Frequency and Patterns of Brain Infarction in Patients With Embolic Stroke of Undetermined Source: NAVIGATE ESUS Trial.

BACKGROUND AND PURPOSE: The spectrum of brain infarction in patients with embolic stroke of undetermined source (ESUS) has not been well characterized. Our objective was to define the frequency and pattern of brain infarcts detected by magnetic resonance imaging (MRI) among patients with recent ESUS participating in a clinical trial. METHODS: 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), an MRI substudy was carried out at 87 sites in 15 countries. Participants underwent an MRI using a specified protocol near randomization. Images were interpreted centrally by those unaware of clinical characteristics. RESULTS: Among the 918 substudy cohort participants, the mean age was 67 years and 60% were men with a median (interquartile range) of 64 (26-115) days between the qualifying ischemic stroke and MRI. On MRI, 855 (93%) had recent or chronic brain infarcts that were multiple in 646 (70%) and involved multiple arterial territories in 62% (401/646). Multiple brain infarcts were present in 68% (510/755) of those without a history of stroke or transient ischemic attack before the qualifying ESUS. Prior stroke/transient ischemic attack (P<0.001), modified Rankin Scale score >0 (P<0.001), and current tobacco use (P=0.01) were associated with multiple infarcts. Topographically, large and/or cortical infarcts were present in 89% (757/855) of patients with infarcts, while in 11% (98/855) infarcts were exclusively small and subcortical. Among those with multiple large and/or cortical infarcts, 57% (251/437) had one or more involving a different vascular territory from the qualifying ESUS. CONCLUSIONS: Most patients with ESUS, including those without prior clinical stroke or transient ischemic attack, had multiple large and/or cortical brain infarcts detected by MRI, reflecting a substantial burden of clinical stroke and covert brain infarction. Infarcts most frequently involved multiple vascular territories. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02313909.

Left Ventricular Dysfunction Among Patients With Embolic Stroke of Undetermined Source and the Effect of Rivaroxaban vs Aspirin: A Subgroup Analysis of the NAVIGATE ESUS Randomized Clinical Trial.

Importance: It is uncertain whether anticoagulation is superior to aspirin at reducing recurrent stroke in patients with recent embolic strokes of undetermined source (ESUS) and left ventricular (LV) dysfunction. Objective: To determine whether anticoagulation is superior to aspirin in reducing recurrent stroke in patients with ESUS and LV dysfunction. Design, Setting, and Participants: Post hoc exploratory analysis of data from the New Approach Rivaroxaban Inhibition of Factor Xa in a Global Trial vs Aspirin to Prevent Embolism in ESUS (NAVIGATE ESUS) trial, a randomized, phase 3 clinical trial with enrollment from December 2014 to September 2017. The study setting included 459 stroke recruitment centers in 31 countries. Patients 50 years or older who had neuroimaging-confirmed ESUS between 7 days and 6 months before screening were eligible. Of the 7213 NAVIGATE ESUS participants, 7107 (98.5%) had a documented assessment of LV function at study entry and were included in the present analysis. Data were analyzed in January 2021. Interventions: Participants were randomized to receive either 15 mg of rivaroxaban or 100 mg of aspirin once daily. Main Outcomes and Measures: The study examined whether rivaroxaban was superior to aspirin at reducing the risk of (1) the trial primary outcome of recurrent stroke or systemic embolism and (2) the trial secondary outcome of recurrent stroke, systemic embolism, myocardial infarction, or cardiovascular mortality during a median follow-up of 10.4 months. LV dysfunction was identified locally through echocardiography and defined as moderate to severe global impairment in LV contractility and/or a regional wall motion abnormality. A Cox proportional hazards model was used to assess for treatment interaction and to estimate the hazard ratios for those randomized to rivaroxaban vs aspirin by LV dysfunction status. Results: LV dysfunction was present in 502 participants (7.1%). Of participants with LV dysfunction, the mean (SD) age was 67 (10) years, and 130 (26%) were women. Among participants with LV dysfunction, annualized primary event rates were 2.4% (95% CI, 1.1-5.4) in those assigned to rivaroxaban vs 6.5% (95% CI, 4.0-11.0) in those assigned aspirin. Among the 6605 participants without LV dysfunction, rates were similar between those assigned to rivaroxaban (5.3%; 95% CI, 4.5-6.2) vs aspirin (4.5%; 95% CI, 3.8-5.3). Participants with LV dysfunction assigned to rivaroxaban vs aspirin had a lower risk of the primary outcome (hazard ratio, 0.36; 95% CI, 0.14-0.93), unlike those without LV dysfunction (hazard ratio, 1.16; 95% CI, 0.93-1.46) (P for treatment interaction = .03). Results were similar for the secondary outcome. Conclusions and Relevance: In this post hoc exploratory analysis, rivaroxaban was superior to aspirin in reducing the risk of recurrent stroke or systemic embolism among NAVIGATE ESUS participants with LV dysfunction. Trial Registration: ClinicalTrials.gov Identifier: NCT02313909.

Intracranial and systemic atherosclerosis in the NAVIGATE ESUS trial: Recurrent stroke risk and response to antithrombotic therapy.

BACKGROUND: Non-stenotic intracranial and systemic atherosclerosis are associated with ischemic stroke. We report frequency and response to anticoagulant vs. antiplatelet prophylaxis of patients with embolic stroke of undetermined source (ESUS) who have non-stenotic intracranial atherosclerosis and/or systemic atherosclerosis. METHODS: Exploratory analysis of the international NAVIGATE ESUS randomized trial comparing rivaroxaban 15mg daily with aspirin 100mg daily in 7213 patients with recent ESUS. Among participants with results of intracranial arterial imaging with either computed tomographic angiography (CTA) or magnetic resonance angiography (MRA), the frequency and predictors of non-stenotic intracranial and systemic atherosclerosis and responses to antithrombotic therapy were assessed. RESULTS: Among 4723 participants with available intracranial CTA or MRA results (65% of the trial cohort), the prevalence of intracranial atherosclerosis was 16% (n=739). Patient features independently associated with intracranial atherosclerosis included East Asian region (odds ratio 2.7, 95%CI 2.2,3.3) and cervical carotid plaque (odds ratio 2.3, 95%CI 1.9,2.7), among others. The rate of recurrent ischemic stroke averaged 4.8%/year among those with intracranial atherosclerosis vs. 5.0.%/year for those without (HR 0.95, 95%CI 0.65, 1.4). Among those with intracranial atherosclerosis, the recurrent ischemic stroke rate was higher if assigned to rivaroxaban (5.8%/year) vs. aspirin (3.7%/year), but the difference was not statistically significant (HR 1.6, 95%CI 0.78, 3.3). There was trend for the effect of antithrombotic treatments to be different according to the presence or absence of intracranial atherosclerosis (pinteraction=0.09). Among participants with evidence of systemic atherosclerosis by either history or imaging (n=3820), recurrent ischemic stroke rates were similar among those assigned to rivaroxaban (5.5%/year) vs. aspirin (4.9%/year)(HR 1.1, 95%CI 0.84, 1.5). CONCLUSIONS: East Asia region was the strongest factor associated with intracranial atherosclerosis. There were no statistically significant differences between rivaroxaban and aspirin prophylaxis for recurrent ischemic stroke in patients with non-stenotic intracranial atherosclerosis and/or systemic atherosclerosis.

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.