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

ECG monitoring in syncope

Electrocardiographic (ECG) monitoring is a well-established procedure in the work-up of patients with syncope or for diagnosing arrhythmias. The investigation of syncope remains, however, challenging and physicians have an increasing armamentarium of diagnostic tools available and with advances in technology the role of these tools has to be continuously evaluated. The gold standard for the diagnosis of syncope is a symptom-ECG correlation, and while many studies have investigated the use and indications of both short-term and long-term monitoring; there is still some uncertainty in their clinical utility and practical approach. The use of ECG monitoring and other diagnostic tools is often subject to a "shot-gun approach" rather than a strict guideline algorithm. A systematic approach and selection of ECG monitoring tools helps permit an effective usage of the limited health care resources available for the management of unexplained syncope. In this review we aim to focus and clarify the role of short-term (Holter and external loop recorders) and long-term (implantable loop recorders) ECG monitoring in the diagnosis and management of patients with unexplained syncope.

Supraventricular and ventricular arrhythmias

Cardiac arrhythmias comprise of a heterogeneous group of disorders which manifest in a wide range of clinical presentations. They can be associated with underlying cardiac disease and portend a grave prognosis, with some arrhythmias being rapidly fatal. Other arrhythmias, however are relatively benign and can be asymptomatic or may be a mere inconvenience for the patient. All primary care physicians can expect to encounter some forms of arrhythmias during the course of their practice. This review article provides a brief overview of the commonly seen tachyarrhythmias for the general practitioner and provides relevant updates on the recent developments in our understanding of their mechanisms and management.

Insertable Cardiac Event Recorder in Detection of Atrial Fibrillation After Cryptogenic Stroke

Background and Purpose—

Atrial fibrillation (AF) is the most frequent risk factor in ischemic stroke but often remains undetected. We analyzed the value of insertable cardiac event recorder in detection of AF in a 1-year cohort of patients with cryptogenic ischemic stroke.

Methods—

All patients with cryptogenic stroke and eligibility for oral anticoagulation were offered the insertion of a cardiac event recorder. Regular follow-up for 1 year recorded the incidence of AF.

Results—

Of the 393 patients with ischemic stroke, 65 (16.5%) had a cryptogenic stroke, and in 22 eligible patients, an event recorder was inserted. After 1 year, in 6 of 22 patients (27.3%), AF was detected.

Conclusions—

These preliminary data show that insertion of cardiac event recorder was eligible in approximately one third of patients with cryptogenic stroke and detected in approximately one quarter of these patients new AF.

Hybrid Therapy for Atrial Fibrillation: where the Knife meets the Catheter

During the past decades there has been a consistent evolution of both surgical and catheter-based techniques for the treatment of stand-alone atrial fibrillation, as alternatives or in combination with anti-arrhythmic drugs. Transcatheter ablation has significantly improved outcomes, despite often requiring multiple procedures and with limited success rates especially in presence of persistent atrial fibrillation. Surgical procedures have dramatically evolved from the original cut-and-sew Maze operation, allowing nowadays for closed-chest epicardial ablations on the beating heart. Recently, the concept of a close collaboration between the cardiac surgeon and the electrophysiologist has emerged as an intriguing option in order to overcome the drawbacks and suboptimal results of both techniques; therefore, the hybrid approach has been proposed as a potentially more successful strategy, allowing for a patient-tailored therapeutical approach. We reviewed the recent advancements either from the transcatheter and surgical standpoint, with a peculiar focus on the current option to merge both techniques along with an up-to-date review of the preliminary clinical experiences with the hybrid, surgical-transcatheter treatment of stand-alone atrial fibrillation.

Progression of atrial fibrillation after a failed initial ablation procedure in patients with paroxysmal atrial fibrillation: a randomized comparison of drug therapy versus reablation

BACKGROUND

The aim of this prospective randomized study was to assess whether an early reablation was superior to antiarrhythmic drug (AAD) therapy in patients with previous failed pulmonary vein isolation.

METHODS AND RESULTS

Patients with paroxysmal atrial fibrillation (AF) eligible for AAD therapy or reablation after a previously failed initial pulmonary vein isolation procedure were eligible for this study and were followed up for 3 years to assess rhythm by means of an implanted cardiac monitor. After the blanking period postablation, 154 patients had symptomatic AF recurrences and were randomized to AAD (n=77) or repulmonary vein isolation (n=77). At the end of follow-up, 61 (79%) patients in the AAD group and 19 (25%) patients in the reablation group demonstrated AF% progression (P<0.01). The AF% at 36 months was significantly greater in the AAD group compared with patients in the reablation group (18.8±11.4% versus 5.6±9.5%, respectively; P<0.01). In addition, 18 (23%) patients in the AAD group and 3 (4%) patients in the reablation group progressed to persistent AF (P<0.01). Furthermore, 45 (58%) of the 77 reablation group patients were free of AF/atrial tachycardia on no AADs; in contrast, in the AAD group, only 9 (12%) of the 77 patients were free of AF/atrial tachycardia (P<0.01) throughout follow-up.

CONCLUSIONS

Redo AF ablation was substantially more effective than AAD in reducing the progression and prevalence of AF after the failure of an initial ablation.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01709682.

[Diagnosis of atrial fibrillation. From the standard ECG to analysis of electrograms]

The early diagnosis of asymptomatic atrial fibrillation is important because of the associated risk for arterial embolism. Routine ECG recording, however, is not effective in asymptomatic patients. The goal of this article is to show the general practitioner and internist how the search for atrial fibrillation can be made more efficacious. For example, recording an ECG in patients older than 65 years with irregularities in their pulse or repeated ECG recording in patients older than 75 years with hypertension shows improved results in this regard. It is interesting that elements of the CHA2DS2-VASc score, which was developed to predict risk for arterial embolism, are also effective for defining populations to screen for atrial fibrillation. In the subgroup of patients with a pacemaker or implantable converter-defibrillator (ICD), histograms or intracardiac electrograms can be used to identify previously undiagnosed atrial fibrillation. The general practitioner should take these results which are usually obtained by a cardiologist into consideration in the follow-up treatment of his or her patients.

Long-term success and follow-up after atrial fibrillation ablation

Atrial fibrillation (AF) is the most prevalent sustained arrhythmia in clinical practice. It is associated with significant morbidity and mortality and has been identified as an independent risk factor for ischemic stroke and thromboembolic events. Catheter ablation has become an established rhythm control therapy in patients with highly symptomatic drug-refractory AF. The definition of ablation success remains controversial since current symptom-based or intermittent electrocardiogram monitoring strategies fail to sufficiently disclose rhythm outcome. This failure is mainly related to the high incidence of asymptomatic AF recurrences, the unpredictable nature of arrhythmia relapses, and the poor correlation of symptoms and AF episodes. There is a clear correlation between the intensity of the monitoring strategy and the sensitivity for it to detect arrhythmia recurrences. Furthermore, several clinical studies assessing the long-term efficacy of catheter ablation procedures have reported late AF recurrences in patients who were initially considered responders to catheter ablation. In certain subsets of patients, precise long-term monitoring may help to guide therapy, e.g. patients in whom withdrawal of antithrombotic therapy may be considered if they are free of arrhythmia recurrences. Recently, sub-cutaneous implantable cardiac monitors (ICM) have been introduced for prolonged and continuous rhythm monitoring. The performance of a leadless ICM equipped with a dedicated AF detection algorithm has recently been assessed in a clinical trial demonstrating a high sensitivity and overall accuracy for identifying patients with AF. The clinical impact of ICM-based follow-up strategies, however, has to be evaluated in prospective clinical trials.

Detection of paroxysmal atrial fibrillation in stroke/tia patients

One-third of stroke and transient ischemic attack (TIA) are cryptogenic, and paroxysmal atrial fibrillation (PAF) has been suggested as a possible cause for these cryptogenic strokes. Multiple studies have recently evaluated long-term cardiac rhythm monitoring with good yield for PAF. The duration of monitoring varies between studies as well as the qualifying event definition. Moreover, the clinical significance of very brief atrial fibrillation events is unclear in the literature. This paper provides an overview of current advances in the detection of paroxysmal atrial fibrillation, the clinical and genetic factors predictive of arrhythmia detection, and the therapeutic dilemma concerning this approach.

Ganglionated plexus ablation vs linear ablation in patients undergoing pulmonary vein isolation for persistent/long-standing persistent atrial fibrillation: a randomized comparison

BACKGROUND

The optimal ablation technique for persistent and long-standing persistent atrial fibrillation (AF) is unclear. Both linear lesion (LL) and ganglionated plexus (GP) ablation have been used in addition to pulmonary vein isolation (PVI), but no direct comparison of the 2 methods exists.

OBJECTIVE

The aim of this study is to assess the comparative safety and efficacy of 2 different ablation strategies-PVI+LL vs PVI+GP ablation -in patients with persistent or long-standing persistent AF.

METHODS

Two hundred sixty-four consecutive patients with persistent/long-standing persistent AF were randomly assigned to 2 different ablation schemes: PVI+LL (n = 132) and PVI+GP (n = 132) ablation. Consistent sinus rhythm (SR) off antiarrhythmic drug was assessed after follow-up of at least 3 years with the use of an implanted monitoring device.

RESULTS

All procedural end points were acutely achieved. At 12 months after a single procedure, 47% of the patients treated with PVI+LL were in SR compared to 54% of the patients treated with PVI+GP (P = .29). At 3 years, 34% of the patients with PVI+LL and 49% of the patients with PVI+GP maintained SR (P = .035). Atrial flutter was more frequent in the PVI+LL group than in PVI+GP group (18% vs 6%; P = .002). After a second procedure in 78 patients of the PVI+LL group and 55 patients of the PVI+GP group, the long-term overall success rate was 52% and 68%, respectively (P = .006).

CONCLUSIONS

PVI+GP ablation confers superior clinical results with less ablation-related left atrial flutter and reduced AF recurrence compared to PVI+LL ablation at 3 years of follow-up.

Incidence of atrial fibrillation detected by implantable loop recorders in unexplained stroke

OBJECTIVES

The usefulness of the implantable loop recorder (ILR) with improved atrial fibrillation (AF) detection capability (Reveal XT) and the factors associated with AF in the setting of unexplained stroke were investigated.

METHODS

A cohort study is reported of 51 patients in whom ILRs were implanted for the investigation of ischemic stroke for which no cause had been found (cryptogenic) following appropriate vascular and cardiac imaging and at least 24 hours of cardiac rhythm monitoring.

RESULTS

The patients were aged from 17 to 73 (median 52) years. Of the 30 patients with a shunt investigation, 22 had a patent foramen ovale (73.3%; 95% confidence interval [CI] 56.5%-90.1%). AF was identified in 13 (25.5%; 95% CI 13.1%-37.9%) cases. AF was associated with increasing age (p = 0.018), interatrial conduction block (p = 0.02), left atrial volume (p = 0.025), and the occurrence of atrial premature contractions on preceding external monitoring (p = 0.004). The median (range) of monitoring prior to AF detection was 48 (0-154) days.

CONCLUSION

In patients with unexplained stroke, AF was detected by ILR in 25.5%. Predictors of AF were identified, which may help to target investigations. ILRs may have a central role in the future in the investigation of patients with unexplained stroke.

Occult atrial fibrillation in cryptogenic stroke: detection by 7-day electrocardiogram versus implantable cardiac monitors

BACKGROUND AND PURPOSE

A significant number of patients with cryptogenic stroke suffer from intermittent atrial fibrillation (iAF) which was not detected during the standard diagnostic procedures. We investigated whether implantation of an insertable cardiac monitor (ICM) is feasible in patients with cryptogenic stroke, and compared the iAF detection rate of the ICM with 7-day Holter monitoring.

METHODS

Sixty patients (median age 63; interquartile range, 48.5-72 years) with acute cryptogenic stroke were included. ICM was implanted 13 days (interquartile range; 10-65 days) after the qualifying event. Seven-day Holter was performed after the ICM was implanted.

RESULTS

The iAF was detected by the ICM in 10 patients (17%; 95% CI, 7% to 26%). Only 1 patient (1.7%; 95% CI, 0% to 5%) had iAF during 7-day Holter monitoring as well (P=0.0077). Episodes of iAF lasting 2 minutes or more were detected 64 (range, 1-556) days after implantation. There were no recurrent strokes during the observation period. The implantation procedure was well tolerated with no adverse events; the daily data transmission protocol was easy to handle by the patients.

CONCLUSIONS

ICM implantation for the detection of iAF during outpatient follow-up is feasible in patients with cryptogenic stroke. ICMs offer a much higher diagnostic yield than 7-day Holter monitoring.

Concomitant surgical atrial fibrillation ablation and event recorder implantation: better monitoring, better outcome?

OBJECTIVES

Concomitant ablation is an established therapy in cardiac surgical patients with atrial fibrillation (AF). Post-discharge care seems to be an essential factor for clinical outcome. We analysed the influence of event recorder (ER) implantation and therapy guidance by the results of continuous rhythm monitoring of consecutive postoperative follow-up by our department of electrophysiology.

METHODS

Between July 2003 and August 2010, 401 cardiac surgical patients underwent concomitant surgical AF ablation therapy. Since August 2009, an ER (REVEAL XT, Medtronic, Inc., Minneapolis, MN, USA) was implanted in 98 patients intraoperatively. ER interrogation was performed by our department of electrophysiology 3, 6 and 12 months postoperatively. Results and outcomes were compared with a matched cohort of patients with ablation and no ER implantation. In those patients, rhythm follow-up was obtained by 24-h Holter ECG. Primary end-point of the study was sinus rhythm rate after 12 months.

RESULTS

Mean patient's age was 67.0 ± 9.7 years, and 68.4% were male. No major ablation-related complications occurred. The overall sinus rhythm rate was 65.3% after 1-year follow-up. The sinus rhythm rate off antiarrhythmic drugs was 60.3%. The conversion rate tended to be higher in patients with an implanted ER (69.3 vs 60.1%, respectively; P = 0.098). Also, the sinus rhythm rate of anti-arrhythmic drugs was higher in the ER group (64.3 vs 56.2). Patients with ER were seen more often by a cardiologist in the first postoperative year (3.1 ± 0.8 vs 1.5 ± 0.9; P < 0.05) and received significantly more additional procedures, like electrical cardioversion or additional catheter-based ablation (16.1 vs 4.3%; P < 0.001; 11.2 vs 3.1%; P < 0.001).

CONCLUSIONS

Implantation of an ER with link-up to a cardiology and/or electrophysiology provides optimized anti-arrhythmic drug management and higher rates of consecutive procedures like cardioversion or additional catheter-based ablation. As a result, a trend to higher sinus rhythm conversion rate was observed after 1-year follow-up.

Development of a method to risk stratify patients with heart failure for 30-day readmission using implantable device diagnostics

The aim of the present study was to evaluate whether diagnostic data collected after a heart failure (HF) hospitalization can identify patients with HF at risk of early readmission. The diagnostic data from cardiac resynchronization therapy defibrillator (CRT-D) devices can identify outpatient HF patients at risk of future HF events. In the present retrospective analysis of 4 studies, we identified patients with CRT-D devices, with a HF admission, and 30-day postdischarge follow-up data. The evaluation of the diagnostic data for impedance, atrial fibrillation, ventricular heart rate during atrial fibrillation, loss of CRT-D pacing, night heart rate, and heart rate variability was modeled to simulate a review of the first 7 days after discharge on the seventh day. Using a combined score created from the device parameters that were significant univariate predictors of 30-day HF readmission, 3 risk groups were created. A Cox proportional hazards model adjusting for age, gender, New York Heart Association class, and length of stay during the index hospitalization was used to compare the groups. The study cohort of 166 patients experienced a total of 254 HF hospitalizations, with 34 readmissions within 30 days. Daily impedance, high atrial fibrillation burden with poor rate control (>90 beat/min) or reduced CRT-D pacing (<90% pacing), and night heart rate >80 beats/min were significant univariate predictors of 30-day HF readmission. Patients in the "high"-risk group for the combined diagnostic had a significantly greater risk (hazard ratio 25.4, 95% confidence interval 3.6 to 179.0, p = 0.001) compared to the "low"-risk group for 30-day readmission for HF. In conclusion, device-derived HF diagnostic criteria evaluated 7 days after discharge identified patients at significantly greater risk of a HF event within 30 days after discharge.

Detection of previously undiagnosed atrial fibrillation in patients with stroke risk factors and usefulness of continuous monitoring in primary stroke prevention

The detection of undiagnosed atrial tachycardia/atrial fibrillation (AT/AF) among patients with stroke risk factors could be useful for primary stroke prevention. We analyzed newly detected AT/AF (NDAF) using continuous monitoring in patients with stroke risk factors but without previous stroke or evidence of AT/AF. NDAF (AT/AF >5 minutes on any day) was determined in patients with implantable cardiac rhythm devices and ≥1 stroke risk factors (congestive heart failure, hypertension, age ≥75 years, or diabetes). All devices were capable of continuously monitoring the daily cumulative time in AT/AF. Of 1,368 eligible patients, NDAF was identified in 416 (30%) during a follow-up of 1.1 ± 0.7 years and was unrelated to the CHADS(2) score (congestive heart failure, hypertension [blood pressure consistently >140/90 mm Hg or hypertension treated with medication], age ≥75 years, diabetes mellitus, previous stroke or transient ischemic attack). The presence of AT/AF >6 hours on ≥1 day increased significantly with increased CHADS(2) scores and was present in 158 (54%) of 294 patients with NDAF and a CHADS(2) score of ≥2. NDAF was sporadic, and 78% of patients with a CHADS(2) score of ≥2 with NDAF experienced AT/AF on <10% of the follow-up days. The median interval to NDAF detection in these higher risk patients was 72 days (interquartile range 13 to 177). In conclusion, continuous monitoring identified NDAF in 30% of patients with stroke risk factors. In patients with NDAF, AT/AF occurred sporadically, highlighting the difficulty in detecting paroxysmal AT/AF using traditional monitoring methods. However, AT/AF also persisted for >6 hours on ≥1 days in most patients with NDAF and multiple stroke risk factors. Whether patients with CHADS(2) risk factors but without a history of AF might benefit from implantable monitors for the selection and administration of anticoagulation for primary stroke prevention merits additional investigation.

Radiofrequency ablation as initial therapy in paroxysmal atrial fibrillation

BACKGROUND

There are limited data comparing radiofrequency catheter ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation.

METHODS

We randomly assigned 294 patients with paroxysmal atrial fibrillation and no history of antiarrhythmic drug use to an initial treatment strategy of either radiofrequency catheter ablation (146 patients) or therapy with class IC or class III antiarrhythmic agents (148 patients). Follow-up included 7-day Holter-monitor recording at 3, 6, 12, 18, and 24 months. Primary end points were the cumulative and per-visit burden of atrial fibrillation (i.e., percentage of time in atrial fibrillation on Holter-monitor recordings). Analyses were performed on an intention-to-treat basis.

RESULTS

There was no significant difference between the ablation and drug-therapy groups in the cumulative burden of atrial fibrillation (90th percentile of arrhythmia burden, 13% and 19%, respectively; P=0.10) or the burden at 3, 6, 12, or 18 months. At 24 months, the burden of atrial fibrillation was significantly lower in the ablation group than in the drug-therapy group (90th percentile, 9% vs. 18%; P=0.007), and more patients in the ablation group were free from any atrial fibrillation (85% vs. 71%, P=0.004) and from symptomatic atrial fibrillation (93% vs. 84%, P=0.01). One death in the ablation group was due to a procedure-related stroke; there were three cases of cardiac tamponade in the ablation group. In the drug-therapy group, 54 patients (36%) underwent supplementary ablation.

CONCLUSIONS

In comparing radiofrequency ablation with antiarrhythmic drug therapy as first-line treatment in patients with paroxysmal atrial fibrillation, we found no significant difference between the treatment groups in the cumulative burden of atrial fibrillation over a period of 2 years. (Funded by the Danish Heart Foundation and others; MANTRA-PAF ClinicalTrials.gov number, NCT00133211.).

Burden of atrial fibrillation and poor rate control detected by continuous monitoring and the risk for heart failure hospitalization

INTRODUCTION

Atrial fibrillation (AF) on electrocardiogram has been identified as a risk factor for hospitalizations in patients with heart failure (HF). We investigated whether continuous AF monitoring can identify when patients with HF are at risk for hospitalization.

METHODS

In this retrospective analysis of data from 4 studies enrolling patients with HF with cardiac resynchronization therapy defibrillator devices with ≥90 days of follow-up (n = 1561), patients were identified as having AF if they had ≥1 day of >5 minutes of AF and >1 hour of total AF during entire follow-up. In patients with AF, device recorded AF burden (AFb) and ventricular rate during AF (VRAF) over the last 30 days was classified on a monthly basis into 3 evaluation groups: (1) ≥1 day of high burden of paroxysmal AF (≥6 hours) or persistent AF (all 30 days with AFb >23 hours) with poor rate control (VRAF >90 beats/min), (2) ≥1 day of high burden of paroxysmal AF with good rate control (VRAF ≤ 90 beats/min), and (3) no days with high burden of AF (AFb <6 hours) or persistent AF with good rate control. Each group was compared with monthly evaluations in patients without AF using an Anderson-Gill model for occurrence of HF hospitalizations in the next 30 days.

RESULTS

Patients with AF (n = 519, 33%) have a greater risk (hazard ratio [HR] 2.0, P < .001) for impending HF hospitalizations during entire follow-up compared with patients with no AF. One day of high burden of paroxysmal AF with good rate control in the last 30 days increases risk for HF hospitalization in the next 30 days (HR 3.4, P < .001). The risk increases further (HR 5.9, P < .001) with 1 day of poor rate control during persistent AF or high burden paroxysmal AF in last 30 days.

CONCLUSION

Evaluation of AFb and rate control information on a monthly basis can identify patients at risk for HF hospitalization in the next 30 days.

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.

A Comprehensive Evaluation of Rhythm Monitoring Strategies for the Detection of Atrial Fibrillation Recurrence

Background—

Intermittent rhythm monitoring (IRM) to detect atrial fibrillation (AF) recurrence is employed to evaluate the success of therapeutic interventions. In a large population of patients with continuous monitoring (CM), we investigated the sensitivity of various frequencies and durations of IRM strategies on the detection of AF recurrence, the dynamics behind AF recurrence detection, and we describe measures to evaluate temporal AF recurrence.

Methods and Results—

Rhythm histories of 647 patients (mean AF burden, 0.12±0.22; median, 0.014; 687 patient-years) with implantable CM devices were reconstructed and analyzed. With the use of computationally intensive simulation, the sensitivity of IRM of various frequencies and durations on the identification of AF recurrence was evaluated. Prolonged-duration IRM was superior to shorter IRM ( P <0.0001). However, even with aggressive IRM strategies, AF recurrence was not detected in a great proportion of patients. The temporal AF burden aggregation (AF density) was directly related to IRM sensitivity ( P <0.0001). Even at similar AF burdens, patients with high-density AF required higher-frequency or prolonged-duration IRM to achieve the same sensitivity as in low-density AF ( P <0.0001). Patients with high-density, low-burden AF benefit the most from CM for detection of AF recurrence.

Conclusions—

IRM follow-up is significantly inferior to CM. IRM strategies will not identify AF recurrence in a great proportion of patients at risk. Temporal AF characteristics play a significant role in AF recurrence detection with the use of IRM. For the scientific, evidence-based evaluation of AF treatments, CM should be strongly recommended. Prospective studies are required to evaluate whether CM to guide clinical management can also improve patient outcomes.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00806689.

2012 HRS/EHRA/ECAS expert consensus statement on catheter and surgical ablation of atrial fibrillation: recommendations for patient selection, procedural techniques, patient management and follow-up, definitions, endpoints, and research trial design

This is a report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation, developed in partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology and the European Cardiac Arrhythmia Society (ECAS), and in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), the Asia Pacific Heart Rhythm Society (APHRS), and the Society of Thoracic Surgeons (STS). This is endorsed by the governing bodies of the ACC Foundation, the AHA, the ECAS, the EHRA, the STS, the APHRS, and the HRS.

Usefulness of continuous electrocardiographic monitoring for atrial fibrillation

The problem of early recognition of atrial fibrillation (AF) is greatly aggravated by the often silent nature of the rhythm disturbance. In about 1/3 of patients with this arrhythmia, patients are not aware of the so-called asymptomatic AF. In the past 15 years, the diagnostic data provided by implanted pacemakers and defibrillators have dramatically increased knowledge about silent AF. The unreliability of symptoms to estimate AF burden and to identify patients with and without AF has been pointed out not only by pacemaker trials but also in patients without implanted devices. The technology for continuous monitoring of AF has been largely validated. It is a powerful tool to detect silent paroxysmal AF in patients without previously documented arrhythmic episodes, such as those with cryptogenic stroke or other risk factors. Early diagnosis triggers earlier treatment for primary or secondary stroke prevention. Today, new devices are also available for pure electrocardiographic monitoring, implanted subcutaneously using a minimally invasive technique. In conclusion, this recent and promising technology adds relevant clinical and scientific information to improve risk stratification for stroke and may play an important role in testing and tailoring the therapies for rhythm and rate control.

Current and emerging indications for implantable cardiac monitors

Implantable cardiac monitors (ICMs) continuously monitor the patient's electrocardiogram and perform real-time analysis of the heart rhythm, for up to 36 months. The current clinical use of ICMs involves the evaluation of transitory symptoms of possible arrhythmic origin, such as unexplained syncope and palpitations. Moreover, ICMs can also be used for the evaluation of difficult cases of epilepsy and unexplained falls, though current indications for their application in these sectors are less clearly defined. Finally, the ability of new-generation ICMs to automatically record arrhythmic episodes suggests that these devices could also be used to study asymptomatic arrhythmias, and thus could be proposed for the long-term evaluation of the total (symptomatic and asymptomatic) arrhythmic burden in patients at risk of arrhythmic events. In particular, ICMs may have an emerging role in the management of patients with atrial fibrillation and in those at risk of ventricular arrhythmias.

Ablation for atrial fibrillation during mitral valve surgery: 1-year results through continuous subcutaneous monitoring

Continuous monitoring of cardiac rhythm may play an important role in measuring the true symptomatic/asymptomatic atrial fibrillation (AF) burden and improve the management of anti-arrhythmic and anti-thrombotic therapies. Forty-seven patients with mitral valve disease and longstanding persistent AF (LSPAF) underwent a left atrial maze procedure with bipolar radiofrequency and valve surgery. The follow-up data recorded by an implanted loop recorder were analysed after 3, 6 and 12 months. On discharge, 40 (85.1%) patients were in stable sinus rhythm, as documented by in-office electrocardiography (ECG), 4 (8.5%) were in pacemaker rhythm and 3 (6.4%) were in AF. One (2.1%) patient died after 7 months. On 12-month follow-up examination, 30 (65.2%) patients had an AF burden <0.5% and were classified as responders. Three (6.5%) of the 16 non-responders had atrial flutter and 13 (27.7%) had documented AF recurrences with an AF burden >0.5%. Two (4.3%) patients with AF recurrences were completely asymptomatic. Among the symptomatic events stored by the patients, only 27.6% was confirmed as genuine AF recurrences according to the concomitant ECG recorded by the implanted loop recorder. A concomitant bipolar maze procedure during mitral valve surgery is effective in treating AF, as proved by detailed 1-year continuous monitoring.

Ganglionated plexi ablation directed by high-frequency stimulation and complex fractionated atrial electrograms for paroxysmal atrial fibrillation

BACKGROUND

The effectiveness of ganglionated plexi (GP) ablation in patients with atrial fibrillation (AF) is ambiguous. Some researchers had already suggested that additional identification of complex fractionated atrial electrograms (CFAE) around the areas with a positive reaction to high-frequency stimulation (HFS) might improve the accuracy of GP's boundaries location, then enhancing the success rate of ablation. The purpose of this study was to assess the safety and efficacy of GP ablation directed by HFS and CFAE in patients with paroxysmal AF (PAF).

METHODS AND RESULTS

Sixty-two patients with PAF (age 57±8 years) underwent GP ablation. Ablation targets were the sites where vagal reflexes were evoked by HFS and additional extended ablation CFAE area around the areas where vagal reflexes were evoked. At 12 months, 71% of patients were free of symptomatic AF. At 3 months after ablation the root mean square successive differences and HF were significantly lower in patients without AF recurrence (P < 0.0001 and P = 0.004). The LF/HF ratio was significantly higher in patients without AF recurrence (P = 0.02).

CONCLUSION

Enhanced GP ablation directed by HFS and CFAE can be safely performed and enables maintenance of sinus rhythm in the majority of patients with PAF for a 12-month period. Denervation of the intrinsic cardiac autonomic nervous system may be the preferable target of catheter ablation of AF.

Atrial fibrillation

The management of atrial fibrillation has evolved greatly in the past few years, and many areas have had substantial advances or developments. Recognition of the limitations of aspirin and the availability of new oral anticoagulant drugs that overcome the inherent drawbacks associated with warfarin will enable widespread application of effective thromboprophylaxis with oral anticoagulants. The emphasis on stroke risk stratification has shifted towards identification of so-called truly low-risk patients with atrial fibrillation who do not need antithrombotic therapy, whereas oral anticoagulation therapy should be considered in patients with one or more risk factors for stroke. New antiarrhythmic drugs, such as dronedarone and vernakalant, have provided some additional opportunities for rhythm control in atrial fibrillation. However, the management of the disorder is increasingly driven by symptoms. The availability of non-pharmacological approaches, such as ablation, has allowed additional options for the management of atrial fibrillation in patients who are unsuitable for or intolerant of drug approaches.

Comprehensive risk reduction in patients with atrial fibrillation: emerging diagnostic and therapeutic options--a report from the 3rd Atrial Fibrillation Competence NETwork/European Heart Rhythm Association consensus conference

While management of atrial fibrillation (AF) patients is improved by guideline-conform application of anticoagulant therapy, rate control, rhythm control, and therapy of accompanying heart disease, the morbidity and mortality associated with AF remain unacceptably high. This paper describes the proceedings of the 3rd Atrial Fibrillation NETwork (AFNET)/European Heart Rhythm Association (EHRA) consensus conference that convened over 60 scientists and representatives from industry to jointly discuss emerging therapeutic and diagnostic improvements to achieve better management of AF patients. The paper covers four chapters: (i) risk factors and risk markers for AF; (ii) pathophysiological classification of AF; (iii) relevance of monitored AF duration for AF-related outcomes; and (iv) perspectives and needs for implementing better antithrombotic therapy. Relevant published literature for each section is covered, and suggestions for the improvement of management in each area are put forward. Combined, the propositions formulate a perspective to implement comprehensive management in AF.

ISHNE/EHRA expert consensus on remote monitoring of cardiovascular implantable electronic devices (CIEDs)

We are in the midst of a rapidly evolving era of technology-assisted medicine. The field of telemedicine provides the opportunity for highly individualized medical management in a way that has never been possible before. Evolving medical technologies using cardiac implantable devices with capabilities for remote monitoring permit evaluation of multiple parameters of cardiovascular physiology and risk, including cardiac rhythm, device function, blood pressure values, the presence of myocardial ischaemia, and the degree of compensation of congestive heart failure. Cardiac risk, device status, and response to therapies can now be assessed with these electronic systems of detection and reporting. This document reflects the extensive experience from investigators and innovators around the world who are shaping the evolution of this rapidly expanding field, focusing in particular on implantable pacemakers, implantable cardioverter defibrillators, devices for cardiac resynchronization therapy (both with and without defibrillation properties), loop recorders, and hemodynamic monitoring devices. This document covers the basic methodologies, guidelines for their use, experience with existing applications, and the legal and reimbursement aspects associated with their use. To adequately cover this important emerging topic, the International Society for Holter and Noninvasive Electrocardiology and the European Heart Rhythm Association combined their expertise in this field. We hope that the development of this field can contribute to improve care of our cardiovascular patients.

Left Atrial Catheter Ablation and Ischemic Stroke

Left atrial catheter ablation (LACA) has become an established therapy to abolish drug-refractory symptomatic paroxysmal and persistent atrial fibrillation. Restoring sinus rhythm by LACA may help to prevent atrial fibrillation-related strokes, but presently there is no evidence from randomized clinical trials to support this notion. This review summarizes the current knowledge and uncertainties regarding LACA and procedure-related ischemic stroke. In fact, most patients who undergo LACA have a rather low annual stroke risk even when left untreated, whereas LACA imposes a risk of procedure-related stroke of ≈0.5% to 1%. In addition, LACA may cause cerebral microemboli, resulting in ischemic lesions. These cerebral lesions, detectable by high-resolution MRI, could contribute to neuropsychological deficits and cognitive dysfunction. Furthermore, recurrent atrial fibrillaton episodes can be detected up to years after LACA and might cause ischemic strokes, especially in those patients in whom therapeutic anticoagulation was discontinued. Further prospective multicenter trials are needed to identify procedure-dependent risk factors for stroke and to optimize postprocedural anticoagulation management.

Use of an Implantable Monitor to Detect Arrhythmia Recurrences and Select Patients for Early Repeat Catheter Ablation for Atrial Fibrillation

Background—

Catheter ablation of atrial fibrillation (AF) has proved effective in curing highly symptomatic patients with paroxysmal AF. The aim of this prospective, randomized study was to identify the optimal treatment of patients with AF recurrences after the first ablation.

Methods and Results—

Two hundred eighty-six patients with paroxysmal AF underwent ablation (circumferential pulmonary vein isolation with linear lesions) and were monitored with an implantable cardiac monitor (Reveal XT, Medtronic). Patients without AF recurrences during the 3-month postablation period were assigned to group 1; those with AF recurrences to group 2. Patients in group 2 were randomly assigned to group 3 or group 4. Group 3 patients were treated only with antiarrhythmic drugs for 6 weeks, with no early reablation during the 3-month postablation period. In the case of AF recurrence after the 3-month postablation period, patients underwent reablation. Group 4 patients were treated according to the onset mechanism of AF recurrences, as detected and stored by the implantable cardiac monitor: antiarrhythmic drug therapy, but no reablation if AF was not preceded by triggers; early reablation if premature atrial beats or atrial tachycardias or flutter triggered AF. All patients were followed up for 1 year to assess maintenance of sinus rhythm in each group. On 12-month follow-up examination, of the 119 (42%) patients in group 1, 112 (94%) had no AF recurrences. Among the 83 patients in group 3, only 27 (33%) had no recurrences. Of the 84 group 4 patients, 67 (80%) had no AF recurrences ( P <0.0001 versus group 3).

Conclusions—

Patients with recurrences after the first AF ablation are likely to respond to a second early ablation when AF is triggered by supraventricular arrhythmias or premature contractions.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01164319.

[Surgical atrial fibrillation ablation therapy and postoperative monitoring]

Atrial fibrillation represents the most common atrial arrhythmia seen in clinical practice. The surgical treatment of atrial fibrillation is recommended in symptomatic patients as well as in asymptomatic patients at low postoperative risk. As a "stand alone" procedure, surgical ablation therapy is indicated after failed catheter ablation therapy, which occurs increasingly due to the high number of catheter-based ablation techniques. In order to gain acceptance among patients as well as referring cardiologists, the surgical ablation procedure ought to be performed in a minimally invasive fashion and with a very high success rate. When applied in an interdisciplinary approach by cardiologists/electrophysiologists and cardiothoracic surgeons, both ablative techniques have the potential to treat atrial fibrillation effectively and in the long-term. In order to document the true heart rhythm after ablation therapy, intermittent "snapshot" ECG documentation ought to be avoided. Small leadless devices that can be implanted subcutaneously enable full heart rhythm disclosure with documentation of atrial arrhythmias. The modern technique of implantable loop recorders permits individualized treatment for each patient.

How to use implantable loop recorders in clinical trials and hybrid therapy

Epidemiological studies show that atrial fibrillation (AF) is associated with a doubling of mortality, even after adjustment for confounders. AF can be asymptomatic, but this does not decrease the thromboembolic risk of the patient. Office ECGs, occasional 24-h Holter recordings and long-term ECG event recording might not be sensitive and accurate enough in patients with AF, especially in those with paroxysmal episodes. In one study, 7 days of continuous monitoring with event recorders detected paroxysmal AF in 20 of 65 patients with a previous negative 24-h Holter recording. Over the last decade, enormous improvements have been made in the technology of implantable devices, which can now store significant information regarding heart rhythm. The first subcutaneous implantable monitor (Reveal XT, Medtronic) was validated for continuous AF monitoring by the XPECT study. The dedicated AF detection algorithm uses irregularity and incoherence of R–R intervals to identify and classify patterns in ventricular conduction. Its sensitivity in identifying patients with AF is >96%. Numerous clinical data from continuous monitoring of AF have recently been published. The first applications of this technology have been in the field of surgical and catheter AF ablation. With regard to cryptogenic stroke, an international randomized trial is ongoing to compare standard care with standard care plus the implantable cardiac monitor for AF detection in patients discharged with the diagnosis of cryptogenic stroke: the Crystal AF trial. Continuous AF monitoring provides an optimal picture of daily AF burden, both symptomatic and asymptomatic. Implantable cardiac monitors have high sensitivity, enable better assessment of therapy success and may guide further AF therapy.

Circulation: Arrhythmia and Electrophysiology Editors' Picks

The following articles are being highlighted as part of the Circulation: Arrhythmia and Electrophysiology Topic Review series. This series will summarize the most important manuscripts, as selected by the editors, published in Circulation: Arrhythmia and Electrophysiology and the rest of the Circulation portfolio. The studies included in this article represent the most-read articles published on the topic of atrial fibrillation in 2009 and 2010.

Circulation Editors' Picks

The following articles are being highlighted as part of Circulation's Topic Review series. This series will summarize the most important manuscripts, as selected by the editors, published in Circulation and the Circulation subspecialty journals. The studies included in this article represent the most read manuscripts published on the topic of arrhythmia and electrophysiology in 2009 and 2010.

Surveillance of AF recurrence post-surgical AF ablation using implantable cardiac monitor

BACKGROUND

Although pulmonary vein isolation is an effective treatment for recurrent atrial fibrillation (AF), there is no consensus on the definition of success or follow-up strategies. Existing data are limited to intermittent Holter or transtelephonic monitoring with reliance on patient symptoms.

OBJECTIVE

We sought to determine the outcomes of surgical ablation and post-ablation AF surveillance with a leadless implantable cardiac monitor (ICM).

METHODS

Forty-five patients with drug-refractory paroxysmal or persistent AF underwent video-assisted epicardial ablation using a bipolar radiofrequency clamp. An ICM was implanted subcutaneously post-ablation to assess AF recurrence. AF recurrence was defined as ≥1 AF episode with a duration of ≥30 s. The device-stored data was downloaded weekly over the internet, and all transmitted events were reviewed.

RESULTS

A total of 1,220 AF automatic and patient-activated AF episodes were analyzed over a follow-up of 12 ± 3 months. Of these episodes, 46% were asymptomatic. Furthermore, only 66% of the patient-activated episodes were AF. AF recurrence was highest in first 4 weeks and substantially decreased 6 months post-ablation. The overall freedom from AF recurrence at the end of follow-up was 60%. When 48-h Holter recordings were compared with the device-stored episodes, the sensitivity of the device to detect AF was 98%, and the specificity was 71%.

CONCLUSIONS

The ICM provides an objective measure of AF ablation success and may be useful in making clinical decisions. This device may be used in future ablation studies to develop a more rigorous definition of procedural success.