Clinical Impact of Oral Anticoagulation in Patients with Atrial High-rate Episodes

The influence of atrial high-rate episodes on stroke and cardiovascular death: an update

Atrial high-rate episodes (AHRE) are atrial tachyarrhythmias detected by continuous rhythm monitoring by pacemakers, defibrillators, or implantable cardiac monitors. Atrial high-rate episodes occur in 10-30% of elderly patients without atrial fibrillation. However, it remains unclear whether the presence of these arrhythmias has therapeutic consequences. The presence of AHRE increases the risk of stroke compared with patients without AHRE. Oral anticoagulation would have the potential to reduce the risk of stroke in patients with AHRE but is also associated with a rate of major bleeding of ∼2%/year. The stroke rate in patients with AHRE appears to be lower than the stroke rate in patients with atrial fibrillation. Wearables like smart-watches will increase the absolute number of patients in whom atrial arrhythmias are detected. It remains unclear whether anticoagulation is effective and, equally important, safe in patients with AHRE. Two randomized clinical trials, NOAH-AFNET6 and ARTESiA, are expected to report soon. They will provide much-needed information on the efficacy and safety of oral anticoagulation in patients with AHRE.

How should I treat patients with subclinical atrial fibrillation and atrial high-rate episodes? Current evidence and clinical importance

Long-term and continuous ECG monitoring using cardiac implantable electronic devices and insertable cardiac monitors has improved the capability of detecting subclinical atrial fibrillation (AF) and atrial high-rate episodes. Previous studies demonstrated a high prevalence (more than 20%) in patients with cardiac implantable electronic devices or insertable cardiac monitors. Subclinical AF and atrial high-rate episodes are often suspected as the cause of prior or potential future ischemic stroke. However, the clinical significance is still uncertain, and the evidence is limited. This review aims to present and discuss the current evidence on the clinical impact of subclinical AF and atrial high-rate episodes. It focuses particularly on the association between the duration of the episodes and major clinical outcomes like thromboembolic events. As subclinical AF and atrial high-rate episodes are presumed to be associated with ischemic strokes, detection will be particularly important in patients with cryptogenic stroke and in high-risk patients for thromboembolism. In this context, it is also interesting whether there is a temporal relationship between the detection of subclinical AF and atrial high-rate episodes and the occurrence of thromboembolic events. In addition, the review will examine the question whether there is a need for a therapy with oral anticoagulation.

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 High-Rate Episodes in Patients with Devices Without a History of Atrial Fibrillation: a Systematic Review and Meta-analysis

PURPOSE

Atrial high-rate episodes (AHREs) recorded with cardiac implantable electronic devices (CIEDs) have been associated with the development of clinical atrial fibrillation (AF) and increase in stroke and death risk. We sought to perform a systematic review with a meta-analysis to evaluate the prevalence of AHREs detected by CIEDs, their association with stroke risk, development of clinical AF, and mortality among patients without a documented history of AF.

METHODS

We searched several databases, ClinicalTrials.gov, references of reviews, and meeting abstract books without any language restrictions up to 9 September 2020. We studied patients with CIEDs in whom AHREs were detected. Exclusion criterion was AF history. Our primary outcome was the risk of ischemic stroke in patients with AHREs.

RESULTS

We deemed eligible eight studies for the meta-analysis enrolling a total of 4322 patients with CIED and without a documented AF history. The overall AHRE incidence ratio was estimated to be 17.56 (95% CI, 8.61 to 35.79) cases per 100 person-years. Evidence of moderate certainty suggests that patients with documented AHREs were 4.45 times (95% CI 2.87-6.91) more likely to develop clinical AF. Evidence of low confidence suggests that AHREs were associated with a 1.90-fold increased stroke risk (95% CI 1.19-3.05). AHREs were not associated with a statistically significant increased mortality risk.

CONCLUSION

The present systematic review and meta-analysis demonstrated that among patients without a documented history of AF, the detection of AHREs by CIEDs was associated with significant increased risk of clinical AF and stroke.

REGISTRATION NUMBER (DOI)

Available in https://doi.org/10.17605/OSF.IO/ZRF6M .

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.

Subclinical Atrial Fibrillation Burden and Adverse Clinical Outcomes in Patients With Permanent Pacemakers

BACKGROUND AND PURPOSE

Unlike clinical atrial fibrillation (AF), the significance of subclinical AF (SCAF) burden in patients with permanent pacemakers has not been fully evaluated.

METHODS

We investigated whether the SCAF burden was associated with increased risks of composite adverse outcomes, including progression to clinical AF, ischemic stroke, myocardial infarction, heart failure-related hospitalization, or cardiac death, in patients without previous AF. To quantify the 6-month SCAF burden, the total cumulative time spent in SCAF during every 6-month follow-up was summed.

RESULTS

During the median 5.2-year follow-up, 496 consecutive permanent pacemaker patients were classified into the no SCAF (no SCAF episode in any device analysis; n=152), low-burden SCAF (6-month SCAF <24 hours in at least one device analysis; n=287), or high-burden SCAF (6-month SCAF ≥24 hours in at least 1 device analysis; n=57) groups. The risk of composite adverse outcomes was greatest in the high-burden SCAF group (P<0.001) and was primarily driven by progression to clinical AF (P<0.001) and ischemic stroke (P<0.001). The presence of high-burden SCAF, which always preceded ischemic stroke events, was independently associated with composite adverse outcomes (odds ratio=20.1 [95% CI, 7.60-52.7], P<0.001) and progression to clinical AF (odds ratio, 36.2 [95% CI, 15.9-87.8], P<0.001).

CONCLUSIONS

In permanent pacemaker patients without preexisting AF, the presence of high-burden SCAF was closely associated with increased risks of composite adverse outcomes, particularly progression to clinical AF and ischemic stroke. Therefore, prospective studies deserve to be performed on the optimal anticoagulation therapy for permanent pacemaker patients with both high-burden SCAF and high stroke risk.

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

Introduction

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

Objective

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

Methods

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

Results

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

Conclusion

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