence (known atrial fibrillation). Data suggest that AFDAS can arise from the interplay of cardiogenic and neurogenic forces. The embolic risk of AFDAS can be understood as a gradient defined by the prevalence of vascular comorbidities, the burden of AF, neurogenic autonomic changes, and the severity of atrial cardiopathy. The balance of existing data indicates that AFDAS has a lower prevalence of cardiovascular comorbidities, a lower degree of cardiac abnormalities than known atrial fibrillation, a high proportion (52%) of very brief (<30 seconds) AF paroxysms, and is more frequently associated with insular brain infarction. These distinctive features of AFDAS may explain its recently observed lower associated risk of stroke than known atrial fibrillation. We present an updated ad-hoc meta-analysis of randomized clinical trials in which the association between prolonged cardiac monitoring and reduced risk of ischemic stroke was nonsignificant (incidence rate ratio, 0.90 [95% CI, 0.71-1.15]). These findings highlight that larger and sufficiently powered randomized controlled trials of prolonged cardiac monitoring assessing the risk of stroke recurrence are needed. Meanwhile, we call for further research on AFDAS and stroke recurrence, and a tailored approach when using prolonged cardiac monitoring after ischemic stroke or transient ischemic attack, focusing on patients at higher risk of AFDAS and, more importantly, at higher risk of cardiac embolism.

Direct oral anticoagulation and severe obesity - One size fits all?

Oral anticoagulation is obligatory in patients with atrial fibrillation (AF) to prevent thromboembolic stroke. Direct direct oral anticoagulants (DOAC) exhibit improved safety over Vitamin K antagonists, but any interference in haemostasis can impact on bleeding. Optimal anticoagulation remains challenging particularly in patients with co-morbidities. International Society of Thrombosis and Haemostasis (ISTH) guidelines recommend avoiding DOAC in patients with severe obesity, and systematic data on individual DOAC drug concentrations, clinical efficacy and safety in relation to body weight are lacking. A new study now provides reassurance that DOAC are safe and effective in a real-world cohort of morbidly obese patients, going some way to fill the knowledge gap pertaining to optimal management of concomitant obesity and AF.

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.

Atrial Fibrosis, Ischaemic Stroke and Atrial Fibrillation

Atrial fibrosis is an important component of the arrhythmic substrate in AF. Evidence suggests that atrial fibrosis also plays a role in increasing the risk of stroke in patients with the arrhythmia. Patients with embolic stroke of undetermined source (ESUS), who are suspected to have AF but are rarely shown to have it, frequently demonstrate evidence of atrial fibrosis; measured using late-gadolinium enhancement MRI, this manifests as atrial remodelling encompassing structural, functional and electrical properties. In this review, the authors discuss the available evidence linking atrial disease, including fibrosis, with the risk of ischaemic stroke in AF, as well as in the ESUS population, in whom it has been linked to recurrent stroke and new-onset AF. They also discuss the implications of this association on future research that may elucidate the mechanism of stroke and stroke prevention strategies in the AF and ESUS populations.

Subclinical Atrial Fibrillation: A Silent Threat with Uncertain Implications

Atrial fibrillation (AF) is one of the most common cardiac arrhythmias. Implantable and wearable cardiac devices have enabled the detection of asymptomatic AF episodes-termed subclinical AF (SCAF). SCAF, the prevalence of which is likely significantly underestimated, is associated with increased cardiovascular and all-cause mortality and a significant stroke risk. Recent advances in machine learning, namely artificial intelligence-enabled ECG (AI-ECG), have enabled identification of patients at higher likelihood of SCAF. Leveraging the capabilities of AI-ECG algorithms to drive screening protocols could eventually allow for earlier detection and treatment and help reduce the burden associated with AF. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Atrial High-Rate Episode Duration Thresholds and Thromboembolic Risk: A Systematic Review and Meta-Analysis

Background

Available evidence supports an association between atrial high‐rate episode (AHRE) burden and thromboembolic risk, but the necessary extent and duration of AHREs to increase the thromboembolic risk remain to be defined. The aim of this systematic review and meta‐analysis was to identify the thromboembolic risk associated with various AHRE thresholds.

Methods and Results

We searched PubMed and Scopus until January 9, 2020, for literature reporting AHRE duration and thromboembolic risk in patients with implantable electronic devices. The outcome assessed was stroke or systemic embolism. Risk estimates were reported as hazard ratio (HR) or relative risk alongside 95% CIs. We used the Paule‐Mandel estimator, and heterogeneity was calculated with I² index. Among 27 studies including 61 919 patients, 23 studies reported rates according to the duration of the longest AHRE and 4 studies reported rates according to the cumulative day‐level AHRE duration. In patients with cardiac implantable devices, AHREs lasting ≥30 seconds significantly increased the risk of stroke or systemic embolism (HR, 4.41; 95% CI, 2.32–8.39; I², 5.5%), which remained consistent for the thresholds of 5 minutes and 6 and 24 hours. Patients with previous stroke or transient ischemic attack and AHREs lasting ≥2 minutes had a marginally increased risk of recurrent stroke or transient ischemic attack. The risk of stroke or systemic embolism was higher in patients with cumulative AHRE ≥24 hours compared with those of shorter duration or no AHRE (HR, 1.25; 95% CI, 1.04–1.52; I², 0%).

Conclusions

This systematic review and meta‐analysis suggests that single AHRE episodes ≥30 seconds and cumulative AHRE duration ≥24 hours are associated with increased risk of stroke or systemic embolism.

Embolic Stroke of Undetermined Source: Approaches in Risk Stratification for Cardioembolism

Ischemic stroke is a leading cause of morbidity and mortality worldwide. Embolic stroke of undetermined source has been recently proposed to categorize nonlacunar ischemic strokes without confirmed etiology after adequate investigation with a likely embolic stroke mechanism. A strategy of empirical anticoagulation for embolic stroke of undetermined source patients is attractive but may only be beneficial in a select subset of patients. Strategies which would help identify the subset of embolic stroke of undetermined source patients most likely to have cardioembolic origin of stroke, and hence benefit from anticoagulation, are needed. This article will review current evidence which may be useful in the development of a risk stratification approach based on arrhythmia monitoring, cardiac imaging, and clinical risk stratification. This approach may be beneficial in clinical practice in improving patient outcomes and reducing stroke recurrence in this population; however, further work is required with active trials underway.

A New Vision at the Interface of Atrial Fibrillation and Stroke

Introduction: Current evidence questions the linear sequence traditionally described in atrial fibrillation, blood stasis, intracavitary thrombus, and embolization to the central nervous system. Currently, new perspectives have been described based on questions from the linearly traditional chronology of events; it is within this scope that the article has its objective.

Evidences: The association of the two entities is biologically plausible and supported by different cohorts with a higher risk of developing atrial fibrillation, especially in the cardioembolic form. Concepts (temporal dissociation, biological gradient, etc.) determine the existence of other factors associated with cardioembolism, not exclusively by atrial fibrillation. The entire cascade of events associated with myopathy and atrial remodeling can generate damage to the myocyte and amplify the prothrombotic status. It is important to clarify that atrial myopathy can present itself as atrial fibrillation initially or not, but should always be considered thrombogenic in all the contexts of their clinical presentation. Considering atrial heart disease as a cause of embolic stroke, it could explain that one-third of strokes are considered cryptogenic.

Conclusions: The traditional model exclusively associating the presence of atrial fibrillation in the genesis of thromboembolism is incomplete. The concept of atrial cardiopathy where cardioembolism occurs in a non-atrial fibrillation dependent manner fits better with current data. The future challenge is to effectively detect the various manifestations of atrial heart disease, generating direct implications for the identification of patients at risk of stroke and also for better management after a cardioembolic event.

Characteristics of patients with atrial high rate episodes detected by implanted defibrillator and resynchronization devices

Aims

Atrial high rate episodes (AHREs) are associated with increased risks of thromboembolism and cardiovascular mortality. However, the clinical characteristics of patients developing AHRE of various durations are not well studied.

Methods and results

This was an ancillary analysis of the multicentre, randomized IMPACT trial. In the present analysis, we classified patients according to the duration of AHRE ≤6 min, >6 min to ≤6 h, >6 to ≤24 h and >24 h, and investigated the association between clinical factors and the development of each duration of AHRE. Of 2718 patients included in the trial, 945 (34.8%) developed AHRE. The incidence rates of each AHRE duration category were 5.4/100, 12.0/100, 6.8/100, and 3.3/100 patient-years, respectively. The incidence rates of AHRE >6 h were significantly higher in patients at high risk of thromboembolism (CHADS₂ score ≥3) compared to those at low risk (CHADS₂ score 1 or 2). Using Cox regression analysis, age ≥65 years and history of atrial fibrillation (AF) and/or atrial flutter (AFL) were risk factors for AHRE >6 min. In addition, hypertension was associated with AHRE >24 h (hazard ratio 2.13, 95% confidence interval 1.24–3.65, P = 0.006).

Conclusion

Atrial high rate episode >6 min to ≤6 h were most prevalent among all AHRE duration categories. Longer AHREs were more common in patients at risk of thromboembolism. Age and history of AF/AFL were risk factors for AHRE >6 min. Furthermore, hypertension showed a strong impact on the development of AHRE >24 h rather than age.

Artificial Intelligence-Enabled ECG to Identify Silent Atrial Fibrillation in Embolic Stroke of Unknown Source

OBJECTIVES

Embolic strokes of unknown source (ESUS) are common and often suspected to be caused by unrecognized paroxysmal atrial fibrillation (AF). An AI-enabled ECG (AI-ECG) during sinus rhythm has been shown to identify patients with unrecognized AF. We pursued this study to determine if the AI-ECG model differentiates between patients with ESUS and those with known causes of stroke, and to evaluate whether the AF prediction by AI-ECG among patients with ESUS was associated with the results of prolonged ambulatory cardiac rhythm monitoring.

MATERIALS AND METHODS

We reviewed consecutive patients admitted with acute ischemic stroke to a comprehensive stroke center between January 2018 and August 2019 and employed the TOAST classification to categorize the mechanisms of ischemia. Use and results of ambulatory cardiac rhythm monitoring after discharge were gathered. We ran the AI-ECG model to obtain AF probabilities from all ECGs acquired during the hospitalization and compared those probabilities in patients with ESUS versus those with known stroke causes (apart from AF), and between patients with and without AF detected by ambulatory cardiac rhythm monitoring.

RESULTS

The study cohort had 930 patients, including 263 patients (28.3%) with known AF or AF diagnosed during the index hospitalization and 265 cases (28.5%) categorized as ESUS. Ambulatory cardiac rhythm monitoring was performed in 226 (85.3%) patients with ESUS. AF probability by AI-ECG was not associated with ESUS. However, among patients with ESUS, the probability of AF by AI-ECG was associated with a higher likelihood of AF detection by ambulatory monitoring (P = 0.004). A probability of AF by AI-ECG greater than 0.20 was associated with AF detection by ambulatory cardiac rhythm monitoring with an OR of 5.47 (95% CI 1.51-22.51).

CONCLUSIONS

AI-ECG may help guide the use of prolonged ambulatory cardiac rhythm monitoring in patients with ESUS to identify those who might benefit from anticoagulation.

Secondary Stroke Prevention Following Embolic Stroke of Unknown Source in the Absence of Documented Atrial Fibrillation: A Clinical Review

Approximately one-third of ischemic strokes are classified as cryptogenic strokes. The risk of stroke recurrence in these patients is significantly elevated with up to one-third of patients with cryptogenic stroke experiencing a further stroke within 10 years. While anticoagulation is the mainstay of treatment for secondary stroke prevention in the context of documented atrial fibrillation (AF), it is estimated that up to 25% of patients with cryptogenic stroke have undiagnosed AF. Furthermore, the historical acceptance of a causal relationship between AF and stroke has recently come under scrutiny, with evidence to suggest that embolic stroke risk may be elevated even in the absence of documented atrial fibrillation attributable to the presence of electrical and structural changes constituting an atrial cardiomyopathy. More recently, the term embolic stroke of unknown source has garnered increasing interest as a subset of patients with cryptogenic stroke in whom a minimum set of diagnostic investigations has been performed, and a nonlacunar infarct highly suspicious of embolic etiology is suspected but in the absence of an identifiable secondary cause of stroke. The ongoing ARCADIA (Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke) randomized trial and ATTICUS (Apixiban for Treatment of Embolic Stroke of Undetermined Source) study seek to further define this novel term. This review summarizes the relationship between AF, embolic stroke, and atrial cardiomyopathy and provides an overview of the clinical relevance of cardiac imaging, electrocardiographic, and serum biomarkers in the assessment of AF and secondary stroke risk. The implications of these findings on therapeutic considerations is considered and gaps in the literature identified as areas for future study in risk stratifying this cohort of patients.

Prevalence and predictors of subclinical atrial fibrillation in hospitalized older adults

Subclinical atrial fibrillation (SCAF) is associated with an increased risk of clinical AF, major cardiovascular events and death. Short-term evidence on SCAF in older populations is scarce, especially in the hospital setting. We performed a cross-sectional study on 60 multimorbid older consecutive patients (aged 80+) admitted to an Internal Medicine and Geriatrics Unit for acute medical diseases with no history of AF, in order to investigate prevalence and predictors of SCAF. Portable ECG monitoring was placed on admission and ECG recording lasted for 5 days. Mean age: 85.7±4.9 years. Female prevalence: 58.3%. High burden of comorbidities: 87.9%. All enrolled patients had CHA₂DS₂-VASc score ≥3. SCAF was detected in 16 patients (26.7%) and 11 patients (18.4%) had at least a SCAF episode lasting 6 minutes or longer. No clinical, laboratory and echocardiographic parameters predicted SCAF. Patients with ≥2004 supraventricular ectopic beats/24h (SVEBs/24h) had a 6-fold higher prevalence of SCAF than patients with <411 SVEBs/24h (p=0.038). Time to first SCAF episode was within 3 days of ECG recording in all enrolled patients. SCAF is highly prevalent in older adults hospitalized for acute diseases. This finding may affect clinical management and prognosis. Our study could foster larger multicenter studies in similar settings.

Atrial Fibrillation Burden Detected by Dual-Chamber Pacemakers as a Predictor for Cardiac Outcomes: A Retrospective Single-Center Cohort Study

Background: Atrial fibrillation (AF) might lead to adverse cardiac consequences. The association between AF burden and cardiac prognosis is unknown. Methods and Results: This retrospective cohort study enrolled 204 patients (117 males; age 74.5 ± 11.5 years) who underwent dual-chamber pacemaker implantation in our center from October 2003 to May 2017. During a median follow-up of 66.5 months, AF could be detected in 153 (75%) of the 204 pacemaker patients. Primary endpoint events (composite cardiac readmission, stroke or systemic embolism, and all-cause death) occurred in 83 cases (40.7%). In logistic regression analysis, AF detection was associated with increased risks of composite endpoints [odds ratio (OR) = 2.9, 95% confidence interval (CI): 1.3-6.2, p = 0.007], and the hazard was mainly driven by increased cardiac readmission (OR = 2.2, 95% CI: 1.1-4.7, p = 0.034). No significantly elevated risk for new-onset stroke, systemic embolism, or deaths were found in patients with AF detected than those without AF recorded. AF duration grade of more than 6 min suggested progressively increased composite endpoints (OR = 1.8, 95% CI: 1.2-2.7, p for trend = 0.005), cardiac readmission (OR = 1.8, 95% CI: 1.2-2.7, p for trend = 0.005), especially heart failure or acute coronary syndrome-associated readmission (OR = 1.8, 95% CI: 1.2-2.9, p for trend = 0.010), than those with shorter (<6 min) or no AF episodes. Kaplan-Meier analyses and Cox regression also suggested that episodes of AF more than 6 min predicted future cardiac events. Conclusions: AF detected by pacemakers were common. Higher AF burden predicted more adverse cardiac outcomes and might suggest the intervention of rhythm control in these population.

Echocardiographic predictors of cardioembolic stroke due to underlying atrial fibrillation: Reliable left atrial remodeling signs in acute stroke

INTRODUCTION

Atrial remodeling due to high-burden atrial fibrillation (AF) is associated with cardioembolic stroke (CES). As not all CESs is caused by AF, we analyzed the diagnostic values of each echocardiographic parameter to distinguish likely AF-related CES in acute stroke patients while in non-AF rhythm.

METHODS

The data of consecutive patients with acute ischemic stroke in sinus rhythm between 2012 and 2015 were obtained. The echocardiographic parameters of patients with CES due to underlying AF (n = 61) and control patients (n = 319) with either large artery atherosclerosis or small-vessel occlusion were compared using receiver operating characteristic curves and logistic regression analyses. Each parameter was reassessed in acute stroke patients through a validation study using the same database with different periods of generalization.

RESULTS

CES patients with underlying AF showed a significantly larger left atrial volume index (LAVi), higher mitral inflow E wave (E), and lower A wave (A) than the controls. The area under the curve (AUC) (95% confidence interval) for diagnosing CES due to underlying AF was significantly higher for LAVi/A than for LAVi (0.785 versus 0.696, P < 0.01). Among patients aged >60 years, the E/A ratio had the highest AUC (0.857) of the parameters. The cut-off values were ≥ 0.70 (sensitivity, 55.7%; specificity, 90.9%) and ≥ 0.82 (sensitivity, 71.4%; specificity, 84.1%) for LAVi/A and the E/A ratio, respectively, in patients >60 years. The cut-off values of all parameters showed similar trends in a validation study.

CONCLUSION

LAVi/A is a useful indicator for distinguishing CES patients with underlying AF regardless of age, and the E/A ratio is reliable among patients aged >60 years in evaluation during acute stroke admission.

Atrial cardiopathy in embolic stroke of undetermined source

INTRODUCTION

Atrial cardiopathy is one of the most common potential sources of thromboembolism for embolic stroke of undetermined source (ESUS). The study aims to investigate the incidence of atrial cardiopathy (defined by severe left atrial enlargement (sLAE) or elevated serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) > 250 pg/ml) in patients with ESUS and compare with other stroke subtypes.

METHODS

We retrospectively collected data of 936 consecutive patients with diffusion-weighted imaging-confirmed acute ischemic stroke. The incidence of atrial cardiopathy was examined in ESUS, large artery atherosclerosis (LAA), and small vessel disease (SVD) strokes. Clinical characteristics were compared between ESUS patients with atrial cardiopathy (AC-ESUS) and patients with atrial fibrillation-induced cardioembolism (AF-CE) stroke.

RESULTS

245 patients were diagnosed with ESUS, while others were diagnosed with LAA (n = 312), SVD (n = 258), and AF-CE (n = 121) strokes. The incidence of sLAE in ESUS patients was higher than in LAA or SVD group (5.3% vs. 1.6% and 1.2%, respectively, p = .005) and higher than in combined LAA/SVD group (5.3% vs. 1.4%, p = .001). The incidence of elevated serum NT-proBNP in ESUS patients was not statistically different from that in LAA or SVD group. Compared with patients with AF-CE stroke, AC-ESUS patients had milder manifestations, had less hemorrhagic transformation, had better short-term outcome, and had fewer in-hospital complications.

CONCLUSIONS

The incidence of sLAE was higher in ESUS patients than in patients with noncardioembolic strokes. AC-ESUS was milder when compared to AF-CE stroke.

Atrial fibrillation and atrial cardiomyopathies

Atrial fibrillation (AF) is the most common arrhythmia among adults. While there have been incredible advances in the management of AF and its clinical sequelae, investigation of atrial cardiomyopathies (ACMs) is becoming increasingly more prominent. ACM refers to the electromechanical changes-appreciated subclinically and/or clinically-that underlie atrial dysfunction and create an environment ripe for the development of clinically apparent AF. There are several subtypes of ACM, distinguished by histologic features. Recent progress in cardiovascular imaging, including echocardiography with speckle-tracking (e.g., strain analysis), cardiovascular magnetic resonance imaging (CMR), and atrial 4-D flow CMR, has enabled increased recognition of ACM. Identification of ACM and its features carry clinical implications, including elevating a patient's risk for development of AF, as well as associations with outcomes related to catheter-based and surgical AF ablation. In this review, we explore the definition and classifications of ACM, its complex relationship with clinical AF, imaging modalities, and clinical implications. We propose next steps for a more unified approach to ACM recognition that can direct further research into this complex field.

Anticoagulant therapy in patients with atrial fibrillation and an implanted cardiac resynchronization therapy device

Aim. To study the efficacy and safety of direct oral anticoagulant (DOAC) therapy after implantation of cardiac resynchronization therapy (CRT) devices in atrial fibrillation (AF) patients with coronary artery disease (CAD) and dilated cardiomyopathy (DCM).

Material and methods. The study included 93 patients followed up from 2014 to 2016 (71 men and 22 women) aged 33-85 years (59,7±10,6) with stable CAD (group 1, n=44) and DCM (group 2, n=49). All patients were diagnosed with AF. The left ventricular ejection fraction (LVEF) was 30,6±3,8%; the left ventricular end-diastolic dimension was 230,9±60,8 mm. All patients received anticoagulants for the prevention of thromboembolic events: a vitamin K antagonist (warfarin) or DOAC. The analysis of medical records, as well as ECG records, echocardiographic, 24-hour ECG monitoring data and information from implanted device was carried out. The follow-up period lasted 24 months.

Results. After 24-month follow-up, positive dynamics was noted in all patients — LVEF increased from 30,6±3,7% to 39,5±5,8%). In patients with DCM, a more pronounced increase in myocardial contractile function was noted. Stroke within time interval from 12 to 24 months developed in two patients taking warfarin, from different groups. Transient ischemic attacks were observed in 6 patients: in one patient from group 1 during the period from inclusion and 12-month visit, and in 5 patients from 12 to 24 months. Out of 5 patients, two belonged to group 1 and three — to group 2, while one patient took aspirin and the other 4 — warfarin. One patient from group 1 with persistent AF and vitamin K antagonist therapy had left atrial appendage thrombosis. Hemorrhagic strokes and major bleeding have not been reported.

Conclusion. Among patients taking DOAC, regardless of the underlying disease (CAD or DCM) and response to CRT, bleeding events were less often recorded, and there were no thromboembolic events.

Atrial Conduction Disorders

Atrial conduction disorders result from impaired propagation of cardiac impulses from the sinoatrial node through the atrial conduction pathways. Disorders affecting interatrial conduction alter P-wave characteristics on the surface electrocardiogram. A variety of P-wave indices reflecting derangements in atrial conduction have been described and have been associated with an increased risk of atrial fibrillation (AF) and stroke. Interatrial block (IAB) is the most well-known of the different P-wave indices and is important clinically due to its ability to predict patients who are at risk of the development of AF and other supraventricular tachycardias. P-Wave Axis is a measure of the net direction of atrial depolarization and is determined by calculating the net vector of the P-wave electrical activation in the six limb-leads using the hexaxial reference system. It has been associated with stroke and it has been proposed that this variable be added to the existing CHA2DS2-VASc score to create a P2-CHA2DS2-VASc score to improve stroke prediction. P-Terminal Force in V1 is thought to be an epiphenomenon of advanced atrial fibrotic disease and has been shown to be associated with a higher risk of death, cardiac death, and congestive heart failure as well as an increased risk of AF. P-wave Dispersion is defined as the difference between the shortest and longest P-wave duration recorded on multiple concurrent surface ECG leads on a standard 12-lead ECG and has also been associated with the development of AF and AF recurrence. Pwave voltage in lead I (PVL1) is thought to be an electrocardiographic representation of cardiac conductive properties and, therefore, the extent of atrial fibrosis relative to myocardial mass. Reduced PVL1 has been demonstrated to be associated with new-onset AF in patients with coronary artery disease and may be useful for predicting AF. Recently a risk score (the MVP risk score) has been developed using IAB and PVL1 to predict atrial fibrillation and has shown a good predictive ability to determine patients at high risk of developing atrial fibrillation. The MVP risk score is currently undergoing validation in other populations. This section reviews the different P-wave indices in-depth, reflecting atrial conduction abnormalities.

Association Between Atrial High-Rate Episodes and Ischemic/Major Bleeding Events in Patients With a Cardiac Implantable Electronic Device - A 10-Year, Single-Center Historical Cohort Study

BACKGROUND

An association between atrial high-rate episode (AHRE) and stroke has been reported, although data for the Asian population are limited. This study aimed to investigate the role of AHRE in ischemic and major bleeding events in patients who underwent a cardiac implantable electronic device (CIED) procedure.Methods and Results:This single-center historical cohort study included 710 patients (age: 78±11 years, 374 women) who underwent a CIED-related procedure between October 2009 and September 2019 at Shimane Prefectural Central Hospital (median follow-up period: 4.5 [2.5, 7] years, 3439 person-years). Based on the maximum AHRE burden, patients were divided into: (1) <6 min; (2) ≥6 min to 24-h; and (3) ≥24-h groups. The cumulative incidence of ischemic (ischemic stroke, systemic embolism, and transient ischemic attack) and major bleeding (≥3 Bleeding Academic Research Consortium bleeding criteria) events after the procedure were compared. Uni- and multivariate analyses were performed to identify factors associated with these events. The incidence of both events increased with the rising AHRE burden, being significantly higher in the ≥24-h group than in the <6 min group. Multivariate analysis found age ≥85 years to be the only independent factor associated with both events.

CONCLUSIONS

Longer AHRE duration is associated with a high number of major bleeding and ischemic events. Monitoring these bleeding risks is mandatory when clinicians are considering anticoagulation therapy for such patients.

Alterations in atrial electrogram amplitude as steady sinus rhythm transitions to paroxysmal atrial fibrillation during continuous monitoring in patients with implantable cardiac devices: Insights from the IMPACT study

OBJECTIVES

We aimed to evaluate whether device measured amplitudes of atrial electrogram (AEGM) would change when measured in sinus rhythm (SR) transitioning to paroxysmal atrial fibrillation (AF) from previous steady SR, and significance of such change.

METHODS

From the IMPACT trial's database we selected two groups; (A) those who developed AF (n = 164), and (B) propensity-matched control (n = 459) who stayed in SR during continuous Home Monitoring (HM) to compare AEGMs amplitudes at baseline SR and transition phase.

RESULTS

During 420.0 ± 349.2 days (mean ± SD) from first postenrollment HM transmission to AF event transmission in Group A, and corresponding 515.3 ± 407.0 days in Group B, baseline and transition AEGM amplitude were 2.88 ± 1.146 and 2.74 ± 1.186 mV, respectively, for Group A (p = .1), and 2.88 ± 1.155 and 2.79 ± 1.145, respectively, for Group B (p < .005). Comparison of differences of AEGM amplitude, 0.14 ± 1.072 mV in Group A and 0.09 ± 0.893 mV in Group B were insignificant (p = .3). Age, sex, and hypertension identified as confounders had no association to AEGM changes (p = NS).

CONCLUSIONS

Independent of age, sex, and hypertension, AEGMs amplitudes decline over a long period of time in patients with defibrillators and substrate for AF. The significance of such change remains unclear as it occurs whether patients develop AF or not, but raises a possibility of progressive atrial myopathy that patients with substrate for AF may be predisposed to.

2021 ISHNE/HRS/EHRA/APHRS Expert 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

Supplemental Digital Content is available in the text.

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 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 mobile health. The promises of predictive analytics but also operational challenges in embedding mobile health into routine clinical care are explored.

2021 ISHNE/HRS/EHRA/APHRS Collaborative Statement on mHealth in Arrhythmia Management: Digital Medical Tools for Heart Rhythm Professionals

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.

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.

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.

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.

Association Between Obesity-Mediated Atrial Fibrillation and Therapy With Sodium Channel Blocker Antiarrhythmic Drugs

Importance

The association between obesity, an established risk factor for atrial fibrillation (AF), and response to antiarrhythmic drugs (AADs) remains unclear.

Objective

To test the hypothesis that obesity differentially mediates response to AADs in patients with symptomatic AF and in mice with diet-induced obesity (DIO) and pacing induced AF.

Design, Setting, and Participants

An observational cohort study was conducted including 311 patients enrolled in a clinical-genetic registry. Mice fed a high-fat diet for 10 weeks were also evaluated. The study was conducted from January 1, 2018, to June 2, 2019.

Main Outcomes and Measures

Symptomatic response was defined as continuation of the same AAD for at least 3 months. Nonresponse was defined as discontinuation of the AAD within 3 months of initiation because of poor symptomatic control of AF necessitating alternative rhythm control therapy. Outcome measures in DIO mice were pacing-induced AF and suppression of AF after 2 weeks of treatment with flecainide acetate or sotalol hydrochloride.

Results

A total of 311 patients (mean [SD] age, 65 [12] years; 120 women [38.6%]) met the entry criteria and were treated with a class I or III AAD for symptomatic AF. Nonresponse to class I AADs in patients with obesity was less than in those without obesity (30% [obese] vs 6% [nonobese]; difference, 0.24; 95% CI, 0.11-0.37; P = .001). Both groups had similar symptomatic response to a potassium channel blocker AAD. On multivariate analysis, obesity, AAD class (class I vs III AAD [obese] odds ratio [OR], 4.54; 95% Wald CI, 1.84-11.20; P = .001), female vs male sex (OR, 2.31; 95% Wald CI, 1.07-4.99; P = .03), and hyperthyroidism (OR, 4.95; 95% Wald CI, 1.23-20.00; P = .02) were significant indicators of the probability of failure to respond to AADs. Pacing induced AF in 100% of DIO mice vs 30% (P < .001) in controls. Furthermore, DIO mice showed a greater reduction in AF burden when treated with sotalol compared with flecainide (85% vs 25%; P < .01).

Conclusions and Relevance

Results suggest that obesity differentially mediates response to AADs in patients and in mice with AF, possibly reducing the therapeutic effectiveness of sodium channel blockers. These findings may have implications for the management of AF in patients with obesity.

Remote monitoring and telemedicine in heart failure: implementation and benefits

PURPOSE OF REVIEW

Remote monitoring (RM) of cardiac implantable electronic devices (CIEDs) is recommended as part of the individualized multidisciplinary follow-up of heart failure (HF) patients. Aim of this article is to critically review recent findings on RM, highlighting potential benefits and barriers to its implementation.

RECENT FINDINGS

Device-based RM is useful in the early detection of CIEDs technical issues and cardiac arrhythmias. Moreover, RM allows the continuous monitoring of several patients' clinical parameters associated with impending HF decompensation, but there is still uncertainty regarding its effectiveness in reducing mortality and hospitalizations. Implementation of RM strategies, together with a proactive physicians' attitude towards clinical actions in response to RM data reception, will make RM a more valuable tool, potentially leading to better outcomes.

What do we do about atrial high rate episodes?

Atrial high rate episodes (AHREs) are defined as asymptomatic atrial tachyarrhythmias detected by cardiac implantable electronic devices with atrial sensing, providing automated continuous monitoring and tracings storage, occurring in subjects with no previous clinical atrial fibrillation (AF) and with no AF detected at conventional electrocardiogram recordings. AHREs are associated with an increased thrombo-embolic risk, which is not negligible, although lower than that of clinical AF. The thrombo-embolic risk increases with increasing burden of AHREs, and moreover, AHREs burden shows a dynamic pattern, with tendency to progression along with time, with potential transition to clinical AF. The clinical management of AHREs, in particular with regard to prophylactic treatment with oral anticoagulants (OACs), remains uncertain and heterogeneous. At present, in patients with confirmed AHREs, as a result of device tracing analysis, an integrated, individual and clinically-guided assessment should be applied, taking into account the patients’ risk of stroke (to be reassessed regularly) and the AHREs burden. The use of OACs, preferentially non-vitamin K antagonists OACs, may be justified in selected patients, such as those with longer AHREs durations (in the range of several hours or ≥24 h), with no doubts on AF diagnosis after device tracing analysis and with an estimated high/very high individual risk of stroke, accounting for the anticipated net clinical benefit, and informed patient’s preferences. Two randomized clinical trials on this topic are currently ongoing and are likely to better define the role of anticoagulant therapy in patients with AHREs.

Antiplatelet patterns and outcomes in patients with atrial fibrillation not prescribed an anticoagulant after stroke

BACKGROUND

To determine association of discharge antiplatelet therapy prescription with 1-year outcomes among patients with AF admitted with acute ischemic stroke and discharged without oral anticoagulation.

METHODS

In a retrospective cohort study from the Get With The Guidelines-Stroke registry, we identified all Medicare fee-for-service beneficiaries 65 years or older with AF or atrial flutter admitted with acute ischemic stroke and discharged without oral anticoagulation from April 2003 through December 2014, and we determined association of discharge antiplatelet therapy prescription with 1-year outcomes using Medicare claims data. Primary outcomes were 1-year mortality and composite endpoint of major adverse cardiovascular/neurologic/bleeding events (MACNBE).

RESULTS

Of 64,228 subjects (median [interquartile range] age, 84 [78-89] years; 62.5% female), 54,621 (85.0%) were discharged with antiplatelet therapy, and 9607 (15.0%) were discharged with no antithrombotic therapy. The unadjusted rates of 1-year mortality were lower among patients receiving antiplatelet therapy (37.3%) than among those receiving no antithrombotic therapy (48.1%); unadjusted rates of MACNBE were lower for those receiving antiplatelet therapy (45.5%) compared with those receiving no antithrombotic therapy (55.2%). After adjusting for potential confounders, antiplatelet therapy prescription was associated with reduced 1-year mortality (adjusted hazard ratio [HR] 0.64, 95% confidence interval [CI] 0.62-0.66, P < .001) and MACNBE (adjusted HR 0.69, 95% CI 0.67-0.71, P < .001).

CONCLUSIONS

Among Medicare beneficiaries with AF admitted for acute ischemic stroke but not discharged on oral anticoagulant therapy, antiplatelet therapy, compared with no antithrombotic therapy, was associated with reduced 1-year mortality and MACNBE.

Explainable artificial intelligence to detect atrial fibrillation using electrocardiogram

INTRODUCTION

Early detection and intervention of atrial fibrillation (AF) is a cornerstone for effective treatment and prevention of mortality. Diverse deep learning models (DLMs) have been developed, but they could not be applied in clinical practice owing to their lack of interpretability. We developed an explainable DLM to detect AF using ECG and validated its performance using diverse formats of ECG.

METHODS

We conducted a retrospective study. The Sejong ECG dataset comprising 128,399 ECGs was used to develop and internally validated the explainable DLM. DLM was developed with two feature modules, which could describe the reason for DLM decisions. DLM was external validated using data from 21,837, 10,605, and 8528 ECGs from PTB-XL, Chapman, and PhysioNet non-restricted datasets, respectively. The predictor variables were digitally stored ECGs, and the endpoints were AFs.

RESULTS

During internal and external validation of the DLM, the area under the receiver operating characteristic curves (AUCs) of the DLM using a 12‑lead ECG in detecting AF were 0.997-0.999. The AUCs of the DLM with VAE using a 6‑lead and single‑lead ECG were 0.990-0.999. The AUCs of explainability about features such as rhythm irregularity and absence of P-wave were 0.961-0.993 and 0.983-0.993, respectively.

CONCLUSIONS

Our DLM successfully detected AF using diverse ECGs and described the reason for this decision. The results indicated that an explainable artificial intelligence methodology could be adopted to the DLM using ECG and enhance the transparency of the DLM for its application in clinical practice.

Home Monitoring of Cardiac Devices in the Era of COVID-19

PURPOSE OF REVIEW

Despite the promise of remote patient monitoring (RPM), this technology remained underutilized secondary to a lack of data transparency and systems issues until the COVID-19 pandemic ushered in a new era of telehealth and virtual solutions out of necessity. This review will explore the data supporting the use of RPM via both implantable and wearable devices in the field of cardiology and the role of home monitoring using RPM in the era of COVID-19.

RECENT FINDINGS

RPM using implantable cardiac devices is a safe alternative to in-person only visits which leads to enhanced patient satisfaction and improved clinical outcomes. Consumer-grade wearable sensors have drastically expanded RPM capabilities from just the sickest cardiac patients to the entire population aiding in early diagnosis and real-time disease management. Home monitoring enabled by automated alert systems tailored specifically to the needs of the patient by the provider will be the cornerstone of a more continuous, patent-centric healthcare model.

Atrial fibrillation: villain or bystander in vascular brain injury

Atrial fibrillation (AF) and stroke are inextricably connected, with classical Virchow pathophysiology explaining thromboembolism through blood stasis in the fibrillating left atrium. This conceptualization has been reinforced by the remarkable efficacy of oral anticoagulant (OAC) for stroke prevention in AF. A number of observations showing that the presence of AF is neither necessary nor sufficient for stroke, cast doubt on the causal role of AF as a villain in vascular brain injury (VBI). The requirement for additional risk factors before AF increases stroke risk; temporal disconnect of AF from a stroke in patients with no AF for months before stroke during continuous ECG monitoring but manifesting AF only after stroke; and increasing recognition of the role of atrial cardiomyopathy and atrial substrate in AF-related stroke, and also stroke without AF, have led to rethinking the pathogenetic model of cardioembolic stroke. This is quite separate from recognition that in AF, shared cardiovascular risk factors can lead both to non-embolic stroke, or emboli from the aorta and carotid arteries. Meanwhile, VBI is now expanded to include dementia and cognitive decline: research is required to see if reduced by OAC. A changed conceptual model with less focus on the arrhythmia, and more on atrial substrate/cardiomyopathy causing VBI both in the presence or absence of AF, is required to allow us to better prevent AF-related VBI. It could direct focus towards prevention of the atrial cardiomyopathy though much work is required to better define this entity before the balance between AF as villain or bystander can be determined.

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.