Cost-Effectiveness of Outpatient Cardiac Monitoring to Detect Atrial Fibrillation After Ischemic Stroke

Soft Bioelectronics for Heart Monitoring

Cardiovascular diseases (CVDs) are a predominant global health concern, accounting for over 17.9 million deaths in 2019, representing approximately 32% of all global fatalities. In North America and Europe, over a million adults undergo cardiac surgeries annually. Despite the benefits, such surgeries pose risks and require precise postsurgery monitoring. However, during the postdischarge period, where monitoring infrastructures are limited, continuous monitoring of vital signals is hindered. In this area, the introduction of implantable electronics is altering medical practices by enabling real-time and out-of-hospital monitoring of physiological signals and biological information postsurgery. The multimodal implantable bioelectronic platforms have the capability of continuous heart sensing and stimulation, in both postsurgery and out-of-hospital settings. Furthermore, with the emergence of machine learning algorithms into healthcare devices, next-generation implantables will benefit artificial intelligence (AI) and connectivity with skin-interfaced electronics to provide more precise and user-specific results. This Review outlines recent advancements in implantable bioelectronics and their utilization in cardiovascular health monitoring, highlighting their transformative deployment in sensing and stimulation to the heart toward reaching truly personalized healthcare platforms compatible with the Sustainable Development Goal 3.4 of the WHO 2030 observatory roadmap. This Review also discusses the challenges and future prospects of these devices.

A battery-less wireless implant for the continuous monitoring of vascular pressure, flow rate and temperature

Devices for monitoring blood haemodynamics can guide the perioperative management of patients with cardiovascular disease. Current technologies for this purpose are constrained by wired connections to external electronics, and wireless alternatives are restricted to monitoring of either blood pressure or blood flow. Here we report the design aspects and performance parameters of an integrated wireless sensor capable of implantation in the heart or in a blood vessel for simultaneous measurements of pressure, flow rate and temperature in real time. The sensor is controlled via long-range communication through a subcutaneously implanted and wirelessly powered Bluetooth Low Energy system-on-a-chip. The device can be delivered via a minimally invasive transcatheter procedure or it can be mounted on a passive medical device such as a stent, as we show for the case of the pulmonary artery in a pig model and the aorta and left ventricle in a sheep model, where the device performs comparably to clinical tools for monitoring of blood flow and pressure. Battery-less and wireless devices such as these that integrate capabilities for flow, pressure and temperature sensing offer the potential for continuous monitoring of blood haemodynamics in patients.

Experience and insights from a prolonged electrocardiographic monitorization with a wearable system after an embolic stroke of unknown source

BACKGROUND

Embolic cerebrovascular events that remain of unknown etiology after a thorough diagnostic evaluation, are known as Embolic Strokes of Undetermined Source (ESUS). Subclinical atrial fibrillation (AF) represents a significant underlying cause of ESUS. Our aims were to examine the overall diagnostic yield of a prolonged cardiac monitoring wearable system (PCMw) after an ESUS to detect AF and factors associated with it, including the time frame from the ESUS event to PCMw initiation. Additionally, to evaluate the frequency of unexpected arrhythmic events (UAE) and their prognostic implications.

METHODS

We retrospectively analyzed 200 ECG recordings (3-leads, 30 days duration) by means of a PCMw in patients with an ESUS to detect AF lasting longer than 30 s, between 2017 and 2021. UAE were defined as arrhythmia events that were not correlated to the main reason of prolonged cardiac monitoring.

RESULTS

AF was detected in 21 patients (10.5%). Patients with AF had more left atrial enlargement (OR = 4.22 [1.59-6.85]; p = .01) and atrial arrythmias in the initial 24-h Holter during hospitalization (OR = 5.73 [2.03-16.49]; p = .001). The detection of AF was significatively higher if the PCMw was worn within the first 30 days after the ESUS compared to beyond 30 days (17% vs. 10.3%; p = .002). Fifty three patients (26.5%) had UAE during PCMw. In six of them these findings led to targeted treatment.

CONCLUSION

PCMw represents a feasible non-invasive device that could reliably detect subclinical AF episodes after an ESUS. Diagnostic yield was significatively higher when used within the first 30 days after the event, especially in selected patients. UAE were common, but did not impact prognosis.

Intensive 90-day textile wearable Holter monitoring: an alternative to detect paroxysmal atrial fibrillation in selected patients with cryptogenic stroke

We aimed to demonstrate the feasibility of 90-day cardiac monitoring with an external Holter device and to find a target population able to benefit from such a technique. Cryptogenic stroke patients were continuously monitored for 90 days with a textile wearable Holter (TWH). Compliance and quality of the monitoring were assessed by the number of hours of ECG stored per month. Mean predictors of pAF, including age, gender, stroke severity, and atrial size (LAVI), were evaluated. One-year follow-up assessed pAF detection outside per protocol monitoring. Out of 224 patients included in 5 stroke centers, 163 patients (72.76%) fulfilled the criteria for the protocol. Median monitoring time was similar among the three months. Per protocol pAF detection reached 35.37% at 90 days. The age (OR 1.095; 95% CI 1.03-1.14) and the LAVI (OR 1.055; 95% CI 1.01-1.09) independently predicted pAF. The cut-off point of 70 years (AUC 0.68) (95% CI 0.60-0.76) predicted pAF with a sensitivity of 75.8% and specificity of 50.5%. The LAVI cut-off point of 28.5 (AUC 0.67) (95% CI 0.56-0.77) had a sensitivity of 63.6% and a specificity of 61.8% to detect pAF. The combination of both markers enhanced the validity of pAF detection sensitivity to 89.6%, with a specificity of 27.59%. These patients had increased risk of pAF during the 90-day monitoring HR 3.23 (χ² 7.15) and beyond 90 days (χ² 5.37). Intensive 90-days TWH monitoring detected a high percentage of pAF. However, a significant number of patients did not complete the monitoring. Patients older than 70 years and with enlarged left atria benefitted more from the protocol.

Cost-Effectiveness of Monitoring Patients Post-Stroke With Mobile ECG During the Hospital Stay

Background

The effectiveness of a nurse‐led in‐hospital monitoring protocol with mobile ECG (iECG) was investigated for detecting atrial fibrillation in patients post‐ischemic stroke or post‐transient ischemic attack. The study aimed to assess the cost‐effectiveness of using iECG during the initial hospital stay compared with standard 24‐hour Holter monitoring.

Methods and Results

A Markov microsimulation model was constructed to simulate the lifetime health outcomes and costs. The rate of atrial fibrillation detection in iECG and Holter monitoring during the in‐hospital phase and characteristics of modeled population (ie, age, sex, CHA2DS2‐VASc) were informed by patient‐level data. Costs related to recurrent stroke, stroke management, medications (new oral anticoagulants), and rehabilitation were included. The cost‐effectiveness analysis outcome was calculated as an incremental cost per quality‐adjusted life‐year gained. As results, monitoring patients with iECG post‐stroke during the index hospitalization was associated with marginally higher costs (A$31 196) and greater benefits (6.70 quality‐adjusted life‐years) compared with 24‐hour Holter surveillance (A$31 095 and 6.66 quality‐adjusted life‐years) over a 20‐year time horizon, with an incremental cost‐effectiveness ratio of $3013/ quality‐adjusted life‐years. Monitoring patients with iECG also contributed to lower recurrence of stroke and stroke‐related deaths (140 recurrent strokes and 20 deaths avoided per 10 000 patients). The probabilistic sensitivity analyses suggested iECG is highly likely to be a cost‐effective intervention (100% probability).

Conclusions

A nurse‐led iECG monitoring protocol during the acute hospital stay was found to improve the rate of atrial fibrillation detection and contributed to slightly increased costs and improved health outcomes. Using iECG to monitor patients post‐stroke during initial hospitalization is recommended to complement routine care.

Use of Prolonged Cardiac Rhythm Monitoring to Identify Atrial Fibrillation After Cryptogenic Stroke

PURPOSE OF REVIEW

Prolonged cardiac monitoring (PCM) improves detection of atrial fibrillation (AF) after cryptogenic stroke. We summarize current research supporting the use of PCM as part of the cryptogenic stroke evaluation, while highlighting areas that require more investigation.

RECENT FINDINGS

Despite increased AF detection with longer durations of PCM, more definitive research is needed to demonstrate how PCM improves clinical outcomes. The optimal type, timing, and length of cardiac monitoring after cryptogenic stoke remains unknown. Clinical calculators will be important to risk stratify which cryptogenic stroke patients are most likely to benefit from PCM. Currently, AF detection after cryptogenic stroke should prompt consideration of anticoagulation, but it is unclear if all durations and timing of AF after stroke should be treated the same. PCM remains an important part of the cryptogenic stroke work up, and detection of AF allows for anticoagulation initiation. Additional research is needed to further refine our application of PCM to cryptogenic stroke.

Use of risk scores for predicting new atrial fibrillation after ischemic stroke or transient ischemic attack-A systematic review

BACKGROUND

Newly detected atrial fibrillation (NDAF) following an ischemic stroke or transient ischemic attack is often paroxysmal in nature. While challenging to detect, extended electrocardiographic (ECG) monitoring is often used to identify NDAF which has resource implications. Prognostic risk scores have been derived which may stratify the risk of NDAF and inform patient selection for ECG monitoring approaches after ischemic stroke/transient ischemic attack.

AIM

The overall aim was to identify risk scores that were derived and/or validated to predict NDAF after ischemic stroke/transient ischemic attack and evaluate their performance.

SUMMARY OF REVIEW

A systematic literature review was undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, with application of the Quality Assessment of Diagnostic Accuracy-2 tool. Published studies, which derived and validated clinical risk scores in patients with ischemic stroke/transient ischemic attack, or externally validated an existing score to predict NDAF after ischemic stroke/transient ischemic attack, were considered and independently screened by two reviewers. Twenty-one studies involving 23 separate cohorts were analyzed from which 17 integer-based risk scores were identified. The overall frequency of NDAF was 9.7% (95% confidence intervals 8%-11.5%; I²= 98%). The performance of the scores varied widely among derivation and validation cohorts (area under the receiver operating characteristic curve (AUC) 0.54-0.94); scores derived from stroke cohorts (12 scores) appeared to perform better (AUC 0.7-0.94) than those derived from non-stroke cohorts (five scores; AUC 0.53-0.79). The scores also varied considerably in their complexity, ascertainment, component variables, participant characteristics, outcome definition, and ease of application limiting their generalizability and utility.

CONCLUSION

Overall, the risk scores identified performed variably in their discriminative ability and the utility of these scores to predict NDAF in clinical practice remains uncertain. Further studies are required using larger prospective cohorts and randomized control trials to evaluate the usefulness of such scores for clinical decision making and preventative intervention.

Personalized medicine drugs and the burden of disease in Germany

Objectives

This study aimed to assess the burden attributable to diseases with subtypes that are indications for the personalized medicine (PM) drugs approved in Germany.

Methods

A secondary analysis of a PM drug database and Global Burden of Disease (GBD) Study 2019 data was conducted. Indications of the PM drugs approved in Germany for biomarker-targeted therapy were matched with disease burden causes to quantify the portion of the disease burden attributable to causes that, in some instances, may be treated with PM drugs.

Results

Between 1995 and 2020, the number of PM drugs approved in Germany rose from 0 to 83. Accordingly, the portion of the disease burden due to causes of disease with subtypes that are PM drug indications has risen. Indications for use of the 83 PM drugs approved in Germany by the end of 2020 related to 39 of 369 GBD causes, to which 7825 disability-adjusted life years (DALYs) or 24.3% of the total burden of 32 162 DALYs per 100 000 population in Germany were attributed. Twenty years earlier, in 2000, 5 PM drugs related to 2 GBD causes, to which 978 DALYs (3.1%) of a total burden of 31 878 DALYs per 100 000 population were attributed. Considering the median frequency of biomarkers that can change pharmacological treatment resulted in estimating that not more than 3.0% (interquartile range: 1.1–7.3) of the current German disease burden is affected by personalized pharmacotherapy.

Conclusions

Mapping PM drug indications to disease burden causes allowed to quantify the disease burden within and outside the domain of personalized pharmacotherapy in Germany.

Quality Improvement in Atrial Fibrillation detection after ischaemic stroke (QUIT-AF)

BACKGROUND

Paroxysmal atrial fibrillation (PAF) is a frequent cause of recurrent stroke but can be difficult to detect because of its episodic and often asymptomatic nature. We sought to improve rate of PAF detection through a quality improvement project (QIP) to deliver early prolonged inpatient cardiac monitoring on the stroke unit (SU).

METHODS

A structured protocol for cardiac monitoring using 5-day event recorders was established. 'In-house' cardiac monitoring was implemented. Performance data on this change in service was analysed prospectively and summary statistics obtained.

RESULTS

One-hundred and two ischaemic stroke (IS) patients undertook 5-day event recorder monitoring. Provision of monitors as an inpatient (IP) increased from 20% (pre-QIP pilot 2018) to 65.7% (during QIP). New AF was detected in 15 patients (14.7% vs 8.6% pre-QIP pilot 2018) with majority of new AF (13 patients; 19%) detected when monitors applied early (IP) after IS.

CONCLUSION

Although this study had a number of limitations, it did demonstrate that early and prolonged non-invasive IP cardiac monitoring could be delivered 'in-house' on the SU and improve AF detection rates.

Prediction of Paroxysmal Atrial Fibrillation From Complexity Analysis of the Sinus Rhythm ECG: A Retrospective Case/Control Pilot Study

Paroxysmal atrial fibrillation (PAF) is the most common cardiac arrhythmia, conveying a stroke risk comparable to persistent AF. It poses a significant diagnostic challenge given its intermittency and potential brevity, and absence of symptoms in most patients. This pilot study introduces a novel biomarker for early PAF detection, based upon analysis of sinus rhythm ECG waveform complexity. Sinus rhythm ECG recordings were made from 52 patients with (n = 28) or without (n = 24) a subsequent diagnosis of PAF. Subjects used a handheld ECG monitor to record 28-second periods, twice-daily for at least 3 weeks. Two independent ECG complexity indices were calculated using a Lempel-Ziv algorithm: R-wave interval variability (beat detection, BD) and complexity of the entire ECG waveform (threshold crossing, TC). TC, but not BD, complexity scores were significantly greater in PAF patients, but TC complexity alone did not identify satisfactorily individual PAF cases. However, a composite complexity score (h-score) based on within-patient BD and TC variability scores was devised. The h-score allowed correct identification of PAF patients with 85% sensitivity and 83% specificity. This powerful but simple approach to identify PAF sufferers from analysis of brief periods of sinus-rhythm ECGs using hand-held monitors should enable easy and low-cost screening for PAF with the potential to reduce stroke occurrence.

Second look Holter ECG in neurorehabilitation

Background

Many stroke survivors suffer recurrent stroke because paroxysmal atrial fibrillation (AF) was missed and no preventive anticoagulation initiated. This prospective cohort study determined the added diagnostic yield of second-look 24-h electrocardiographic recording (ECG) in a population at high risk for AF: patients who suffered a stroke of such severity that they require inpatient neurorehabilitation.

Methods

We enrolled 508 patients with ischemic stroke admitted to post-acute inpatient neurorehabilitation and determined whether AF was detected during acute care at the referring hospital. Second-look baseline and 24-h Holter ECG were then conducted during neurorehabilitation. Primary outcome was number of newly detected AF with duration of > 30 s; secondary outcomes were number of newly detected absolute arrhythmia of 10–30 s and < 10 s duration. For comparison, we further enrolled 100 patients with hemorrhagic stroke without history of AF (age = 72 + 11 years, 51% female).

Results

In 206 of the 508 ischemic stroke patients, AF had been detected during acute phase work-up (age = 78 + 10 years, 55% female). For the remaining 302 ischemic stroke patients, no AF was detected during acute phase work-up (age = 74 + 9 years; 47% female). Second-look 24-h ECG showed previously missed AF of > 30 s in 20 of these patients, i.e. 6.6% of the sample, and shorter absolute arrhythmia in 50 patients (i.e. 16.5%).

Conclusions

Second-look 24-Hour ECG performed during post-acute inpatient neurorehabilitation has a high diagnostic yield and should become a standard component of recurrent stroke prevention.

Cost-Effectiveness of Extended Electrocardiogram Monitoring for Atrial Fibrillation After Stroke

Background and Purpose:

Management of cryptogenic stroke involves the identification of modifiable risk factors, such as atrial fibrillation (AF). Extended rhythm monitoring increases AF detection rates but at an increased device cost compared with conventional Holter monitoring. The objective of the study was to identify and synthesize the existing literature on the cost-effectiveness of prolonged rhythm monitoring devices for AF detection in cryptogenic stroke.

Methods:

We conducted a systematic review of available economic evaluations of prolonged ECG monitoring for AF detection following cryptogenic stroke compared with standard care.

Results:

Of the 530 unique citations, 8 studies assessed the cost-utility of prolonged ECG monitoring compared with standard care following cryptogenic stroke. The prolonged ECG monitoring strategies included 7-day ambulatory monitoring, 30-day external loop recorders or intermittent ECG monitoring, and implantable loop recorders. The majority of cost-utility analyses reported incremental cost-effectiveness ratios below $50 000 per QALY gained; and two studies reported a cost-savings.

Conclusions:

There is limited economic literature on the cost-effectiveness of extended ECG monitoring devices for detection of atrial fibrillation in cryptogenic stroke. In patients with cryptogenic stroke, extended ECG monitoring for AF detection may be economically attractive when traditional willingness-to-pay thresholds are adopted. However, there was substantial variation in the reported ICERs. The direct comparison of cost-effectiveness across technologies is limited by heterogeneity in modeling assumptions.

Time trends and patient selection in the use of continuous electrocardiography for detecting atrial fibrillation after stroke: a nationwide cohort study

BACKGROUND AND PURPOSE

Clinical use of continuous electrocardiography (cECG) for detecting atrial fibrillation (AF) after stroke is unclear. In a Danish nationwide cohort, we described post-stroke time trends in outpatient cECG usage and AF incidence and characterized factors associated with cECG use.

METHODS

Patients without AF discharged after their first ischaemic stroke between 2010 and 2016 were identified from Danish nationwide registries. cECG included Holter or event recording within 120 days from discharge. Cumulative incidence analysis and multivariable adjusted logistic regression were used to assess time trends and factors associated with cECG usage and AF.

RESULTS

The study population comprised 39 641 patients. Cumulative use of cECG increased threefold from 3.3% [95% confidence intervals (CI), 2.8-3.8] in 2010 to 10.5% (95% CI, 9.7-11.3) in 2016. Correspondingly, cumulative incidence of post-stroke AF increased from 1.9% (95% CI, 1.5-2.3) to 2.8% (95% CI, 2.4-3.2). Of all cECG-evaluated patients, 6.3% received an AF diagnosis versus 2.2% of the unevaluated. Receiving cECG was associated with increased odds of AF (odds ratio, 3.4; 95% CI, 2.8-4.0). Lower age, milder strokes and less comorbidity were associated with increased odds of receiving cECG. In contrast, risk factors for AF were increasing age and more comorbidity.

CONCLUSIONS

Post-stroke outpatient cECG use and AF incidence have increased over time, but screening rates were low. cECG use was associated with tripled odds of detecting AF. There was a disparity between factors associated with cECG use and risk factors of AF. This raise questions as to the appropriateness of the current clinical approach to post-stoke AF detection.

Frequency of de novo atrial fibrillation in patients presenting with acute ischemic cerebrovascular stroke

BACKGROUND

Atrial fibrillation (AF) affects millions of people worldwide and can remain undiagnosed for years. It is a major cause of cerebrovascular stroke (CVS); hence, early detection is extremely important in order to decrease the risk of CVS. We conducted a retrospective observational study looking into the prevalence of silent AF in 3299 patients admitted from January 2014 to December 2017 in a tertiary care stroke specialized center. Ischemic CVS was confirmed either by using multislice computed tomography (MSCT) or magnetic resonance imaging (MRI) of the brain. AF was diagnosed by electrocardiography (ECG) at the time of admission or during the hospital stay. Patients with a history of AF were excluded from the study.

RESULTS

Of the 3299 patients admitted by acute ischemic CVS, 707 (21.43%) had a history of AF and thus were excluded from the study. Of the remaining 2592 patients eligible for the study, 1666 (64.27%) were males with a mean age of 56.06 years (± 16.01). A total of 2313 (89.24%) patients remained in sinus rhythm throughout the hospital stay, 211 (8.14%) patients were in AF on admission, and 68 (2.62 %) patients developed AF during their hospital stay. The total number of newly diagnosed patients with AF was 279 (10.76%).

CONCLUSION

The prevalence of de novo atrial fibrillation in patients presented with acute cerebrovascular stroke is high. The implementation of good screening programs can significantly reduce the risk of disabilities and morbidities.

Fast-Track Long Term Continuous Heart Monitoring in a Stroke Clinic: A Feasibility Study

Background: Paroxysmal atrial fibrillation (PAF) or flutter is prevalent among patients with cryptogenic stroke. The goal of this study was to investigate the feasibility of incorporating a fast-track, long term continuous heart monitoring (LTCM) program within a stroke clinic. Method: We designed and implemented a fast-track LTCM program in our stroke clinics. The instrument that we used for the study was the ZioXT® device from IRhythm™ Technologies. To implement the program, all clinic support staff received training on the skin preparation and proper placement of the device. We prospectively followed every patient who had a request from one of our inpatient or outpatient stroke or neurology providers to receive LTCM. We recorded patients' demographics, the LTCM indication, as well as related quality measures including same-visit placement, wearing time, analyzable time, LTCM application to the preliminary finding time, as well as patients' out of pocket cost. Results: Out of 501 patients included in the study, 467 (93.2%) patients (mean age 65.9 ± 13; men: 48%) received LTCM; and 92.5% of the patients had the diagnosis of stroke or TIA. 93.7% of patients received their LTCM during the same outpatient visit in the stroke clinic. The mean wearing time for LTCM was 12.1 days (out of 14 days). The average analyzable time among our patients was 95.0%. Eighteen (3.9%, 95%CI: 2.4-6.0) patients had at least one episode of PAF that was sustained for more than 30 s. The rate of PAF was 5.9% (95% CI: 3.5-9.2) among patients with the diagnosis of stroke. Out of 467 patients, 392 (84%) had an out-of-pocket cost of < $100. Conclusion: It is feasible to implement a fast-track cardiac monitoring as part of a stroke clinic with proper training of stroke providers, clinic staff, and support from a cardiology team.

Brain Natriuretic Peptide and Discovery of Atrial Fibrillation After Stroke

Background and Purpose—

Diagnosing paroxysmal atrial fibrillation (pAF) can be challenging after acute ischemic stroke. Enhanced and prolonged Holter-ECG monitoring (EPM) improves the detection rate but is not feasible for all patients. We hypothesized that brain natriuretic peptide (BNP) may help to identify patients with stroke at high risk for pAF to select patients for EPM more effectively.

Methods—

Patients with acute cerebral ischemia ≥60 years presenting in sinus rhythm and without history of AF were included into a prospective, randomized multicenter study to receive either EPM (3× 10-day Holter-ECG) or usual stroke care diagnostic work-up. BNP plasma levels were measured on randomization and 3 months thereafter. Levels were compared between patients with and without pAF detected by means of EPM or usual care. Furthermore, the number needed to screen for EPM depending on BNP cut offs was calculated.

Results—

A total of 398 patients were analyzed. In 373 patients (93.7%), BNP was measured at baseline and in 275 patients (69.1%) after 3 months. pAF was found in 27 patients by means of EPM and in 9 patients by means of usual care ( P =0.002). Median BNP was higher in patients with pAF as compared to patients without AF in both study arms at baseline (57.8 versus 28.3 pg/mL in the EPM arm, P =0.0003; 46.2 versus 27.7 pg/mL, P =0.28 in the control arm) and after 3 months (74.9 versus 31.3 pg/mL, P =0.012 in the EPM arm, 99.3 versus 26.3 pg/mL, P =0.02 in the control arm). Applying a cut off of 100 pg/mL, the number needed to screen was reduced from 18 by usual care to 3 by EPM.

Conclusions—

BNP measured early after ischemic stroke identifies a subgroup of patients with stroke at increased risk for AF, in whom EPM is particularly efficacious.

Registration—

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01855035.

Searching for Atrial Fibrillation Poststroke: A White Paper of the AF-SCREEN International Collaboration

Cardiac thromboembolism attributed to atrial fibrillation (AF) is responsible for up to one-third of ischemic strokes. Stroke may be the first manifestation of previously undetected AF. Given the efficacy of oral anticoagulants in preventing AF-related ischemic strokes, strategies of searching for AF after a stroke using ECG monitoring followed by oral anticoagulation (OAC) treatment have been proposed to prevent recurrent cardioembolic strokes. This white paper by experts from the AF-SCREEN International Collaboration summarizes existing evidence and knowledge gaps on searching for AF after a stroke by using ECG monitoring. New AF can be detected by routine plus intensive ECG monitoring in approximately one-quarter of patients with ischemic stroke. It may be causal, a bystander, or neurogenically induced by the stroke. AF after a stroke is a risk factor for thromboembolism and a strong marker for atrial myopathy. After acute ischemic stroke, patients should undergo 72 hours of electrocardiographic monitoring to detect AF. The diagnosis requires an ECG of sufficient quality for confirmation by a health professional with ECG rhythm expertise. AF detection rate is a function of monitoring duration and quality of analysis, AF episode definition, interval from stroke to monitoring commencement, and patient characteristics including old age, certain ECG alterations, and stroke type. Markers of atrial myopathy (eg, imaging, atrial ectopy, natriuretic peptides) may increase AF yield from monitoring and could be used to guide patient selection for more intensive/prolonged poststroke ECG monitoring. Atrial myopathy without detected AF is not currently sufficient to initiate OAC. The concept of embolic stroke of unknown source is not proven to identify patients who have had a stroke benefitting from empiric OAC treatment. However, some embolic stroke of unknown source subgroups (eg, advanced age, atrial enlargement) might benefit more from non-vitamin K-dependent OAC therapy than aspirin. Fulfilling embolic stroke of unknown source criteria is an indication neither for empiric non-vitamin K-dependent OAC treatment nor for withholding prolonged ECG monitoring for AF. Clinically diagnosed AF after a stroke or a transient ischemic attack is associated with significantly increased risk of recurrent stroke or systemic embolism, in particular, with additional stroke risk factors, and requires OAC rather than antiplatelet therapy. The minimum subclinical AF duration required on ECG monitoring poststroke/transient ischemic attack to recommend OAC therapy is debated.

Prevalence and Risk Factors for Paroxysmal Atrial Fibrillation and Flutter Detection after Cryptogenic Ischemic Stroke

INTRODUCTION

Long-term cardiac monitoring with implantable loop recorders (ILRs) has revealed occult paroxysmal atrial fibrillation and flutter (PAF) in a substantial minority of cryptogenic ischemic stroke (CIS) patients. Herein, we aim to define the prevalence, clinical relevance, and risk factors for PAF detection following early poststroke ILR implantation.

MATERIALS AND METHODS

A retrospective study of CIS patients (n = 100, mean age 65.8 years; 52.5% female) who underwent ILR insertion during, or soon after, index stroke admission. Patients were prospectively followed by the study cardiac electrophysiologist who confirmed the PAF diagnosis. Univariate and multivariate analyses compared clinical, laboratory, cardiac, and imaging variables between PAF patients and non-PAF patients.

RESULTS

PAF was detected in 31 of 100 (31%) CIS patients, and anticoagulation was initiated in almost all (30 of 31, 96.8%). Factors associated with PAF detection include older age (mean [year] 72.9 versus 62.9; P = .003), white race (odds ratio [OR], 4.5; confidence interval [CI], 1.8-10.8; P = .001), prolonged PR interval (PR > 175 ms; OR, 3.3; CI, 1.2-9.4; P = .022), larger left atrial (LA) diameter (mean [cm] 3.7 versus 3.5; P = .044) and LA volume index (mean [cc/m²]; 30.6 versus 24.2; P = .014), and lower hemoglobin (Hb)A1c (mean [%] 6.0 versus 6.4; P = .036). Controlling for age, obesity (body mass index > 30 kg/m²; OR, 1.2; CI, 1.1-1.4; P = .033) was independently associated with PAF detection.

DISCUSSION

PAF was detected with high prevalence following early postcryptogenic stroke ILR implantation and resulted in significant management changes. Older age, increased PR interval, LA enlargement, and lower HbA1c are significantly associated with PAF detection. Controlling for age, obesity is an independent risk factor. A larger prospective study is warranted to confirm these findings.

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.

Cardiac magnetic resonance imaging: a new tool to identify cardioaortic sources in ischaemic stroke

Stroke of undetermined aetiology or 'cryptogenic' stroke accounts for 30-40% of ischaemic strokes despite extensive diagnostic evaluation. The role and yield of cardiac imaging is controversial. Cardiac MRI (CMR) has been used for cardiac disorders, but its use in cryptogenic stroke is not well established. We reviewed the literature (randomised trials, exploratory comparative studies and case series) on the use of CMR in the diagnostic evaluation of patients with ischaemic stroke. The literature on the use of CMR in the diagnostic evaluation of ischaemic stroke is sparse. However, studies have demonstrated a potential role for CMR in the diagnostic evaluation of patients with cryptogenic stroke to identify potential aetiologies such as cardiac thrombi, cardiac tumours, aortic arch disease and other rare cardiac anomalies. CMR can also provide data on certain functional and structural parameters of the left atrium and the left atrial appendage which have been shown to be associated with ischaemic stroke risk. CMR is a non-invasive modality that can help identify potential mechanisms in cryptogenic stroke and patients who may be targeted for enrolment into clinical trials comparing anticoagulation to antiplatelet therapy in secondary stroke prevention. Prospective studies are needed to compare the value of CMR as compared to transthoracic and transesophageal echocardiography in the diagnostic evaluation of cryptogenic stroke.

Semi-automatic software based detection of atrial fibrillation in acute ischaemic stroke and transient ischaemic attack

BACKGROUND AND PURPOSE

Paroxysmal atrial fibrillation (PAF) is often asymptomatic and increases the risk of ischaemic stroke. Detection of PAF is challenging but crucial because a change of treatment decreases the risk of ischaemic stroke. Post-stroke investigations recommend at least 24-h continuous cardiac rhythm monitoring. Extended monitoring detects more PAF but is limited by costs due to manual analysis. Interpretive software might be a reasonable screening tool. The aim was to validate the performance and utility of Pathfinder SL software compared to manual analysis.

METHODS

In all, 135 ischaemic stroke patients with no prior history of PAF or atrial fibrillation and who had done a 7-day continuous electrocardiogram monitoring (Holter) were included. Manual analysis was compared with Pathfinder SL software including a systematic control of registered events.

RESULTS

Seventeen (12.6%) patients were diagnosed with PAF (atrial fibrillation > 30 s). Pathfinder SL software including a systematic control of events registered 16 (94.1%) patients with PAF. Manually 15 (88.2%) patients were detected with PAF. Pathfinder SL had a negative predictive value of 99% and sensitivity of 94%.

CONCLUSIONS

Pathfinder SL software including a systematic evaluation of events is an acceptable alternative compared to manual analysis in PAF detection following ischaemic stroke. It is less time consuming and therefore a reliable, cheaper alternative compared to manual analysis.

Potential Cost-Effectiveness of Ambulatory Cardiac Rhythm Monitoring After Cryptogenic Stroke

Background and Purpose—

Prolonged ambulatory ECG monitoring after cryptogenic stroke improves detection of covert atrial fibrillation, but its long-term cost-effectiveness is uncertain.

Methods—

We estimated the cost-effectiveness of noninvasive ECG monitoring in patients aged ≥55 years after a recent cryptogenic stroke and negative 24-hour ECG. A Markov model used observed rates of atrial fibrillation detection and anticoagulation from a randomized controlled trial (EMBRACE) and the published literature to predict lifetime costs and effectiveness (ischemic strokes, hemorrhages, life-years, and quality-adjusted life-years [QALYs]) for 30-day ECG (primary analysis) and 7-day or 14-day ECG (secondary analysis), when compared with a repeat 24-hour ECG.

Results—

Prolonged ECG monitoring (7, 14, or 30 days) was predicted to prevent more ischemic strokes, decrease mortality, and improve QALYs. If anticoagulation reduced stroke risk by 50%, 30-day ECG (at a cost of USD $447) would be highly cost-effective ($2000 per QALY gained) for patients with a 4.5% annual ischemic stroke recurrence risk. Cost-effectiveness was sensitive to stroke recurrence risk and anticoagulant effectiveness, which remain uncertain, especially at higher costs of monitoring. Shorter duration (7 or 14 days) monitoring was cost saving and more effective than an additional 24-hour ECG; its cost-effectiveness was less sensitive to changes in ischemic stroke risk and treatment effect.

Conclusions—

After a cryptogenic stroke, 30-day ECG monitoring is likely cost-effective for preventing recurrent strokes; 14-day monitoring is an attractive value alternative, especially for lower risk patients. These results strengthen emerging recommendations for prolonged ECG monitoring in secondary stroke prevention. Cost-effectiveness in practice will depend on careful patient selection.

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.

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.

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.

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.

Atrial Fibrillation Monitoring in Cryptogenic Stroke: the Gaps Between Evidence and Practice

Identifying occult paroxysmal atrial fibrillation as the etiology of cryptogenic stroke has been a top research priority in the past decade. This is because prompt initiation of anticoagulation has significantly decreased subsequent stroke risk. Available evidence suggests that prolonged cardiac monitoring after stroke increases the likelihood of detecting atrial fibrillation. However, further research is required to fill in the gaps in regard to the optimal period of monitoring, candidates for monitoring, etc. Here, we review the current evidence supporting the use of prolonged monitoring for cryptogenic stroke patients and discuss the directions of future research.

Genetic risk for atrial fibrillation could motivate patient adherence to warfarin therapy: a cost effectiveness analysis

Background

Atrial fibrillation (AF) increases risk of stroke, and although this stroke risk can be ameliorated by warfarin therapy, some patients decline to adhere to warfarin therapy. A prospective clinical study could be conducted to determine whether knowledge of genetic risk for AF could increase adherence to warfarin therapy for patients who initially declined therapy. As a prelude to a potential prospective clinical study, we investigated whether the use of genetic information to increase adherence could be cost effective.

Methods

Markov model assessed costs and utilities of two care strategies for AF patients who declined warfarin therapy. In the usual care strategy patients received aspirin. In the test strategy genetic risk for AF was assessed (genotype of the 4q25 locus) and some patients with a positive genetic test (≥1 risk allele) were assumed to adhere to warfarin therapy. The remaining patients received aspirin. The incremental cost-effectiveness ratio (ICER) was the ratio of the costs differential and the quality adjusted life-years (QALYs) differential for the two strategies.

Results

We found that the 4q25 genetic testing strategy, compared with the usual care strategy (aspirin therapy), would be cost-effective (ICER $ 47,148) if 2.1 % or more of the test positive patients were to adhere to warfarin therapy. The test strategy would become a cost saving strategy if 5.3 % or more of the test positive patients were to adhere to warfarin therapy. If 20 % of test positive patients were to adhere to warfarin therapy in a hypothetical cohort of 1000 patients, 7 stroke events would be prevented and 3 extra-cranial major bleeding events would be caused over 5 years, resulting in a cost savings of ~ $250,000 and a net gain of 9 QALYs.

Discussion

A clinical study to assess the impact of patient knowledge of genetic risk of AF on adherence to warfarin therapy would be merited because even a modest increase in patient adherence would make a genetic testing strategy cost-effective.

Conclusion

Providing patients who declined warfarin therapy with information about their genetic risk of AF would be cost effective if this genetic risk information resulted in modest increases in adherence.

Detection and Predictors of Paroxysmal Atrial Fibrillation in Acute Ischemic Stroke and Transient Ischemic Attack Patients in Singapore

BACKGROUND

Detection of paroxysmal atrial fibrillation (pAF) is important for optimal secondary stroke prevention. Data are limited from Asia regarding inpatient occurrence and predictors of pAF to optimize electrocardiographic (ECG) monitoring despite it having nearly two thirds of the world's population and different subtypes of stroke from the West.

METHODS

We analyzed a prospective dataset comprising 370 acute ischemic stroke (AIS) and 25 transient ischemic attack (TIA) patients without known atrial fibrillation who underwent continuous ECG monitoring (CEM) in an acute stroke unit from July 2012 to February 2013. The median duration of monitoring was 61 hours.

RESULTS

There were 31 cases of pAF. The detection rate was 8% for both AIS and TIA patients. It occurred less often in lacunar infarcts (3%) compared to nonlacunar infarcts (10%) (P = .047). The detection rates in cryptogenic infarcts (10%) and infarcts of known causes (7%) were not significantly different (P = .224). The predictors of pAF according to logistic regression were hemorrhagic conversion (P = .006), scattered infarcts (P = .007), radiological cardiomegaly (P = .007), occlusion of symptomatic artery (P = .023), and older age (P < .001).

CONCLUSIONS

pAF occurred in 8% of AIS and TIA in a hospitalized cohort of Asian patients. All patients without known atrial fibrillation should undergo CEM for at least 3 days during hospitalization and priority given to patients with predictors of pAF in centers with resource constraints.

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.

Acute and chronic impact of cardiovascular events on health state utilities

BACKGROUND

Cost-utility models are frequently used to compare treatments intended to prevent or delay the onset of cardiovascular events. Most published utilities represent post-event health states without incorporating the disutility of the event or reporting the time between the event and utility assessment. Therefore, this study estimated health state utilities representing cardiovascular conditions while distinguishing between acute impact including the cardiovascular event and the chronic post-event impact.

METHODS

Health states were drafted and refined based on literature review, clinician interviews, and a pilot study. Three cardiovascular conditions were described: stroke, acute coronary syndrome (ACS), and heart failure. One-year acute health states represented the event and its immediate impact, and post-event health states represented chronic impact. UK general population respondents valued the health states in time trade-off tasks with time horizons of one year for acute states and ten years for chronic states.

RESULTS

A total of 200 participants completed interviews (55% female; mean age = 46.6 y). Among acute health states, stroke had the lowest utility (0.33), followed by heart failure (0.60) and ACS (0.67). Utility scores for chronic health states followed the same pattern: stroke (0.52), heart failure (0.57), and ACS (0.82). For stroke and ACS, acute utilities were significantly lower than chronic post-event utilities (difference = 0.20 and 0.15, respectively; both p < 0.0001).

CONCLUSIONS

Results add to previously published utilities for cardiovascular events by distinguishing between chronic post-event health states and acute health states that include the event and its immediate impact. Findings suggest that acute versus chronic impact should be considered when selecting scores for use in cost-utility models. Thus, the current utilities provide a unique option that may be used to represent the acute and chronic impact of cardiovascular conditions in economic models comparing treatments that may delay or prevent the onset of cardiovascular events.

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.

Cost-Effectiveness of Angiographic Imaging in Isolated Perimesencephalic Subarachnoid Hemorrhage

Background and Purpose—

The purpose of this study is to perform a comprehensive cost-effectiveness analysis of all possible permutations of computed tomographic angiography (CTA) and digital subtraction angiography imaging strategies for both initial diagnosis and follow-up imaging in patients with perimesencephalic subarachnoid hemorrhage on noncontrast CT.

Methods—

Each possible imaging strategy was evaluated in a decision tree created with TreeAge Pro Suite 2014, with parameters derived from a meta-analysis of 40 studies and literature values. Base case and sensitivity analyses were performed to assess the cost-effectiveness of each strategy. A Monte Carlo simulation was conducted with distributional variables to evaluate the robustness of the optimal strategy.

Results—

The base case scenario showed performing initial CTA with no follow-up angiographic studies in patients with perimesencephalic subarachnoid hemorrhage to be the most cost-effective strategy ($5422/quality adjusted life year). Using a willingness-to-pay threshold of $50 000/quality adjusted life year, the most cost-effective strategy based on net monetary benefit is CTA with no follow-up when the sensitivity of initial CTA is >97.9%, and CTA with CTA follow-up otherwise. The Monte Carlo simulation reported CTA with no follow-up to be the optimal strategy at willingness-to-pay of $50 000 in 99.99% of the iterations. Digital subtraction angiography, whether at initial diagnosis or as part of follow-up imaging, is never the optimal strategy in our model.

Conclusions—

CTA without follow-up imaging is the optimal strategy for evaluation of patients with perimesencephalic subarachnoid hemorrhage when modern CT scanners and a strict definition of perimesencephalic subarachnoid hemorrhage are used. Digital subtraction angiography and follow-up imaging are not optimal as they carry complications and associated costs.

Clinically important atrial arrhythmia and stroke risk: a UK-wide online survey among stroke physicians and cardiologists

BACKGROUND

A recording of ≥30 s is required for diagnosis of paroxysmal atrial fibrillation (AF) when using ambulatory electrocardiography (ECG) monitoring. It is unclear if shorter runs of atrial arrhythmia are relevant with regard to stroke risk.

AIM

To assess current management of patients with atrial arrhythmia of <30 s duration detected on ambulatory ECG.

DESIGN

Online survey.

METHODS

An online survey was sent to cardiologists and stroke physicians in the UK, via their national societies.

RESULTS

A total of 205 clinicians responded to the survey (130 stroke physicians, 64 cardiologists, 11 other). Regarding diagnosis of AF, 87% of responders would accept a single 12-lead ECG. In contrast, only 45% would accept a single episode lasting <30 s detected on ambulatory monitoring. There was more agreement with regard to the decision to anticoagulate. When asked whether they would anticoagulate eight hypothetical patients with non-diagnostic paroxysms of AF, there was a mean agreement of responses of 78.6%, with up to 94.1% agreement for high-risk patients. There was a trend suggesting that stroke physicians were more likely to accept an atrial arrhythmia of <30 s as 'AF' than cardiology specialists [OR 1.63 (95% CI 0.88-3.01), P = 0.12].

CONCLUSIONS

There is a lack of consensus on the diagnosis and management of patients with brief runs of atrial arrhythmia detected on ambulatory ECG. Further research is needed to clarify the risk of stroke in this unique population of patients.

Clinical predictors of risk for atrial fibrillation: implications for diagnosis and monitoring

OBJECTIVE

To create a risk score using clinical factors to determine whom to screen and monitor for atrial fibrillation (AF).

PATIENTS AND METHODS

The AF risk score was developed based on the summed odds ratios (ORs) for AF development of 7 accepted clinical risk factors. The AF risk score is intended to assess the risk of AF similar to how the CHA2DS2-VASc score assesses stroke risk. Seven validated risk factors for AF were used to develop the AF risk score: age, coronary artery disease, diabetes mellitus, sex, heart failure, hypertension, and valvular disease. The AF risk score was tested within a random population sample of the Intermountain Healthcare outpatient database. Outcomes were stratified by AF risk score for OR and Kaplan-Meier analysis.

RESULTS

A total of 100,000 patient records with an index follow-up from January 1, 2002, through December 31, 2007, were selected and followed up for the development of AF through the time of this analysis, May 13, 2013, through September 6, 2013. Mean ± SD follow-up time was 3106±819 days. The ORs of subsequent AF diagnosis of patients with AF risk scores of 1, 2, 3, 4, and 5 or higher were 3.05, 12.9, 22.8, 34.0, and 48.0, respectively. The area under the curve statistic for the AF risk score was 0.812 (95% CI, 0.805-0.820).

CONCLUSION

We developed a simple AF risk score made up of common clinical factors that may be useful to possibly select patients for long-term monitoring for AF detection.

Silent Atrial Fibrillation: A Critical Review

Atrial fibrillation (AF) in the most common cardiac arrhythmia, and is associated with an increased risk of thromboembolic events. Silent AF is an asymptomatic form of AF incidentally diagnosed during a routine test or manifesting as an arrhythmia-related complication. Although recent trials have clearly demonstrated that patients with sub-clinical AF are at increased risk of stroke, the real incidence of this form of AF is still unknown. In fact, studies about silent AF had been performed only in specific subgroups of patients such as those with implantable cardiac devices, with recent cryptogenic stroke or transient ischemic attack, and recently undergoing AF ablation. Continuous ECG-monitoring in patients without implantable cardiac devices may improve silent AF detection but its cost-effectiveness actually is not well established in all kind of patients. Moreover, recent data have revealed that only a small number of these patients may have sub-clinical AF within the month prior to their stroke suggesting a lack of temporal relationship between the stroke and the AF episode. This paper will review available data on different diagnostic tools for silent AF detection with a focus on their cost-effectiveness, analyzing the direct correlation between the arrhythmia and embolic events, and discussing areas of uncertainty where further research is required.

Finding atrial fibrillation in stroke patients: Randomized evaluation of enhanced and prolonged Holter monitoring--Find-AF(RANDOMISED) --rationale and design

BACKGROUND

Detecting paroxysmal atrial fibrillation (AF) in patients with ischemic strokes presenting in sinus rhythm is challenging because episodes are often short, occur randomly, and are frequently asymptomatic. If AF is detected, recurrent thromboembolism can be prevented efficiently by oral anticoagulation. Numerous uncontrolled studies using various electrocardiogram (ECG) devices have established that prolonged ECG monitoring increases the yield of AF detection, but most established procedures are time-consuming and costly. The few randomized trials are mostly limited to cryptogenic strokes. The optimal method, duration, and patient selection remain unclear. Repeated prolonged continuous Holter ECG monitoring to detect paroxysmal AF within an unspecific stroke population may prove to be a widely applicable, effective secondary prevention strategy.

STUDY DESIGN

Find-AFRANDOMISED is a randomized and controlled prospective multicenter trial. Four hundred patients 60 years or older with manifest (symptoms ≥24 hours or acute computed tomography/magnetic resonance imaging lesion) and acute (symptoms ≤7 days) ischemic strokes will be included at 4 certified stroke centers in Germany. Those with previously diagnosed AF/flutter, indications/contraindications for oral anticoagulation, or obvious causative blood vessel pathologies will be excluded. Patients will be randomized 1:1 to either enhanced and prolonged Holter ECG monitoring (10 days at baseline and after 3 and 6 months) or standard of care (≥24-hour continuous ECG monitoring, according to current stroke guidelines). All patients will be followed up for at least 12 months.

OUTCOMES

The primary end point is newly detected AF (≥30 seconds) after 6 months, confirmed by an independent adjudication committee. We plan to complete recruitment in autumn 2014. First results can be expected by spring 2016.

Cryptogenic stroke: A diagnostic challenge

Cryptogenic, or unexplained, stroke is present in about 30%-40% of ischemic stroke patients. Pursuing a stroke mechanism is important in such patients to better choose therapy to reduce the stroke recurrence risk. Intracranial vessel imaging and cardiac evaluation with transesophageal echocardiogram and outpatient cardiac monitoring may help identify the stroke mechanism. This article highlights the diagnostic yield of various tests in identifying a stroke mechanism in stroke patients whose initial diagnostic evaluation is negative, and the implications for treatment.

Validation and clinical use of a novel diagnostic device for screening of atrial fibrillation

AIMS

Patients with asymptomatic and undiagnosed atrial fibrillation (AF) are at increased risk of heart failure and ischaemic stroke. In this study, we validated a new diagnostic device, the MyDiagnostick, for detection of AF by general practitioners and patients. It records and stores a Lead I electrocardiogram (ECG) which is automatically analysed for the presence of AF.

METHODS AND RESULTS

In total, 192 patients (age 69.4 ± 12.6 years) were asked to hold the MyDiagnostick for 1 min, immediately before a routine 12-lead ECG was recorded. Atrial fibrillation detection and ECGs stored by the MyDiagnostick were compared with the cardiac rhythm on the 12-lead ECG. In a second part of the study, the MyDiagnostick was used to screen for AF during influenza vaccination in the general practitioner's office. Atrial fibrillation was present in 53 out of the 192 patients (27.6%). All AF patients were correctly detected by the MyDiagnostick (sensitivity 100%; 95% confidence interval 93-100%). MyDiagnostick AF classification in 6 out of 139 patients in sinus rhythm was considered false positive (specificity 95.9%; 95% confidence interval 91.3-98.1%). During 4 h of influenza vaccination in 676 patients (age 74 ± 7.1 years), the MyDiagnostick correctly diagnosed AF in all 55 patients (prevalence 8.1%). In 11 patients (1.6%), AF was not diagnosed before, all with a CHA2DS2VASc score of >1.

CONCLUSION

The high AF detection performance of the MyDiagnostick, combined with the ease of use of the device, enables large screening programmes for detection of undiagnosed AF.

Atrial fibrillation in patients with cryptogenic stroke

BACKGROUND

Atrial fibrillation is a leading preventable cause of recurrent stroke for which early detection and treatment are critical. However, paroxysmal atrial fibrillation is often asymptomatic and likely to go undetected and untreated in the routine care of patients with ischemic stroke or transient ischemic attack (TIA).

METHODS

We randomly assigned 572 patients 55 years of age or older, without known atrial fibrillation, who had had a cryptogenic ischemic stroke or TIA within the previous 6 months (cause undetermined after standard tests, including 24-hour electrocardiography [ECG]), to undergo additional noninvasive ambulatory ECG monitoring with either a 30-day event-triggered recorder (intervention group) or a conventional 24-hour monitor (control group). The primary outcome was newly detected atrial fibrillation lasting 30 seconds or longer within 90 days after randomization. Secondary outcomes included episodes of atrial fibrillation lasting 2.5 minutes or longer and anticoagulation status at 90 days.

RESULTS

Atrial fibrillation lasting 30 seconds or longer was detected in 45 of 280 patients (16.1%) in the intervention group, as compared with 9 of 277 (3.2%) in the control group (absolute difference, 12.9 percentage points; 95% confidence interval [CI], 8.0 to 17.6; P<0.001; number needed to screen, 8). Atrial fibrillation lasting 2.5 minutes or longer was present in 28 of 284 patients (9.9%) in the intervention group, as compared with 7 of 277 (2.5%) in the control group (absolute difference, 7.4 percentage points; 95% CI, 3.4 to 11.3; P<0.001). By 90 days, oral anticoagulant therapy had been prescribed for more patients in the intervention group than in the control group (52 of 280 patients [18.6%] vs. 31 of 279 [11.1%]; absolute difference, 7.5 percentage points; 95% CI, 1.6 to 13.3; P=0.01).

CONCLUSIONS

Among patients with a recent cryptogenic stroke or TIA who were 55 years of age or older, paroxysmal atrial fibrillation was common. Noninvasive ambulatory ECG monitoring for a target of 30 days significantly improved the detection of atrial fibrillation by a factor of more than five and nearly doubled the rate of anticoagulant treatment, as compared with the standard practice of short-duration ECG monitoring. (Funded by the Canadian Stroke Network and others; EMBRACE ClinicalTrials.gov number, NCT00846924.).