Carotid plaques and detection of atrial fibrillation in embolic stroke of undetermined source

Dual Antiplatelet Therapy After Embolic Stroke of Undetermined Source: A Subgroup Analysis of the CHANCE-2 Trial

BACKGROUND

The atherosclerotic sources of embolism are a significant contributor to embolic stroke of undetermined source (ESUS). However, there is limited evidence for the efficacy of intensive dual antiplatelet therapy for ESUS. We conducted an investigation to determine whether gene-directed dual antiplatelet therapy could reduce the risk of recurrent stroke in patients with ESUS.

METHODS

CHANCE-2 (Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events-II) was an investigator-initiated, multicenter, randomized, double-blind, placebo-controlled trial that objectively compared ticagrelor plus aspirin and clopidogrel plus aspirin in patients with minor stroke or transient ischemic attack who carried CYP2C19 loss-of-function alleles in China. All study participants were classified into ESUS and non-ESUS groups for the prespecified exploratory analysis. Cox proportional hazards models were used to assess the interaction of the state of ESUS with the effects of dual antiplatelet therapy with ticagrelor-aspirin versus clopidogrel-aspirin, adjusting for sociodemographic and clinical factors.

RESULTS

The subgroup analysis comprised 5796 participants (90.4% of the total 6412 participants) in the CHANCE-2 trial, with a median age of 64.9 years (range, 57.0-71.4 years), of whom 1964 (33.9%) were female. These participants underwent diffusion-weighted imaging as part of the study protocol. After systematic evaluation, 15.2% of patients (881/5796) were deemed to have ESUS. The incidence of stroke recurrence in patients with ESUS was found to be 5.6% in the ticagrelor-aspirin group and 9.2% in the clopidogrel-aspirin group (hazard ratio, 0.57 [95% CI, 0.33-0.99]; P=0.04). In patients without ESUS, the respective incidence rates were 5.6% and 7.5% (hazard ratio, 0.72 [95% CI, 0.58-0.90]; P<0.01). The P value was 0.56 for the treatment × ESUS status interaction effect.

CONCLUSIONS

In this prespecified exploratory analysis, ticagrelor with aspirin was superior to clopidogrel with aspirin for preventing stroke at 90 days in patients with acute ischemic stroke or transient ischemic attack who carried CYP2C19 loss-of-function alleles and were classified as ESUS.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04078737.

Embolic strokes of undetermined source: a clinical consensus statement of the ESC Council on Stroke, the European Association of Cardiovascular Imaging and the European Heart Rhythm Association of the ESC

One in six ischaemic stroke patients has an embolic stroke of undetermined source (ESUS), defined as a stroke with unclear aetiology despite recommended diagnostic evaluation. The overall cardiovascular risk of ESUS is high and it is important to optimize strategies to prevent recurrent stroke and other cardiovascular events. The aim of clinicians when confronted with a patient not only with ESUS but also with any other medical condition of unclear aetiology is to identify the actual cause amongst a list of potential differential diagnoses, in order to optimize secondary prevention. However, specifically in ESUS, this may be challenging as multiple potential thromboembolic sources frequently coexist. Also, it can be delusively reassuring because despite the implementation of specific treatments for the individual pathology presumed to be the actual thromboembolic source, patients can still be vulnerable to stroke and other cardiovascular events caused by other pathologies already identified during the index diagnostic evaluation but whose thromboembolic potential was underestimated. Therefore, rather than trying to presume which particular mechanism is the actual embolic source in an ESUS patient, it is important to assess the overall thromboembolic risk of the patient through synthesis of the individual risks linked to all pathologies present, regardless if presumed causally associated or not. In this paper, a multi-disciplinary panel of clinicians/researchers from various backgrounds of expertise and specialties (cardiology, internal medicine, neurology, radiology and vascular surgery) proposes a comprehensive multi-dimensional assessment of the overall thromboembolic risk in ESUS patients through the composition of individual risks associated with all prevalent pathologies.

Real-world effectiveness and safety of evolocumab in very high-risk atherosclerotic cardiovascular disease patients with acute ischemic stroke

BACKGROUND

We investigated evolocumab's real-world effectiveness and safety on a background of statin therapy in the acute phase of ischemic stroke (IS) patients with a very high-risk of atherosclerotic cardiovascular disease (ASCVD).

METHODS

A real-world, single-center, retrospective study was conducted in the neurology department at Tianjin Huanhu Hospital in China. Patients were divided into two groups: evolocumab treatment (140 mg every two weeks) or the standard of care (SOC) group. The primary efficacy outcome of the study was the achievement of a targeted lipid control rate and the incidence of major adverse cardiovascular events (MACE) by the end of the follow-up. MACE was defined as a composite of various cardiovascular events, cerebrovascular events such as stroke or TIA, and event-related deaths. Propensity score matching (PSM) analysis was utilized to account for confounding factors between groups. Survival analyses were performed using the Kaplan-Meier method and COX regression modeling.

RESULTS

1080 AIS patients with very high-risk ASCVD were recruited. After PSM, there were 528 individuals, with 206 in the evolocumab group and 322 in the SOC group. At 12 months of follow-up, the proportion of LDL-C < 1.4mmol/L and ≥ 50% reduction was 44.91% in the evolocumab group, compared with only 3.12% of SOC-treated patients (p < 0.01). The median follow-up time for clinical events was 15 months. The evolocumab group was associated with a lower risk of cerebrovascular events compared to the SOC group (HR, 0.45; 95% CI, 0.23-0.89; p = 0.02).

CONCLUSIONS

This real-world study suggested that evolocumab on a background of statin reduced the LDL-C levels significantly and lowered the incidence of recurrent cerebrovascular events in the very high-risk ASCVD patients with AIS in China.

Value of HAVOC and Brown ESUS-AF scores for atrial fibrillation on implantable cardiac monitors after embolic stroke of undetermined source

OBJECTIVES

Up to 20 % of ischemic strokes are associated with overt atrial fibrillation (AF). Furthermore, silent AF was detected by an implantable cardiac monitor (ICM) in 1 in 3 cryptogenic strokes in the CRYSTAL AF study. An ESC position paper has suggested a HAVOC score ≥ 4 or a Brown ESUS-AF score ≥ 2 as criteria for ICM implantation after cryptogenic stroke, but neither of these criteria has been developed or validated in ICM populations. We assessed the performance of HAVOC and Brown ESUS-AF scores in a cohort of ICM patients implanted after embolic stroke of undetermined source (ESUS).

METHODS

All patients implanted with an ICM for ESUS between February 2016 and February 2022 at two French University Hospitals were retrospectively included. Demographic data, cardiovascular risk factors, and clinical and biological data were collected after a review of electronic medical records. HAVOC and Brown ESUS-AF scores were calculated for all patients.

FINDINGS

Among the 384 patients included, 106 (27 %) developed AF during a mean follow-up of 33 months. The scores performances for predicting AF during follow-up were: HAVOC= AUC: 68.5 %, C-Index: 0.662, and Brown ESUS-AF=AUC: 72.9 %, C-index 0.712. Compared with the CHA2DS2-VASc score, only the Brown ESUS-AF score showed significant improvement in NRI/IDI. Furthermore, classifying patients according to the suggested HAVOC and Brown ESUS-AF thresholds, only 24 % and 31 % of the cohort, respectively, would have received an ICM, and 58 (55 %) and 47 (44 %) of the AF patients, respectively, would not have been implanted with an ICM.

CONCLUSION

HAVOC and Brown ESUS-AF scores showed close and moderate performance in predicting AF on ICM after cryptogenic stroke, with a significant lack of sensitivity. Specific risk scores should be developed and validated in large ICM cohorts.

Dual Antiplatelet Therapies and Causes in Minor Stroke or Transient Ischemic Attack: A Prespecified Analysis in the CHANCE-2 Trial

BACKGROUND

It is unclear whether patients with different stroke/transient ischemic attack etiologies benefit differently from gene-directed dual antiplatelet therapy. This study explored the efficacy and safety of ticagrelor-aspirin versus clopidogrel-aspirin in transient ischemic attack or minor stroke with different causes in the CHANCE-2 trial (Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events-II).

METHODS

This was a prespecified analysis of the CHANCE-2 trial, which enrolled 6412 patients with minor stroke or transient ischemic attack who carried CYP2C19 loss-of-function alleles. Patients with centralized evaluation of TOAST (Trial of ORG 10172 in Acute Stroke Treatment) classification of large-artery atherosclerosis, small-vessel occlusion, and stroke of undetermined cause were included. The primary efficacy outcome was new stroke, and the primary safety outcome was severe or moderate bleeding, both within 90 days. Cox proportional hazards models were used to assess the interaction of TOAST classification with the effects of dual antiplatelet therapy with ticagrelor-aspirin versus clopidogrel-aspirin.

RESULTS

A total of 6336 patients were included in this study. In patients administered ticagrelor-aspirin and clopidogrel-aspirin, respectively, stroke recurred in 85 (9.8%) and 88 (10.7%) patients with large-artery atherosclerosis (hazard ratio, 0.86 [95% CI, 0.63-1.18]; P=0.34); 32 (3.6%) and 61 (7.0%) patients with small-vessel occlusion (hazard ratio, 0.51 [95% CI, 0.33-0.79]; P=0.002); and 68 (4.8%) and 87 (5.9%) patients with stroke of undetermined cause (hazard ratio, 0.80 [95% CI, 0.58-1.10]; P=0.17), with P=0.08 for the treatment×cause subtype interaction effect. There were no significant differences in severe or moderate bleeding events in patients with different cause and different treatment.

CONCLUSIONS

In this prespecified analysis of the CHANCE-2 trial, the efficacy and safety of ticagrelor-aspirin versus clopidogrel-aspirin in preventing new stroke were consistent in patients with different causes. The influence of stroke cause on benefit of gene-guided antiplatelet therapy should be explored by further trials.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04078737.

Etiologic reclassification of cryptogenic stroke after implantable cardiac monitoring and computed tomography angiography re-assessment

INTRODUCTION

Different mechanisms may underlie cryptogenic stroke, including subclinical atrial fibrillation (AF), nonstenotic carotid plaques (NCP), and aortic arch atherosclerosis (AAA). In a cohort of cryptogenic stroke patients, we aimed to: (1) evaluate the prevalence of subclinical AF, NCP, and AAA, and reclassify the etiology accordingly; (2) compare the clinical features of patients with reclassified etiology with those with confirmed cryptogenic stroke.

METHODS

Data of patients hospitalized for cryptogenic stroke between January 2018 and February 2021 were retrospectively analyzed. Patients were included if they received implantable cardiac monitoring (ICM) to detect subclinical AF. Baseline computed tomography angiography (CTA) was re-evaluated to assess NCP and AAA. Since aortic plaques with ulceration/intraluminal thrombus were considered pathogenetic during the initial workup, only patients with milder AAA were included. Stroke etiology was reclassified as "cardioembolic", "atherosclerotic", or "mixed" based on the detection of AF and NCP/AAA. Patients with "true cryptogenic" stroke (no AF, ipsilateral NCP, or AAA detected) were compared with those with reclassified etiology.

RESULTS

Among 63 patients included, 21 (33%) were diagnosed with AF (median follow-up time of 15 months), 12 (19%) had ipsilateral NCP, and 6 (10%) had AAA. Stroke etiology was reclassified in 30 patients (48%): cardioembolic in 14 (22%), atherosclerotic in 9 (14%), and mixed in 7 (11%). Patients with true cryptogenic stroke were younger compared to those with reclassified etiology (p = 0.001).

DISCUSSION

One or more potential covert stroke sources can be recognized in half of the patients with a cryptogenic stroke through long-term cardiac monitoring and focused CTA re-assessment.

Screening for atrial fibrillation to prevent stroke in elderly individuals with or without preexisting cardiovascular disease: A post hoc analysis of the randomized LOOP Study

BACKGROUND

An evidence-based approach for risk stratification of subclinical atrial fibrillation (AF) and hereby AF screening is lacking. This study aimed to investigate whether established cardiovascular diseases (CVD) could help to identify the population more likely to benefit from AF screening.

METHODS

The LOOP Study randomized AF-naïve individuals aged ≥70 years and with additional stroke risk factors to either screening with implantable loop recorder (ILR) and subsequent anticoagulation upon detection of new-onset AF episodes ≥6 min, or usual care. In this sub-study, all participants were divided into two risk groups according to the presence/absence of CVD (defined as ischemic heart disease, heart failure, previous stroke, valvular heart disease, or peripheral artery disease).

RESULTS

A total of 1997 (33.3%) had CVD at baseline and experienced higher incidences of stroke or systemic arterial embolism (SAE), ischemic stroke, stroke/SAE/cardiovascular death, and all-cause death (adjusted HR 1.34 [1.06-1.69], 1.31 [1.02-1.69], 1.49 [1.23-1.79], and 1.59 [1.36-1.85], respectively) than those without. For ILR screening versus usual care, there was no decrease in stroke/SAE, ischemic stroke, or stroke/SAE/cardiovascular death among participants with CVD (adjusted p-values >0.05), whereas significant reductions in these outcomes were obtained by screening among those without CVD (adjusted HR 0.64 [0.44-0.93], 0.54 [0.35-0.82], 0.64 [0.46-0.87], respectively); adjusted p-values for interaction ≤0.05.

CONCLUSIONS

In an elderly, at-risk population, ILR screening did not prevent stroke significantly in individuals with CVD, whereas screening was associated with approximately 40% stroke risk reduction among those without CVD. However, these findings should be considered as hypothesis-generating and warrant further study.

Atherosclerosis as a Potential Cause of Deep Embolic Stroke of Undetermined Source: A 3T High‐Resolution Magnetic Resonance Imaging Study

Background

The potential causes or sources of embolic stroke of undetermined source (ESUS) vary. This study aimed to investigate the main cause of deep ESUS by evaluating nonstenotic intracranial atherosclerotic plaque.

Methods and Results

We retrospectively screened consecutive patients with unilateral anterior circulation ESUS. After excluding the patients with possible embolism from an extracranial artery such as aortic arch plaque, carotid plaque, and so on, the enrolled patients with ESUS were categorized into 2 groups: deep ESUS and cortical with/without deep ESUS. All patients underwent intracranial high‐resolution magnetic resonance imaging to assess the characteristics of nonstenotic intracranial atherosclerotic plaque. Biomarkers of atrial cardiopathy (ie, P‐wave terminal force in lead V1 on ECG, NT‐proBNP [N‐terminal pro–brain natriuretic peptide] and left atrial diameter) were collected. A total of 155 patients with ipsilateral nonstenotic intracranial atherosclerotic plaque were found, with 76 (49.0%) in deep ESUS and 79 (51.0%) in cortical with/without deep ESUS. We found more prevalent plaque in the M1 segment of the middle cerebral artery and the ostia of the perforator, with a smaller remodeling index plaque burden, and less frequent occurrence of complicated plaque in deep ESUS versus cortical with/without deep ESUS. Higher BNP (brain natriuretic peptide) levels and a higher prevalence of atrial cardiopathy in cortical with/without deep ESUS versus deep ESUS. Moreover, the discrimination of vulnerable plaque for predicting ESUS was significantly enhanced after adjusting for or further excluding patients with deep ESUS.

Conclusions

The current study provides the first high‐resolution magnetic resonance imaging evidence that cortical with/without deep ESUS and deep ESUS should be 2 distinct entities and that atherosclerosis, not embolism, might be the main cause of deep ESUS.

The characteristics of intracranial plaques of unilateral, anterior circulation embolic stroke of undetermined source: an analysis of different subtypes based on high-resolution imaging

BACKGROUND AND PURPOSE

To investigate the characteristics of non-stenotic intracranial plaque (NSIP) among embolic stroke of undetermined source (ESUS) subtypes by high-resolution magnetic resonance imaging (HR-MRI).

METHODS

we retrospectively enrolled consecutive patients with ESUS who were mandatory for HR-MRI. Based the location and arterial supply of the infarct, ESUS were categorized into three types: cortical ESUS, subcortical ESUS and mixed ESUS. The NSIP parameters including plaque location, morphology (plaque distribution, remodeling index and plaque burden) and composition (thick fibrous cap, discontinuity of plaque surface, intraplaque hemorrhage and complicated plaque) were evaluated among subtypes.

RESULTS

Among 243 patients, there were 87 (35.8%) cortical ESUS, 127 (52.3%) subcortical ESUS and 29 (11.9%) mixed ESUS. We found significant differences in plaque location (P < 0.001), plaque quadrant (P < 0.001), remodeling index (P < 0.001), plaque burden (P < 0.001), discontinuity of plaque surface (P < 0.001), intraplaque hemorrhage (P = 0.001) and complicated plaque (P < 0.001) of ipsilateral NISP among different ESUS subtypes, except for fibrous cap (P = 0.135). But we found no differences among contralateral NISP. In addition, the clinical characteristics of the differences among ESUS subtypes were striking, including age (P = 0.004), initial National Institute of Health Stroke Scale (P < 0.001), coronary artery disease (P = 0.039), serum urea (P = 0.011) and creatinine (P = 0.002).

CONCLUSION

This is the first report of significantly heterogeneous characteristics of ipsilateral NSIP and clinical findings among ESUS subtypes, which may suggest their different underlying mechanisms.

A critical assessment of the current pharmacotherapy for the treatment of embolic strokes of undetermined source

INTRODUCTION

"Embolic stroke of undetermined source" (ESUS) is a term coined to identify non-lacunar stroke whose mechanism is likely to be embolic, and the source remains unidentified. The best antithrombotic treatment for preventing stroke recurrence in this population has not been delineated.

AREAS COVERED

The authors summarize and critically appraise the currently available evidence about the antithrombotic treatment for preventing stroke recurrence in patients with ESUS. Randomized trials addressing this topic were identified through MEDLINE (accessed by PubMed, as of November 2021, week 4).

EXPERT OPINION

Recent randomized trials have failed to demonstrate a significant benefit of direct oral anticoagulants over aspirin in reducing the recurrence of cerebral infarctions in unselected cohorts of patients with ESUS. The heterogeneity and often overlap of embolic sources may be possible explanations for the overall absence of a benefit of oral anticoagulants in ESUS as a single homogeneous entity. The results of these trials and their subgroup analyses have provided important cues to understand the pathophysiology of ESUS. They have, furthermore, increased in the interest in researchers in identifying distinct etiological phenotypes within this stroke population. There is a good rationale for ongoing and future investigations in order to tailor antithrombotic treatment according to individual features of patients with ESUS.

Advances in Recurrent Stroke Prevention: Focus on Antithrombotic Therapies

The past decade has seen significant advances in stroke prevention. These advances include new antithrombotic agents, new options for dyslipidemia treatment, and novel techniques for surgical stroke prevention. In addition, there is greater recognition of the benefits of multifaceted interventions, including the role of physical activity and dietary modification. Despite these advances, the aging of the population and the high prevalence of key vascular risk factors pose challenges to reducing the burden of stroke. Using a cause-based framework, current approaches to prevention of cardioembolic, cryptogenic, atherosclerotic, and small vessel disease stroke are outlined in this paper. Special emphasis is given to recent trials of antithrombotic agents, including studies that have tested combination treatments and responses according to genetic factors.

Atrial cardiopathy and non-stenotic intracranial complicated atherosclerotic plaque in patients with embolic stroke of undetermined source

OBJECTIVE

To assess (1) the association between atrial cardiopathy (AC) and non-stenotic intracranial complicated atherosclerotic plaque (NICAP) in patients with embolic stroke of undetermined source (ESUS) or small-vessel disease (SVD), and (2) the performance of previously proposed biomarkers to identify AC as the underlying aetiology in ESUS.

METHODS

Based on our high-resolution MRI (HR-MRI) cohort, 403 subjects (243 ESUS and 160 SVD) were enrolled in the final analysis. All patients underwent intracranial HR-MRI to assess the presence of ipsilateral NICAP. Biomarkers of AC (ie, P-wave terminal force in lead V1 (PTFV1) on ECG, N-terminal probrain natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T and left atrial diameter) were collected within 24 hours after admission.

RESULTS

Among patients without ipsilateral NICAP, we found an association between the presence of AC (adjusted OR (aOR): 4.76, 95% CI 2.48 to 9.14), increased PTFV1 (aOR: 5.70, 95% CI: 2.43 to 13.39) and NT-proBNP (aOR: 1.65, 95% CI: 1.16 to 2.35) with ESUS. This association was not evident among patients with ipsilateral NICAP. The discrimination between ESUS versus SVD by AC/AC-related biomarkers was significantly improved after excluding ipsilateral NICAP. Similarly, the discrimination between ESUS and SVD by ipsilateral NICAP was notably augmented after excluding AC, PTFV1 and NT-proBNP.

INTERPRETATION

AC is more prevalent in patients who had ESUS without ipsilateral NICAP compared with patients with, implying that AC and ipsilateral NICAP are two distinct, competing aetiologies of ESUS. Among the AC biomarkers studied in this analysis, PTFV1 seems to be the most informative.

Non-contrast mDixon MR angiography of the neck: Comparison with time-of-flight MR angiography in normal subjects

We investigated the feasibility of non-contrast three-dimensional modified Dixon (mDixon) magnetic resonance angiography (MRA) to evaluate the carotid artery.We studied 30 normal patients who underwent non-contrast mDixon and conventional time-of-flight (TOF) MRA of the neck with a clinical 3T MR scanner. Carotid artery signal-to-noise ratio (SNR) and contrast-to-noise ratio were compared between mDixon-MRA and TOF-MRA. Two readers independently evaluated vessel sharpness, image contrast, and overall image quality using a 4-point scale.SNR was significantly higher on mDixon-MRA than TOF-MRA (P < .01). There was no significant difference in contrast-to-noise ratio. The visual score for vessel sharpness was significantly higher on mDixon-MRA than TOF-MRA (P < .01), whereas the score for contrast was significantly higher on TOF-MRA (P < .01).Although non-contrast three-dimensional mDixon-MRA showed lower visual contrast than conventional TOF-MRA, it provided images with significantly higher SNR and better vessel sharpness than TOF-MRA.

Non-stenotic Carotid Plaques in Embolic Stroke of Unknown Source

Embolic stroke of unknown source (ESUS) represents one in five ischemic strokes. Ipsilateral non-stenotic carotid plaques are identified in 40% of all ESUS. In this narrative review, we summarize the evidence supporting the potential causal relationship between ESUS and non-stenotic carotid plaques; discuss the remaining challenges in establishing the causal link between non-stenotic plaques and ESUS and describe biomarkers of potential interest for future research. In support of the causal relationship between ESUS and non-stenotic carotid plaques, studies have shown that plaques with high-risk features are five times more prevalent in the ipsilateral vs. the contralateral carotid and there is a lower incidence of atrial fibrillation during follow-up in patients with ipsilateral non-stenotic carotid plaques. However, non-stenotic carotid plaques with or without high-risk features often coexist with other potential etiologies of stroke, notably atrial fibrillation (8.5%), intracranial atherosclerosis (8.4%), patent foramen ovale (5-9%), and atrial cardiopathy (2.4%). Such puzzling clinical associations make it challenging to confirm the causal link between non-stenotic plaques and ESUS. There are several ongoing studies exploring whether select protein and RNA biomarkers of plaque progression or vulnerability could facilitate the reclassification of some ESUS as large vessel strokes or help to optimize secondary prevention strategies.

Characteristics of Recurrent Ischemic Stroke After Embolic Stroke of Undetermined Source: Secondary Analysis of a Randomized Clinical Trial

Importance

The concept of embolic stroke of undetermined source (ESUS) unifies a subgroup of cryptogenic strokes based on neuroimaging, a defined minimum set of diagnostic tests, and exclusion of certain causes. Despite an annual stroke recurrence rate of 5%, little is known about the etiology underlying recurrent stroke after ESUS.

Objective

To identify the stroke subtype of recurrent ischemic strokes after ESUS, to explore the interaction with treatment assignment in each category, and to examine the consistency of cerebral location of qualifying ESUS and recurrent ischemic stroke.

Design, Setting, and Participants

The NAVIGATE-ESUS trial was a randomized clinical trial conducted from December 23, 2014, to October 5, 2017. The trial compared the efficacy and safety of rivaroxaban and aspirin in patients with recent ESUS (n = 7213). Ischemic stroke was validated in 309 of the 7213 patients by adjudicators blinded to treatment assignment and classified by local investigators into the categories ESUS or non-ESUS (ie, cardioembolic, atherosclerotic, lacunar, other determined cause, or insufficient testing). Five patients with recurrent strokes that could not be defined as ischemic or hemorrhagic in absence of neuroimaging or autopsy were excluded. Data for this secondary post hoc analysis were analyzed from March to June 2019.

Interventions

Patients were randomly assigned to receive rivaroxaban, 15 mg/d, or aspirin, 100 mg/d.

Main Outcomes and Measures

Association of recurrent ESUS with stroke characteristics.

Results

A total of 309 patients (205 men [66%]; mean [SD] age, 68 [10] years) had ischemic stroke identified during the median follow-up of 11 (interquartile range [IQR], 12) months (annualized rate, 4.6%). Diagnostic testing was insufficient for etiological classification in 39 patients (13%). Of 270 classifiable ischemic strokes, 156 (58%) were ESUS and 114 (42%) were non-ESUS (37 [32%] cardioembolic, 26 [23%] atherosclerotic, 35 [31%] lacunar, and 16 [14%] other determined cause). Atrial fibrillation was found in 27 patients (9%) with recurrent ischemic stroke and was associated with higher morbidity (median change in modified Rankin scale score 2 [IQR, 3] vs 0 (IQR, 1]) and mortality (15% vs 1%) than other causes. Risk of recurrence did not differ significantly by subtype between treatment groups. For both the qualifying and recurrent strokes, location of infarct was more often in the left (46% and 54%, respectively) than right hemisphere (40% and 37%, respectively) or brainstem or cerebellum (14% and 9%, respectively).

Conclusions and Relevance

In this secondary analysis of randomized clinical trial data, most recurrent strokes after ESUS were embolic and of undetermined source. Recurrences associated with atrial fibrillation were a minority but were more often disabling and fatal. More extensive investigation to identify the embolic source is important toward an effective antithrombotic strategy.

Trial Registration

ClinicalTrials.gov Identifier: NCT02313909.

Atrial cardiopathy in embolic stroke of undetermined source

INTRODUCTION

Atrial cardiopathy is one of the most common potential sources of thromboembolism for embolic stroke of undetermined source (ESUS). The study aims to investigate the incidence of atrial cardiopathy (defined by severe left atrial enlargement (sLAE) or elevated serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) > 250 pg/ml) in patients with ESUS and compare with other stroke subtypes.

METHODS

We retrospectively collected data of 936 consecutive patients with diffusion-weighted imaging-confirmed acute ischemic stroke. The incidence of atrial cardiopathy was examined in ESUS, large artery atherosclerosis (LAA), and small vessel disease (SVD) strokes. Clinical characteristics were compared between ESUS patients with atrial cardiopathy (AC-ESUS) and patients with atrial fibrillation-induced cardioembolism (AF-CE) stroke.

RESULTS

245 patients were diagnosed with ESUS, while others were diagnosed with LAA (n = 312), SVD (n = 258), and AF-CE (n = 121) strokes. The incidence of sLAE in ESUS patients was higher than in LAA or SVD group (5.3% vs. 1.6% and 1.2%, respectively, p = .005) and higher than in combined LAA/SVD group (5.3% vs. 1.4%, p = .001). The incidence of elevated serum NT-proBNP in ESUS patients was not statistically different from that in LAA or SVD group. Compared with patients with AF-CE stroke, AC-ESUS patients had milder manifestations, had less hemorrhagic transformation, had better short-term outcome, and had fewer in-hospital complications.

CONCLUSIONS

The incidence of sLAE was higher in ESUS patients than in patients with noncardioembolic strokes. AC-ESUS was milder when compared to AF-CE stroke.

Supracardiac atherosclerosis in embolic stroke of undetermined source: the underestimated source

The term 'embolic stroke of undetermined source' (ESUS) is used to describe patients with a non-lacunar ischaemic stroke without any identified embolic source from the heart or the arteries supplying the ischaemic territory, or any other apparent cause. When the ESUS concept was introduced, covert atrial fibrillation was conceived to be the main underlying cause in the majority of ESUS patients. Another important embolic source in ESUS is the atherosclerotic plaque in the carotid, vertebrobasilar, and intracranial arteries, or the aortic arch-collectively described as supracardiac atherosclerosis. There is emerging evidence showing that the role of supracardiac atherosclerosis is larger than it was initially perceived. Advanced imaging methods are available to identify plaques which high embolic risk. The role of novel antithrombotic strategies in these patients needs to be assessed in randomized controlled trials. This review presents the evidence which points towards a major aetiological association between atherosclerotic plaques and ESUS, summarizes the imaging features which may aid to identify plaques more likely to be associated with ESUS, discusses strategies to reduce the associated stroke risk, and highlights the rationale for future research in this field.

Symptomatic nonstenotic carotid disease: Evaluation of a proposed classification scheme in a prospective cohort

INTRODUCTION

Unraveling symptomatic nonstenotic carotid disease (SyNC) as a stroke etiology from other cryptogenic stroke may have important implications for defining natural history and for tailoring secondary prevention strategies. We aim to describe the characteristics of the plaques in a prospectively-collected cohort of patients with non-invasive imaging suggesting symptomatic carotid stenosis but whose DSA demonstrated nonstenotic atheromatous disease, and to evaluate the recurrence rate depending on the type of SyNC.

METHODS

We reviewed prospectively-collected data for patients presenting with new neurologic events and non-invasive imaging suggestive of moderate or severe (≥50%) carotid stenosis between July 2016 and October 2018. Patients were included in the present study if the degree of stenosis on DSA was < 50%. We assigned these patients into groups based on a previously-proposed working definition of SyNC, and analyzed the rate of recurrent stroke in the following 6 months.

RESULTS

28 patients had DSA-confirmed < 50% stenosis and constituted the study cohort. The median age was 73 years and 64% were male; median presenting NIHSS was 1 (IQR 0-3). The great majority (86%) of carotid plaques had high-risk features including ulcerated plaque (n = 21, 75%) and plaque > 3 mm thick (n = 18, 64%). 17 of 28 patients (61%) met classification criteria for "definite" or "probable" SyNC. Three of five patients in the "definite SyNC" group experienced recurrent neurologic events.

CONCLUSION

The majority of patients with non-invasive imaging suggesting carotid stenosis harbor symptomatic carotid disease per current classifications despite DSA stenosis < 50%. Current classification schema may allow for risk stratification of SyNC patients and these findings warrant further study.

Rhythm monitoring strategies for atrial fibrillation detection in patients with cryptogenic stroke: A systematic review and meta-analysis

Objective

To summarize data on atrial fibrillation (AF) detection rates and predictors across different rhythm monitoring strategies in patients with cryptogenic stroke (CS) or embolic stroke of undetermined source (ESUS).

Methods

MEDLINE, Embase, and Web of Science were searched to identify all published studies providing relevant data through July 6, 2020. Random-effects meta-analysis method was used to pool estimates.

Results

We included 47 studies reporting on a pooled population of 8,215 patients with CS or ESUS. Using implantable cardiac monitor (ICM), the pooled rate of AF was 12.2% (95% CI 9.4–15.0) at 3 months, 16.0% (95% CI 13.2–18.8) at 6 months, 18.7% (95% CI 15.7–21.7) at 12 months, 22.8% (95% CI 19.1–26.5) at 24 months, and 28.5% (95% CI 17.6–39.3) at 36 months. AF rates were significantly higher in patients with ESUS vs CS (22.0% vs 14.2%; p < 0.001) at 6 months, and in studies using Reveal LINQ vs Reveal XT ICM (19.1% vs 13.0%; p = 0.001) at 12 months. Using mobile cardiac outpatient telemetry (MCOT), the pooled rate of AF was 13.7% (95% CI 10.2–17.2) at 1 month. Predictors of AF detection with ICM included older age, CHA₂DS₂-VASc score, left atrial enlargement, P wave maximal duration and prolonged PR interval.

Conclusion

The yield of ICM increases with the duration of monitoring. More than a quarter of patients with CS or ESUS will be diagnosed with AF during follow-up. About one in seven patients had AF detected within a month of MCOT, suggesting that a non-invasive rhythm monitoring strategy should be considered before invasive monitoring.

Embolic Stroke of Undetermined Source and Patent Foramen Ovale: Risk of Paradoxical Embolism Score Validation and Atrial Fibrillation Prediction

[Figure: see text].

[Embolic stroke of undetermined source (ESUS) - Classification of a new stroke entity]

Embolic stroke of undetermined source (ESUS) represents a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging and if after a carefully performed diagnostic evaluation, a specific, well recognized cause of stroke has not been identified. This review article analyses the basics of the ESUS concept and provides an overview of the evidence from recent cohort studies. The definition, aetiology and diagnosis of ESUS are reassessed. Targeted diagnostics in ESUS patients can reduce the number of cryptogenic strokes by making a specific diagnosis.

Cardiovascular magnetic resonance imaging and its role in the investigation of stroke: an update

Recent advances in complementary diagnostic exams have helped to clarify stroke etiology, not only by helping to confirm established stroke causes but also by unveiling new possible stroke mechanisms. Etiological investigation for cardioembolic stroke has benefited in the last years from information provided by studies analysing serum biomarkers, heart rhythm monitoring and imaging methods like cardiovascular magnetic resonance (CMR) imaging. CMR has been particularly important for the characterization of possible new cardioembolic stroke mechanisms including atrial cardiomyopathy, silent myocardial infarction and cardiomyopathies.

Atrial Fibrillation in Patients with Embolic Stroke of Undetermined Source during 3 Years of Prolonged Monitoring with an Implantable Loop Recorder

BACKGROUND

 Undocumented atrial fibrillation (AF) is suspected as a main stroke cause in patients with embolic stroke of undetermined source (ESUS), but its prevalence is largely unknown. This prospective study therefore aimed at delineating the prevalence of AF in patients with ESUS using continuous cardiac monitoring by implantable loop recorder (ILR) with daily remote interrogation over a period of 3 years and its clinical consequences, including recurrent stroke.

METHODS

 In consecutive patients with an ESUS diagnosis after complete work-up, an ILR was implanted and followed by daily remote monitoring until AF was detected or a follow-up of at least 3 years was completed. Additionally, the ILR was interrogated in-hospital in 6-month intervals.

RESULTS

 A total of 123 patients (74 male, mean age 65 ± 9 years) were enrolled and completed the 3 years study period. AF was detected in 51 patients (41.4%). In 43 of the 51 AF positive patients (84%) oral anticoagulation was established. Recurrent strokes occurred in 18 patients (14.6%) of this ESUS population, 9 of these patients being AF positive (17.6% of the AF-positive patients) and 9 being AF negative (12.5% of AF-negative patients). Patients with AF were slightly older than patients without AF (63.1 ± 8.8 vs. 67.5 ± 9.6 years, p = 0.12). Other parameters such as CHA₂DS₂-VASc score, infarct localization, micro- and macroangiopathy, carotid or aortic plaques, or stroke recurrence were not significantly different between groups.

CONCLUSION

 In ESUS patients, early implantation of an ILR with cardiac monitoring and remote transmission over a 3-year period detected AF in 41.4% and resulted in oral anticoagulation in 84% of these patients.

Carotid Atherosclerosis and Patent Foramen Ovale in Embolic Stroke of Undetermined Source

BACKGROUND

Carotid atherosclerosis and likely pathogenic patent foramen ovale (PFO) are two potential embolic sources in patients with embolic stroke of undetermined source (ESUS). The relationship between these two mechanisms among ESUS patients remains unclear.

AIM

To investigate the relation between carotid atherosclerosis and likely pathogenic PFO in patients with ESUS. We hypothesized that ipsilateral carotid atherosclerotic plaques are less prevalent in ESUS with likely pathogenic PFO compared to patients with likely incidental PFO or without PFO.

METHODS

The presence of PFO was assessed with transthoracic echocardiography with microbubble test and, when deemed necessary, through trans-oesophageal echocardiography. The presence of PFO was considered as likely incidental if the RoPE (Risk of Paradoxical Embolism) score was 0-6 and likely pathogenic if 7-10.

RESULTS

Among 374 ESUS patients (median age: 61years, 40.4% women), there were 63 (49.6%) with likely incidental PFO, 64 (50.4%) with likely pathogenic PFO and 165 (44.1%) with ipsilateral carotid atherosclerosis. The prevalence of ipsilateral carotid atherosclerosis was lower in patients with likely pathogenic PFO (7.8%) compared to patients with likely incidental PFO (46.0%) or patients without PFO (53.0%) (p<0.001). After adjustment for multiple confounders, the prevalence of ipsilateral carotid atherosclerosis remained lower in patients with likely pathogenic PFO compared to patients with likely incidental PFO or without PFO (adjusted OR=0.32, 95%CI:0.104-0.994, p=0.049).

CONCLUSIONS

The presence of carotid atherosclerosis is inversely related to the presence of likely pathogenic PFO in patients with ESUS.

Nonstenotic Carotid Plaque in Embolic Stroke of Undetermined Source: Interplay of Arterial and Atrial Disease

BACKGROUND AND PURPOSE

Approximately one-sixth of all ischemic strokes are attributable to embolic stroke of undetermined source (ESUS). Recent analyses suggest that atrial cardiopathy and nonstenotic carotid plaque (nsCP) may represent 2 distinct underlying causes in patients with ESUS, although both diseases share common risk factors and are pathophysiologically intertwined. In this study, we, therefore, aimed to search for associations between nsCP and markers of atrial remodeling and function in patients with embolic stroke.

METHODS

Sixty-eight patients with ESUS or atrial fibrillation (AF)-related stroke proven by imaging who underwent comprehensive echocardiographic studies, including measurements of left atrial function and remodeling, were considered. Patients with ESUS underwent a follow-up of at least 1 year after index stroke. For 20 patients with ESUS, NT-proBNP (N-terminal pro-B-type natriuretic peptide) values were available. Presence of nsCP was evaluated considering Duplex sonography and computed tomography angiography and was further categorized in possibly or probably symptomatic nsCP.

RESULTS

ESUS patients with nsCP tended to have higher values of septal and lateral total atrial conduction times (P=0.071 and P=0.072, respectively), left atrial volume index (P=0.077), and revealed significantly higher strain rates during early diastole (P=0.013) as well as higher NT-proBNP values (P=0.010) than ESUS patients without nsCP. Moreover, septal total atrial conduction time was significantly longer in ESUS patients with possibly symptomatic nsCP compared with those without (P=0.015). Comparison of ESUS with AF patients revealed significantly higher proportions of nsCP (P=0.010), possibly symptomatic nsCP (P=0.037), and probably symptomatic nsCP (P=0.036) in patients with atrial fibrillation-related stroke. In the regression analysis adjusted for vascular risk factors probably symptomatic nsCP remained significantly associated with AF (P=0.048, odds ratio: 4.46 [95% CI, 1.02-19.56]).

CONCLUSIONS

Presence of nsCP is associated with AF and markers of left atrial disease in patients with embolic stroke. Therefore, a thorough evaluation regarding atrial cardiopathy and AF in patients with ESUS should not be restricted if nsCP are found, even if high-risk plaque characteristics are evident.

Data-driven machine-learning analysis of potential embolic sources in embolic stroke of undetermined source

BACKGROUND AND PURPOSE

Hierarchical clustering, a common 'unsupervised' machine-learning algorithm, is advantageous for exploring potential underlying aetiology in particularly heterogeneous diseases. We investigated potential embolic sources in embolic stroke of undetermined source (ESUS) using a data-driven machine-learning method, and explored variation in stroke recurrence between clusters.

METHODS

We used a hierarchical k-means clustering algorithm on patients' baseline data, which assigned each individual into a unique clustering group, using a minimum-variance method to calculate the similarity between ESUS patients based on all baseline features. Potential embolic sources were categorised into atrial cardiopathy, atrial fibrillation, arterial disease, left ventricular disease, cardiac valvulopathy, patent foramen ovale (PFO) and cancer.

RESULTS

Among 800 consecutive ESUS patients (43.3% women, median age 67 years), the optimal number of clusters was four. Left ventricular disease was most prevalent in cluster 1 (present in all patients) and perfectly associated with cluster 1. PFO was most prevalent in cluster 2 (38.9% of patients) and associated significantly with increased likelihood of cluster 2 [adjusted odds ratio: 2.69, 95% confidence interval (CI): 1.64-4.41]. Arterial disease was most prevalent in cluster 3 (57.7%) and associated with increased likelihood of cluster 3 (adjusted odds ratio: 2.21, 95% CI: 1.43-3.13). Atrial cardiopathy was most prevalent in cluster 4 (100%) and perfectly associated with cluster 4. Cluster 3 was the largest cluster involving 53.7% of patients. Atrial fibrillation was not significantly associated with any cluster.

CONCLUSIONS

This data-driven machine-learning analysis identified four clusters of ESUS that were strongly associated with arterial disease, atrial cardiopathy, PFO and left ventricular disease, respectively. More than half of the patients were assigned to the cluster associated with arterial disease.

Cardiac natriuretic peptides for diagnosis of covert atrial fibrillation after acute ischaemic stroke: a meta-analysis of diagnostic accuracy studies

Background and purpose

Detection of atrial fibrillation (AF) after acute ischaemic stroke is pivotal for the timely initiation of anticoagulation to prevent recurrence. Besides heart rhythm monitoring, various blood biomarkers have been suggested as complimentary diagnostic tools for AF. We aimed to summarise data on the performance of cardiac natriuretic peptides for the diagnosis of covert AF after acute ischaemic stroke and to assess their potential clinical utility.

Methods

We searched PubMed and Embase for prospective studies reporting the performance of B-type natriuretic peptide (BNP) or N-terminal pro-BNP (NT-proBNP) for the diagnosis of covert AF after acute ischaemic stroke. Summary diagnostic performance measures were pooled using bivariate meta-analysis with a random-effect model.

Results

We included six studies focusing on BNP (n=1930) and three studies focusing on NT-proBNP (n=623). BNP had a sensitivity of 0.83 (95% CI 0.64 to 0.93), a specificity of 0.74 (0.67 to 0.81), a positive likelihood ratio of 3.2 (2.6 to 4.0) and a negative likelihood ratio of 0.23 (0.11 to 0.49). NT-proBNP had a sensitivity of 0.91 (0.65 to 0.98), a specificity of 0.77 (0.52 to 0.91), a positive likelihood ratio of 3.9 (1.8 to 8.7) and a negative likelihood ratio of 0.12 (0.03 to 0.48). Considering a pretest probability of 20%, BNP and NT-proBNP had post-test probabilities of 45% and 50%.

Conclusions

NT-proBNP has a better performance than BNP for the diagnosis of covert AF after acute ischaemic stroke. Both biomarkers have low post-test probabilities and may not be used as a stand-alone decision-making tool for the diagnosis of covert AF in patients with acute ischaemic stroke. However, they may be useful for a screening strategy aiming to select patients for long-term monitoring of the heart rhythm.

Atrial Cardiopathy and Likely Pathogenic Patent Foramen Ovale in Embolic Stroke of Undetermined Source

BACKGROUND

 Atrial cardiopathy and likely pathogenic patent foramen ovale (PFO) are two potential embolic sources in patients with embolic stroke of undetermined source (ESUS). The relationship between these two mechanisms among ESUS patients remains unclear.

METHODS

 Atrial cardiopathy was defined as increased left atrial diameter index (> 23 mm/m²) or left atrial volume index (> 34 mL/m²), or PR prolongation (≥ 200 ms), or presence of supraventricular extrasystoles in the electrocardiograms performed during hospitalization for the index stoke. The presence of PFO was assessed by transthoracic echocardiography with microbubble test or by transesophageal echocardiography. The presence of PFO was considered as likely pathogenic if the Risk of Paradoxical Embolism score was 7 to 10.

RESULTS

 Among 367 ESUS patients with available information about the presence of PFO and the presence of atrial cardiopathy (median age: 61 years, 40.6% women), likely pathogenic PFO was diagnosed in 62 (16.9%) and atrial cardiopathy in 122 (33.2%). Only 4 patients (1.1%) had both likely pathogenic PFO and atrial cardiopathy. The prevalence of atrial cardiopathy was lower in patients with likely pathogenic PFO (6.5%) compared with patients with likely incidental PFO (31.2%) or without PFO (40.6%) (Pearson's chi-square test: 26.08, p < 0.001; adjusted odds ratio [OR]: 0.28, 95% confidence interval [CI]: 0.09-0.86). The prevalence of likely pathogenic PFO was lower in patients with atrial cardiopathy compared with patients without atrial cardiopathy (3.3% vs. 23.7%, respectively [Pearson's chi-square test: 24.13, p < 0.001; adjusted OR: 0.2, 95% CI: 0.02-0.6]).

CONCLUSION

 The presence of atrial cardiopathy is inversely related to the presence of likely pathogenic PFO in patients with ESUS.

Machine Learning Prediction of Stroke Mechanism in Embolic Strokes of Undetermined Source

BACKGROUND AND PURPOSE

One-fifth of ischemic strokes are embolic strokes of undetermined source (ESUS). Their theoretical causes can be classified as cardioembolic versus noncardioembolic. This distinction has important implications, but the categories' proportions are unknown.

METHODS

Using data from the Cornell Acute Stroke Academic Registry, we trained a machine-learning algorithm to distinguish cardioembolic versus non-cardioembolic strokes, then applied the algorithm to ESUS cases to determine the predicted proportion with an occult cardioembolic source. A panel of neurologists adjudicated stroke etiologies using standard criteria. We trained a machine learning classifier using data on demographics, comorbidities, vitals, laboratory results, and echocardiograms. An ensemble predictive method including L1 regularization, gradient-boosted decision tree ensemble (XGBoost), random forests, and multivariate adaptive splines was used. Random search and cross-validation were used to tune hyperparameters. Model performance was assessed using cross-validation among cases of known etiology. We applied the final algorithm to an independent set of ESUS cases to determine the predicted mechanism (cardioembolic or not). To assess our classifier's validity, we correlated the predicted probability of a cardioembolic source with the eventual post-ESUS diagnosis of atrial fibrillation.

RESULTS

Among 1083 strokes with known etiologies, our classifier distinguished cardioembolic versus noncardioembolic cases with excellent accuracy (area under the curve, 0.85). Applied to 580 ESUS cases, the classifier predicted that 44% (95% credibility interval, 39%-49%) resulted from cardiac embolism. Individual ESUS patients' predicted likelihood of cardiac embolism was associated with eventual atrial fibrillation detection (OR per 10% increase, 1.27 [95% CI, 1.03-1.57]; c-statistic, 0.68 [95% CI, 0.58-0.78]). ESUS patients with high predicted probability of cardiac embolism were older and had more coronary and peripheral vascular disease, lower ejection fractions, larger left atria, lower blood pressures, and higher creatinine levels.

CONCLUSIONS

A machine learning estimator that distinguished known cardioembolic versus noncardioembolic strokes indirectly estimated that 44% of ESUS cases were cardioembolic.

Ipsilateral Nonstenotic Carotid Disease in Minor Ischemic Stroke: an Exploratory Analysis of The POINT Randomized Clinical Trial

BACKGROUND AND AIM

Ipsilateral nonstenotic carotid disease is increasingly recognized as an etiology of ischemic stroke, however tailored treatment strategies are lacking. We aimed to examine clinical characteristics and treatment effects in patients with minor ischemic stroke associated with ipsilateral nonstenotic carotid disease in the Platelet Oriented Inhibition in New TIA and Minor Ischemic Stroke (POINT) trial.

METHODS

We performed an exploratory analysis of the interaction of the treatment effects of aspirin plus clopidogrel versus aspirin monotherapy, stratified by presence of ipsilateral nonstenotic carotid disease in patients with minor ischemic stroke in the POINT trial.

RESULTS

For this exploratory analysis, 167 patients presenting with ischemic stroke and ipsilateral nonstenotic carotid disease, defined as 1%-49% carotid stenosis ipsilateral to the corresponding territory of ischemic stroke, and 833 patients no carotid disease were included. Compared to patients with no carotid disease, patients with ipsilateral nonstenotic carotid disease were older (68.5 ± 11.3 years versus 61.3 ± 12.8 years; P < 0.001), and had a higher prevalence of hypertension (76.6% versus 59.2%, P < 0.001), ischemic heart disease (13.8% versus 5.4%, P < 0.001), and tobacco use (past: 34.1% versus 25.2%, P = 0.005; present: 27.5% versus 22.8%, P = 0.005). 5.4% of patients with ipsilateral nonstenotic carotid disease had recurrent ischemic stroke within 14 days. Patients receiving dual antiplatelet therapy had a numerical reduction in recurrent ischemic stroke compared to patients receiving aspirin monotherapy, however the exploratory analysis was underpowered to detect a statistically significant difference in treatment effect (HR 0.50, 95% CI 0.18-1.40, P = 0.19).

CONCLUSION

Patients with minor ischemic stroke and ipsilateral nonstenotic carotid disease had a high risk of early stroke recurrence in the POINT trial. Dual antiplatelet therapy provided a non-statistically significant reduction in recurrent ischemic stroke with no difference in safety outcomes compared to aspirin monotherapy. Further study is needed to determine if early and short duration dual antiplatelet therapy is beneficial for all patients with ipsilateral nonstenotic carotid disease.

Embolic Stroke of Undetermined Source: Gateway to a New Stroke Entity?

Embolic stroke of unknown source (ESUS) is currently thought to represent a subpopulation of cryptogenic strokes defined by its embolic stroke pattern on imaging, and if after a carefully performed diagnostic evaluation, a specific, well-recognized cause of stroke has not been identified. The concept was primarily established to justify and enable the conduct of the ESUS trials, such as Randomized, Double-Blind, Evaluation in Secondary Stroke Prevention Comparing the Efficacy and Safety of the Oral Thrombin Inhibitor Dabigatran Etexilate versus Acetylsalicylic Acid in Patients with Embolic Stroke of Undetermined Source (RESPECT-ESUS) and New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial versus aspirin to Prevent Embolism in Embolic Stroke of Undetermined Source (NAVIGATE-ESUS). With both studies having neutral results, the question arises if the ESUS concept is misleading or rather a gateway for a modern understanding of stroke etiology. This review will analyze the background of the ESUS concept, overview the results and the impact of the recent multicenter trials and cohort studies, and discuss the definition, etiology, and diagnosis of ESUS.

Identification of patients with embolic stroke of undetermined source and low risk of new incident atrial fibrillation: The AF-ESUS score

Background and aims

Only a minority of patients with Embolic Stroke of Undetermined Source (ESUS) receive prolonged cardiac monitoring despite current recommendations. The identification of ESUS patients who have low probability of new diagnosis of atrial fibrillation (AF) could potentially support a strategy of more individualized allocation of available resources and hence, increase their diagnostic yield. We aimed to develop a tool that can identify ESUS patients who have low probability of new incident AF.

Methods

We performed multivariate stepwise regression in a pooled dataset of consecutive ESUS patients from three prospective stroke registries to identify predictors of new incident AF. The coefficient of each independent covariate of the fitted multivariable model was used to generate an integer-based point scoring system.

Results

Among 839 patients (43.1% women, median age 67.0 years) followed-up for a median of 24.3 months (2999 patient-years), 125 (14.9%) had new incident AF. The proposed score assigns 3 points for age ≥ 60 years; 2 points for hypertension; −1 point for left ventricular hypertrophy reported at echocardiography; 2 points for left atrial diameter >40 mm; −3 points for left ventricular ejection fraction <35%; 1 point for the presence of any supraventricular extrasystole recorded during all available 12-lead standard electrocardiograms performed during hospitalization for the ESUS; −2 points for subcortical infarct; −3 points for the presence of non-stenotic carotid plaques. The rate of new incident AF during follow-up was 1.97% among the 42.3% of the cohort who had a score of ≤0, compared to 26.9% in patients with > 0 (relative risk: 13.7, 95%CI: 5.9--31.5). The area under the curve of the score was 84.8% (95%CI: 79.9--86.9%). The sensitivity and negative predictive value of a score of ≤0 for new incident AF during follow-up were 94.9% (95%CI: 89.3--98.1%) and 98.0% (95%CI: 95.8--99.3%), respectively.

Conclusions

The proposed AF-ESUS score has high sensitivity and high negative predictive value to identify ESUS patients who have low probability of new incident AF. Patients with a score of 1 or more may be better candidates for prolonged automated cardiac monitoring.

Clinical trial registration

URL: https://www.clinicaltrials.gov / Unique identifier: NCT02766205.

Left atrial diameter thresholds and new incident atrial fibrillation in embolic stroke of undetermined source

BACKGROUND AND PURPOSE

We analyzed consecutive patients with embolic stroke of undetermined source (ESUS) from three prospective stroke registries to compare the prognostic performance of different LAD thresholds for the prediction of new incident AF.

METHODS

We calculated the sensitivity, specificity, positive prognostic value (PPV), negative prognostic value (NPV) and Youden's J-statistic of different LAD thresholds to predict new incident AF. We performed multivariate stepwise regression with forward selection of covariates to assess the association between the LAD threshold with the highest Youden's J-statistic and AF detection.

RESULTS

Among 675 patients followed for 2437 patient-years, the mean LAD was 38.5 ± 6.8 mm. New incident AF was diagnosed in 115 (17.0%) patients. The LAD threshold of 40mm yielded the highest Youden's J-statistic of 0.35 with sensitivity 0.69, specificity 0.66, PPV 0.27 and NPV 0.92. The likelihood of new incident AF was nearly twice in patients with LAD > 40 mm compared to LAD ≤ 40 mm (HR:1.92, 95%CI:1.24-2.97, p = 0.004). The 10-year cumulative probability of new incident AF was higher in patients with LAD>40 mm compared to LAD ≤ 40 mm (53.5% and 22.4% respectively, log-rank-test: 28.2, p < 0.001). The annualized rate of stroke recurrence of 4.0% in the overall population did not differ significantly in patient above vs. below this LAD threshold (HR:0.96, 95%CI:0.62-1.48, p = 0.85).

CONCLUSIONS

The LAD threshold of 40 mm has the best prognostic performance among other LAD values to predict new incident AF after ESUS. The diagnostic yield of prolonged cardiac rhythm monitoring in patients with LAD ≤ 40 mm seems low; therefore, such patients may have lower priority for prolonged cardiac monitoring.

Embolic Stroke of Undetermined Source and Sleep Disorders

Background and Purpose—

Compared with other causes of ischemic stroke, the mechanism of action of embolic stroke of undetermined source (ESUS) remains unclear, with previous literature suggesting that ESUS may be due to an undetected cardioembolic source. This study aimed to improve our understanding of the pathophysiology of ESUS through current knowledge of sleep disorders.

Methods—

Patients were included in this study if they sustained an ischemic stroke and completed either polysomnography or a home sleep apnea test. Strokes were classified into 1 of 6 mechanisms and were compared with the presence of sleep disorders (ie, obstructive sleep apnea, periodic limb movements, and abnormalities in sleep architecture).

Results—

There was a significant relationship between obstructive sleep apnea and cardioembolic stroke mechanism compared with the other stroke mechanisms ( P =0.018). There was no significant relationship between obstructive sleep apnea and ESUS ( P =0.585). Patients with ESUS were significantly more likely to have an elevated periodic limb movement index ( P =0.037) and prolonged sleep onset latency ( P =0.0166) compared with patients with other causes of stroke.

Conclusions—

ESUS was not associated with markers of cardioembolic stroke such as obstructive sleep apnea. There was a significant relationship between ESUS and elevated periodic limb movements and impaired sleep architecture, which suggests that ESUS may have a multifactorial underlying pathophysiology.

Characteristics and outcomes of Embolic Stroke of Undetermined Source according to stroke severity

Background and aims

Patients with embolic strokes of undetermined source (ESUS) usually present with mild symptoms. We aimed to compare the baseline characteristics between mild and severe ESUS, identify predictors for severe ESUS, and assess outcomes of patients with severe ESUS.

Methods

In the AF-ESUS (AF-ESUS) dataset, we stratified ESUS severity using the median National Institutes of Health Stroke Scale (NIHSS) score on admission as cut-off. We performed multivariable stepwise regression analyses to identify independent predictors of severe ESUS and to assess the association between ESUS severity and stroke recurrence, death, and new incident atrial fibrillation (AF) on follow-up. The 10-year cumulative probabilities of outcome incidence were estimated by the Kaplan–Meier product limit method.

Results

In 772 patients (median NIHSS: 6 (interquartile range: 3–12)), 414 (53.6%) patients had severe ESUS (i.e. NIHSS ≥6). Female sex was the only independent predictor for severe ESUS (odds ratio: 1.72 (1.27–2.33)). The rates of recurrence (3.3%/year vs. 3.4%/year, adjusted-hazard ratio: 1.09 (0.73–1.62)) and new incident AF (13.5% vs. 17.0%, adjusted odds ratio: 0.67 (0.44–1.03)) were similar between severe and mild ESUS, but mortality was higher (5.4%/year vs. 3.7%/year, adjusted-hazard ratio: 1.51 (1.05–2.16)) in severe ESUS. The 10-year cumulative probability for stroke recurrence was similar between severe and mild ESUS (38.1% (29.2–48.6) vs. 36.6% (27.8–47.0), log-rank test: 0.01, p = 0.920). The 10-year cumulative probability of death was higher in patients with severe ESUS compared with mild ESUS (40.5% (32.5–50.0) vs. 34.0% (26.0–43.6) respectively; log-rank test: 4.54, p = 0.033).

Conclusions

Women have more severe ESUS compared with men. Patients with severe ESUS have similar rates of stroke recurrence and new incident AF, but higher mortality compared with mild ESUS.

External Performance of the HAVOC Score for the Prediction of New Incident Atrial Fibrillation

Background and Purpose—

The HAVOC score (hypertension, age, valvular heart disease, peripheral vascular disease, obesity, congestive heart failure, coronary artery disease) was proposed for the prediction of atrial fibrillation (AF) after cryptogenic stroke. It showed good model discrimination (area under the curve, 0.77). Only 2.5% of patients with a low-risk HAVOC score (ie, 0–4) were diagnosed with new incident AF. We aimed to assess its performance in an external cohort of patients with embolic stroke of undetermined source.

Methods—

In the AF-embolic stroke of undetermined source dataset, we assessed the discriminatory power, calibration, specificity, negative predictive value, and accuracy of the HAVOC score to predict new incident AF. Patients with a HAVOC score of 0 to 4 were considered as low-risk, as proposed in its original publication.

Results—

In 658 embolic stroke of undetermined source patients (median age, 67 years; 44% women), the median HAVOC score was 2 (interquartile range, 3). There were 540 (82%) patients with a HAVOC score of 0 to 4 and 118 (18%) with a score of ≥5. New incident AF was diagnosed in 95 (14.4%) patients (28.8% among patients with HAVOC score ≥5 and 11.3% among patients with HAVOC score 0–4 [age- and sex-adjusted odds ratio, 2.29 (95% CI, 1.37–3.82)]). The specificity of low-risk HAVOC score to identify patients without new incident AF was 88.7%. The negative predictive value of low-risk HAVOC score was 85.1%. The accuracy was 78.0%, and the area under the curve was 68.7% (95% CI, 62.1%–73.3%).

Conclusions—

The previously reported low rate of AF among embolic stroke of undetermined source patients with low-risk HAVOC score was not confirmed in our cohort. Further assessment of the HAVOC score is warranted before it is routinely implemented in clinical practice.

Atrial Cardiopathy and Nonstenosing Large Artery Plaque in Patients With Embolic Stroke of Undetermined Source

Background and Purpose- Atrial cardiopathy and atherosclerotic plaque are two potential mechanisms underlying embolic strokes of undetermined source (ESUS). The relationship between these two mechanisms among ESUS patients remains unclear. A better understanding of their association may inform targeted secondary prevention strategies. Methods- We examined the association between atrial cardiopathy and atherosclerotic plaque in the NAVIGATE ESUS trial (New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial Versus ASA to Prevent Embolism in Embolic Stroke of Undetermined Source), which enrolled 7213 patients with recent ESUS during 2014 to 2017. For this analysis, we included patients with data on left atrial dimension, location of brain infarction, and cervical large artery plaque. The variables of primary interest were left atrial diameter and cervical plaque ipsilateral to brain infarction. Secondary markers of atrial cardiopathy were premature atrial contractions on Holter monitoring and newly diagnosed atrial fibrillation. For descriptive purposes, left atrial enlargement was defined as ≥4.7 cm. Multivariable logistic regression was used to examine the association between atrial cardiopathy markers and ipsilateral plaque after adjustment for age, sex, body mass index, hypertension, diabetes mellitus, current smoking, and hyperlipidemia. Results- Among 3983 eligible patients, 235 (5.9%) had left atrial enlargement, 939 (23.6%) had ipsilateral plaque, and 94 (2.4%) had both. Shared risk factors for left atrial enlargement and ipsilateral plaque were male sex, white race, hypertension, tobacco use, and coronary artery disease. Despite shared risk factors, increasing left atrial dimension was not associated with ipsilateral plaque after adjustment for covariates (odds ratio per cm, 1.1 [95% CI, 1.0-1.2]; P=0.08). We found no consistent associations between secondary markers of atrial cardiopathy and ipsilateral plaque. Conclusions- In a large population of patients with ESUS, we did not observe a notable association between atrial cardiopathy and atherosclerotic plaque, and few patients had both conditions. These findings suggest that atrial cardiopathy and atherosclerotic plaque may be distinct, nonoverlapping risk factors for stroke among ESUS patients.

Carotid Plaque With High-Risk Features in Embolic Stroke of Undetermined Source: Systematic Review and Meta-Analysis

Background and Purpose- An ipsilateral mild carotid stenosis, defined as plaque with <50% luminal narrowing, is identified in nearly 40% of patients with embolic stroke of undetermined source and could represent an unrecognized source of atheroembolism. We aimed to summarize data about the frequency of mild carotid stenosis with high-risk features in embolic stroke of undetermined source. Methods- We searched Pubmed and Ovid-Embase for studies reporting carotid plaque imaging features in embolic stroke of undetermined source. The prevalence of ipsilateral and contralateral mild carotid stenosis with high-risk features was pooled using random-effect meta-analysis. Results- Eight studies enrolling 323 participants were included. The prevalence of mild carotid stenosis with high-risk features in the ipsilateral carotid was 32.5% (95% CI, 25.3-40.2) compared with 4.6% (95% CI, 0.1-13.1) in the contralateral carotid. The odds ratio of finding a plaque with high-risk features in the ipsilateral versus the contralateral carotid was 5.5 (95% CI, 2.5-12.0). Conclusions- Plaques with high-risk features are 5 times more prevalent in the ipsilateral compared with the contralateral carotid in embolic stroke of undetermined source, suggesting a relationship to stroke risk.

Efficacy and Safety of Rivaroxaban Versus Aspirin in Embolic Stroke of Undetermined Source and Carotid Atherosclerosis

Background and Purpose—

The sources of emboli in patients with embolic stroke of undetermined source (ESUS) are multiple and may not respond uniformly to anticoagulation. In this exploratory subgroup analysis of patients with carotid atherosclerosis in the NAVIGATE (New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial Versus ASA to Prevent Embolism)-ESUS trial, we assessed whether the treatment effect in this subgroup is consistent with the overall trial population and investigated the association of carotid atherosclerosis with recurrent ischemic stroke.

Methods—

Carotid atherosclerosis was analyzed either as the presence of mild (ie, 20%–49%) atherosclerotic stenosis or, separately, as the presence of carotid plaque. Primary efficacy outcome was ischemic stroke recurrence. Safety outcomes were major bleeding and symptomatic intracerebral bleeding.

Results—

Carotid plaque was present in 40% of participants and mild carotid stenosis in 11%. There was no significant difference in ischemic stroke recurrence between rivaroxaban- and aspirin-treated patients among 490 patients with carotid stenosis (5.0 versus 5.9/100 patient-years, respectively, hazard ratio [HR], 0.85; 95% CI, 0.39–1.87; P for interaction of treatment effect with patients without carotid stenosis 0.78) and among 2905 patients with carotid plaques (5.9 versus 4.9/100 patient-years, respectively, HR, 1.20; 95% CI, 0.86–1.68; P for interaction of treatment effect with patients without carotid stenosis 0.2). Among patients with carotid plaque, major bleeding was more frequent in rivaroxaban-treated patients compared with aspirin-treated (2.0 versus 0.5/100 patient-years, HR, 3.75; 95% CI, 1.63–8.65). Patients with carotid stenosis had similar rate of ischemic stroke recurrence compared with those without (5.4 versus 4.9/100 patient-years, respectively, HR, 1.11; 95% CI, 0.73–1.69), but there was a strong trend of higher rate of ischemic stroke recurrence in patients with carotid plaque compared with those without (5.4 versus 4.3/100 patient-years, respectively, HR, 1.23; 95% CI, 0.99–1.54).

Conclusions—

In ESUS patients with carotid atherosclerosis, we found no difference in efficacy between rivaroxaban and aspirin for prevention of recurrent stroke, but aspirin was safer, consistent with the overall trial results. Carotid plaque was much more often present ipsilateral to the qualifying ischemic stroke than contralateral, supporting an important etiological role of nonstenotic carotid disease in ESUS.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02313909.

Prevalence and Overlap of Potential Embolic Sources in Patients With Embolic Stroke of Undetermined Source

Background

We aimed to assess the prevalence and degree of overlap of potential embolic sources (PES) in patients with embolic stroke of undetermined source (ESUS).

Methods and Results

In a pooled data set derived from 3 prospective stroke registries, patients were categorized in ≥1 groups according to the PES that was/were identified. We categorized PES as follows: atrial cardiopathy, atrial fibrillation diagnosed during follow‐up, arterial disease, left ventricular disease, cardiac valvular disease, patent foramen ovale, and cancer. In 800 patients with ESUS (43.1% women; median age, 67.0 years), 3 most prevalent PES were left ventricular disease, arterial disease, and atrial cardiopathy, which were present in 54.4%, 48.5%, and 45.0% of patients, respectively. Most patients (65.5%) had >1 PES, whereas only 29.7% and 4.8% of patients had a single or no PES, respectively. In 31.1% of patients, there were ≥3 PES present. On average, each patient had 2 PES (median, 2). During a median follow‐up of 3.7 years, stroke recurrence occurred in 101 (12.6%) of patients (23.3 recurrences per 100 patient‐years). In multivariate analysis, the risk of stroke recurrence was higher in the atrial fibrillation group compared with other PES, but not statistically different between patients with 0 to 1, 2, or ≥3 PES.

Conclusions

There is major overlap of PES in patients with ESUS. This may possibly explain the negative results of the recent large randomized controlled trials of secondary prevention in patients with ESUS and offer a rationale for a randomized controlled trial of combination of anticoagulation and aspirin for the prevention of stroke recurrence in patients with ESUS.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02766205.

Prevalence of Nonstenotic Carotid Plaque in Stroke Due to Atrial Fibrillation Compared to Embolic Stroke of Undetermined Source

BACKGROUND

Embolic stroke of undetermined source (ESUS) accounts for about 20% of strokes. Nonstenotic cervical arterial plaque may be a mechanism of stroke in a subset of these patients.

METHODS

A cohort of consecutive patients with ischemic stroke was retrospectively identified from a stroke registry. Patients with unilateral anterior circulation embolic stroke due to atrial fibrillation (AF) or consistent with ESUS who underwent computed tomographic neck angiography were included. The prespecified primary outcome was a comparison of the prevalence of carotid plaque greater than or equal to 3 mm thickness ipsilateral versus contralateral to the infarct side.

RESULTS

Of 772 screened patients, 96 patients with ESUS and 99 patients with AF were included. Plaque greater than or equal to 3 mm was more frequently ipsilateral than contralateral to the infarct in patients with ESUS (41% versus 29%, P = .03), and plaque thickness was greater ipsilateral compared to contralateral (median 2.5 versus 2.2 mm, P = .02). No significant differences in plaque characteristics ipsilateral compared to contralateral were found in patients with AF. The prevalence of ipsilateral versus contralateral plaque was greater in ESUS patients less than or equal to 65 years old (48% versus 19%, P < .01), but no different in patients greater than 65 years old (35% versus 39%, P = .57).

CONCLUSIONS

Nonstenotic cervical carotid plaque is more common ipislateral to the infarction in patients with ESUS, but not in patients with AF, supporting an underlying atheroembolic mechanism in a subset of ESUS patients. This association might be greater in younger ESUS patients.