Improving Thromboprophylaxis Using Atrial Fibrillation Diagnostic Capabilities in Implantable Cardioverter-Defibrillators

Device-detected atrial high rate episodes and the risk of stroke/thrombo-embolism and atrial fibrillation incidence: a systematic review and meta-analysis

BACKGROUND

Atrial High Rate Episodes (AHRE) are asymptomatic atrial tachy-arrhythmias detected through continuous monitoring with a cardiac implantable electronic device. The risks of stroke/Thromboembolic (TE) events and incident clinical Atrial Fibrillation (AF) associated with AHRE varies markedly.

OBJECTIVES

To assess the relationship between AHRE and TE events, and between AHRE and incident clinical AF.

METHODS

This systematic review and meta-analysis was conducted following the PRISMA recommendations. PubMed, Scopus, and Google Scholar were searched from inception to 18/02/2021 for studies reporting TE events and incident clinical AF in patients with AHRE, as compared with patients without.

RESULTS

Ten out of 8081 records fulfilled the inclusion criteria, for a total of 37 266 patients. Seven out of ten studies excluded patients with prior history of clinical AF (4961 patients), embracing the most recent definition of AHRE. The risk ratio (RR) for TE events in AHRE patients was 2.13 (95% CI: 1.53-2.95, I²: 0%). The incidence of clinical AF was reported in four studies excluding patients with a history of clinical AF (3574 patients). The RR for incident clinical AF was 3.34 (95%CI: 1.89-5.90, I²: 73%).

CONCLUSIONS

AHRE are significantly associated with systemic thromboembolism and incident clinical AF. Further studies are needed to improve patients' risk stratification and management.

Continuous monitoring of sleep-disordered breathing with pacemakers: Indexes for risk stratification of atrial fibrillation and risk of stroke

BACKGROUND

Sleep apnea (SA) is a risk factor for atrial fibrillation (AF). Advanced pacemakers are now able to calculate indexes of SA severity.

HYPOTHESIS

We investigated the changes in pacemaker-measured indexes of SA, we assessed their predictive value for AF occurrence and the associated risk of stroke and death at long-term.

METHODS

We enrolled 439 recipients of a pacemaker endowed with an algorithm for the calculation of a Respiratory Disturbance Index (RDI). The RDI variability was measured over the first 12 months after implantation, as well as its potential association with the occurrence of AF, defined as device-detected cumulative AF burden ≥6 hoursours in a day.

RESULTS

The individual RDI mean was 30 ± 18 episodes/h, and the RDI maximum was 59 ± 21 episodes/h. RDI ≥30 episodes/h was detected in 351 (80%) patients during at least one night. The proportion of nights with RDI ≥30 episodes/h was 14% (2%-36%). AF ≥6 hours was detected in 129 (29%) patients during the first 12 months. The risk of AF was higher in patients with RDI maximum ≥63 episodes/h (HR:1.74; 95%CI: 1.22-2.48; P = .001) and with RDI mean ≥ 46 episodes/h (HR:1.63; 95%CI: 1.03-2.57; P = .014). The risk of all-cause death or stroke was higher in patients with AF burden ≥6 hours (HR:1.75; 95%CI: 1.06-2.86; P = .016). Moreover, among patients with no previous history of AF the risk was higher in those with RDI maximum ≥63 episodes/h (HR:1.96; 95%CI: 1.06-3.63; P = .031).

CONCLUSIONS

Pacemaker-detected SA showed a considerable variability during follow-up. We confirmed the association between RDI and higher risk of AF, and we observed an association between higher RDI maximum and all-cause death or stroke among patients with no previous history of AF.

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.

Occurrence of atrial fibrillation in pacemaker patients and its association with sleep apnea and heart rate variability

AIMS

Sleep apnea (SA) is a risk factor for atrial fibrillation (AF) occurrence. Sympathovagal imbalance is a mechanism that predisposes to the development of AF and that occurs in SA. Some pacemakers can detect SA events and continuously measure a time domain measure of heart rate variability (HRV), i.e. the standard deviation of 5-min median atrial-atrial sensed intervals (SDANN). We evaluated the association between the occurrence of AF and device-detected SA and SDANN in patients who received pacemakers.

METHODS

We enrolled 150 consecutive patients undergoing implantation of a dual-chamber pacemaker, capable of SA and SDANN estimation. The SA was defined as severe if the Respiratory Disturbance Index was ≥30 episodes/h for at least one night during the first week after implantation.

RESULTS

Sixteen patients in permanent AF were excluded from our analysis. During follow-up, AF (cumulative device-detected AF duration > 6 h/day) occurred in 24(18%) patients out of the remaining 134 patients. Severe SA was detected in 84 patients. SDANN values were available in 74 patients and the median value was 76 ms [25°-75°percentile:58-77]. The risk of AF was higher in patients with severe SA (log-rank test; p = .033). The presence of either or both conditions (severe SA and SDANN < 76 ms) was associated with shorter time to AF event (p = .042) and was an independent predictor of AF (hazard ratio: 2.37; 95%CI:1.08 to 5.21; p = .033).

CONCLUSION

In pacemaker patients, device-diagnosed severe SA and reduced SDANN are associated with a higher risk of AF.

Role of cardiovascular implantable electronic devices in delivering individualized disease-guided management of patients with non-valvular atrial fibrillation and high bleeding risk

BACKGROUND

Many patients with non-valvular atrial fibrillation (NVAF) with high risk for thromboembolic stroke and bleeding may not wish to continue long-term oral anticoagulants (OACs) to avoid bleeding complications. We aimed to investigate whether AF burden assessment by cardiovascular implantable electronic devices (CIEDs) would allow an individualised disease-guided approach for safe withdrawal of long-term OAC in high-risk patients.

METHODS AND RESULTS

We studied 145 patients (age 77.6 ± 10.6 years; 49.7% females) with NVAF, CHA₂DS₂-VASc score ≥2, HAS-BLED score ≥3, in whom CIEDs were implanted. These patients wished to stay off long-term OAC based on their previous adverse bleeding event/s or due to similar events witnessed in the family or friend circle. These patients were grouped into 'low AF burden' [n = 121 (83%)], or 'high AF burden' [n = 24 (17%)] defined as <24 hours or >24 hours cumulatively in 30 consecutive days respectively, and followed for 51.2 ± 29.8 months. All patients with 'low AF burden' were allowed to discontinue OAC, but OAC was resumed in 1 patient who experienced TIA. Bleeding events developed in 9 out of 24 (37.5%) patients with 'high AF burden' who were maintained on OAC, as compared to 3 out of 121 (2.47%) patients with 'low AF burden' who were off OAC (p <.05). There were 9 (6.2%) deaths unrelated to AF treatment approach.

CONCLUSIONS

In NVAF patients, AF burden assessment by CIEDs allows an individualised disease-guided approach to safe withdrawal of long-term OAC in patients with high bleeding risk who do not wish to continue long-term anticoagulation.

Importance of monitoring zones in the detection of arrhythmias in patients with implantable cardioverter-defibrillators under remote monitoring

INTRODUCTION

Implantable cardioverter-defibrillator (ICD) monitoring zones (MZ) provide passive features that do not interfere with the functioning of active treatment zones. However, it is not known for certain whether programming an MZ affects arrhythmia detection by the ICD. The aim of the present study is to assess the clinical relevance of MZ in a population of patients with ICDs.

METHODS

In this retrospective analysis of patients with ICDs, with or without cardiac resynchronization therapy, for primary prevention under remote monitoring, the MZ was analyzed and recorded arrhythmias were assessed in detail.

RESULTS

A total of 221 patients were studied (77% men; age 64±12 years). Mean ejection fraction was 30±12%. The mean follow-up was 63±35 months. One hundred and seventy-four MZ events were documented in 139 patients (62.9%): 74 of non-sustained ventricular tachycardia (NSVT), 42 of supraventricular tachycardia, 44 of atrial fibrillation/atrial flutter, and five cases of noise. Among the 137 patients who presented with arrhythmias in the MZ (excluding two cases with noise detection only), 22 (16.1%) received appropriate shocks and/or antitachycardia pacing (ATP), while of the other 84 patients, 15.5% received appropriate ICD treatment (p=NS). In patients who presented with NSVT in the MZ, 15 (20.5%) received appropriate shocks and/or ATP. In accordance with the MZ findings, physicians decided to change outpatient medication in 41.7% of all patients in whom arrhythmic events were reported.

CONCLUSION

Ventricular and supraventricular arrhythmias are common findings in the MZ of ICD patients. Programming an MZ is valuable in the diagnosis of arrhythmias and may be a useful tool in clinical practice.

Silent atrial fibrillation in patients with an implantable cardioverter defibrillator and coronary artery disease (INDICO AF) trial: study rationale and design

Background

Timely detection of atrial fibrillation (AF) in implantable cardioverter defibrillator (ICD) patients is clinically important for prevention of AF-related complications and inappropriate shocks. Patients with coronary artery disease (CAD) and a dual or triple chamber ICD show a high incidence of device-detected AF. Whether CAD patients with a single chamber ICD carry a similar risk for device-detected AF remains unknown.

Study design

The INDICO AF trial is an investigator-initiated, multicentre, observational study evaluating the incidence of subclinical AF (SCAF) in CAD patients who will receive a single chamber ICD as primary prevention for sudden cardiac death (SCD). Fifty patients will receive a single chamber ICD with an integrated RR interval based AF detection algorithm. In combination with remote monitoring, rhythm data will be collected monthly. The primary endpoint is the incidence of SCAF at 1 year of follow-up; secondary endpoints include time until 10 and 20% of the patients have a first episode of SCAF. All patients in whom SCAF is detected will be invited for an outpatient visit and will receive adequate anticoagulation treatment when appropriate according to the CHA2DS2-VASc score and current guidelines.

Conclusion

The INDICO AF trial will quantify the incidence of SCAF in patients with an ICD and CAD. The study will underscore the clinical value of SCAF detection in single chamber ICD patients using remote patient monitoring and may improve patient care. This trial is registered at trialregister.nl with trial NTR6910.

Screening for Atrial Fibrillation

Approximately 10% of ischemic strokes are associated with atrial fibrillation (AF) first diagnosed at the time of stroke. Detecting asymptomatic AF would provide an opportunity to prevent these strokes by instituting appropriate anticoagulation. The AF-SCREEN international collaboration was formed in September 2015 to promote discussion and research about AF screening as a strategy to reduce stroke and death and to provide advocacy for implementation of country-specific AF screening programs. During 2016, 60 expert members of AF-SCREEN, including physicians, nurses, allied health professionals, health economists, and patient advocates, were invited to prepare sections of a draft document. In August 2016, 51 members met in Rome to discuss the draft document and consider the key points arising from it using a Delphi process. These key points emphasize that screen-detected AF found at a single timepoint or by intermittent ECG recordings over 2 weeks is not a benign condition and, with additional stroke factors, carries sufficient risk of stroke to justify consideration of anticoagulation. With regard to the methods of mass screening, handheld ECG devices have the advantage of providing a verifiable ECG trace that guidelines require for AF diagnosis and would therefore be preferred as screening tools. Certain patient groups, such as those with recent embolic stroke of uncertain source (ESUS), require more intensive monitoring for AF. Settings for screening include various venues in both the community and the clinic, but they must be linked to a pathway for appropriate diagnosis and management for screening to be effective. It is recognized that health resources vary widely between countries and health systems, so the setting for AF screening should be both country- and health system-specific. Based on current knowledge, this white paper provides a strong case for AF screening now while recognizing that large randomized outcomes studies would be helpful to strengthen the evidence base.

Atrial fibrillation burden and atrial fibrillation type: Clinical significance and impact on the risk of stroke and decision making for long-term anticoagulation

Atrial fibrillation (AF) is a common arrhythmia increasing the risk of morbidity and adverse outcomes (stroke, heart failure, death). AF is found in 1-2% of the general population, with increasing prevalence with aging. Its exact epidemiological profile is incomplete and underestimated, because 10-40% of AF patients (particularly the elderly) can be asymptomatic ("clinically silent or subclinical AF"), with occasional electrocardiographic diagnosis. The research interest on silent AF has increased by the evidence that its outcome is no less severe, in terms of risks of stroke and death, than that for symptomatic patients. Data collected from more than 18,000 patients indicate that cardiac implantable electrical devices (CIEDs) are validated tools for detecting silent AF and measuring the time spent in AF, defined as "AF burden." A maximum daily AF burden of ≥5-6min, but particularly ≥1h, is associated with a significant increase in the risk of stroke, and may be clinically relevant to improve current risk stratification based on risk scores and for "personalizing" prescription of oral anticoagulants. An in-depth study of the temporal relationship between AF and ischemic stroke showed that data from CIEDs reveal a complex scenario, by which AF is certainly a risk factor for cardioembolic stroke, with a cause-effect relationship related to atrial thrombi, but can also be a simple "marker of risk," with a noncausal association with stroke. In such cases, stroke is possibly related to atheroemboli from the aorta, the carotid arteries, or other sources.

Annual atrial tachyarrhythmia burden determined by device interrogation in patients with cardiac implanted electronic devices is associated with a risk of ischaemic stroke independent of known risk factors

OBJECTIVES

This study evaluated the risk of non-fatal ischaemic stroke associated with increased long-term cumulative duration of atrial tachycardia (AT).

METHODS

We retrospectively reviewed the records of 260 patients with cardiovascular implantable electronic devices capable of monitoring AT. Patients were separated into zero, low and high AT burden groups. The cut-off point between low and high AT burden was defined by the median value of AT burden in the non-zero AT burden groups (5% in 1 year, about 18 days annually). The primary outcome was non-fatal ischaemic stroke.

RESULTS

The mean patient age was 63.3 ± 13.7 years, the average follow-up was 7.0 years and 10 patients had strokes. Multivariate analysis showed only hypertension and a diagnosis of atrial fibrillation (AF) were associated with stroke. The risk of stroke in patients with hypertension was 12.57-fold higher than in those without hypertension, and was 20.81-fold higher in patients with paroxysmal AF and 162.59-fold higher in patients with chronic AF than in those without AF. Kaplan-Meier analysis showed that stroke-free survival was significantly different in the three AT burden groups (P = 0.002, long-rank test); the rate was greatest in the zero AT burden group, followed by the low AT burden group and was lowest in the high AT burden group.

CONCLUSIONS

Patients who accumulated an AT duration exceeding 5% (18 days) of the total time in any of the 1-year periods are more likely to have an ischaemic stroke than those who have a low or zero AT burden.

Monitoring Atrial Fibrillation After Catheter Ablation

Although catheter ablation is an effective treatment for recurrent atrial fibrillation (AF), there is no consensus on the definition of success or follow-up strategies. Symptoms are the major motivation for undergoing catheter ablation in patients with AF, however it is well known that reliance on perception of AF by patients after AF ablation results in an underestimation of recurrence of the arrhythmia. Because symptoms of AF occurrence may be misleading, a reliable assessment of rhythm outcome is essential for the definition of success in both clinical care and research trials. Continuous rhythm monitoring over long periods of time is superior to intermittent recording using external monitors to detect the presence of AF episodes and to quantify the AF burden. Today, new devices implanted subcutaneously using a minimally invasive technique have been developed for continuous AF monitoring. Implantable devices keep detailed information about arrhythmia recurrences and might allow identification of very brief episodes of AF, the significance of which is still uncertain. In particular, it is not known whether there is any critical value of daily AF burden that has a prognostic significance. This issue remains an area of active discussion, debate and investigation. Further investigation is required to determine if continuous AF monitoring with implantable devices is effective in reducing stroke risk and facilitating maintenance of sinus rhythm after AF ablation.

AF burden is important - fact or fiction?

Asymptomatic atrial fibrillation (AF) is common and in view of its prognostic impact (the same as of clinically overt AF) knowledge of the overall AF burden (defined as the amount of time spent in AF) appears to be important, both for scientific and clinical reasons. Data collected on more than 12,000 patients indicate that cardiac implantable electrical devices (CIEDs) are validated tools for measuring AF burden and that AF burden is associated with an increased risk of stroke. A maximum daily AF burden of ≥ 1 h carries important negative prognostic implications and may be a clinically relevant parameter for improving risk stratification for stroke. Decision-making should primarily consider the context in which asymptomatic, subclinical arrhythmias are detected (i.e. primary or secondary prevention of stroke and systemic embolism) and the risk profile of every individual patient with regard to thromboembolic and haemorrhagic risk, as well as patient preferences and values. Continuous monitoring using CIEDs with extensive data storage capabilities allow in-depth study of the temporal relationship between AF and ischaemic stroke. The relationships between AF and stroke are complex. AF is certainly a risk factor for cardioembolic stroke, with a cause-effect relationship between the arrhythmia and a thromboembolic event, the latter being related to atrial thrombi. However, AF can also be a simple 'marker of risk', with a non-causal association between the arrhythmia and stroke, the latter being possibly related to atheroemboli from the aorta, the carotid arteries or from other sources.

ICD programming

BACKGROUND

Appropriate ICD programming is the key to prevent inappropriate shock delivery, that is closely associated to a negative patients' outcome.

METHODS

Review of the literature on ICD therapy to generate ICD programmings that can be applied to the broad population of ICD and CRT-D carriers.

RESULTS

Arrhythmia detection should occur with a detection time ranging 9″-12″ in the VF zone, and 15″-60″ in the VT zone. Discriminator should be applied at least up to 200 bpm. ATP therapy is applied to all VTs up to 250 bpm, with a success rate of 70%. Inappropriate shocks should occur in <3.6% of patients.

CONCLUSION

Tailored ICD programming can be achieved following evidence from large ICD trials. Pre-defined settings that are saved on the programmer and that can be uploaded at device implantation help to ensure optimal programming and to avoid random errors.

Device-detected atrial fibrillation and risk for stroke: an analysis of >10,000 patients from the SOS AF project (Stroke preventiOn Strategies based on Atrial Fibrillation information from implanted devices)

Objective

The aim of this study was to assess the association between maximum daily atrial fibrillation (AF) burden and risk of ischaemic stroke.

Background

Cardiac implanted electronic devices (CIEDs) enhance detection of AF, providing a comprehensive measure of AF burden.

Design, setting, and patients

A pooled analysis of individual patient data from five prospective studies was performed. Patients without permanent AF, previously implanted with CIEDs, were included if they had at least 3 months of follow-up. A total of 10 016 patients (median age 70 years) met these criteria. The risk of ischaemic stroke associated with pre-specified cut-off points of AF burden (5 min, 1, 6, 12, and 23 h, respectively) was assessed.

Results

During a median follow-up of 24 months, 43% of 10 016 patients experienced at least 1 day with at least 5 min of AF burden and for them the median time to the maximum AF burden was 6 months (inter-quartile range: 1.3–14). A Cox regression analysis adjusted for the CHADS₂ score and anticoagulants at baseline demonstrated that AF burden was an independent predictor of ischaemic stroke. Among the thresholds of AF burden that we evaluated, 1 h was associated with the highest hazard ratio (HR) for ischaemic stroke, i.e. 2.11 (95% CI: 1.22–3.64, P = 0.008).

Conclusions

Device-detected AF burden is associated with an increased risk of ischaemic stroke in a relatively unselected population of CIEDs patients. This finding may add to the basis for timely and clinically appropriate decision-making on anticoagulation treatment.

The MOnitoring Resynchronization dEvices and CARdiac patiEnts (MORE-CARE) randomized controlled trial: phase 1 results on dynamics of early intervention with remote monitoring

Background

Remote monitoring (RM) in patients with advanced heart failure and cardiac resynchronization therapy defibrillators (CRT-D) may reduce delays in clinical decisions by transmitting automatic alerts. However, this strategy has never been tested specifically in this patient population, with alerts for lung fluid overload, and in a European setting.

Objective

The main objective of Phase 1 (presented here) is to evaluate if RM strategy is able to reduce time from device-detected events to clinical decisions.

Methods

In this multicenter randomized controlled trial, patients with moderate to severe heart failure implanted with CRT-D devices were randomized to a Remote group (with remote follow-up and wireless automatic alerts) or to a Control group (with standard follow-up without alerts). The primary endpoint of Phase 1 was the delay between an alert event and clinical decisions related to the event in the first 154 enrolled patients followed for 1 year.

Results

The median delay from device-detected events to clinical decisions was considerably shorter in the Remote group compared to the Control group: 2 (25^th-75^th percentile, 1-4) days vs 29 (25^th-75^th percentile, 3-51) days respectively, P=.004. In-hospital visits were reduced in the Remote group (2.0 visits/patient/year vs 3.2 visits/patient/year in the Control group, 37.5% relative reduction, P<.001). Automatic alerts were successfully transmitted in 93% of events occurring outside the hospital in the Remote group. The annual rate of all-cause hospitalizations per patient did not differ between the two groups (P=.65).

Conclusions

RM in CRT-D patients with advanced heart failure allows physicians to promptly react to clinically relevant automatic alerts and significantly reduces the burden of in-hospital visits.

Trial Registration

Clinicaltrials.gov NCT00885677; http://clinicaltrials.gov/show/NCT00885677 (Archived by WebCite at http://www.webcitation.org/6IkcCJ7NF).

Relevance of Monitoring Atrial Fibrillation in Clinical Practice

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