Unexpected low prevalence of atrial fibrillation in cryptogenic ischemic stroke: a prospective study

Clinical utilisation of implantable loop recorders in adults with Fabry disease-a multi-centre snapshot study

Fabry disease (FD) is an X-linked deficiency of alpha-galactosidase-A, leading to lysosomal storage of sphingolipids in multiple organs. Myocardial accumulation contributes to arrhythmia and sudden death, the most common cause of FD mortality. Therefore, there is a need for risk stratification and prediction to target device therapy. Implantable loop recorders (ILRs) allow for continual rhythm monitoring for up to 3 years. Here, we performed a retrospective study to evaluate current ILR utilisation in FD and quantify the burden of arrhythmia that was detected, which resulted in a modification of therapy. This was a snapshot assessment of 915 patients with FD across three specialist centres in England during the period between 1 January 2000 and 1 September 2022. In total, 22 (2.4%) patients underwent clinically indicated ILR implantation. The mean implantation age was 50 years and 13 (59%) patients were female. Following implantation, nine (41%) patients underwent arrhythmia detection, requiring intervention (six on ILR and three post-ILR battery depletion). Three patients experienced sustained atrial high-rate episodes and were started on anticoagulation. Three had non-sustained tachyarrhythmia and were started on beta blockers. Post-ILR battery depletion, one suffered complete heart block and two had sustained ventricular tachycardia, all requiring device therapy. Those with arrhythmia had a shorter PR interval on electrocardiography. This study demonstrates that ILR implantation in FD uncovers a high burden of arrhythmia. ILRs are likely to be underutilised in this pro-arrhythmic cohort, perhaps restricted to those with advanced FD cardiomyopathy. Following battery depletion in three patients as mentioned above, greater vigilance and arrhythmia surveillance are advised for those experiencing major arrhythmic events post-ILR monitoring. Further work is required to establish who would benefit most from implantation.

Detection of atrial fibrillation using an implantable loop recorder in patients with previous cryptogenic stroke: the SPIDER-AF registry (Stroke Prevention by Increasing DEtection Rates of Atrial Fibrillation)

BACKGROUND

The use of implantable loop recorder (ILR) to detect atrial fibrillation (AF) in patients with a history of cryptogenic stroke (CS) has seldom been investigated in "real-world" settings.

OBJECTIVE

This study aimed to present the results of the Stroke Prevention by Increasing DEtection Rates of Atrial Fibrillation (SPIDER-AF) registry.

METHOD

SPIDER is a multicentric, observational registry, including 35 facilities all over Germany. It enrolled outpatients without AF history and with CS before ILR implantation.

RESULTS

We included 500 patients (mean age 63.1 ± 12.7 years), 304 (60.8%) were males, with previous stroke (72.6%) and TIA (27.4%). After inclusion, all were followed for at least 12 months. AF was detected in 133 (26.8%), 25.3% of patients with previous stroke and 29.9% with TIA (p = 0.30). AF was detected after a median of 121.5 days (IQR 40.5-223.0). AF was primarily paroxysmal (95.7% after stroke, 100% after TIA). In 19.5% (n = 26) anticoagulation was not administered after AF detection. Mean CHA2DS2-VASc score (OR 1.22; CI 1.01-1.49; p = 0.037) and age > 70 years (OR 0.41; CI 0.19-0.88; p = 0.0020) correlated with AF. Repeat cerebrovascular events at follow-up (28; 5.6%) correlated with AF (OR = 2.17; CI 1.00-4.72; p = 0.049). AF (p = 0.91) and recurrent events (p = 0.43) occurred similarly in females and males.

CONCLUSIONS

In the context of cryptogenic strokes ILRs are a valuable tool for early detection of AF. In a real-world scenario, the anticoagulation therapy remains inadequate despite diagnosed AF in a relevant subset of patients requiring optimization of patient management.

Subcutaneouscardiac Rhythm Monitors: A Comprehensive Review

Subcutaneous loop recorders (SCRMs) are subcutaneous electronic devices which have revolutionized the field of arrhythmia detection. They have become increasingly appealing due to advances such as miniaturization of device, longer battery life, bluetooth capabilities and relatively simple implantation technique without the need for complex surgical suites. They can be implanted in the office, patient bedside without the need to go to the operating room. One of the most common indications for their implantation is detection of atrial fibrillation (AF) after a cryptogenic stroke. They have also been utilized for assessing the success of rhythm control strategies such post pulmonary venous isolation. More recently studies have assessed the utility of SCRMs for detecting silent AF in at risk populations such as patients with sleep apnea or those on hemodialysis. In this paper, we review the evolution of SCRMs, the clinical studies assessing their value for different indications, their role incurrent clinical practice and future avenues in the era of smart wearable devices like apple watch etc.

Insertable cardiac monitors for detection of atrial fibrillation after cryptogenic stroke: a meta-analysis

BACKGROUND

In recent years, the implantable cardiac monitors (ICM) have enhanced the recognition ability of atrial fibrillation (AF), which makes ICM have a new application in AF detection. We conducted a meta-analysis to determine the total incidence of newly found AF detected by ICM after cryptogenic stroke and to evaluate the factors related to the detection of AF.

METHODS

A literature search was conducted in the PubMed, EMBASE, Web of Science, and Cochrane library databases until March 1, 2020. Studies that reported the detection rate of AF using ICM in cryptogenic stroke patients with negative initial AF screening were analyzed.

RESULTS

A total of 23 studies were included. The overall proportion of AF detected by ICM in cryptogenic stroke patients was 25% (95% confidence interval [CI], 22-29%). The rate of AF detected by ICM was independently related to both cardiac monitoring time (coefficient = 0.0003; 95% CI, 0.0001-0.0005; P = 0.0001) and CHA₂DS₂-VASc score (coefficient = 0.0834; 95% CI, 0.0339-0.1329; P = 0.001). In subgroup analysis, we found a significant difference in the detection rate of AF for monitoring duration (< 6 months: 9.6% [95% CI, 4.4-16.4%]; ≥ 6 and ≤ 12 months: 19.3% [95% CI, 15.9-23.0%]; > 12 and ≤ 24 months: 23.6% [95% CI, 19.9-27.5%]; > 24 months and ≤ 36 months: 36.5% [95% CI, 24.2-49.9%]; P < 0.001), and continent (Europe: 26.5% [95% CI, 22.2-31.0%]; North America: 16.0% [95% CI, 10.3-22.6%]; Asia: 17.4% [95% CI, 12.4-23.0%]; P = 0.005).

CONCLUSIONS

The longer the time of ICM monitoring after cryptogenic stroke, the higher the detection rate of AF. Further research is still needed to determine the optimal duration of long-term cardiac monitoring.

Atrial high-rate episodes: prevalence, stroke risk, implications for management, and clinical gaps in evidence

Self-terminating atrial arrhythmias are commonly detected on continuous rhythm monitoring, e.g. by pacemakers or defibrillators. It is unclear whether the presence of these arrhythmias has therapeutic consequences. We sought to summarize evidence on the prevalence of atrial high-rate episodes (AHREs) and their impact on risk of stroke. We performed a comprehensive, tabulated review of published literature on the prevalence of AHRE. In patients with AHRE, but without atrial fibrillation (AF), we reviewed the stroke risk and the potential risk/benefit of oral anticoagulation. Atrial high-rate episodes are found in 10–30% of AF-free patients. Presence of AHRE slightly increases stroke risk (0.8% to 1%/year) compared with patients without AHRE. Atrial high-rate episode of longer duration (e.g. those >24 h) could be associated with a higher stroke risk. Oral anticoagulation has the potential to reduce stroke risk in patients with AHRE but is associated with a rate of major bleeding of 2%/year. Oral anticoagulation is not effective in patients with heart failure or survivors of a stroke without AF. It remains unclear whether anticoagulation is effective and safe in patients with AHRE. Atrial high-rate episodes are common and confer a slight increase in stroke risk. There is true equipoise on the best way to reduce stroke risk in patients with AHRE. Two ongoing trials (NOAH-AFNET 6 and ARTESiA) will provide much-needed information on the effectiveness and safety of oral anticoagulation using non-vitamin K antagonist oral anticoagulants in patients with AHRE.

Silencing of Long Non-coding RNA GAS5 Suppresses Neuron Cell Apoptosis and Nerve Injury in Ischemic Stroke Through Inhibiting DNMT3B-Dependent MAP4K4 Methylation

Ischemic stroke is associated with various physiological and pathological processes including neuronal apoptosis. Growth-arrest-specific transcript 5 (GAS5), a long non-coding RNA (lncRNA), has been recently reported to affect ischemic stroke-induced neuron apoptosis, while its mechanisms remain largely undefined. Through in silico analysis, GAS5 was predicted to interact with the promoter of MAP4K4. The aim of the present study was therefore to investigate the possible role of GAS5 in the progression of ischemic stroke via regulation of mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) methylation. The expression of MAP4K4 was found to be lowly expressed in the clinical samples collected from 55 patients. MAP4K4 was suggested to be methylated in an in vitro model of oxygen-glucose deprivation (OGD)-treated mouse primary cortical neurons, while its overexpression could inhibit OGD-induced neuronal apoptosis. A series of dual-luciferase reporter, RIP, RNA pull-down, ChIP MSP, and BSP assays confirmed that GAS5 significantly induced MAP4K4 methylation and downregulated MAP4K4 expression through the recruitment of DNA methyltransferase 3B (DNMT3B). An in vivo ischemic stroke model was developed using middle cerebral artery occlusion (MCAO). Upregulation of GAS5 promoted OGD-induced neuronal apoptosis in the in vitro model and increased cerebral infarction size and neurological score in the in vivo model by reducing MAP4K4 expression. Collectively, the present study highlights that silencing GAS5 may inhibit neuronal apoptosis and improve neurological function in ischemic stroke by suppressing DNMT3B-mediated MAP4K4 methylation, which contributes to better understanding of the pathologies of ischemic stroke and development of novel therapeutic options for this disease.

Cryptogenic stroke and atrial fibrillation in a real-world population: the role of insertable cardiac monitors

The incidence of atrial fibrillation (AF) in cryptogenic stroke (CS) patients has been studied in carefully controlled clinical trials, but real-world data are limited. We investigated the incidence of AF in clinical practice among CS patients with an insertable cardiac monitor (ICM) placed for AF detection. Patients with CS admitted to our Stroke Unit were included in the study; they received an ICM and were monitored for up to 3 years for AF detection. All detected AF episodes of at least 120 sec were considered. From March 2016 to March 2019, 58 patients (mean age 68.1 ± 9.3 years, 67% male) received an ICM to detect AF after a CS. No patients were lost to follow-up. AF was detected in 24 patients (41%, AF group mean age 70.8 ± 9.4 years, 62% male) after a mean time of 6 months from ICM (ranging from 2 days to 2 years) and 8 months after CS (ranging from 1 month to 2 years). In these AF patients, anticoagulant treatment was prescribed and nobody had a further stroke. In conclusion, AF episodes were detected via continuous monitoring with ICMs in 41% of implanted CS patients. AF in CS patients is asymptomatic and difficult to diagnose by strategies based on intermittent short-term recordings. Therefore, we suggest that ICMs should be part of daily practice in the evaluation of CS patients.

MR-imaging pattern is not a predictor of occult atrial fibrillation in patients with cryptogenic stroke

Background

To date, insertable cardiac monitors (ICMs) are the most effective method for the detection of occult atrial fibrillation (AF) in cryptogenic stroke. The overall detection rate after 12 months, however, is low and ranges between 12.4 and 33.3%, even if clinical predictors are considered. Ischemic stroke patients due to cardiogenic embolism present with particular lesion patterns. In patients with cryptogenic stroke, MR-imaging pattern may be a valuable predictor for AF.

Methods

This is an MRI-based, retrospective, observational, comparative, single-center study of 104 patients who underwent ICM implantation after cryptogenic stroke. The findings were compared to a reference group with related stroke etiology, i.e., 166 patients with embolic stroke due to AF detected for the first time by long-term ECG. Lesion patterns were evaluated with regard to affected territories, distribution (cortical, lacunar, scattered), lesion volume, and lesion size (diameter of the lesion size > 20 mm).

Results

The MR-imaging analysis of acute ischemic lesions yielded no association between AF and lesion size or volume, arterial vessel distribution, or the number of affected territories. There was no significant difference between the cohorts regarding ischemic patterns (cortical lesions, scattered lesions, and lacunar infarcts). An important clinical inference of our findings is that 10% (2 of 20) of cases in the ICM group in whom AF was detected had a lacunar infarct pattern. Similar results were shown in cases of ischemic stroke patients with AF detected for the first time by long-term ECG, with 10.9% (16 of 147) of them showing lacunar infarcts. The analysis of chronic MRI lesions revealed no differences between the groups in the rate of chronic lesions, arterial vessel distribution, or the number of affected territories. Left atrial size (LA size) and the presence of atrial runs in long-term ECG were independently associated with AF.

Conclusions

In this MRI-based analysis of patients with cryptogenic stroke who had received ICM implantation, the detection rate of AF in patients with ICM was not related to the imaging pattern. In addition, the lacunar infarct pattern should not be an exclusion criterion for ICM insertion in patients with cryptogenic stroke. ICM insertion in patients with cryptogenic stroke should not be evaluated solely on the basis of reference to infarct patterns.

Duration of Implantable Cardiac Monitoring and Detection of Atrial Fibrillation in Ischemic Stroke Patients: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Current guidelines do not provide firm directions on atrial fibrillation (AF) screening after ischemic stroke (IS). We sought to investigate the association of implantable cardiac monitoring (ICM) duration with the yield of AF detection in IS patients.

METHODS

We included studies reporting AF detection rates by ICM in IS patients with negative initial AF screening. We excluded studies reporting prolonged cardiac monitoring with devices other than ICM, not providing AF detection rates or monitoring duration, and reporting overlapping data for the same population. The random-effects model was used for all pooled estimates and meta-regression analyses.

RESULTS

We included 28 studies (4,531 patients, mean age 65 years). In meta-regression analyses, the proportion of AF detection by ICM was independently associated with monitoring duration (coefficient=0.015; 95% confidence interval [CI], 0.005 to 0.024) and mean patient age (coefficient=0.009; 95% CI, 0.003 to 0.015). No associations were detected with other patient characteristics, including IS subtype (cryptogenic vs. embolic stroke of undetermined source) or time from IS onset to CM implantation. In subgroup analyses, significant differences (P<0.001) in the AF detection rates were found for ICM duration (<6 months: 5% [95% CI, 3% to 6%]; ≥6 and ≤12 months: 21% [95% CI, 16% to 25%]; >12 and ≤24 months: 26% [95% CI, 22% to 31%]; >24 months: 34% [95% CI, 29% to 39%]).

CONCLUSION

s Extended duration of ICM monitoring and increased patient age are factors that substantially increase AF detection in IS patients with initial negative AF screening.

Implantable Loop Recorders for Cryptogenic Stroke (Plus Real-World Atrial Fibrillation Detection Rate with Implantable Loop Recorders)

Cryptogenic stroke (CS) represents 10%-40% of ischemic strokes and is associated with significant morbidity and mortality and high risk of recurrence. Undetected atrial fibrillation is an important consideration in these patients. Tools for electrocardiographic monitoring range from 12-lead electrocardiogram to implantable loop recorders (ILRs). ILRs have become an important tool for long-term electrocardiogram monitoring in CS patients. Advancements in ILR technology are needed to ensure more robust connectivity and to help triage incoming data. An unresolved issue is what duration of AF indicates that the CS patient is at high risk for recurrent stroke and thus would benefit from initiation of anticoagulation.

Newer technologies for detection of atrial fibrillation

Atrial fibrillation is a common arrhythmia that is associated with increased risk of stroke, which can be reduced with appropriate anticoagulation treatment. However, it remains underdiagnosed in contemporary clinical practice using conventional detection methods, resulting in missed opportunities to implement appropriate treatment. Newer technologies developed in recent years can potentially enhance the detection of atrial fibrillation and overcome certain limitations of the conventional methods. However, uncertainties remain about their use and the significance of atrial fibrillation detected by some of these newer technologies. This review examines the evidence supporting the use of some of these technologies and evaluates their applications in certain clinical scenarios.

Extended ECG monitoring with an implantable loop recorder in patients with cryptogenic stroke: time schedule, reasons for explantation and incidental findings (results from the TRACK-AF trial)

BACKGROUND

Implantable loop recorders (ILR) may be used to detect occult atrial fibrillation (AF) in patients with cryptogenic stroke. At present, there has been no description on the incidental findings of stored episodes in these patients. Furthermore, no standard practice has been established with respect to the duration of continued ECG monitoring in these patients.

MATERIALS AND METHODS

In the prospective monocentric study (TRACK-AF), a total of 173 patients with cryptogenic stroke received an ILR for detection of AF between November 2010 and December 2014. Before implantation all patients had undergone recommended protocols for detection of stroke causes.

RESULTS

During a mean follow-up of 24.8 ± 11.5 months, atrial tachyarrhythmias were detected in n = 33 pts (19.1%). Diagnosis of AF was made after a mean of 10.7 ± 11.4 months, time to first AF detection ranged between 0.2 and 39.8 months. In 15 patients (8.7%), other incidental findings were stored in the ILR memory. Short episodes of sinus arrest at night not requiring a permanent pacemaker were present in 8 pts (4.6%). DDD-pacemaker implantation due to sinus arrest or symptomatic bradyarrhythmias occurred in 5 patients (2.9%) after a median monitoring period of 23.1 ± 7.4 months. Further incidental findings were atrial flutter and an AV-nodal-reentry tachycardia in one patient, respectively. Both patients underwent successful catheter ablation. So far, ILR were explanted in 111 pts, and 71 ILR were explanted before end of service status of the battery. Main reason for ILR explantation was patients' preference (51%), followed by battery depletion (24%) and diagnosis of AF (15%).

CONCLUSION

The present study revealed a significant number of ECG findings during continued ECG monitoring for AF in patients with cryptogenic stroke. Apart from AF (17.5% during the first 1.5 years), other clinical relevant arrhythmias requiring, e.g., pacemaker implantations, were observed. With respect to these findings, we recommend to extend ILR monitoring to the end of battery life. However, acceptance of continued ECG monitoring until battery depletion was poor; in 71 patients (64%), the ILR were explanted before the end of battery life.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov: NCT02641678.

Long-term monitoring to detect atrial fibrillation with the indwelling implantable cardiac monitors

An increasing number of detection tools are available and several detection strategies have been described to pursue the diagnosis of atrial fibrillation to prevent ischemic stroke. Monitoring tools include standard electrocardiography, snapshot single-lead recordings with professional or personal devices (e.g. smartphone-based), Holter monitor, external devices with long-term recording capabilities, and cardiac implantable electronic devices, including pacemakers, implantable cardioverter defibrillators and insertable cardiac monitors. Insertable cardiac monitors have shown high sensitivity and specificity for the detection of atrial fibrillation, allow up to three years of continuous monitoring, do not require cooperation of the patient, are well tolerated, have a short device-related time delay between detection of atrial fibrillation and notification to the physician, provide information on atrial fibrillation burden and are minimally invasive. On the other hand, insertable cardiac monitors require a considerable use of resources to process the recordings and have a significant initial cost. Studies conducted with insertable cardiac monitors on patients with prior stroke and on patients with risk factors for stroke but no prior cerebrovascular events or atrial fibrillation have consistently shown a measurable incidence of atrial fibrillation at follow-up. However, the effectiveness of oral anticoagulations in reducing the incidence of ischemic stroke in patients with atrial fibrillation lasting less than 24 h, though reasonable, is currently unproven. The future of atrial fibrillation detection tools and atrial fibrillation detection strategies will be influenced by ongoing studies exploring whether oral anticoagulations reduce the incidence of stroke in patients with atrial fibrillation burden lower than 24 h.

Subclinical atrial fibrillation in patients with recent transient ischemic attack

BACKGROUND

Atrial fibrillation (AF) is a major risk factor of stroke, but the association between AF and transient ischemic attack (TIA) is less clear. Despite this, patients with TIA are included in stroke trials.

AIMS

To determine the 1-year incidence of AF in TIA patients using an insertable cardiac monitor (ICM); second, to determine factors associated with incident AF in these patients.

METHODS

Prospective cohort study of patients with TIA with normal standard electrocardiogram (ECG) and 72-hour Holter monitoring (HM). Exclusion criteria were as follows: age < 18 or > 81 years; prior AF/stroke; ongoing oral anticoagulation therapy or contraindication for it; significant carotid artery stenosis; uncertain TIA diagnosis. Eligible patients received an ICM and were followed for 12 months.

RESULTS

From November 2013 to October 2015, 809 patients were diagnosed with TIA. In total, 235 patients were eligible. Nine (3.8%) of these had AF on standard ECG or HM. Of the remaining patients, 121 refused ICM implantation. In total, 105 patients (median age 65.4 years [range 27.1-80.8], 46% males) received an ICM, which revealed AF in 7 (6.7%). Factors associated with new-onset AF were a history of recurrent TIA (odds ratio [OR] 11.5, 95% confidence interval [CI] 2.1-63.6) and heart failure (OR 12.7, 95% CI 1.71-96.83).

CONCLUSIONS

The 1-year incidence of AF in TIA patients with normal ECG and HM was 6.7% using an ICM. Factors associated with development of AF were recurrent TIA and heart failure.

Detection and management of atrial fibrillation after cryptogenic stroke or embolic stroke of undetermined source

Cryptogenic stroke (CS) and embolic stroke of unknown source (ESUS) represent a major challenge to healthcare systems worldwide. Atrial fibrillation (AF) is commonly found after CS or ESUS. Independent of the mechanism of the index CS or ESUS, detection of AF in these patients offers the opportunity to reduce the risk of stroke recurrence by prescribing an anticoagulant instead of aspirin. The detection of AF may be pursued with different monitoring strategies. Comparison of monitoring strategies should take into account that AF detection rates reported in published studies, and then pooled in meta-analyses, are not only a function of the monitoring strategy itself, but also depend on patient-related, device-related, and study design-related factors. Once AF is found, the decision to anticoagulate a patient should be made on the basis of AF burden and the baseline risk of the patient. Empirical anticoagulation in patients with ESUS and no evidence of AF is an intriguing but still-unproven strategy and therefore should not be adopted outside of randomized clinical trials.

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.

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.

Atrial high-rate episodes and stroke prevention

While the benefit of oral anticoagulants (OACs) for stroke prevention in patients with atrial fibrillation (AF) is well established, it is not known whether oral anticoagulation is indicated in patients with atrial high-rate episodes (AHRE) recorded on a cardiac implantable electronic device, sometimes also called subclinical AF, and lasting for at least 6 min in the absence of clinically diagnosed AF. Clinical evidence has shown that short episodes of rapid atrial tachycarrhythmias are often detected in patients presenting with stroke and transient ischaemic attack. Patients with AHRE have a higher likelihood of suffering from subsequent strokes, but their stroke rate seems lower than in patients with diagnosed AF, and not all AHRE episodes correspond to AF. The prognostic and pathological significance of AHRE is not yet fully understood. Clinical trials of OAC therapy are being conducted to determine whether therapeutic intervention would be beneficial to patients experiencing AHRE in terms of reducing the risk of stroke.

Embolic stroke and after-admission atrial fibrillation

BACKGROUND

Although atrial fibrillation (AF) is a leading cause of recurrent embolic stroke, secondary AF after stroke has been reported frequently. Because of the different treatment each uses, it is important to detect the exact stroke-etiology.

OBJECTIVES

The aim of this study was to compare the embolic stroke in patients with known AF and after-admission AF (AAAF).

METHODS

Between October 2002 and July 2009, those who were diagnosed with AF (n=354) were enrolled in our study out of a total of 2026 acute ischemic stroke (IS) patients. The embolic lesion patterns were assessed by two stroke specialists who were blinded to the clinical information.

RESULTS

Among 354 IS patients with AF, the number of patients with embolic stroke was 314. Patients with embolic stroke were younger and more likely to have larger left atrial (LA)/Aortic diameter ratio. Approximately 90.4% of those with known AF had embolic stroke, while <60% of patients with AAAF had embolic stroke. Nevertheless, anticoagulants were prescribed similarly in both groups at discharge. The LA/Aortic diameter ratio<1.5 was significantly related to AAAF. After adjusting for multiple co-variables, compared to the patients with known AF, patients with AAAF had reduced risk of embolic stroke (Odds ratio 0.11, 95% Confidence interval 0.03-0.36, p-value<0.001).

CONCLUSIONS

Compared to AAAF after stroke, known AF was associated with embolic stroke. Therefore, we suggest that stroke etiology and some novel echocardiographic indicators such as LA enlargement might be contemplated before routine using of anticoagulants in IS patients with AF.

Cardiac monitoring for detection of atrial fibrillation after TIA: A systematic review and meta-analysis

Background and purpose

The detection rate of atrial fibrillation has not been studied specifically in transient ischemic attack (TIA) patients although extrapolation from ischemic stroke may be inadequate. We conducted a systematic review and meta-analysis to determine the rate of newly diagnosed atrial fibrillation using different methods of ECG monitoring in TIA.

Methods

A comprehensive literature search was performed following a pre-specified protocol the PRISMA statement. Prospective observational studies and randomized controlled trials were considered that included TIA patients who underwent cardiac monitoring for >12 h. Primary outcome was frequency of detection of atrial fibrillation ≥30 s. Analyses of subgroups and of duration and type of monitoring were performed.

Results

Seventeen studies enrolling 1163 patients were included. The pooled atrial fibrillation detection rate for all methods was 4% (95% CI: 2–7%). Yield of monitoring was higher in selected (higher age, more extensive testing for arrhythmias before enrolment, or presumed cardioembolic/cryptogenic cause) than in unselected cohorts (7% vs 3%). Pooled mean atrial fibrillation detection rates rose with duration of monitoring: 4% (24 h), 5% (24 h to 7 days) and 6% (>7 days), respectively. Yield of non-invasive was significantly lower than that of invasive monitoring (4% vs. 11%). Significant heterogeneity was observed among studies (I2=60.61%).

Conclusion

This first meta-analysis of atrial fibrillation detection in TIA patients finds a lower atrial fibrillation detection rate in TIA than reported for IS and TIA cohorts in previous meta-analyses. Prospective studies are needed to determine actual prevalence of atrial fibrillation and optimal diagnostic procedure for atrial fibrillation detection in TIA.

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.

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.

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.

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.

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 .

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.

Very Short Paroxysms Account for More Than Half of the Cases of Atrial Fibrillation Detected after Stroke and TIA: A Systematic Review and Meta-Analysis

Background

Guidelines suggest that only poststroke atrial fibrillation episodes lasting 30 s or longer should be considered for anticoagulation. However, little evidence supports this recommendation.

Aims

We performed a systematic review and meta-analysis to investigate the frequency of poststroke atrial fibrillation lasting less than 30 s in stroke and transient ischemic attack patients.

Methods

We searched PubMed, Embase, and Scopus from 1980 to June 30, 2014 for studies reporting the detection of poststroke atrial fibrillation of less than 30 s and of 30 s or longer. The primary endpoint was the proportion of screened patients diagnosed with poststroke atrial fibrillation lasting less than 30 s. The secondary endpoint was the proportion of patients diagnosed with poststroke atrial fibrillation shorter than 30 s among the overall number of patients in whom a poststroke atrial fibrillation was detected after stroke or transient ischemic attack.

Results

From 28 290 titles, we included nine studies in the random-effects meta-analysis. Among stroke and transient ischemic attack patients without a history of atrial fibrillation, 9·0% (95% confidence interval: 4·9–14·3) experienced episodes of poststroke atrial fibrillation shorter than 30 s. An additional 6·5% (95% confidence interval: 3·2–10·9) experienced episodes of poststroke atrial fibrillation longer than 30 s. Among all patients with poststroke atrial fibrillation, 56·3% (95% confidence interval: 37·7–74·0) had poststroke atrial fibrillation episodes shorter than 30 s during diagnostic evaluation. Conclusions The clinical and prognostic significance of poststroke atrial fibrillation episodes shorter than 30 s is unknown. The high frequency of poststroke atrial fibrillation episodes shorter than 30 s justify further investigation into the risk of stroke recurrence and the risk–benefit profile of anticoagulation for this patient population.

Resting 12-lead electrocardiogram reveals high-risk sources of cardioembolism in young adult ischemic stroke

BACKGROUND

The diagnostic work-up to reveal etiology in a young ischemic stroke (IS) patient includes evaluation for high-risk source of cardioembolism (HRCE), since this subtype associates with high early recurrence rate and mortality. We investigated the association of ECG findings with a final etiologic subgroup of HRCE in a cohort of young patients with first-ever IS.

METHODS

The Helsinki Young Stroke Registry includes IS patients aged 15 to 49 years admitted between 1994 and 2007. Blinded to other clinical data, we analyzed a 12-lead resting ECG obtained 1-14 days after the onset of stroke symptoms in 690 patients. We then compared the ECG findings between a final diagnosis of HRCE (n=78) and other/undetermined causes (n=612). We used multivariate logistic regression to study the association between ECG parameters and HRCE.

RESULTS

Of our cohort (63% male), 35% showed ECG abnormality, the most common being T-wave inversion (16%), left ventricular hypertrophy (14%), prolonged P-wave (13%), and prolonged QTc (12%). 3% had atrial fibrillation (AF), and 4% P-terminal force (PTF). Of the continuous parameters, longer QRS-duration, QTc, and wider QRS-T-angle independently associated with HRCE. After AF, PTF had the strongest independent association with HRCE (odds ratio=44.32, 95% confidence interval=[10.51-186.83]), followed by a QRS-T angle >110° (8.29 [3.55-19.32]), T-wave inversion (5.06, 2.54-10.05), and prolonged QTc (3.02 [1.39-6.56]).

CONCLUSION

Routine ECG provides useful information for directing the work-up of a young IS patient. In addition to AF, PTF in particular showed a strong association with etiology of HRCE.

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.

Electrocardiographic monitoring for detecting atrial fibrillation after ischemic stroke or transient ischemic attack: systematic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is a major cause of stroke. Although standard investigations after an event include electrocardiographic monitoring, the optimal duration to detect AF is unclear. We performed a systematic review and meta-analysis to determine whether the duration of electrocardiographic monitoring after an ischemic event is related to the detection of AF.

METHODS AND RESULTS

Prospective studies that reported the proportion of new AF diagnosed using electrocardiographic monitoring for > 12 hours in patients with recent stroke or transient ischemic attack were analyzed. Studies were excluded if the stroke was hemorrhagic or AF was previously diagnosed. A total of 31 articles met inclusion criteria. Longer duration of monitoring was associated with an increased detection of AF when examining monitoring time as a continuous variable (P < 0.001 for metaregression analysis). When dichotomizing studies based on monitoring duration, studies with monitoring lasting ≤ 72 hours detected AF in 5.1%, whereas monitoring lasting ≥ 7 days detected AF in 15%. The proportion of new diagnosis increased to 29.15% with extended monitoring for 3 months. Significant heterogeneity within studies was detected for both groups (≤ 72 hours, I(2) = 91.3%; ≥ 7 days, I(2) =7 5.8). When assessing the odds of AF detection in the 3 randomized controlled trial, there was a 7.26 increased odds of AF with long-term monitoring (95% confidence intervals [3.99-12.83]; P value < 0.001).

CONCLUSIONS

Longer duration of electrocardiographic monitoring after cryptogenic stroke is associated with a greater detection of AF. Future investigation is needed to determine the optimal duration of long-term monitoring.

Cryptogenic Stroke And Role Of Loop Recorder

Ischemic stroke is an important cause of morbidity and mortality when untreated. Identifying atrial fibrillation is important because atrial fibrillation ischemic related strokes are associated with an increased risk of disability and death compared with strokes of other etiologies and tend to recur without anticoagulation. However, atrial fibrillation detection can be difficult when it is asymptomatic and paroxistic and may be the underlying cause of some cryptogenic strokes or strokes of unknown origin. In this review, the different methods of cardiac monitoring to detect atrial fibrillation in patients with cryptogenic stroke are summarized, with a focus on loop recorder monitoring.

Cryptogenic stroke: Is silent atrial fibrillation the culprit?

BACKGROUND

Stroke without an identifiable cause is frightening to patients and their families and is frustrating for the caring physician. Approximately 30% of patients with cardiac implanted electronic devices have some evidence of atrial fibrillation (AF), and much of it is silent: asymptomatic, and previously unrecognized.

OBJECTIVE

The purpose of this review is to examine "silent AF" as a potential cause of cryptogenic stroke.

METHODS/RESULTS

We begin by reviewing most of the published literature on screening for AF with different monitoring technologies in the setting of cryptogenic stroke. We present the results of 2 recent large randomized trials, CRYSTAL AF and EMBRACE, which compare standard of care monitoring in cryptogenic stroke patients to invasive and noninvasive monitoring strategies, respectively. Finally, we review the relationship of silent AF to stroke in the cardiac implanted electronic device population. Patient selection, duration of monitoring, sensitivity and specificity of monitoring technology, patient compliance, and several other factors affect the yield of AF detection during monitoring.

CONCLUSION

Data suggest that silent AF is identified in approximately 30% of cryptogenic stroke patients and has important therapeutic implications. Oral anticoagulation likely should be prescribed when silent AF is detected.

Cryptogenic stroke and underlying atrial fibrillation

BACKGROUND

Current guidelines recommend at least 24 hours of electrocardiographic (ECG) monitoring after an ischemic stroke to rule out atrial fibrillation. However, the most effective duration and type of monitoring have not been established, and the cause of ischemic stroke remains uncertain despite a complete diagnostic evaluation in 20 to 40% of cases (cryptogenic stroke). Detection of atrial fibrillation after cryptogenic stroke has therapeutic implications.

METHODS

We conducted a randomized, controlled study of 441 patients to assess whether long-term monitoring with an insertable cardiac monitor (ICM) is more effective than conventional follow-up (control) for detecting atrial fibrillation in patients with cryptogenic stroke. Patients 40 years of age or older with no evidence of atrial fibrillation during at least 24 hours of ECG monitoring underwent randomization within 90 days after the index event. The primary end point was the time to first detection of atrial fibrillation (lasting >30 seconds) within 6 months. Among the secondary end points was the time to first detection of atrial fibrillation within 12 months. Data were analyzed according to the intention-to-treat principle.

RESULTS

By 6 months, atrial fibrillation had been detected in 8.9% of patients in the ICM group (19 patients) versus 1.4% of patients in the control group (3 patients) (hazard ratio, 6.4; 95% confidence interval [CI], 1.9 to 21.7; P<0.001). By 12 months, atrial fibrillation had been detected in 12.4% of patients in the ICM group (29 patients) versus 2.0% of patients in the control group (4 patients) (hazard ratio, 7.3; 95% CI, 2.6 to 20.8; P<0.001).

CONCLUSIONS

ECG monitoring with an ICM was superior to conventional follow-up for detecting atrial fibrillation after cryptogenic stroke. (Funded by Medtronic; CRYSTAL AF ClinicalTrials.gov number, NCT00924638.).

Detection of atrial fibrillation after ischemic stroke or transient ischemic attack: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Atrial fibrillation (AF) confers a high risk of recurrent stroke, although detection methods and definitions of paroxysmal AF during screening vary. We therefore undertook a systematic review and meta-analysis to determine the frequency of newly detected AF using noninvasive or invasive cardiac monitoring after ischemic stroke or transient ischemic attack.

METHODS

Prospective observational studies or randomized controlled trials of patients with ischemic stroke, transient ischemic attack, or both, who underwent any cardiac monitoring for a minimum of 12 hours, were included after electronic searches of multiple databases. The primary outcome was detection of any new AF during the monitoring period. We prespecified subgroup analysis of selected (prescreened or cryptogenic) versus unselected patients and according to duration of monitoring.

RESULTS

A total of 32 studies were analyzed. The overall detection rate of any AF was 11.5% (95% confidence interval, 8.9%-14.3%), although the timing, duration, method of monitoring, and reporting of diagnostic criteria used for paroxysmal AF varied. Detection rates were higher in selected (13.4%; 95% confidence interval, 9.0%-18.4%) than in unselected patients (6.2%; 95% confidence interval, 4.4%-8.3%). There was substantial heterogeneity even within specified subgroups.

CONCLUSIONS

Detection of AF was highly variable, and the review was limited by small sample sizes and marked heterogeneity. Further studies are required to inform patient selection, optimal timing, methods, and duration of monitoring for detection of AF/paroxysmal AF.

Improved Detection of Silent Atrial Fibrillation Using 72-Hour Holter ECG in Patients With Ischemic Stroke

Background and Purpose—

Adequate diagnosis of atrial fibrillation (AF), including paroxysmal AF, is an important part of stroke workup. Prolonged ECG monitoring may improve the detection of paroxysmal, previously undiagnosed AF (unknown AF). Therefore, we evaluated systematic 72-hour Holter ECG monitoring to detect unknown AF for the workup of patients with stroke.

Methods—

Unselected survivors of a stroke or transient ischemic attack (TIA) without known AF were enrolled in a prospective, multicenter cohort study of 72-hour Holter ECG monitoring in 9 German secondary and tertiary stroke centers between May 2010 and January 2011. In addition to standardized workup of stroke pathogenesis according to the German Stroke Unit protocol, all patients underwent 72-hour Holter ECG monitoring directly after admission. All ECGs were centrally analyzed by 2 independent observers. We determined the proportion of unknown AF and compared the detection rates of 72- and 24-hour monitoring.

Results—

A total of 1135 patients were enrolled (mean age, 67 years [SD, 13.1 years], 45% women, 29% TIA). Unknown AF was detected in 49 out of 1135 patients (4.3%, [95% confidence interval, 3.4–5.2%]) by 72-hour ECG monitoring. Unknown AF was diagnosed in 29 patients (2.6%) within the first 24 hours of ECG monitoring, and in 20 more patients only by 72 hours of ECG monitoring. The number needed to screen by 72-hour ECG was 55 patients (95% confidence interval [35–123]) for each additional AF diagnosis. Patients with unknown AF were significantly older and had more often a history of previous stroke. Patients with unknown AF were equally distributed within categories of pathogenesis according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification.

Conclusions—

In unselected survivors of stroke or TIA, 72-hour ECG monitoring is feasible and improves the detection rate of silent paroxysmal AF.

Left atrial appendage volume increased in more than half of patients with cryptogenic stroke

BACKGROUND

Ischemic strokes without a well-defined etiology are labeled as cryptogenic, and account for 30-40% of strokes in stroke registries. The left atrial appendage (LAA) is the most typical origin for intracardiac thrombus formation when associated with atrial fibrillation. Here, we examined whether increased LAA volume detected with cardiac computed tomography (cCT) constitutes a risk factor in cryptogenic stroke patients.

METHODS

This study included 82 stroke/TIA patients (57 males; mean age, 58 years) with a diagnosis of cryptogenic stroke after extensive radiological and cardiological investigations. Cases were classified using the TOAST criteria modified by European Association of Echocardiography recommendations for defining cardiac sources of embolism. Forty age- and gender-matched control subjects without cardiovascular diseases were selected for pair-wise comparisons (21 males; mean age, 54 years). LAA volume adjusted for body surface area was measured three dimensionally by tracing the LAA borders on electrocardiogram-gated CT slices.

RESULTS

In control subjects, mean LAA volume was 3.4±1.1 mL/m(2). Mean+2SD, which was considered the upper limit for normal LAA volume was 5.6 mL/m(2). In paired Student t-test between the patient group and matched controls, LAA volume was 67% larger in cryptogenic stroke/TIA patients (5.7±2.0 mL/m(2) vs. 3.4±1.1 mL/m(2); P<0.001). Forty-five (55%) patients with cryptogenic stroke/TIA had enlarged LAA.

CONCLUSION

LAA is significantly enlarged in more than half of patients with cryptogenic stroke/TIA. LAA thrombosis may contribute to the pathogenesis of stroke in patients considered to have cryptogenic stroke after conventional evaluation.

Role of extended external loop recorders for the diagnosis of unexplained syncope, pre-syncope, and sustained palpitations

AIMS

To assess the diagnostic yield of new external loop recorders (ELRs) in patients with history of syncope, pre-syncope, and sustained palpitations.

METHODS AND RESULTS

Since 2005, we have established a registry including patients who consecutively received ELR monitoring for unexplained syncope or pre-syncope/palpitations. The registry included 307 patients (61% females, age 58 ± 19 years, range 8-94 years) monitored by high-capacity memory ELR of two subsequent generations: SpiderFlash-A(®) (SFA(®), Sorin CRM), storing two-lead electrocardiogram (ECG) patient-activated recordings by loop-recording technique (191 patients, 54 patients with syncope, years 2005-09), and SpiderFlash-T(®) (SFT(®)), adding auto-trigger detection for pauses, bradycardia, and supraventricular/ventricular arrhythmias (116 patients, 38 patients with syncope, years 2009-12). All the patients previously underwent routine workup for syncope or palpitation, including one or more 24 h Holter, not conclusive for diagnosis. Mean monitoring duration was 24.1 ± 8.9 days. Among 215 patients with palpitations, a conclusive diagnosis was obtained in 184 patients (86% diagnostic yield for palpitation). Among 92 patients with syncope, a conclusive diagnosis was obtained in 16 patients (17% clinical diagnostic yield for syncope), with recording during syncope of significant arrhythmias in 9 patients, and sinus rhythm in 7 patients. Furthermore, asymptomatic arrhythmias were de novo detected in 12 patients (13%), mainly by auto-trigger detection, suggesting an arrhythmic origin of the syncope.

CONCLUSIONS

The diagnostic yield of ELR in patients with syncope, pre-syncope, or palpitation of unknown origin after routine workup was similar to implantable loop recorder (ILR) within the same timeframe, therefore, ELR could be considered for patients candidate for long-term ECG monitoring, stepwise before ILR.