Optimal use of antithrombotic agents in recent small subcortical strokes accompanied by atrial fibrillation

BACKGROUND

This study aimed to evaluate the efficacy and safety of anticoagulants (AC) and antiplatelets (APT) in patients with recent small subcortical infarctions (RSSI) and atrial fibrillation (AF).

METHODS

We utilized a prospective multicenter stroke registry database to identify patients with RSSI with a concurrent diagnosis of AF. Propensity score matching analysis was used to balance baseline differences among the AC-only, APT-only, and their combination groups. The main outcomes of interest were time to occurrence of minor and major bleeding, stroke recurrence, and all-cause mortality. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for each outcome were calculated using the multivariable Cox proportional hazard regression analysis.

RESULTS

Of the 404 eligible patients, 28.2% received APT only, 53.0% received AC only, and 18.9% received a combination of both. Notable differences were observed between these groups in terms of the 1-year stroke recurrence (APT, 32.5%; AC, 5.6%; APT + AC, 9.2%) and all-cause mortality (APT, 21.9%; AC, 6.1%; APT + AC, 14.5%), whereas the rates of bleeding events were comparable. The multivariable analysis indicated a significant association of AC alone with reduced risks of severe bleeding, stroke recurrence, and all-cause mortality compared with APT alone (aHR 0.64, 95% CI 0.41-0.98; aHR 0.11, 95% CI 0.06-0.22; aHR 0.22, 95% CI 0.11-0.44, respectively). The combination group showed a reduced risk of stroke recurrence compared to APT alone (aHR 0.19, 95% CI 0.08-0.46). These findings remained consistent with the propensity score-matched analysis.

CONCLUSION

AC showed better clinical outcomes than APT in patients with RSSI and AF. Additionally, combination therapy with AC and APT was associated with a lower risk of stroke recurrence than APT alone.

Infarcts of a Cardioembolic Source Mimicking Lacunar Infarcts: Case Series With Clinical and Radiological Correlation

Lacunar strokes are the hallmark of cerebral small vessel disease. There are several well-established mechanisms for the pathogenesis of lacunar stroke, but the cardioembolic mechanism is not well-established. Three cases of acute ischemic stroke following elective cardiac and cerebral catheterization are reported. These cases had typical lacunar-looking infarcts on neuroimaging despite strong evidence of an embolic source with temporal correlation. Awareness of such findings and pathogenesis may help investigational workup and management of these patients.

Use of the insertable Holter with remote detection in the etiological diagnosis of cryptogenic stroke: Analysis of 73 patients

INTRODUCTION

Cryptogenic stroke constitutes 25% of all ischemic strokes, of which 20-30% are due to atrial fibrillation (AF). With the aim of increasing the detection rate, implantable long-term monitoring devices have emerged. The study of the profile of the ideal candidate subsidiary to such monitoring would provide a better understanding of the mechanisms underlying this subtype of stroke.

OBJECTIVE

To determine which variables are related and can predict the detection of silent AF in patients with cryptogenic stroke.

PATIENTS AND METHODS

This is a longitudinal cohort with recruitment from March 2017 to May 2022. They are patients with an implantable monitoring device and cryptogenic stroke with a minimum monitoring of one year.

RESULTS

The total number of patients included was 73, with a mean age of 58.8 years, 56.2% were male. AF was detected in 21 patients (28.8%). The most frequent cardiovascular risk factors were hypertension (47.9%) and dyslipidemia (45.2%). The most frequent topography was cortical (52%). Regarding the echocardiographic parameters, 22% had a dilated left atrium, 19% had a patent foramen ovale, and 22% had high-density supraventricular tachycardia (>1%) on Holter monitoring. In the multivariate analysis, the only variable that predicts AF is the presence of high-density supraventricular tachycardia, with an area under the curve of 0.726 (CI 0.57-0.87, p=0.04), sensitivity of 47.6%, specificity of 97.5%, positive predictive value of 90.9%, negative predictive value of 78.8%, and accuracy of 80.9%.

CONCLUSIONS

The presence of high-density supraventricular tachycardia can be indicative for predicting silent AF. No other variables have been observed that allow us to predict detection of AF in these patients.

Lacunar stroke: mechanisms and therapeutic implications

Lacunar stroke is a marker of cerebral small vessel disease and accounts for up to 25% of ischaemic stroke. In this narrative review, we provide an overview of potential lacunar stroke mechanisms and discuss therapeutic implications based on the underlying mechanism. For this paper, we reviewed the literature from important studies (randomised trials, exploratory comparative studies and case series) on lacunar stroke patients with a focus on more recent studies highlighting mechanisms and stroke prevention strategies in patients with lacunar stroke. These studies suggest that lacunar stroke is a heterogeneous disease with various mechanisms, including most commonly lipohyalinosis and less commonly atheromatous disease and cardioembolism, highlighting the importance of a careful review of brain and neurovascular imaging, a cardiac and systemic evaluation. A better understanding of pathomechanisms of neurological deterioration may lead to investigating the utility of novel treatment strategies and optimisation of short-term antithrombotic treatment strategies to reduce the risk of neurological deterioration and prevent long-term disability in patients with lacunar stroke.

Research Priorities in Atrial Fibrillation Screening: A Report From a National Heart, Lung, and Blood Institute Virtual Workshop

Clinically recognized atrial fibrillation (AF) is associated with higher risk of complications, including ischemic stroke, cognitive decline, heart failure, myocardial infarction, and death. It is increasingly recognized that AF frequently is undetected until complications such as stroke or heart failure occur. Hence, the public and clinicians have an intense interest in detecting AF earlier. However, the most appropriate strategies to detect undiagnosed AF (sometimes referred to as subclinical AF) and the prognostic and therapeutic implications of AF detected by screening are uncertain. Our report summarizes the National Heart, Lung, and Blood Institute's virtual workshop focused on identifying key research priorities related to AF screening. Global experts reviewed major knowledge gaps and identified critical research priorities in the following areas: (1) role of opportunistic screening; (2) AF as a risk factor, risk marker, or both; (3) relationship between AF burden detected with long-term monitoring and outcomes/treatments; (4) designs of potential randomized trials of systematic AF screening with clinically relevant outcomes; and (5) role of AF screening after ischemic stroke. Our report aims to inform and catalyze AF screening research that will advance innovative, resource-efficient, and clinically relevant studies in diverse populations to improve the diagnosis, management, and prognosis of patients with undiagnosed AF.

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.

Advances in Understanding the Pathophysiology of Lacunar Stroke: A Review

Importance

Stroke is the second leading cause of death in the world, and nearly one-third of ischemic strokes are lacunar strokes (LSs) or small subcortical infarcts. Although smaller in size, they create large problems, leaving many patients with intellectual and physical disabilities. Because there are limitations in understanding the underlying pathophysiology of LS, the development of novel therapies has been slow.

Observations

When the term lacune was described in the 1800s, its underlying pathophysiological basis was obscure. In the 1960s, C. Miller Fisher, MD, performed autopsy studies that showed that vessels supplying lacunes displayed segmental arteriolar disorganization, characterized by vessel enlargement, hemorrhage, and fibrinoid deposition. For these pathologic changes, he coined the term lipohyalinosis. Since that time, few attempts have been made to reconcile this pathologic description with modern mechanisms of cerebral small vessel disease (CSVD). During the past 6 years, progress has been made in understanding the clinical mechanisms, imaging characteristics, and genetic basis of LS.

Conclusions and Relevance

Questions persist regarding the order of events related to the initiation and progression of CSVD, how LS is related to other sequelae of CSVD, and whether LS is part of a systemic disease process. The relative roles of aging, oxidative stress, mechanical stress, genetic predisposition, and other vascular risk factors should be further studied, especially in the era of widespread antihypertensive use. Although understanding of endothelial dysfunction has increased, future work on the role of media and adventitial dysfunction should be explored. Recent advances in mapping the brain vasculome may generate new hypotheses. The investigation of new therapeutic targets, aimed at reversing CSVD processes and promoting neural repair after LS, depends upon further understanding these basic mechanisms.

Atherothrombotic stroke in non-valvular atrial fibrillation

The review analyzes data on the detection rate of and the abilities to predict and prevent non-cardioembolic strokes in non-valvular atrial fibrillation. According to accumulated facts, vitamin K antagonists in non-valvular atrial fibrillation are noted to be inferior to antiplatelet drugs in efficiency in preventing non-cardioembolic (atherothrombotic in particular) strokes, and the widespread use of oral anticoagulants in combination with antiplatelet drugs does not generally reduce the incidence of poor outcomes, markedly increasing the risk of serious bleeding. Nevertheless, it is conceivable that this combination antithrombotic therapy may be useful for certain categories of patients at the highest risk for atherothrombotic stroke and at relatively low risk for hemorrhagic complications. Cohorts of patients, to whom such an approach should be reasonable considered to be applied, have not yet been identified.

Pathophysiology of Lacunar Stroke: History's Mysteries and Modern Interpretations

Since the term "lacune" was adopted in the 1800s to describe infarctions from cerebral small vessels, their underlying pathophysiological basis remained obscure until the 1960s when Charles Miller Fisher performed several autopsy studies of stroke patients. He observed that the vessels displayed segmental arteriolar disorganization that was associated with vessel enlargement, hemorrhage, and fibrinoid deposition. He coined the term "lipohyalinosis" to describe the microvascular mechanism that engenders small subcortical infarcts in the absence of a compelling embolic source. Since Fisher's early descriptions of lipohyalinosis and lacunar stroke (LS), there have been many advancements in the understanding of this disease process. Herein, we review lipohyalinosis as it relates to modern concepts of cerebral small vessel disease (cSVD). We discuss clinical classifications of LS as well as radiographic definitions based on modern neuroimaging techniques. We provide a broad and comprehensive overview of LS pathophysiology both at the vessel and parenchymal levels. We also comment on the role of biomarkers, the possibility of systemic disease processes, and advancements in the genetics of cSVD. Lastly, we assess preclinical models that can aid in studying LS disease pathogenesis. Enhanced understanding of this highly prevalent disease will allow for the identification of novel therapeutic targets capable of mitigating disease sequelae.

Noncardioembolic Stroke in Patients with Atrial Fibrillation

Atrial fibrillation (AF) could be a coincidental finding in certain patients with ischemic stroke and increased burden of underlying cardiovascular disease. Concomitant large-vessel atheromatosis and cerebral small vessel disease may be the actual cause of stroke, and distinguishing between different pathophysiologic mechanisms could impose substantial diagnostic difficulties. Despite routine use of oral anticoagulants (OACs) in patients with AF based on their risk for embolism (ie, CHA2DS2-Vasc score), antithrombotic agents may exert differential effects depending on stroke etiology and stroke subtyping should be evaluated as an additional component of risk stratification that could facilitate optimal management. In the present study, we summarize the evidence on noncardioembolic (non-CE) stroke and treatment approaches based on different stroke subtypes in patients with AF. In particular, approximately one-third of patients with AF seem to suffer a non-CE stroke. Within this category, 11% to 24% of patients present high-grade carotid stenosis and 9% to 16% of ischemic strokes are classified as lacunar. In terms of secondary prevention, the effectiveness of OACs in preventing non-CE stroke has been disputed. Additional large-scale prospective studies are warranted to assess the pathophysiologic stroke mechanisms in patients with AF and compare the differential efficacy of antithrombotic treatment strategies in non-CE ischemic syndromes.

Accurate etiology diagnosis in patients with stroke and atrial fibrillation: A role for brain natriuretic peptide

BACKGROUND

Atrial fibrillation (AF) is the leading cause of cardioembolic stroke (CES), and patients with stroke and AF are frequently assumed to have CES. However, strokes presumably due to atherosclerotic pathophysiologies in large or small vessels can also occur in patients with AF. The aims of the present study were to clarify the prevalence of and factors related to a non-cardioembolic etiology in acute stroke patients with AF.

METHODS

From March 2011 through May 2017, consecutive acute ischemic stroke patients with AF were retrospectively recruited. The concomitant presence of non-cardioembolic features (small vessel occlusion [SVO] or large artery atherosclerosis [LAA]) on imaging was evaluated. The frequency of and factors associated with co-existing SVO/LAA features were assessed.

RESULTS

A total of 560 consecutive patients with AF and acute stroke (237 women; median age 78 [IQR 71-85] years; NIHSS score 9 [3-20]) were enrolled. Of these, 42 (7.5%) had co-existing SVO/LAA features. Multivariable logistic regression analysis showed that the brain natriuretic peptide level (BNP, OR 0.78, p = .030 per 100 pg/mL increase) was independently and negatively associated with co-existing SVO/LAA features and receiver operating characteristic curve analysis revealed the practical cut-off BNP value was 130 pg/mL (sensitivity 54% and specificity 68%).

CONCLUSION

SVO/LAA features were found in 7.5% of acute stroke patients with AF. A relatively low BNP level on admission was independently associated with co-existing SVO/LAA features. Thorough examination for a more appropriate etiology may be particularly necessary in acute stroke patients with AF and a relatively low BNP level.

Diffusion magnetic resonance imaging in cerebral small vessel disease

Cerebral small vessel disease (SVD) is frequent in the elderly, and accounts for a wide spectrum of clinical and radiological manifestations. This report summarizes the most important findings obtained using diffusion MRI (DWI) in SVD. With DWI and apparent diffusion coefficient (ADC) maps, recent ischemic lesions can easily be detected after acute stroke in SVD, while even multiple simultaneous lesions may be observed. Microstructural changes are frequent in SVD, with increases in diffusivity and decreases in anisotropy being the most reliable findings observed, mainly in white matter. These tissue changes are associated with clinical severity and especially executive dysfunction. They can also precede the usual MRI markers of SVD, such as white matter hyperintensities, microbleeds and lacunes. Thus, DWI may reveal surrogate markers of SVD progression and offer a better understanding of their underlying mechanisms.