Silent Atrial Fibrillation Research Articles

Atrial Arrhythmia Burden on Long-Term Monitoring in Asymptomatic Patients Late After Atrial Fibrillation Ablation

Patients appearing free of atrial fibrillation (AF) based on limited electrocardiographic monitoring/clinical history late after ablation may still have a large silent AF burden and thus have failed ablations and may be at risk of thromboembolism. We evaluated long-term monitoring (LTM; 7 days or 1 year) in 203 patients off antiarrhythmic drugs who were clinically free of AF >1 year after ablation. A 7-day monitor was done in 186 and 17 had pacemakers in whom the most recent year was analyzed. Arrhythmia recurrence was >30 seconds of AF, flutter, or tachycardia. LTM was done 3.1 ± 1.3 years (range 1.1 to 7.3) after the last ablation. AF recurred in only 8 of 186 (4.3%) on 7-day monitoring. One had persistent AF. For the other 7, AF burden was 0.0075% to 3.34% with 3 of 7 having an AF burden ≤0.037%. AF recurred in 4 of 17 patients (23.5%) with pacemakers. The 4 patients with pacemakers and AF had a 1-year AF burden of 0.0037% to 0.16%. Given the longer duration of monitoring, pacemakers detected more AF than 7-day monitors (p <0.011). AF duration before ablation was the only predictor of AF recurrence on LTM (p = 0.01). In patients with symptomatic AF who appeared free of AF on clinical grounds an average of 3 years after ablation, AF burden on LTM was low. In conclusion, monitoring by implanted devices detects more AF than 7-day monitors, most patients exceeding the failure definition of >30 seconds have a small AF burden, and when using LTM for follow-up the definition of "ablation failure" may be better described by an AF burden >0.5% rather than a single 30-second arrhythmia recurrence.

Pacemaker clinic: an opportunity to detect silent atrial fibrillation and improve antithrombotic treatment: Response

Pacemaker clinic: an opportunity to detect silent atrial fibrillation and improve antithrombotic treatment: Response

Improved screening for silent atrial fibrillation after ischaemic stroke

To what extent silent paroxysmal atrial fibrillation (AF) is present in ischaemic stroke patients has not been established. We hypothesized that brief intermittent long-term electrocardiogram (ECG) recordings at regular time intervals are more effective than short-term continuous ECG monitoring in detecting silent AF episodes. Consecutive patients who had suffered an ischaemic stroke/transient ischaemic attack (TIA) and were without known AF underwent a 24 h continuous ECG recording and performed 10 s rhythm registrations using a hand-held ECG recorder twice daily for 30 days and when arrhythmia symptoms occured. Two hundred and forty-nine stroke patients were included. Mean National Institute of Health Stroke Scale (NIHSS) score was 0.9 (0-10). In total, 17 patients were diagnosed with AF. One hundred and eight AF episodes were diagnosed in 15 patients using intermittent recording, out of which 22% where unscheduled symptom triggered episodes. In three patients AF was diagnosed with both methods and in two patients AF was detected exclusively with 24 h Holter monitoring. A significant difference in favour of the hand-held ECG was shown between the two methods (P = 0.013). The total prevalence of AF was 6.8% and increased to 11.8% in patients ≥75 years. No AF was found in patients <65 years. Prolonged brief intermittent arrhythmia screening substantially improves the detection of silent paroxysmal AF in patients with a recent ischaemic stroke/TIA, and thus facilitates the detection of patients who should receive oral anticoagulant treatment.

Cryptogenic embolic stroke in a girl with a trisomy 21 mosaic

Stroke in trisomy 21 may be due to cardioembolism, atherosclerosis, vasculitis, moyamoya disease, sinus venous thrombosis, internal carotid hypoplasia or infections like endocarditis with septic emboli, meningitis or brain abscess. In rare cases, however, stroke etiology remains unexplained. We present a 19 year old Caucasian girl with trisomy 21 with a 47XX+21 karyotype who suffered at age 11years from a transient ischemic attack with left hemiparesis, and at age 17years from an ischemic stroke in the territory of the right cerebral medial artery. She suffered from arterial hypertension, obesity and hypercholesterolemia. Since blood coagulation studies, immunologic parameters, blood cultures, 24-h Holter monitoring, transthoracic and transesophageal echocardiography, magnetic resonance angiography of the extra- and intracranial vessels, thoracic and abdominal aorta and renal arteries did not provide any explanation for the stroke, implantation of a loop recorder is considered in order to detect episodes of clinically silent atrial fibrillation.

Delayed Thromboembolic Events after Successful Catheter Ablation for Atrial Fibrillation

Background: Stroke remains the most devastating complication of atrial fibrillation (AF). Whether the risk of stroke persists following successful ablation of AF remains unknown. We present three cases of stroke after successful ablation. Methods and results: (1) 58 yo underwent pulmonary vein isolation (PVI) six years prior for persistent AF. Then required two more procedures (last 2.5 years earlier). Warfarin ceased 12 months later. Pacemaker interrogation (implanted for sinus node disease) showed no arrhythmia. He was asymptomatic. CHADS2 score 3. He presented with arm weakness. A CT confirmed left ischaemic stroke. (2) 78 yo underwent PVI and roofline ablation two years prior for PAF. Warfarin ceased 12 months later. He was asymptomatic; had 7d monitoring three monthly for one year, then six-monthly with no arrhythmia. CHADS2 score 2. He presented with left hemiplegia which resolved. MRI head was normal. (3) 65 yo underwent PVI and roofline ablation 4.5 years prior for PAF. Warfarin ceased three months later. She was asymptomatic; had 7d monitoring three monthly for one year, then six monthly with no arrhythmia. CHADS2 score 1. She presented with expressive dysphasia. Following CT underwent thrombolysis with complete recovery. TEE and carotid ultrasound were performed in each case to exclude other causes of embolic events. Each patient has been anticoagulated with warfarin. Conclusions: An ongoing risk of stroke after AF ablation may exist. Whether this represents a persistent “thrombogenic atria”, silent undetected AF, primary cerebro-vascular disease or ongoing vascular disease with non-cardiac emboli, is unknown. It raises caution of anticoagulation after AF ablation.

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.

Intermittent Broca’s aphasia management in an emergency unit: from theory to practice

Although Broca's aphasia (BA) may mimic different neurological illness, its sudden onset often requires an emergency approach. In this paper, the management of a case of intermittent BA occurred in a young woman without history of neurological, cardiovascular and arrhythmic diseases is discussed. Diffusion-weighted magnetic resonance imaging showed two areas of hypoperfusion in the terminal branches of the left medial cerebral artery not previously diagnosed by computed tomography. Although there were no eligibility criteria for thrombolysis, patient received intravenous treatment with recombinant tissue-type plasminogen activator (rt-PA) over 1 h and at the end of rt-PA infusion aphasia completely disappeared without neurological sequelae. Transesophageal echocardiography revealed a thrombus in the left atrial appendage not previously detected by transthoracic echocardiography. In the month following the cardioembolic stroke, heart rhythm was monitored for 30 days by an external loop recorder and during this test two episodes of silent lone atrial fibrillation were collected.

173 Silent atrial fibrillation in olmsted county: A community-based study

173 Silent atrial fibrillation in olmsted county: A community-based study

The CHADS 2 score predicts ischemic stroke in the absence of atrial fibrillation among subjects with coronary heart disease: Data from the Heart and Soul Study

We sought to evaluate the prognostic performance of the CHADS(2) score for prediction of ischemic stroke/transient ischemic attack (TIA) in subjects with coronary heart disease (CHD) without atrial fibrillation (AF). In 916 nonanticoagulated outpatients with stable CHD and no AF by baseline electrocardiogram, we calculated CHADS(2) scores (congestive heart failure, hypertension, age ≥75 years, diabetes [1 point each], and prior stroke or TIA [2 points]). The primary outcome was time to ischemic stroke or TIA over a mean follow-up of 6.4 ± 2.3 years. Over 5,821 person-years of follow-up, 40 subjects had an ischemic stroke/TIA (rate 0.69/100 person-years, 95% CI 0.50-0.94). Compared with subjects with low (0-1) CHADS(2) scores, those with intermediate (2-3) and high (4-6) CHADS(2) scores had an increased rate of stroke/TIA, even after adjustment for age, tobacco, antiplatelet therapy, statins, and angiotensin inhibitors (CHADS(2) score 2-3: HR 2.4, 95% CI 1.1-5.3, P = .03; CHADS(2) score 4-6: HR 4.0, 95% CI 1.5-10.6, P = .006). Model discrimination (c-statistic = 0.65) was comparable with CHADS(2) model fit in published AF-only cohorts. The CHADS(2) score predicts ischemic stroke/TIA in subjects with stable CHD and no baseline AF. The event rate in non-AF subjects with high CHADS(2) scores (5-6) was comparable with published rates in AF patients with moderate CHADS(2) scores (1-2), a population known to derive benefit from stroke prevention therapies. These findings should inform efforts to determine whether stroke prevention therapies or screening for silent AF may benefit subjects with stable CHD and high CHADS(2) scores.

Pacemaker clinic: an opportunity to detect silent atrial fibrillation and improve antithrombotic treatment

The prevalence of atrial fibrillation (AF) in patients with pacemakers is high, and often passes unnoticed. Our aim was to assess the use of antithrombotic treatment in this group of patients. All patients who came to our institution to have their pacemakers checked during the year 2008 were included in this study. The atrial activity was assessed by slowing down the paced frequency if necessary, and by the analysis of atrial electrograms in atrial-based pacemakers. The appropriateness of the antithrombotic treatment was evaluated by a cardiologist. Out of 585 patients, 216 (36.9%) displayed AF at some point during the 5.5-year monitoring period (1.5-11), although only 58 (9.9%) displayed it at the time of the implant. Of these 216, 58% were men, with an average age of 80 years (76-86 years). The pacemaker was implanted in response to an atrioventricular block (AVB) in 46.3% of the cases, sinoatrial node disorder in 24.1% of the cases, and slow AF in 25.9% of the cases. The CHADS2 score was 0 points in 4.2% (9) of the cases, 1 point in 19% (41) of the cases, and ≥ 2 points in 77% (173) of the cases. Despite this, only 58.3% of the cases received anticoagulant treatment. The existence of arrhythmia at the time of implantation [odds ratio (OR) = 4.25; 95% confidence interval (95% CI), 1.72-10.51; P = 0.002] and the implantation of a pacemaker with atrioventricular synchronization (OR = 13.23; 95% CI, 2.89-60.56; P = 0.001) were associated with the use of anticoagulant treatment in those cases with CHADS2>2. Atrial fibrillation is common in patients fitted with pacemakers. Despite the high risk of embolism, an underuse of anticoagulant treatment was observed.

CARDIOGENIC INSULTS

Based on the current data available in the literature and the results of his studies, the author characterizes the implication of cardiac diseases in the pathogenesis of cardioembolic and hemodynamic insults. Cardiogenic insults are demonstrated to account for as high as 40% of all the causes of ischemic insult. The leading causes of cardioembolic stroke are considered to be nonrheumatic atrial fibrillation, postinfarct changes, and rheumatic heart disease. The pathogenesis of hemodynamic insult (HDI) may be also caused by cardiac pathology that can singly affect blood pressure levels via cardiac output variations. Silent myocardial ischemia, atrial fibrillation, and sick sinus syndrome are regarded as the most common cardiogenic causes of HDI. The importance of a target cardiological study of patients with ischemic insult is accentuated for the effective secondary prevention of cardiogenic insults.

Short-term ECG for out of hospital detection of silent atrial fibrillation episodes

Objectives. We evaluated a short-term ECG, thumb ECG, for detection of asymptomatic atrial fibrillation (AF) episodes. The aim was to evaluate registration efficacy, sensitivity, specificity, quality and feasibility in patients with special emphasis on asymptomatic AF. Design. One hundred patients registered their cardiac rhythm with 12-lead ECG immediately followed by thumb ECG. The registrations were compared blindly. A second group of 12 patients, who had successfully undergone cardioversion, performed rhythm registration twice daily for 30 days. A third group of 606 individuals underwent an AF screening procedure. Results. Thumb ECG correctly diagnosed AF (sensitivity) in 96% and sinus rhythm (specificity) in 92% compared with 12-lead ECG. In the group of cardioverted patients, 466 registrations were validated: 95% had satisfactory quality for diagnosis: four patients experienced AF recurrence in which three were asymptomatic. In the third group 12 persons were diagnosed with AF, six of these had neither symptoms nor a history of AF. Conclusions. Short-term ECG is able to diagnose AF with a high sensitivity, specificity and simple application making detection of asymptomatic AF possible for screening purposes.

Frequency, Duration, and Predictors of Newly-Diagnosed Atrial Fibrillation Following Dual-Chamber Pacemaker Implantation in Patients Without a Previous History of Atrial Fibrillation

The Silent Atrial Fibrillation Detection With Stored EGMs (SAFE) registry is the first prospective study to characterize the incidence, duration, and predictors of atrial high-rate episodes (AHREs) in patients without previous clinically diagnosed atrial fibrillation after dual-chamber pacemaker implantation. Patients underwent in-clinic device interrogation at 2 weeks and then 3, 6, and 12 months after implantation. An AHRE was defined as an atrial tachyarrhythmia with an atrial rate > or =180 beats/min lasting > or =5 minutes. During the first month after pacemaker implantation, AHREs were identified in 68 patients (4.6%). Thirty-four of these patients (50%) did not have AHREs beyond the first month after implantation; these patients were older than those who continued to have AHREs (79 +/- 9 vs 74 +/- 12 years, p = 0.05). Within the first 6 months after pacemaker implantation, 150 patients (10%) experienced a total of 455 AHREs, of which only 28 (6%) prompted clinical visits. The 6-month freedom from an AHRE was 82%. Overall, 75% of patients with AHREs had multiple episodes; most AHREs lasted 5 to 60 minutes. In conclusion, 6 months after dual-chamber pacemaker implantation, 10% of patients experienced > or =1 AHRE, usually lasting 5 to 60 minutes. Some patients had AHREs only within the first 30 days after implantation, suggesting the possibility of transient atrial proarrhythmia related to lead insertion.

NT-ProBNP Predicts Rhythm Stability After Cardioversion of Lone Atrial Fibrillation

The aim of the present study was: (1) to determine the predictive value of N-terminal pro-B-type natriuretic peptide (NT-proBNP) on the success of an elective direct-current cardioversion; and (2) to assess the ability to monitor rhythm stability after electrical cardioversion in patients with lone atrial fibrillation (AF). Fifty-three patients with lone AF were provided with an Holter-ECG for a follow-up period of 4 weeks after elective cardioversion. NT-proBNP serum levels were measured before and 4 weeks after cardioversion. All patients presented with increased NT-proBNP serum levels (median 874 pg/ml, interquartile range 703-1,355) before cardioversion. Thirty patients were in sinus rhythm (SR) during follow-up. These patients showed a significant NT-proBNP-decrease (759 pg/ml, 618-1,139 to 318 pg/ml, 200-523, p<0.05). Nineteen patients experienced a relapse of AF. NT-proBNP was significantly higher prior to cardioversion in comparison to patients without relapse (p<0.05) and remained unchanged during follow-up (1,124 pg/ml, 925-1,542 vs 1,256 pg/ml, 945-1,509, p=NS). Four patients had short periods of silent AF detected by Holter ECG. These patients had a smaller decrease in NT-proBNP than patients with stable SR. The area under the curve of the receiver-operating characteristic curve was 0.8 for NT-proBNP to predict a successful cardioversion. Using an optimized cut-off level of 900 pg/ml, successful cardioversion can be predicted with high accuracy. The probability of a successful cardioversion correlates inversely with NT-proBNP values. The short-term success of a cardioversion might be predicted by prior determination of NT-proBNP.

Abstract 2648: Transient Atrial Fibrillation Within the First Month After Dual Chamber Pacemaker Implantation

Background: Following pacemaker (PPM) implant, atrial fibrillation (AF) is often diagnosed for the first time based on detection of stored atrial high rate episodes (AHRE). However, there are no prospective data regarding the time course of developing AF following dual chamber PPM implantation. Methods: We evaluated data from the Silent Atrial Fibrillation Detection with Stored EGMs (SAFE) registry, which was a multi-center, prospective registry of patients undergoing dual chamber PPM implant. No patient had prior history of AF . Device interrogations were performed at 2-week, 3-, 6-, and 12-months post-implantation. An AHRE was defined as an atrial rate ≥ 180 bpm lasting ≥ 5 minutes. Results: 1488 patients (55% male, 74 ± 12 years) underwent PPM implantation. During the first month, 47 (3.7%) patients were diagnosed with AF for the first time. In 33 (70%) of these 47 patients, AF lasted between 5 and 60 minutes. Overall, the mean duration of AF was 133 ± 276 minutes (range: 5.4 minutes – 22.9 hours). A majority (81%) of these early episodes occurred within the first 15 days of implant. Twenty-four (51%) of these 47 patients did not have AF beyond this first month. Patients who did and did not have AF beyond the first month were similar with respect to baseline demographics, the use of active versus passive atrial leads, duration of first AF event, and time to first AF episode (Table ). Conclusions: In the SAFE registry, nearly 4% of patients with no history of AF exhibited AF in the first 30 days after PPM implant, with a majority occurring within the first 15 days post-implant. However, half of these patients failed to have another AHRE after the first month. These ``transient” episodes of AF may represent proarrhythmia from atrial lead insertion, de novo AF, or simply first-detection AF that was previously silent. Long-term follow-up studies are needed to determine the clinical significance of these transient episodes. SAFE: Demographics Among Patients with AF within 30 Days of Implant

Asymptomatic recurrences of atrial fibrillation after pulmonary vein isolation

The purpose of this study was to determine the occurrence of asymptomatic episodes of atrial fibrillation (AF) and wrong AF perception after pulmonary vein isolation (PVI). We evaluated the success of ablation by using the following measurements: (i) clinical symptoms and duration of symptoms noticed by patients and (ii) synchronous event recording (ER). Eighty patients with paroxysmal AF underwent PVI and were provided repeatedly with a portable ER upon discharge and every 3 months for a year. The ER automatically detects arrhythmias by a detection algorithm and can also be manually triggered by the patient. In 46/80 patients (57.5%), episodes of AF were documented. Asymptomatic AF was detected in 21.3%. In 9/80 patients (11.3%), who reported clinical AF recurrence, no AF could be shown by ER. We compared patients' perception to have suffered AF episodes with the ERs and found a sensitivity of 75% and a specificity of 92%. Reliance on perception of AF by patients after PVI results in an underestimation of recurrence of the arrhythmia. We observed a maximal occurrence of silent AF or wrong perception of AF in 26/80 (32.6%) patients.

What evidence do we have to replace in-hospital implantable cardioverter defibrillator follow-up?

Due to the increasing number of patients with an implantable cardioverter defibrillator (ICD), new options for ICD patient follow-up management are required. Patients with ICD indication according to the guidelines received an ICD with Home Monitoring technology. The devices enabled the transmission of the relevant episode, therapy, and system integrity data. Patients were followed for 12 months with routine controls every 3 months. The physician analyzed the Home Monitoring data before the routine follow-up visit (FU) and gave a forecast on the necessity of the pending FU, which was compared with the evaluation after the FU. Based on the derived forecast reliability, a patient management scheme was developed and its impact on patient safety was assessed retrospectively. A total of 271 patients were enrolled (40 f, mean age 62+/-12 years, mean LVEF 39+/-15%, 65% ischemic heart disease, 20% cardiomyopathy) and followed for 339+/-109 days. Of 908 pairs of Home Monitoring data and FU data evaluation, 129 there were false negative results for 92 patients. Safety concerns from false negative forecasts can be minimized with a patient management scheme containing the following elements: 1) never skip the first routine FU; 2) never skip a routine FU for a patient having already shown pacing threshold problems; 3) perform FU following hospitalizations; 4) perform FU following episode detection by the ICD; and 5) perform a routine FU if the patient reports symptoms. The retrospective analysis showed, that if the patients had been managed using this scheme, 503 of 1079 routine FU could have been skipped with only one safety concern, a three month delay in the detection of silent paroxysmal atrial fibrillation in one patient. Home Monitoring in ICD therapy over 12 months is feasible. The data transmitted relevantly contribute to a remarkable reduction of follow-up burden and enable the individualization of routine follow-up.

Quality of Life in Older Patients With Atrial Fibrillation

This review summarizes what is known about quality of life (QOL) in older patients with atrial fibrillation (AF). The studies reviewed in this paper represent an increasingly broad repertoire of therapies for the treatment of AF and suggest that QOL in older patients does improve with treatment. The most dramatic improvements in QOL are noted in patients who are highly symptomatic and have poorer QOL at baseline. The data from studies where ablation and pacing therapy is used for treatment in patients with refractory AF vividly demonstrate this statement. There is also evidence of improvement in QOL in those with less severe symptoms, though it is extremely challenging to measure improvements in older patients who are asymptomatic (e.g., silent AF) or mildly symptomatic. Recommendations about new knowledge needed to optimize outcomes, particularly QOL, in patients with AF are based on these findings and the gaps in existing knowledge.

Remote monitoring of implantable cardioverter defibrillators: a prospective analysis.

A prospective study evaluating the functionality and ease of use of the Medtronic CareLink Network, "CareLink," was conducted at ten investigational sites. This internet-based remote monitoring service allows clinicians to remotely manage their patients' implantable cardioverter defibrillators (ICDs) and chronic diseases. The network is comprised of a patient monitor, a secure server, and clinician and patient websites. Under clinician direction, patients interrogated their ICDs at home, and transmitted data to secure servers via a standard telephone line. Comprehensive device data and a 10-second presenting rhythm electrogram were captured by the monitor and available for access and review on the clinician website. The information could also be printed using a standard desktop computer with internet access. During this study, patients were asked to transmit device data twice, at least 7 days apart, as scheduled by the clinic. Monitor functionality was assessed, and ease of using the system components was evaluated via questionnaires completed by patients and clinicians following each data transmission and review. Fifty-nine patients (64 +/- 14 years, range 22-85 years) completed 119 transmissions with only 14 calls to the study support center. Clinician review of data transmissions revealed several clinically significant findings, including silent AF discovery, assessment of antiarrhythmic drug efficacy in a previously diagnosed AF patient, previously unobserved atrial undersensing, and ventricular tachycardia. ICD patients found the monitor easy to use. Clinicians were pleased with the performance of the network and the quality of the web-accessed data, and found it comparable to an in-office device interrogation. CareLink is a practical tool for routine device management and may allow timely identification of clinically important issues.

1166-210 Silent atrial fibrillation: An important contributor to total burden of atrial fibrillation in Olmsted, County, MN (1980–1989)

1166-210 Silent atrial fibrillation: An important contributor to total burden of atrial fibrillation in Olmsted, County, MN (1980–1989)