Device-detected Atrial Tachyarrhythmias Research Articles

Optimizing indices of atrial fibrillation susceptibility and burden to evaluate atrial fibrillation severity, risk and outcomes

Atrial fibrillation (AF) has heterogeneous patterns of presentation concerning symptoms, duration of episodes, AF burden, and the tendency to progress towards the terminal step of permanent AF. AF is associated with a risk of stroke/thromboembolism traditionally considered dependent on patient-level risk factors rather than AF type, AF burden, or other characterizations. However, the time spent in AF appears related to an incremental risk of stroke, as suggested by the higher risk of stroke in patients with clinical AF vs. subclinical episodes and in patients with non-paroxysmal AF vs. paroxysmal AF. In patients with device-detected atrial tachyarrhythmias, AF burden is a dynamic process with potential transitions from a lower to a higher maximum daily arrhythmia burden, thus justifying monitoring its temporal evolution. In clinical terms, the appearance of the first episode of AF, the characterization of the arrhythmia in a specific AF type, the progression of AF, and the response to rhythm control therapies, as well as the clinical outcomes, are all conditioned by underlying heart disease, risk factors, and comorbidities. Improved understanding is needed on how to monitor and modulate the effect of factors that condition AF susceptibility and modulate AF-associated outcomes. The increasing use of wearables and apps in practice and clinical research may be useful to predict and quantify AF burden and assess AF susceptibility at the individual patient level. This may help us reveal why AF stops and starts again, or why AF episodes, or burden, cluster. Additionally, whether the distribution of burden is associated with variations in the propensity to thrombosis or other clinical adverse events. Combining the improved methods for data analysis, clinical and translational science could be the basis for the early identification of the subset of patients at risk of progressing to a longer duration/higher burden of AF and the associated adverse outcomes.

Atrial Tachyarrhythmia Prevalence in Patients with Implantable Cardiac Resynchronization Defibrillators

Background Although studied far less extensively than AF, device-detected atrial tachyarrhythmias (AT) have been associated with higher thromboembolism (TE) risk in heart failure (HF) patients. CHA 2 DS 2 -VASc is the gold standard for clinical prediction of TE risk in patients with AF. However, as new research defines the relationship between ATs and TE events, it is increasingly important to understand how traditional cardiovascular health factors correlate with AT prevalence and associated TE risk. Objective The goal of this analysis is to examine the incidence of ATs and TEs in patients with heart failure and identify associations with other cardiovascular health factors. Methods The data set was collected as part of the IMPACT study, a multicenter, randomized trial which utilized daily remote monitoring to identify ATs in subjects implanted with ICDs or CRT-Ds. All subjects had a CHADS 2 risk score greater than or equal to 1. The analysis described herein utilized the IMPACT study data for HF patients implanted with a CRT-D device. NYHA score was assessed by a qualified clinical investigator at enrollment or within 7 days prior. All potential subjects with permanent AF at time of enrollment were excluded. Subjects were considered to have AT during follow-up if maximum daily burden was equal to or exceeded 1% (equal to 14.4 minutes). Results The overall prevalence of AT was 22.6%, with 209 out of 925 CRT-D subjects evaluated over a mean follow up duration of 1.9 years. In comparison, 14.1% of the subjects had a history of atrial tachyarrhythmias prior to enrollment. The study group was 69% male with a mean age of 66 years and left ventricular ejection fraction (LVEF) of 27%. Subjects with AT had a mean of 45 events per study-year and burden of 5.2% over the study duration. In this data set, AT prevalence during follow-up appears to have a strong positive association with NYHA score, with a correlation coefficient of 0.96 ( Figure 1 ). TE events occurred in 20 subjects (2.1%) at a rate of 1.1 event per 100 subject-years. TE event rate was not positively associated with NYHA score (correlation coefficient of -0.73). Conclusion The overall trend between NYHA class and AT prevalence is consistent with results demonstrated in previous research findings which link AF prevalence to HF severity. Additional analysis is required to more fully understand the relationship between NYHA class and AT prevalence for HF subjects with an implanted CRT-D device.

Approach to device-detected subclinical atrial fibrillation

Subclinical atrial fibrillation, a commonly encountered entity in patients with implantable devices, has been associated with a number of adverse outcomes – the most important of which is thromboembolism. Through the detection of atrial high rate episodes, implanted devices offer a method to monitor for atrial fibrillation over extended periods of time. Several studies have demonstrated that patients with device-detected atrial tachyarrhythmias have an increased incidence of stroke, especially in the presence of additional risk factors. Yet, there are many uncertainties with limited evidence from randomised clinical studies and no formal guidelines to inform management in this population. This contributes to marked practice heterogeneity, underrecognition and missed opportunities for stroke prevention. We propose a logical approach to management of patients with device-detected atrial high rate episodes pending additional data from ongoing trials.

Clinical Implications of Brief Device-Detected Atrial Tachyarrhythmias in a Cardiac Rhythm Management Device Population: Results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes.

The RATE Registry (Registry of Atrial Tachycardia and Atrial Fibrillation Episodes) is a prospective, outcomes-oriented registry designed to document the prevalence of atrial tachycardia and/or fibrillation (AT/AF) of any duration in patients with pacemakers and implantable cardioverter defibrillators (ICDs) and evaluate associations between rigorously adjudicated AT/AF and predefined clinical events, including stroke. The appropriate clinical response to brief episodes of AT/AF remains unclear. Rigorously adjudicated electrogram (EGM) data were correlated with adjudicated clinical events with logistic regression and Cox models. Long episodes of AT/AF were defined as episodes in which the onset and/or offset of AT/AF was not present within a single EGM recording. Short episodes of AT/AF were defined as episodes in which both the onset and offset of AT/AF were present within a single EGM recording. We enrolled 5379 patients with pacemakers (N=3141) or ICDs (N=2238) at 225 US sites (median follow-up 22.9 months). There were 359 deaths. There were 478 hospitalizations among 342 patients for clinical events. We adjudicated 37 531 EGMs; 50% of patients had at least one episode of AT/AF. Patients with clinical events were more likely than those without to have long AT/AF (31.9% vs. 22.1% for pacemaker patients and 28.7% vs. 20.2% for ICD patients; P<0.05 for both groups). Only short episodes of AT/AF were documented in 9% of pacemaker patients and 16% of ICD patients. Patients with clinical events were no more likely than those without to have short AT/AF (5.1% vs. 7.9% for pacemaker patients and 11.5% vs. 10.4% for ICD patients; P=0.21 and 0.66, respectively). In the RATE Registry, rigorously adjudicated short episodes of AT/AF, as defined, were not associated with increased risk of clinical events compared with patients without documented AT/AF. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00837798.

Subclinical Atrial Tachyarrhythmias:Implantable Devices and Remote Monitoring.

Atrial fibrillation (AF) and Atrial Tachyarrhythmias (AT) are the most common clinical arrhythmias and their worst issue is a well-recognized correlation with ischemic stroke. High incidence of "subclinical" AF/ATs has been demonstrated in several trials (TRENDS, ASSERT, CRYSTAL AF, EMBRACE) in patients with both cardiac implantable electronic devices (CIEDS) and external loop recorders. Moreover, a relationship between device-detected AF/ATs and stroke risk has been observed in the same studies. However, while the net clinical benefit of the antithrombotic treatment is well established in patients with "clinical" atrial fibrillation, there may be a lower benefit in patients with device-detected arrhythmias. Subclinical AF/ATs may be considered as a marker of stroke risk rather than the proximate cause and their burden may be used in combination with CHA2DS2-VASC and HAS-BLED scores to identify high-risk population who deserves anticoagulation. Today the remote monitoring associated with the CIEDs is effective in the early detecting of AF/ATs by avoiding delays in the therapy evaluation, as demonstrated by several trials (TRUST, CONNECT, COMPAS). However clinical evidence for stroke risk reduction by remote monitoring is still awaited; the recent trial IMPACT failed to demonstrate that the handling of the anticoagulation therapy guided by device-detected ATs and remote monitoring improves the patients' outcome. The challenges for clinicians are to deal with the huge data entry, to define new organizational models, to improve device patient management and to continuously update AF guidelines in according to the great amount of data offered by the new technology.

32 * Development of new-onset atrial tachyarrhythmia and risk of stroke in the implantable cardiac device population

Background: Atrial tachyarrhythmias (ATA) are associated with increased risk of stroke. Implantable cardiac devices (ICDs) can detect and store these arrhythmias. This study investigated the role of stroke risk stratification tools, CHADS2 and CHA2DS2-VASc, in predicting new-onset ATAs in the ICD population. Methods: Retrospective-observational cohort study. Baseline CHADS2 and CHA2DS2-VASc scores were calculated for 158 patients (mean (SD) age 74 (13) years; 63% male) implanted with a cardiac device, between January 2006-December 2009, with no documented ATAs pre-implant. Incidence of device-detected ATAs was recorded within 1-year and >1-year post-implant. Results: During follow up, 50 (31.6%) developed ATAs; 21 (13.3%) within first year. Median (IQR) CHADS2 and CHA2DS2-VASc scores were 2 (2) and 4(2), respectively; no difference in median CHADS2 & CHA2DS2-VASc scores between those who developed ATA and those who did not (p=0.45 and p=0.60, respectively). Cox regression demonstrated that none of the individual stroke risk factors or overall CHADS2 scores [HR (95% CI) 1.13 (0.80-1.46); p 0.33] predicted ATA development, however the CHA2DS2-VASc score appeared to approach significance [HR 1.16 (1.01-1.35); p 0.056]. The overall median time to ATA onset was 337 days. In patients with a CHA2DS2-VASc score=4,5,6 or 7, median time to ATA onset occurred earlier (222, 334, 107 & 94 days, respectively) compared to those with a CHA2DS2-VASc score of 2 or 3 (429 & 951 days, respectively) (Figure). Conclusions: All ICD patients with a CHA2DS2-VASc score ≥ 2 should be followed-up more frequently to identify ATA development and offered effective stroke prevention with oral anticoagulation, where appropriate. ![Graphic][1] Figure Event-free survival from atrial-tachyarrhythmia according to CHA2DS2-VASc score at baseline [1]: /embed/inline-graphic-1.gif

Relevance of Electrical Remodeling in Human Atrial Fibrillation

Background— In animal models of atrial fibrillation (AF), changes in atrial electrophysiological properties are associated with the development of AF. Their relevance to human AF is unclear. Methods and Results— The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial enrolled 2580 patients receiving a dual-chamber pacemaker, who were older than the age of 65 and had a history of hypertension, but no history of AF. Serial noninvasive electrophysiological testing was performed over 2 years in a subgroup of 485 patients. There were no differences in the clinical characteristics between patients with and those without device-detected atrial tachyarrhythmias during the first year. Patients with atrial tachyarrhythmias had longer paced (153±29 versus 145±28 ms; P =0.046) and sensed (128±46 versus 118±25 ms; P =0.06) P-wave durations and were more likely to have AF induced during electrophysiological testing (23.5% versus 13.6%; P =0.03). They had similar corrected sinus node recovery times at 90 bpm (388±554 versus 376 ± 466 ms; P =0.86), atrial effective refractory periods at 90 bpm (250±32 versus 248±36 ms; P =0.70), and rate-adaptive shortening of the atrial effective refractory periods (14±13 versus 12±14 ms; P =0.11). There were no significant differences in the change in electrophysiological properties over 2 years between patients with and those without atrial tachyarrhythmias. Conclusions— Prolonged P-wave duration, but not differences in atrial effective refractory periods, was associated with the development of atrial tachyarrhythmias in pacemaker patients.

Device-detected atrial tachyarrhythmias: what do we know?

This editorial refers to ‘Detection of atrial high-rate events by continuous Home Monitoring: clinical significance in the heart failure–cardiac resynchronization therapy population’ by N. Shanmugam et al. , on page 230 Depending on one's perspective, modern pacemakers and defibrillators provide physicians with a wealth or burden of diagnostic information. Currently, there is great interest in the ability of these devices to monitor thoracic impedance, ST-segments, and other physiological parameters.1,2 However, the ability to document and characterize otherwise undetected atrial tachyarrhythmias, referred to as atrial high-rate episodes (AHRE), has been available for >10 years.3 Despite this familiarity with AHRE, there remains a formidable knowledge gap which stands between physicians and the optimal use of these data for patient care. As paroxysmal atrial fibrillation appears to pose the same risk of stroke as sustained episodes,4 it is tempting to simply assume that AHRE should be managed like conventionally diagnosed atrial fibrillation. However, these otherwise silent atrial tachyarrhythmias may have a significantly different prognosis and the impact of prophylactic oral anticoagulation may be quite different in this population. The ASSERT (A Symptomatic Stroke and atrial fibrillation Evaluation …

The Influence of Symptoms and Device Detected Atrial Tachyarrhythmias on Medical Management: Insights from A‐HIRATE

The influence of symptoms and device-detected atrial tachyarrhythmias (AT) on the management of AT in a pacemaker population has not been well described. We report the influence of symptoms and device detected AT on pharmacological disease management. Group 1 (n = 331) included patients without and Group 2 (n = 96) included patients with prior history of AT with an approved pacemaker indication. Dual chamber pacemakers, (kappa 700 or kappa 900, Medtronic, Minneapolis, MN, USA) were implanted. The impact of symptoms, AT burden, a history of AT, and time since implant on changes in the use of anticoagulation, beta-blockers, and antiarrhythmic drugs was analyzed. A total of 232 patients experienced at least one atrial high rate episode (AHRE). AT burden was higher in Group 2. Symptoms were reported by 154 patients in Group 1 and 47 patients in Group 2. Among patients experiencing AHRE, symptoms were reported in 17 patients in Group 1 (5.3%) and 22 patients in Group 2 (24.7%). Changes in antiarrhythmic drugs and anticoagulation were influenced by history of AT and AT burden, while changes in the use of beta-blockers were influenced by symptoms. The probability of a pharmacologic therapy change decreased with time since implant for all agents except coumadin. Pharmacologic AT therapy is differentially influenced by patient-reported symptoms of AT compared to device-detected asymptomatic AT. Anticoagulation and antiarrhythmic therapies are influenced by device detection of asymptomatic AT, whereas initiation of beta-blockers is more strongly influenced by symptoms.