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

2017 ISHNE-HRS expert consensus statement on ambulatory ECG and external cardiac monitoring/telemetry

Ambulatory ECG (AECG) is very commonly employed in a variety of clinical contexts to detect cardiac arrhythmias and/or arrhythmia patterns which are not readily obtained from the standard ECG. Accurate and timely characterization of arrhythmias is crucial to direct therapies that can have an important impact on diagnosis, prognosis or patient symptom status. The rhythm information derived from the large variety of AECG recording systems can often lead to appropriate and patient-specific medical and interventional management. The details in this document provide background and framework from which to apply AECG techniques in clinical practice, as well as clinical research.

Bayés syndrome and acute cardioembolic ischemic stroke

Bayés syndrome is an under-recognized clinical condition characterized by advanced interatrial block. Bayés syndrome is a subclinical disease that manifests electrocardiographically as a prolonged P wave duration > 120 ms with biphasic morphology ± in the inferior leads. The clinical relevance of Bayés syndrome lies in the fact that is a clear arrhythmological syndrome and has a strong association with supraventricular arrhythmias, particularly atypical atrial flutter and atrial fibrillation. Likewise, Bayés syndrome has been recently identified as a novel risk factor for non-lacunar cardioembolic ischemic stroke and vascular dementia. Advanced interatrial block can be a risk for embolic stroke due to its known sequelae of left atrial dilation, left atrial electromechanical dysfunction or atrial tachyarrhythmia (paroxysmal or persistent atrial fibrillation), conditions predisposing to thromboembolism. Bayés syndrome may be responsible for some of the unexplained ischemic strokes and shall be considered and investigated as a possible cause for cryptogenetic stroke. In summary, Bayés syndrome is a poorly recognized cardiac rhythm disorder with important cardiologic and neurologic implications.

Cryptogenic ischemic stroke and prevalence of asymptomatic atrial fibrillation: a prospective study

BACKGROUND

Atrial fibrillation is responsible for up to one-third of ischemic strokes, and is also associated with silent cerebral infarctions and transient ischemic attacks (TIAs). The self-terminating and often asymptomatic nature of paroxysmal atrial fibrillation (PAF) may lead to its underdiagnosis. A continuous and long-term heart rhythm monitoring can be useful in unmasking PAF episodes.

OBJECTIVE

Prevalence of asymptomatic PAF in patients suffering a cryptogenic stroke, at risk for atrial fibrillation but without any history of arrhythmia or palpitations, using a continuous electrocardiographic monitoring.

METHODS

One hundred and forty-two consecutive patients were admitted to the Stroke Unit of 'Città della Salute e della Scienza' Hospital of Turin between June 2010 and March 2013 and discharged with the diagnosis of ischemic cryptogenic stroke. Sixty fulfilled predefined inclusion criteria. Follow-up was carried on and completed for the 54 patients who consented to implantable loop recorder (ILR) implantation. After ILR implantation, trans-telephonic data were collected monthly.

RESULTS

Atrial fibrillation episodes lasting more than 5 min were recorded in 25 patients (46%), median detection time was 5.4 months (range 1-18) and median duration of atrial fibrillation episodes was 20 h (range 7 min-8 days) with 19 patients (76%) remaining asymptomatic and the others experiencing weakness and dyspnoea but not palpitations.

CONCLUSION

Long-term heart rhythm monitoring is successful in unmasking silent atrial fibrillation in 46% of patients suffering a cryptogenic stroke with concomitant atrial fibrillation risk factors, but without history of arrhythmia or palpitations.

Silent atrial fibrillation: epidemiology, diagnosis, and clinical impact

Silent or subclinical asymptomatic atrial fibrillation (SAF) has currently gained wide interest in the epidemiologic, neurologic, and cardiovascular communities. It is well known that the electrophysiological and mechanical effects of symptomatic and silent atrial fibrillation (AF) are the same. It is probable that because "AF begets AF," progression from paroxysmal to persistent or permanent AF might be more rapid in patients with long-term unrecognized and untreated SAF, because no treatment is sought by or provided to such patients. Moreover, SAF is common and has significant clinical implications. The clinical consequences of SAF, which include emboli (silent or symptomatic), heart failure, and early mortality, are of paramount importance. Consequently, SAF should be considered in estimating the prevalence of the disease and its impact on morbidity, mortality, and quality of life. Several diagnostic methods of arrhythmia detection utilizing the surface electrocardiogram (ECG), subcutaneous ECG, or intracardiac devices have been utilized to seek meaningful arrhythmic markers of SAF. Whereas a wide range of clinical risk factors of SAF have been validated in the literature, there is an ongoing search for those arrhythmic risk factors that precisely identify and prognosticate outcome events in diverse populations at risk of SAF. Modern diagnostic modalities for the identification of SAF exist, but should be further explored, validated, and tailored to each patient needs. The scientific community should undertake the clinical challenge of identifying and treating SAF.

Cryptogenic Stroke: Making the Management Less Cryptic

Cryptogenic stroke (CS) accounts for 20% to 40% of ischemic strokes. CS is defined as a cortical infarct suggestive of an embolic stroke with no identifiable cardiac etiology, large vessel occlusive disease, or small vessel lacunar stroke. The likely etiologies for CS are patent foramen ovale (PFO) and paroxysmal atrial fibrillation, which can be detected by transesophageal echocardiography and long-term cardiac rhythm monitoring. In a busy academic hospital, the stroke service is frequently asked to provide a rational approach to patients with such a presentation. The 2011 American Heart Association/American Stroke Association recommends that antiplatelet therapy is "reasonable" (Class IIa; Level of Evidence B) for patients with PFO and a clinical presentation of CS. Confounding PFO management is the lack of a controlled trial comparing anticoagulation with antiplatelet therapy in patients with CS, despite the belief that the primary mechanism of PFO-mediated stroke would be that it serves as a conduit for venous emboli. Data from 3 recent prospective PFO closure device trials further compound the management protocols for these patients. Also complicating the management of CS is increasing evidence that paroxysmal atrial fibrillation may be found as often as 30% with extensive monitoring and long-term follow-up of 36 months. Based on these recent developments, we summarize the factors that we deemed relevant in our approach to patients with CS.

Utility of Duranta, a wireless patch-type electrocardiographic monitoring system developed in Japan, in detecting covert atrial fibrillation in patients with cryptogenic stroke: A case report

RATIONALE

Subcutaneous implantable electrocardiographs are highly effective in detecting covert atrial fibrillation (AF) in cryptogenic stroke. However, these invasive devices are not indicated for all cryptogenic stroke patients, and noninvasive improvements over conventional Holter-type ambulatory electrocardiography are needed. We evaluated the clinical application and effectiveness of Duranta (ImageONE Co., Ltd.), a wireless patch-type electrocardiographic monitoring system developed in Japan for chronically ill patients or home-based patients at the end of life. A Duranta device was used to detect covert AF in patients with acute ischemic stroke of undetermined source with no sign of AF during cardiographic monitoring ≥24 hours postadmission.

PATIENT CONCERNS

A 72-year-old man with severe aortic stenosis was admitted to our hospital with dysarthria and right upper limb weakness. Diffusion-weighted plain head magnetic resonance imaging (MRI) showed acute cerebral infarctions across the left middle cerebral artery territory. Twelve-lead electrocardiography, Holter-type ambulatory electrocardiography, and cardiographic monitoring for ≥24 hours revealed no AF, indicating a probable diagnosis of artery-to-artery embolism following left common carotid artery stenosis detected by carotid ultrasound imaging and cerebral angiography.

INTERVENTIONS

However, because of high blood brain natriuretic peptide (BNP) and valvular heart disease, continuous monitoring using Duranta was performed from the 2nd to 13th days after onset to exclude possible cardioembolic stroke. Waveform and heart rate trend graph analysis showed paroxysmal AF (PAF) occurred on the 5th and 9th days after onset. PAF did not occur at any other time during the observation period. The quality of the cardiograms sufficed for analysis and diagnosis of AF. The lightweight compact device can be placed quickly with no movement restriction. These features and our findings show the usefulness of the Duranta device for long-term continuous monitoring.

LESSONS

A noninvasive wireless patch-type electrocardiographic monitoring system, Duranta, placed at the precordium, was useful in detecting covert AF in cryptogenic stroke patients, warranting further investigation.

Electrocardiographic and Echocardiographic predictors of paroxysmal atrial fibrillation detected after ischemic stroke

BACKGROUND

Detection of atrial fibrillation after ischemic stroke is challenging due to its paroxysmal nature. We aimed to assess predictors of paroxysmal atrial fibrillation using non-invasive surface ECG and transthoracic echocardiography to select candidates for atrial fibrillation screening.

METHODS

Ischemic stroke patients without documented atrial fibrillation (n = 110, 67 ± 10 years, 40 female) and a control group of age- and gender-matched patients with history of paroxysmal atrial fibrillation prior to stroke (n = 55, 67 ± 10 years, 19 female) comprised the study sample. Using non-invasive ECG monitoring for three weeks, short episodes of paroxysmal atrial fibrillation were detected in 24 of 110 patients (22 %). The standard 12-lead ECG with sinus rhythm at stroke onset was digitally processed and analyzed. Transthoracic echocardiography data were reviewed for these patients.

RESULTS

Atrial fibrillation history was independently associated with P terminal force in lead V 1 > 40 mm*ms (OR 4.04 95 % CI 1.34-12.14, p = 0.013) and left atrial volume index (OR 1.08 95 % CI 1.03-1.13, p = 0.002; for LAVI > 40 mL/m² OR 6.40 95 % CL 1.47-27.91, p = 0.013). Among patients without atrial fibrillation history, no ECG characteristics were predictive of atrial fibrillation detected after stroke. Left atrial volume index remained an independent predictor of atrial fibrillation detected after stroke (OR 1.09 95 % CI 1.02-1.16, p = 0.017). A cutoff of <40 mL/m² had an 84 % negative predictive value for ruling out atrial fibrillation on ambulatory monitoring with a sensitivity of 50 % and a specificity of 86 %.

CONCLUSION

In a post hoc analysis, left atrial dilatation assessed by left atrial volume index independently predicted atrial fibrillation after stroke in patients without prior atrial fibrillation history, while the other clinical or ECG markers were not predictive of atrial fibrillation detected early after ischemic stroke.

TRIAL REGISTRATION

This study is a post hoc analysis from the prospective case-control study registered in December 2011, ClinicalTrials.gov ID: NCT01325545 .

The role of empiric superior vena cava isolation in atrial fibrillation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

It is not clear whether additional empiric superior vena cava isolation (SVCI) to pulmonary vein isolation (PVI) results in low recurrences of atrial fibrillation. We aimed to perform a systematic review and meta-analysis of all randomized controlled trials (RCTs) that evaluated role of empiric SVCI in atrial fibrillation ablation.

METHODS

We searched PubMed, EMBASE, Cochrane, Scopus, and relevant references for RCTs (inception April 15, 2016 without language restrictions) and performed meta-analysis using random effects model. Recurrence rates of atrial fibrillations, procedural times, fluoroscopic times, and adverse events were the measured outcomes.

RESULTS

Three RCTs with a total population of 526 were analyzed. There was no difference in the recurrence rate between PVI plus SVCI versus PVI alone when comparison was made across all types of AF (39 vs 60; odds ratio 0.68; 95 % CI 0.43-1.07; P = 0.73; I ² = 0 %). When analysis was restricted only to paroxysmal AF, there was a trend towards low recurrence rate in combination group without statistical significance (19 vs 35, OR 0.54; 95 % CI 0.29-1.00; P = 0.05; I ² = 0). Similarly, no difference was noted between two groups in procedural (weighted mean difference [WMD] 10.12; 95 % CI -9.84 to 30.08; P = 0.32; I ² = 85 %) and fluoroscopic time (WMD 4.66; 95 % CI -0.92 to 10.25; P = 0.1; I ² = 94). Adverse events were similar in both groups.

CONCLUSION

Empiric SVCI does not provide additional benefit to PVI alone for atrial fibrillation ablation.

Secondary Stroke Prevention: Improving Diagnosis and Management with Newer Technologies

Treatment of hypertension, diabetes, high cholesterol, smoking cessation, and healthy lifestyle have all contributed to the decline in the incidence of vascular disease over the last several decades. Patients who suffer an acute stroke are at a high risk for recurrence. Introduction of newer technologies and their wider use allows for better identification of patients in whom the risk of recurrence following an acute stroke may be very high. Traditionally, the major focus for diagnosis and management has focused on patient history, examination, imaging for carotid stenosis/occlusion, and detection of AF and paroxysmal AF (PAF) with 24-48 h cardiac monitoring. This review focuses on the usefulness of three newer investigative tools that are becoming widely available and lead to better prevention. Continuous ambulatory blood pressure measurements for 24 h or longer and 3D Doppler measures of the carotid arteries provide key useful information on the state of vascular health and enhance our ability to monitor the response to preventive therapies. Furthermore, the detection of PAF can be significantly improved with prolonged cardiac monitoring for 3 weeks or longer, enabling the initiation of appropriate prevention therapy. This review will focus on the potential impact and importance of these emerging technologies on the prevention of recurrent stroke in high-risk patients.

Total atrial conduction time to predict occult atrial fibrillation after cryptogenic stroke

BACKGROUND

Insertable cardiac monitor (ICM) increases the detection rate of occult atrial fibrillation (AF) after cryptogenic stroke. The aim of this study was to evaluate the prognostic significance of total atrial conduction time (TACT) assessed by tissue Doppler imaging (PA-TDI interval) to predict AF presence in patients with cryptogenic stroke.

METHODS

Ninety patients (57.7 ± 12.3 years, 48 % women) after acute cryptogenic stroke and ICM implantation were prospective recruited at four centers for continuous rhythm monitoring. In all patients, TACT was measured by PA-TDI interval via echocardiography. Patients were followed up (331 ± 186 days) for detection of AF (defined by episode lasting ≥30 s).

RESULTS

AF was detected in 16 patients (18 %) during follow-up (331 ± 186 days). The median period to AF detection was 30 days (q1-q3; 16-62 days). Patients who exhibited occult AF were characterized by significantly longer PA-TDI intervals (154.7 ± 12.6 vs. 133.9 ± 9.5 ms, p < 0.0001). The cut-off value of PA-TDI interval at 145 ms demonstrated sensitivity and specificity for AF detection of 93.8 and 90.5 %, respectively. In multivariate analysis, CHA2DS2-VASc score (HR 1.96 per 1 point, p < 0.01) and longer PA-TDI interval (HR 4.05 per 10 ms, p < 0.0001) were independent predictors of occult AF.

CONCLUSION

Our data suggest that measurement of TACT could help to predict future AF detection in patients with cryptogenic stroke. The clinical importance of prolonged rhythm monitoring or indication of direct anticoagulation therapy after cryptogenic stroke based on TACT should be further investigated.

Assessment of atrial fibrillation ablation outcomes with clinic ECG, monthly 24-h Holter ECG, and twice-daily telemonitoring ECG

Differences in the methodologies for evaluating atrial fibrillation (AF) ablation outcomes should be evaluated. In the present study, we compared the AF ablation outcomes among periodic clinic electrocardiography (ECG), 24-h Holter ECG, and telemonitoring ECG to evaluate the differences among these methods. In addition, we evaluated the AF-free survival rate for each method with different durations of the blanking period. A total of 30 AF patients were followed up for 6 months after initial catheter ablation, with clinic ECG on every clinic visit, monthly 24-h Holter ECG, and telemonitoring ECG twice daily and upon symptoms. AF relapse was defined as AF or atrial tachycardia detected with any of the methods. Two patients dropped out of the study, and 28 patients were followed up for 8.8 ± 2.7 months. Patients underwent 3.6 ± 0.8 clinic ECG, 5.1 ± 0.8 Holter ECG, and 273 ± 68 telemonitoring ECG examinations. During the first, second, third, fourth, fifth, and sixth months of follow-up, Holter ECG detected relapses in 11.1, 8.3, 11.5, 15.4, 4.2, and 4.8 % of patients and telemonitoring ECG detected relapses in 32.1, 25.0, 25.0, 17.9, 28.6, and 17.9 % of patients, respectively. When no duration was set for the blanking period, the AF-free survival rate was significantly lower with telemonitoring ECG (46.4 %) than with Holter ECG (78.6 %, P = 0.013) or clinic ECG (85.7 %, P = 0.002). In addition, when the duration of the blanking period was set to 3 months, the AF-free survival rate was significantly lower with telemonitoring ECG than with clinic ECG (92.9 vs. 71.4 %, P = 0.041). The AF ablation outcomes with twice-daily telemonitoring ECG might differ from those with clinic ECG when the duration of the blanking period is 0-3 months. A follow-up based solely on clinic ECG might underestimate AF recurrence.

Long-term Arrhythmia Monitoring in Cryptogenic Stroke: Who, How, and for How Long?

Cryptogenic stroke and transient ischemic attack (TIA) account for approximately one-third of stroke patients [1]. Paroxys-mal atrial fibrillation (PAF) has been suggested as a major etiology of these cryptogenic strokes [2, 3]. PAF can be difficult to diagnose because it is intermittent, often brief, and asymptomatic. PAF might be more prevalent than persistent atrial fibrillation in stroke and TIA patients, especially in younger populations [4, 5]. In patients with atrial fibrillation, anticoagulation provides significant risk reduction [6]. A new generation of oral anticoagulants has been approved for non-valvular atrial fibrillation, providing a variety of therapeutic options for patients with atrial fibrillation and risk of stroke [7]. Prior practice included an admission electrocardiogram (ECG) and continuous telemetry monitoring while in hospital [8]. However, this approach can lead to under-detection of brief asymptomatic events, which can occur at variable intervals, often outside of the hospital setting. Technological advancements have led to devices that can monitor cardiac rhythms outside of the hospital for longer durations resulting in higher yield of detection of atrial fibrillation events. Moreover, recent studies show that the normal monitoring time for arrhythmias may be shorter than ideal in order to detect atrial fibrillation, and increasing this interval could significantly improve detection of atrial fibrillation in these patients [9, 10]. The aim of this study is to review the literature in order to define what subgroup of patients, with what methodologies, and for how long monitoring for atrial fibrillation should occur in patients presenting with cryptogenic stroke.

How and When to Screen for Atrial Fibrillation after Stroke: Insights from Insertable Cardiac Monitoring Devices

The introduction of insertable cardiac monitoring devices has dramatically altered our understanding of the role of intermittent atrial fibrillation in cryptogenic stroke. In this narrative review we discuss the incidence, timing and relationship between atrial fibrillation and cryptogenic stroke, how to select patients for monitoring and the value and limitations of different monitoring strategies. We also discuss the role of empirical anticoagulation, and atrial fibrillation burden as a means of tailoring anticoagulation in patients at high risk of bleeding.

Optimal Duration of Monitoring for Atrial Fibrillation in Cryptogenic Stroke: A Nonsystematic Review

Atrial fibrillation (AF) is the most common form of cardiac arrhythmias and an independent risk factor for stroke. Despite major advances in monitoring strategies, clinicians tend to miss the diagnoses of AF and especially paroxysmal AF due mainly to its asymptomatic presentation and the rather limited duration dedicated for monitoring for AF after a stroke, which is 24 hours as per the current recommended guidelines. Hence, determining the optimal duration of monitoring for paroxysmal atrial fibrillation after acute ischemic stroke remains a matter of debate. Multiple trials were published in regard to this matter using both invasive and noninvasive monitoring strategies for different monitoring periods. The data provided by these trials showcase strong evidence suggesting a longer monitoring strategy beyond 24 hours is associated with higher detection rates of AF, with the higher percentage of patients detected consequently receiving proper secondary stroke prevention with anticoagulation and thus justifying the cost-effectiveness of such measures. Overall, we thus conclude that increasing the monitoring duration for AF after a cryptogenic stroke to at least 72 hours will indeed enhance the detection rates, but the cost-effectiveness of this monitoring strategy compared to longer monitoring durations is yet to be established.

North American Thrombosis Forum, AF Action Initiative Consensus Document

The North American Thrombosis Forum Atrial Fibrillation Action Initiative consensus document is a comprehensive yet practical briefing document focusing on stroke and bleeding risk assessment in patients with atrial fibrillation, as well as recommendations regarding anticoagulation options and management. Despite the breadth of clinical trial data and guideline recommendation updates, many clinicians continue to struggle to synthesize the disparate information available. This problem slows the uptake and utilization of updated risk prediction tools and adoption of new oral anticoagulants. This document serves as a practical and educational reference for the entire medical community involved in the care of patients with atrial fibrillation.

Uncovering Atrial Fibrillation Beyond Short-Term Monitoring in Cryptogenic Stroke Patients: Three-Year Results From the Cryptogenic Stroke and Underlying Atrial Fibrillation Trial

BACKGROUND

Atrial fibrillation (AF) can be a cause of previously diagnosed cryptogenic stroke. However, AF can be paroxysmal and asymptomatic, thereby making detection with routine ECG methods difficult. Oral anticoagulation is highly effective in reducing recurrent stroke in patients with AF, but its initiation is dependent on the detection of AF. Cryptogenic Stroke and Underlying Atrial Fibrillation (CRYSTAL AF) is the first randomized study to report the detection of AF in cryptogenic stroke patients using continuous long-term monitoring via insertable cardiac monitors (ICM).

METHODS AND RESULTS

Patients with prior cryptogenic stroke were randomized to control (n=220) or ICM (n=221) and followed for ≤36 months. Cumulative AF detection rates in the ICM arm increased progressively during this period (3.7%, 8.9%, 12.4%, and 30.0% at 1, 6, 12, and 36 months, respectively), but remained low in the control arm (3.0% at 36 months). This resulted in oral anticoagulation prescription in 94.7% of ICM patients with AF detected at 6 months, 96.6% at 12 months, and 90.5% at 36 months. Among ICM patients with AF detected, the median time to AF detection was 8.4 months, 81.0% of first AF episodes were asymptomatic, and 94.9% had at least 1 day with >6 minutes of AF.

CONCLUSIONS

Three-year monitoring by ICM in cryptogenic stroke patients demonstrated a significantly higher AF detection rate compared with routine care. Given the frequency of asymptomatic first episodes and the long median time to detection, these findings highlight the limitations of using traditional AF detection methods. The majority of patients with AF were prescribed oral anticoagulation therapy.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov; Unique identifier: NCT00924638.

Efficacy of Solitaire Stent Arterial Embolectomy in Treating Acute Cardiogenic Cerebral Embolism in 17 Patients

Background

Thrombolysis with rtPA is the only accepted drug therapy for acute ischemic stroke. Since acute cerebral stroke is so pervasive, newly developed recanalization methods have the potential for wide-ranging impacts on patient health and safety. We explored the efficacy and safety of Solitaire stent arterial embolectomy in the treatment of acute cardiogenic cerebral embolism.

Material/Methods

Between October 2012 and June 2015, 17 patients underwent Solitaire stent arterial embolectomy, either alone or in combination with rtPA intravenous thrombolysis, to treat acute cardiogenic cerebral embolism. Sheath placement time, vascular recanalization time, number of embolectomy attempts, and IV rtPA dose and time were recorded. Success and safety of the recanalization procedure, as well as clinical outcomes, were assessed. These results were compared to 16 control patients who were treated using only rtPA IV thrombolysis.

Results

Full recanalization of the occluded arteries was achieved in 15 (88.2%) of the Solitaire stent patients. NIH Stroke Scale scores of embolectomy patients improved by an average of 12.59±8.24 points between admission and discharge, compared to 5.56±5.96 in the control group (P<0.05). Glasgow Coma Score improvement between admission and discharge was also significantly higher in the embolectomy group (P<0.05). There was no significant difference in symptomatic intracerebral hemorrhage, high perfusion encephalopathy, incidence of hernia, or mortality between the 2 groups (P>0.05).

Conclusions

Solitaire stent embolectomy is a safe and effective alternative to simple venous thrombolytic therapy, and it can significantly improve short-term neurological function and long-term prognosis in acute cardiogenic cerebral embolism.

Does left atrial appendage (LAA) occlusion device alter the echocardiography and electrocardiogram parameters in patients with atrial fibrillation?

BACKGROUND

The alterations of echocardiography and electrocardiogram (ECG) in patients received left atrial appendage LAA occlusion therapy are still unclear. The present study was to evaluate the influence of LAA occlusion device on echocardiography and ECG changes in patients with atrial fibrillation (AF).

METHODS

Seventy-three patients who had undergone Watchman, LAmbre and Lefort were enrolled in this study. Echocardiography and ECG results at pre- and post-operation were collected. Besides, echocardiography was also performed during follow-up visits at 1, 6 and 12months after discharge.

RESULTS

After LAA occlusion, a slight and measureable movement of QRS electric axis was observed in most patients. The significant differences were also observed in heart rate (HR) and the mean-mean QT interval between pre- and post-operation for all patients. There existed no significant difference in echocardiographic parameters between before and after device implantation. However, a larger left atrial (LA) diameter was detected by echocardiography during follow-up visit at 6months when compared with pre-operation parameters. Similarly, aortic root diameter (ARD) was also larger during follow-up at 12months than the baseline dimension in pre-operation.

CONCLUSIONS

LAA occlusion device resulted in a slightly movement in QRS axis, reduced HR and increased the mean-mean QT interval duration. In addition, LA diameter and ARD seemed to be larger after device implantation.

Left Atrial Function Is Impaired in Some Patients With Stroke of Undetermined Etiology: Potential Implications for Evaluation and Therapy

INTRODUCTION AND OBJECTIVES

Stroke etiology remains undetermined in up to 30% of cases. Paroxysmal atrial fibrillation is found in 20% to 28% of patients with stroke initially classified as being of undetermined etiology. The aim of our study was to analyze left atrial function in ischemic stroke patients to identify patterns associated with cardioembolic etiology and to determine whether the patterns identified can be found in individuals initially classified as having a stroke of undetermined etiology.

METHODS

We studied a cohort of in-hospital ischemic stroke patients referred for transthoracic echocardiography. Treating neurologists determined stroke etiology based on the TOAST classification. Left atrial contractile function was assessed using 2-dimensional echocardiography to determine their ejection fraction and speckle tracking to measure left atrial strain rate: a-wave. Left atrial function was compared between stroke etiology subgroups and healthy controls.

RESULTS

Ninety-seven patients (aged 67±15 years) with ischemic stroke (16.5% large-artery atherosclerosis, 15.5% small-vessel occlusion, 11.3% cardioembolic, 5.1% other determined etiology, 51.1% undetermined etiology) and 10 healthy volunteers (aged 63±7 years) were included. Left atrial ejection fraction was significantly decreased only in patients with stroke of cardioembolic and undetermined etiology compared with the control group (31.5±17.2%, 40.2±17.1%, and 59.1±8.4%, respectively; P=.004). The left atrial strain rate was significantly lower in patients with stroke caused by cardioembolic or undetermined etiology, or large-artery atherosclerosis compared with controls (-0.86±0.49, -1.31±0.56, -1.5±0.47, -2.37±1.18, respectively; P<.001).

CONCLUSIONS

Patients with stroke of undetermined etiology with left atrial function (ejection fraction and strain) similar to that of cardioembolic stroke patients may be misclassified and could potentially benefit from prolonged electrocardiography monitoring. Left atrial function analysis (ejection fraction and strain) might help to identify potential cardioembolic sources in patients with stroke of undetermined etiology.

The Evolution and Application of Cardiac Monitoring for Occult Atrial Fibrillation in Cryptogenic Stroke and TIA

OPINION STATEMENT

The evaluation of the stroke and transient ischemic attack (TIA) patient has been historically predominated by the initial evaluation in the hospital setting. As the etiology of stroke has eluded us in approximately one third of all acute events, the medical community has been eager to seek the answer to this mystery. In recent years, we have seen an explosion of innovations and trends allowing for a more detailed post stroke assessment strategy aimed at the identification of occult atrial fibrillation as the etiologic cause for the cryptogenic event. This has been achieved through the evolution and aggressive application and study of prolonged and advanced cardiac monitoring. This review is aimed to clarify and elucidate the standard and novel cardiac monitoring methods that have become available for use by the medical community and expected in the higher level care of cryptogenic stroke and TIA patients. These cardiac monitoring methods and devices are as heterogeneous as our patient population and have their own advantages and disadvantages. Many factors may be taken into consideration in choosing the appropriate cardiac monitoring method and are highlighted for consideration in this review. With a judicious approach to investigating the cryptogenic stroke population, and applying a wealth of novel treatment options, we may move forward into a new era of stroke prevention.

An update on insertable cardiac monitors: examining the latest clinical evidence and technology for arrhythmia management

Continuous cardiac rhythm monitoring has undergone compelling progress over the past decades. Cardiac monitoring has emerged from 12-lead electrocardiograms being performed at the discretion of the treating physician to in-hospital telemetry, Holter monitoring, prolonged external event monitoring and most recently toward insertable device monitoring for several years. Significant advantages and disadvantages pertaining to these monitoring options will be addressed in this review. Insertable cardiac monitors have several advantages over external monitoring techniques and may signify a clinical turning point in the field of arrhythmia management. However, their role in the detection of paroxysmal atrial fibrillation after cryptogenic strokes has yet to evolve. This will be the main focus of this review. Issues surrounding patient selection, clinical relevance and determination of cost-effectiveness for prolonged cardiac monitoring require further studies. Furthermore, insertable cardiac monitoring has not only the potential to augment diagnostic capabilities but also to improve the management of paroxysmal atrial fibrillation.

Atrial cardiopathy: a broadened concept of left atrial thromboembolism beyond atrial fibrillation

Atrial fibrillation (AF) has long been associated with a heightened risk of ischemic stroke and systemic thromboembolism, but recent data require a re-evaluation of our understanding of the nature of this relationship. New findings about the temporal connection between AF and stroke, alongside evidence linking markers of left atrial abnormalities with stroke in the absence of apparent AF, suggest that left atrial thromboembolism may occur even without AF. These observations undermine the hypothesis that the dysrhythmia that defines AF is necessary and sufficient to cause thromboembolism. In this commentary, we instead suggest that the substrate for thromboembolism may often be the anatomic and physiological atrial derangements associated with AF. Therefore, our understanding of cardioembolic stroke may be more complete if we shift our representation of its origin from AF to the concept of atrial cardiopathy.

Detection of Silent Atrial Fibrillation aFter Ischemic StrOke (SAFFO) guided by implantable loop recorder: multicentre Italian trial based on stroke unit network with paired cardio-arrhythmology units (Italian Neurocardiology Unit Network)

RATIONALE

Atrial fibrillation is associated with a high risk of stroke and its prevalence increases in subjects aged ≥65 years. After an ischemic stroke, the use of standard monitoring methods may underestimate the detection rate of atrial fibrillation. Hence, it is very likely that even patients having a first atherothrombotic or lacunar stroke with high burden of vascular risk factors are exposed to increased risk of developing atrial fibrillation in the subsequent years and atrial fibrillation may be the cause underlying possible recurrent strokes AIM AND HYPOTHESIS: The Silent Atrial Fibrillation aFter Ischemic StrOke (SAFFO) trial has the objective to evaluate the detection of atrial fibrillation or atrial flutter as first diagnosis by implantable loop recorder in patients with first-ever atherothrombotic or lacunar stroke. We hypothesize that the detection will be higher than that observed by using standard cardiac monitoring

METHODS AND DESIGN

SAFFO is a prospective, multicenter, randomized, controlled, open-label trial with blinded assessment of outcome measures. Patients who fulfill inclusion criteria will be randomized to either continuous monitoring using an implantable loop recorder plus standard monitoring (intervention arm) or standard heart rhythm monitoring alone (control arm) with a ratio of 1:1 STUDY OUTCOMES: The primary endpoint is the detection of atrial fibrillation/atrial flutter as first diagnosis in the first 12 months of the study period

DISCUSSION

If positive, SAFFO trial could have important clinical implications in terms of changing the standard diagnostic protocol in patients with atherothrombotic and lacunar stroke, and of increasing the shift of secondary prevention treatment from antiplatelet to anticoagulant therapy.

Insertable cardiac monitors in the diagnosis of syncope and the detection of atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Insertable or implantable cardiac monitors (ICMs) continuously monitor the heart rhythm and record irregularities over 3 years, enabling the diagnosis of infrequent rhythm abnormalities associated with syncope and stroke. The enhanced recognition capabilities of recent ICM models are able to accurately detect atrial fibrillation (AF) and have led to new applications of ICMs for the detection and monitoring of AF.

METHODS AND RESULTS

Based on a systematic literature search, two indications were identified for ICMs for which considerable evidence, including randomized studies, exists: diagnosing the underlying cardiac cause of unexplained recurrent syncope and detecting AF in patients after cryptogenic stroke (CS). Three randomized controlled trials (RCTs) were identified that compared the effectiveness of ICMs in diagnosing patients with unexplained syncope (n = 556) to standard of care. A meta-analysis was conducted in order to generate an overall effect size and confidence interval of the diagnostic yield of ICMs versus conventional monitoring. In the indication CS, one RCT and five observational studies were included in order to assess the performance of ICMs in diagnosing patients with AF (n = 1129). Based on these studies, there is strong evidence that ICMs provide a higher diagnostic yield for detecting arrhythmias in patients with unexplained syncope and for detection of AF in patients after CS compared to conventional monitoring.

CONCLUSIONS

Prolonged monitoring with ICMs is an effective tool for diagnosing the underlying cardiac cause of unexplained syncope and for detecting AF in patients with CS. In all RCTs, ICMs have a superior diagnostic yield compared to conventional monitoring.

Cost-effectiveness of an insertable cardiac monitor to detect atrial fibrillation in patients with cryptogenic stroke

Background and aims

Documentation of atrial fibrillation is required to initiate oral anticoagulation therapy for recurrent stroke prevention. Atrial fibrillation often goes undetected with traditional electrocardiogram monitoring techniques. We evaluated whether atrial fibrillation detection using continuous long-term monitoring with an insertable cardiac monitor is cost-effective for preventing recurrent stroke in patients with cryptogenic stroke, in comparison to the standard of care.

Methods

A lifetime Markov model was developed to estimate the cost-effectiveness of insertable cardiac monitors from a UK National Health Service perspective using data from the randomized CRYSTAL-AF trial and other published literature. We also conducted scenario analyses (CHADS2 score) and probabilistic sensitivity analyses. All costs and benefits were discounted at 3.5%.

Results

Monitoring cryptogenic stroke patients with an insertable cardiac monitor was associated with fewer recurrent strokes and increased quality-adjusted life years compared to the standard of care (7.37 vs 7.22). Stroke-related costs were reduced in insertable cardiac monitor patients, but overall costs remained higher than the standard of care (£19,631 vs £17,045). The incremental cost-effectiveness ratio was £17,175 per quality-adjusted life years gained, compared to standard of care in the base-case scenario, which is below established quality-adjusted life years willingness-to-pay thresholds. When warfarin replaced non-vitamin-K oral anticoagulants as the main anticoagulation therapy, the incremental cost-effectiveness ratio was £13,296 per quality-adjusted life years gained.

Conclusion

Insertable cardiac monitors are a cost-effective diagnostic tool for the prevention of recurrent stroke in patients with cryptogenic stroke. The cost-effectiveness results have relevance for the UK and across value-based healthcare systems that assess costs relative to outcomes.

Detection of occult paroxysmal atrial fibrilation by implantable long-term electrocardiographic monitoring in cryptogenic stroke and transient ischemic attack population: a study protocol for prospective matched cohort study

BACKGROUND

Cardio-embolic etiology is the most frequently predicted cause of cryptogenic stroke/TIA. Detection of occult paroxysmal atrial fibrillation is crucial for selection of appropriate medication.

METHODS

Enrolment of eligible cryptogenic stroke and TIA patients began in 2014 and will continue until 2018. The patients undergo long-term (12 months) ECG monitoring (implantable loop recorder) and testing for PITX2 (chromosome 4q25) and ZFHX3 (chromosome 16q22) gene mutations. There will be an appropriate control group of age- and sex-matched healthy volunteers. To analyse the results descriptive statistics, statistical tests for group differences, and correlation analyses will be used.

DISCUSSION

In our study we are focusing on a possible correlation between detection of atrial fibrillation by an implantable ECG recorder, and PITX2 and/or ZFHX3 gene mutations in cryptogenic stroke/TIA patients. A correlation could lead to implementation of this genomic approach to cryptogenic stroke/TIA diagnostics and management. The results will be published in 2018.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02216370 .

Home Screening for Detecting Subclinical Atrial Fibrillation

The advent of cardiac implanted electronic devices with accurate atrial arrhythmia diagnostic capabilities has revealed a large burden of "silent " atrial fibrillation that is present in the cardiac population. Many studies have been completed, and many more are ongoing, to determine the correct treatment course when these atrial arrhythmias are detected. Alongside the development of accurate atrial diagnostics within the devices, has been the growth an entire network of wireless home monitoring capability. It is now possible to see, over the internet, individual patients' atrial arrhythmia burden on every day. This capability has tremendous promise for patient care, with the possibility of reducing strokes, decreasing heart failure, preventing cardiomyopathies, and likely substantially reducing health care costs. As this innovative diagnostic capability is generating large amounts of data, protocols for what should be done with the plethora of new information are being developed. In the pages that follow, we will present what is known about home monitoring for silent atrial fibrillation, and present the results of recent studies published in this arena.

Stroke Event Rates and the Optimal Antithrombotic Choice of Patients With Paroxysmal Atrial Fibrillation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

The risks of stroke or systemic embolism and major bleeding are considered similar between paroxysmal and sustained atrial fibrillation (AF), and warfarin has demonstrated superior efficacy to aspirin, irrespective of the AF type. However, with the advent of novel oral anticoagulants (NOACs) and antiplatelet agents, the optimal antithrombotic prophylaxis for paroxysmal AF remains unclear.We searched Medline, Embase, CENTRAL, and China Biology Medicine up to October week 1, 2015. Randomized controlled trials of AF patients assigned to NOACs, warfarin, or antiplatelets, with reports of outcomes stratified by the AF type, were included. A fixed-effects model was used if no statistically significant heterogeneity was indicated; otherwise, a random-effects model was used.Six studies of 69,990 nonvalvular AF patients with ≥1 risk factor for stroke were included. Postantithrombotic treatment, paroxysmal AF patients showed lower risks of stroke (risk ratio [RR], 0.72; 95% confidence interval [CI], 0.59-0.87), stroke or systemic embolism (RR, 0.74; 95% CI, 0.63-0.86), and all-cause mortality (RR, 0.75; 95% CI, 0.67-0.83), while the major bleeding risk was comparable (RR, 0.96; 95% CI, 0.85-1.08). We were unable to detect the superiority of anticoagulation over antiplatelets for paroxysmal AF (RR, 0.72; 95% CI, 0.43-1.23), while it was more effective than antiplatelets for sustained AF (RR, 0.42; 95% CI, 0.33-0.54). NOACs showed superior efficacy over warfarin and trended to show reduced major bleeding irrespective of the AF type.The AF type is a predictor for thromboembolism, and might be helpful in stroke risk stratification model in combination with other risk factors. With the appearance of novel anticoagulant and antiplatelet agents, the best antithrombotic choice for paroxysmal AF needs further exploration.

Paroxysmal Atrial Fibrillation in Cryptogenic Stroke: an Overlooked Explanation?

Approximately one third of ischemic strokes are labeled cryptogenic because the etiology is unknown despite a thorough evaluation. Paroxysmal atrial fibrillation carries the same risk of ischemic stroke as persistent atrial fibrillation and has increasingly gained attention as a potential source of cryptogenic stroke. Recent trials utilizing long-term cardiac monitoring devices have demonstrated high rates of previously undetected paroxysmal atrial fibrillation in patients with cryptogenic stroke. Newly detected atrial fibrillation has subsequently changed treatment and increased the use of oral anticoagulation in these studies. Other trials have shown an increased risk of stroke and thromboembolism in patients with device-detected subclinical tachyarrhythmias. Together, these studies suggest an important relationship between episodes of paroxysmal atrial fibrillation and the risk of cryptogenic stroke, but further investigations are needed to guide diagnostic and therapeutic decisions.

A Comparison of Atrial Fibrillation Monitoring Strategies After Cryptogenic Stroke (from the Cryptogenic Stroke and Underlying AF Trial)

Ischemic stroke cause remains undetermined in 30% of cases, leading to a diagnosis of cryptogenic stroke. Paroxysmal atrial fibrillation (AF) is a major cause of ischemic stroke but may go undetected with short periods of ECG monitoring. The Cryptogenic Stroke and Underlying Atrial Fibrillation trial (CRYSTAL AF) demonstrated that long-term electrocardiographic monitoring with insertable cardiac monitors (ICM) is superior to conventional follow-up in detecting AF in the population with cryptogenic stroke. We evaluated the sensitivity and negative predictive value (NPV) of various external monitoring techniques within a cryptogenic stroke cohort. Simulated intermittent monitoring strategies were compared to continuous rhythm monitoring in 168 ICM patients of the CRYSTAL AF trial. Short-term monitoring included a single 24-hour, 48-hour, and 7-day Holter and 21-day and 30-day event recorders. Periodic monitoring consisted of quarterly monitoring through 24-hour, 48-hour, and 7-day Holters and monthly 24-hour Holters. For a single monitoring period, the sensitivity for AF diagnosis was lowest with a 24-hour Holter (1.3%) and highest with a 30-day event recorder (22.8%). The NPV ranged from 82.3% to 85.6% for all single external monitoring strategies. Quarterly monitoring with 24-hour Holters had a sensitivity of 3.1%, whereas quarterly 7-day monitors increased the sensitivity to 20.8%. The NPVs for repetitive periodic monitoring strategies were similar at 82.6% to 85.3%. Long-term continuous monitoring was superior in detecting AF compared to all intermittent monitoring strategies evaluated (p <0.001). Long-term continuous electrocardiographic monitoring with ICMs is significantly more effective than any of the simulated intermittent monitoring strategies for identifying AF in patients with previous cryptogenic stroke.

Challenges and misconceptions in the aetiology and management of atrial fibrillation-related strokes

Strokes, whether ischaemic or haemorrhagic, are the most feared complications of atrial fibrillation (AF) and its treatment. Vitamin K antagonists have been the mainstay of stroke prevention. Recently, direct oral anticoagulants have been introduced. The advantages and disadvantages of these treatment strategies have been extensively discussed. In this narrative review, we discuss dilemmas faced by primary care clinicians in the context of stroke and transient ischaemic attack (TIA) in patients with AF. We discuss the classification of stroke, the different types of stroke seen with AF, the prognosis of AF-related strokes, the early management after AF-related stroke or TIA and the therapeutic options after anticoagulant-associated intracerebral haemorrhage. Most importantly, we aim to dispel common misconceptions on the part of non-stroke specialists that can lead to suboptimal stroke prevention and management.

Holter monitoring to detect silent atrial fibrillation in high-risk subjects: the Perugia General Practitioner Study

Atrial fibrillation (AF) is diagnosed for the first time in about 5 % of patients admitted for acute ischemic stroke. Advanced aged and arterial hypertension are risk factors for AF. We evaluated the prevalence of silent AF in subjects with advanced age and systemic arterial hypertension. Subjects of both gender, aged 65 years or more with systemic arterial hypertension were randomly identified from the patient lists of the participating general practitioners in the Perugia area, in Italy. Study subjects underwent baseline 12-lead ECG and, if this did not show AF, 48-h Holter monitoring was performed. AF was known and confirmed by 12-lead ECG in 4 out of the 308 evaluated subjects (1.3 %). Baseline 12-lead ECG showed no cases of silent AF. Holter monitoring was performed in 300 subjects, mean age 70 ± 4. Twenty-six recordings were not evaluable for the presence of artifacts; therefore, 274 subjects were included in the analysis. Holter monitoring showed AF in 27 out of 274 subjects (10 %; 95 % confidence interval 6.4-13.5 %); AF was longer than 30 s in four of the subjects. In 56 additional subjects, Holter monitoring revealed excessive supraventricular ectopic activity (20 %; 95 % confidence interval 15.3-24.7 %). Holter monitoring was able to detect silent AF in about 10 % of subjects aged 65 or above with systemic arterial hypertension. The risk of stroke associated with screened silent AF should be carefully evaluated.

Predictors of new onset atrial fibrillation during 10-year follow-up after first-ever ischemic stroke

BACKGROUND

Paroxysmal atrial fibrillation (AF) may be underdiagnosed in ischemic stroke patients but may be pivotal for initiation of oral anticoagulation therapy. We assessed clinical and ECG predictors of new-onset AF during 10-year follow-up (FU) in ischemic stroke patients.

METHODS

The study sample comprised of 227 first-ever ischemic stroke patients without AF (median age 73, interquartile range 25%-75% 63-80years, 92 female) and 1:1 age- and gender-matched controls without stroke and AF enrolled in the Lund Stroke Register from March 2001 to February 2002. New-onset AF during FU was assessed by screening through regional ECG database and by record linkage with Swedish National Patient Register. The standard 12-lead sinus rhythm ECGs at stroke admission were retrieved from electronic database and digitally processed. Clinical baseline characteristics were studied using medical records.

RESULTS

During FU, AF was found in 39 stroke patients and 30 controls, p=0.296. In stroke patients in multivariate Cox regression analysis AF was associated with hypertension (HR 3.45 CI 95% 1.40-3.49, p=0.007) and QRS duration (HR 1.02 CI 95% 1.00-1.03, p=0.049). High cardiovascular risk was predictive for AF development: for CHADS2≥4 HR 2.46 CI 95% 1.45-4.18, p=0.001 and for CHA2DS2-VASc≥5 HR 2.29 CI 95% 1.43-3.68, p=0.001. New onset AF was not associated with baseline ischemic stroke: HR 1.46 95% CI 0.90-2.35, p=0.121.

CONCLUSION

High CHADS2 and CHA2DS2-VASc scores, but not baseline ischemic stroke, predict new onset AF in FU. QRS duration might be considered a potential risk marker for prediction of AF after ischemic stroke.

Emerging role of digital technology and remote monitoring in the care of cardiac patients

Current available mobile health technologies make possible earlier diagnosis and long-term monitoring of patients with cardiovascular diseases. Remote monitoring of patients with implantable devices and chronic diseases has resulted in better outcomes reducing health care costs and hospital admissions. New care models, which shift point of care to the outpatient setting and the patient's home, necessitate innovations in technology.

Aetiological diagnosis of middle-aged and elderly cryptogenic ischaemic cerebral vascular disease

Although tremendous efforts have been made to explore the potential aetiologies of cryptogenic ischaemic cerebral vascular disease (CICVD), it remains a great challenge for neurologists to get a comprehensive picture of CICVD across the world. Part of the reason why is that the vast majority of studies have focussed on CICVD in young stroke patients while the underlying causes of CICVD in middle-aged or elderly stroke population have not been fully investigated. The focus of this paper has been dedicated to review the different studies that explore the aetiologies of CICVD cases in this patient population. While there is a set of heterogeneous causes that can lead to CICVD in middle-aged and elderly patients, our review reveals that emboli originated from or across occult places within the heart or produced by transient arrhythmias could possibly be the main culprit. Dislodged aortic plaques might also account for certain CICVD cases and in fewer cases, hereditary arteriopathy and thrombophilia can also play a role. The aforementioned factors have similar roles in middle-aged and elderly CICVD patients as in their younger counterparts. However, more studies are needed to explore the role of these factors in older patients.

Predictors of Finding Occult Atrial Fibrillation After Cryptogenic Stroke

Background and Purpose—

Occult paroxysmal atrial fibrillation (AF) is found in a substantial minority of patients with cryptogenic stroke. Identifying reliable predictors of paroxysmal AF after cryptogenic stroke would allow clinicians to more effectively use outpatient cardiac monitoring and ultimately reduce secondary stroke burden.

Methods—

We analyzed a retrospective cohort of consecutive patients who underwent 28-day mobile cardiac outpatient telemetry after cryptogenic stroke or transient ischemic stroke. Univariate and multivariable analyses were performed to identify clinical, echocardiographic, and radiographic features associated with the detection of paroxysmal AF.

Results—

Of 227 patients with cryptogenic stroke (179) or transient ischemic stroke (48), 14% (95% confidence interval, 9%–18%) had AF detected on mobile cardiac outpatient telemetry, 58% of which was ≥30 seconds in duration. Age >60 years (odds ratio, 3.7; 95% confidence interval, 1.3–11) and prior cortical or cerebellar infarction seen on neuroimaging (odds ratio, 3.0; 95% confidence interval, 1.2–7.6) were independent predictors of AF. AF was detected in 33% of patients with both factors, but only 4% of patients with neither. No other clinical features (including demographics, CHA 2 DS 2 -VASc [combined stroke risk score: congestive heart failure, hypertension, age, diabetes, prior stroke/transient ischemic attack, vascular disease, sex] score, or stroke symptoms), echocardiographic findings (including left atrial size or ejection fraction), or radiographic characteristics of the acute infarction (including location, topology, or number) were associated with AF detection.

Conclusions—

Mobile cardiac outpatient telemetry detects AF in a substantial proportion of cryptogenic stroke patients. Age >60 years and radiographic evidence of prior cortical or cerebellar infarction are robust indicators of occult AF. Patients with neither had a low prevalence of AF.

Detection of occult atrial fibrillation in patients with embolic stroke of uncertain source: a work in progress

Atrial fibrillation accounts for a substantial proportion of ischemic strokes of known etiology and may be responsible for an additional subset of the 25–40% of strokes of unknown cause (so-called cryptogenic). Oral anticoagulation is significantly more effective than antiplatelet therapy in the secondary prevention of atrial fibrillation-related strokes, providing justification for developing more sensitive approaches to detecting occult paroxysms of atrial fibrillation. In this article, we summarize the current state of knowledge regarding the value of in-hospital and out-patient monitoring for detecting atrial fibrillation in the context of cryptogenic stroke. We review the evidence for and against screening with standard Holter monitors, external loop recorders, the newer real-time continuous attended cardiac monitoring systems, cardiac implantable electronic devices, and insertable loop recorders. We review key questions regarding prolonged cardiac arrhythmia monitoring, including the relationship between duration of the atrial fibrillation episode and risk of thromboembolism, frequency of monitoring and its impact on the diagnostic yield in detecting occult or subclinical atrial fibrillation, and the temporal proximity of device-detected atrial fibrillation to stroke events. We conclude by proposing avenues for further research.