Classification of Covert Brain Infarct Subtype and Risk of Death and Vascular Events

Estimated Pulse-Wave Velocity and Magnetic Resonance Imaging Markers of Cerebral Small-Vessel Disease in the NOMAS

BACKGROUND

Pulse-wave velocity is a measure of arterial stiffness and a risk factor for cardiovascular disease. Recently, an estimated pulse-wave velocity (ePWV) was introduced that was predictive of increased risk of cardiovascular disease. Our objective was to determine whether ePWV was associated with cerebral small-vessel disease on magnetic resonance imaging.

METHODS AND RESULTS

We included 1257 participants from the NOMAS (Northern Manhattan Study). The ePWV values were calculated using a nonlinear function of age and mean arterial blood pressure. The association between ePWV and white matter hyperintensity volume was assessed. Modification by race and ethnicity was evaluated. Associations between ePWV and other cerebral small-vessel disease markers, covert brain infarcts, cerebral microbleeds, and enlarged perivascular spaces, were explored as secondary outcomes. Mean±SD age of the cohort was 64±8 years; 61% were women; 18% self-identified as non-Hispanic Black, 67% as Hispanic, and 15% as non-Hispanic White individuals. Mean±SD ePWV was 11±2 m/s in the total NOMAS population and was similar across race and ethnic groups. The ePWV was significantly associated with white matter hyperintensity volume (β=0.23 [95% CI, 0.20-0.26]) after adjustment. Race and ethnicity modified the association between ePWV and white matter hyperintensity volume, with stronger associations in Hispanic and non-Hispanic Black individuals. Significant associations were found between ePWV and covert brain infarcts, cerebral microbleeds, and perivascular spaces after adjustment.

CONCLUSIONS

The ePWV function may provide a vascular mechanism for deleterious cerebrovascular outcomes in individuals with cerebral small-vessel disease and is particularly apparent in the racial and ethnic minorities represented in the NOMAS cohort.

Relationships of Hematocrit With Chronic Covert and Acute Symptomatic Lacunar Ischemic Lesions

BACKGROUND AND OBJECTIVES

Red blood cell (RBC) concentrations are known to associate with ischemic stroke. It is unclear whether RBC concentrations associate specifically with small vessel disease lacunar infarcts. We investigated the hypothesis that RBC concentrations associate with both chronic covert and acute symptomatic brain MRI lacunar infarcts.

METHODS

A cross-sectional observational analysis was performed across 2 cohorts with available hematocrit (as the assessment of RBC concentration exposure) and MRI outcome data. The primary setting was a population-based cohort of stroke-free, older adult (>50 years) participants from the Northern Manhattan Study (NOMAS) enrolled between 2003 and 2009. A second replication sample consisted of patients admitted with acute stroke and enrolled into the Columbia Stroke Registry (CSR) between 2005 and 2020. Associations of hematocrit with (1) chronic, covert lacunar infarcts and (2) symptomatic (i.e., acute) lacunar strokes were separately assessed from the NOMAS and CSR cohorts, respectively, using general additive models after adjusting for relevant covariates.

RESULTS

Of 1,218 NOMAS participants analyzed, 6% had chronic, covert lacunar infarcts. The association between hematocrit and these covert lacunar infarcts was U-shaped (χ2 = 9.21 for nonlinear associations; p = 0.03), with people with hematocrit extremes being more likely to have covert lacunar infarcts. Of the 1,489 CSR patients analyzed, 23% had acute lacunar strokes. In this sample, only the relationships of increased hematocrit concentrations and lacunar strokes were replicated (adjusted coefficient β = 0.020; SE = 0.009; p = 0.03).

DISCUSSION

We identified relationships of hematocrit with MRI lacunar infarcts in both stroke-free and ischemic stroke cohorts, respectively. The relationship between increased hematocrit concentrations with lacunar infarcts was replicated in both cohorts. Further studies are required to clarify the mechanisms behind the relationships of hematocrit with ischemic cerebral small vessel disease.

The role of intracranial artery calcification (IAC) in stroke subtype and risk of vascular events

OBJECTIVE

To test the hypothesis that intracranial arterial calcification (IAC) is associated with intracranial large artery stenosis (ILAS) and a higher risk of vascular events and mortality.

METHOD

We leveraged data from two cohorts, the New York-Presbyterian Hospital/Columbia University Irving Medical Center Stroke Registry Study (NYP/CUIMC-SRS) and the Northern Manhattan Study (NOMAS) to test our hypotheses. We measured IAC using CT scans of participants in both cohorts and expressed IAC as present (vs not) and in tertiles. For the CUIMC-SRS, demographic, clinical and ILAS status was collected retrospectively. In NOMAS, we used research brain MRI and MRA to define asymptomatic ILAS and covert brain infarcts(CBI). We built models adjusted for demographics and vascular risk factors for cross-sectional and longitudinal analyses.

RESULTS

Cross-sectionally, IAC was associated with ILAS in both cohorts (OR 1.78, 95% CI: 1.16-2.73 for ILAS-related stroke in the NYP/CUIMC-SRS and OR 3.07, 95%CI 1.13-8.35 for ILAS-related covert brain infarcts in NOMAS). In a meta-analysis of both cohorts, IAC in the upper (HR 1.25, 95%CI 1.01-1.55) and middle tertile (HR 1.27, 95%CI 1.01-1.59) was associated with higher mortality compared with participants with no IAC. There were no longitudinal associations between IAC and risk of stroke or other vascular events.

CONCLUSION

In these multiethnic populations, IAC is associated with symptomatic and asymptomatic ILAS as well as higher mortality. IAC may be a useful marker of higher mortality, the role of IAC as an imaging marker of risk of stroke is less certain.

Ischemic stroke recurrence and mortality in different imaging phenotypes of ischemic cerebrovascular disease: The SMART-MR Study

Background:

Diagnosis of cerebrovascular disease is based on both clinical and radiological findings, however, they do not always correlate.

Aims:

To investigate ischemic stroke recurrence and mortality in patients with different imaging phenotypes of ischemic cerebrovascular disease.

Methods:

Within the SMART-MR study, a prospective patient cohort with arterial disease, cerebrovascular diseases of participants at baseline were classified as no cerebrovascular disease (reference group, n = 828), symptomatic cerebrovascular disease ( n = 204), covert vascular lesions ( n = 156), or imaging negative ischemia ( n = 90) based upon clinical and MRI findings. Ischemic strokes and deaths were collected at 6 month-intervals up to 17 years of follow-up. With Cox regression, relationships between phenotype and ischemic stroke recurrence, cardiovascular mortality, and non-vascular mortality were studied adjusted for age, sex, and cardiovascular risk factors.

Results:

Compared to reference group risk for recurrent ischemic stroke was increased not only in the symptomatic cerebrovascular disease (HR 3.9, 95% CI 2.3–6.6), but also in the covert vascular lesion (HR 2.5, 95% CI 1.3–4.8) and the imaging negative ischemia groups (HR 2.4, 95% CI 1.1–5.5). Risk for cardiovascular mortality was increased in the symptomatic cerebrovascular disease (HR 2.2, 95% CI 1.5–3.2) and covert vascular lesions groups (HR 2.3, 95% CI 1.5–3.4), while the risk was less strong but also increased in the imaging negative ischemia group (HR 1.7, 95% CI 0.9–3.0).

Conclusions:

People with all imaging phenotypes of cerebrovascular disease have increased risk of recurrent ischemic stroke and mortality compared to other arterial diseases. Strict preventive measures should be performed even when imaging findings or clinical symptoms are absent.

Data access statement:

For use of anonymized data, a reasonable request has to be made in writing to the UCC-SMART study group and the third party has to sign a confidentiality agreement.

Covert Brain Infarction as a Risk Factor for Stroke Recurrence in Patients With Atrial Fibrillation

BACKGROUND

We aimed to evaluate covert brain infarction (CBI), frequently encountered during the diagnostic work-up of acute ischemic stroke, as a risk factor for stroke recurrence in patients with atrial fibrillation (AF).

METHODS

For this prospective cohort study, from patients with acute ischemic stroke hospitalized at 14 centers between 2017 and 2019, we enrolled AF patients without history of stroke or transient ischemic attack and divided them into the CBI (+) and CBI (-) groups. The 2 groups were compared regarding the 1-year cumulative incidence of recurrent ischemic stroke and all-cause mortality using the Fine and Gray subdistribution hazard model with nonstroke death as a competing risk and the Cox frailty model, respectively. Each CBI lesion was also categorized into either embolic-appearing (EA) or non-EA pattern CBI. Adjusted hazard ratios and 95% CIs of any CBI, EA pattern CBI only, non-EA pattern CBI only, and both CBIs were estimated.

RESULTS

Among 1383 first-ever stroke patients with AF, 578 patients (41.8%) had CBI. Of these 578 with CBI, EA pattern CBI only, non-EA pattern CBI only, and both CBIs were 61.8% (n=357), 21.8% (n=126), and 16.4% (n=95), respectively. The estimated 1-year cumulative incidence of recurrent ischemic stroke was 5.2% and 1.9% in the CBI (+) and CBI (-) groups, respectively (P=0.001 by Gray test). CBI increased the risk of recurrent ischemic stroke (adjusted hazard ratio [95% CI], 2.91 [1.44-5.88]) but did not the risk of all-cause mortality (1.32 [0.97-1.80]). The EA pattern CBI only and both CBIs elevated the risk of recurrent ischemic stroke (2.76 [1.32-5.77] and 5.39 [2.25-12.91], respectively), while the non-EA pattern only did not (1.44 [0.40-5.16]).

CONCLUSIONS

Our study suggests that AF patients with CBI might have increased risk of recurrent stroke. CBI could be considered when estimating the stroke risk in patients with AF.

Chronic cerebral infarctions and white matter lesions link to long-term survival after a first ischemic event: A cohort study

BACKGROUND AND PURPOSE

To investigate the association of different phenotypes, count, and locations of chronic covert brain infarctions (CBI) with long-term mortality in patients with first-ever manifest acute ischemic stroke (AIS) or transient ischemic attack (TIA). Additionally, to analyze their potential interaction with white matter hyperintensities (WMH) and predictive value in addition to established mortality scores.

METHODS

Single-center cohort study including consecutive patients with first-ever AIS or TIA with available MRI imaging from January 2015 to December 2017. Blinded raters adjudicated CBI phenotypes and WMH (age-related white matter changes score) according to established definitions. We compared Cox regression models including prespecified established predictors of mortality using Harrell's C and likelihood ratio tests.

RESULTS

A total of 2236 patients (median [interquartile range] age: 71 [59-80] years, 43% female, National Institutes of Health Stroke Scale: 2 [1-6], median follow-up: 1436 days, 21% death during follow-up) were included. Increasing WMH (per point adjusted Hazard Ratio [aHR] = 1.29 [1.14-1.45]), but not CBI (aHR = 1.21 [0.99-1.49]), were independently associated with mortality. Neither CBI phenotype, count, nor location was associated with mortality and there was no multiplicative interaction between CBI and WMH (p > .1). As compared to patients without CBI or WMH, patients with moderate or severe WMH and additional CBI had the highest hazards of death (aHR = 1.62 [1.23-2.13]). The Cox regression model including CBI and WMH had a small but significant increment in Harrell's C when compared to the model including 14 clinical variables (0.831 vs. 0.827, p < .001).

DISCUSSION

WMH represent a strong surrogate biomarker of long-term mortality in first-ever manifest AIS or TIA patients. CBI phenotypes, count, and location seem less relevant. Incorporation of CBI and WMH slightly improves predictive capacity of established risk scores.

Covert Brain Infarcts in Patients with Philadelphia Chromosome-Negative Myeloproliferative Disorders

Backgrounds and Purpose. Philadelphia chromosome-negative myeloproliferative disorders (Ph-negative MPD) are a rare group of hematological diseases, including three distinct pathologies: essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). They most often manifest with thrombotic complications, including cerebrovascular events. Covert brain infarcts (CBIs) are defin ed as predominantly small ischemic cerebral lesions that are detected using magnetic resonance imaging (MRI) in the absence of clinical stroke events. The relationship between MPD and CBIs remains unclear. Methods. Included in the study were 103 patients with the diagnosis of Ph-MPD (according to WHO 2016 criteria) (median age—47 (35; 54) years; 67% female). In total, 38 patients had ET, 42 had PV, and 23 had PMF. They underwent clinical examination, routine laboratory analyses (complete blood count), brain MRI, ultrasound carotid artery, flow-mediated dilatation (as a measure of endothelial dysfunction—FMD). Results. Overall, 23 patients experienced an ischemic stroke (as per MRI and/or clinical history), of which 16 (15.5%) could be classified as CBIs. The rate of CBIs per MPD subtype was statistically non-significant between groups (p = 0.35): ET–13.2%, PV–21.4%, and PMF–8.7%. The major vascular risk factors, including arterial hypertension, carotid atherosclerosis, and prior venous thrombosis, were not associated with CBIs (p > 0.05). Age was significantly higher in patients with CBIs compared to patients without MRI ischemic lesions: 50 (43; 57) years vs. 36 (29; 48) (p = 0.002). The frequency of headaches was comparable between the two groups. CBIs were associated with endothelial dysfunction (OR - 0.71 (95% CI: 0.49–0.90; p = 0.02)) and higher hemoglobin levels (OR—1.21 (95% CI: 1.06–1.55); p =0.03). Conclusions. CBIs are common in patients with Ph-negative MPD. Arterial hypertension and carotid atherosclerosis were not associated with CBIs in this group of patients. The most significant factors in the development of CBIs were endothelial dysfunction (as measured by FMD) and high hemoglobin levels. Patients with Ph-negative MPD and CBIs were older and had more prevalent endothelial dysfunction.

Automated detection and segmentation of intracranial hemorrhage suspect hyperdensities in non-contrast-enhanced CT scans of acute stroke patients

Objectives

Artif icial intelligence (AI)–based image analysis is increasingly applied in the acute stroke field. Its implementation for the detection and quantification of hemorrhage suspect hyperdensities in non-contrast-enhanced head CT (NCCT) scans may facilitate clinical decision-making and accelerate stroke management.

Methods

NCCTs of 160 patients with suspected acute stroke were analyzed regarding the presence or absence of acute intracranial hemorrhages (ICH) using a novel AI-based algorithm. Read was performed by two blinded neuroradiology residents (R1 and R2). Ground truth was established by an expert neuroradiologist. Specificity, sensitivity, and area under the curve were calculated for ICH and intraparenchymal hemorrhage (IPH) detection. IPH-volumes were segmented and quantified automatically by the algorithm and semi-automatically. Intraclass correlation coefficient (ICC) and Dice coefficient (DC) were calculated.

Results

In total, 79 of 160 patients showed acute ICH, while 47 had IPH. Sensitivity and specificity for ICH detection were 0.91 and 0.89 for the algorithm; 0.99 and 0.98 for R1; and 1.00 and 0.98 for R2. Sensitivity and specificity for IPH detection were 0.98 and 0.89 for the algorithm; 0.83 and 0.99 for R1; and 0.91 and 0.99 for R2. Interreader reliability for ICH and IPH detection showed strong agreements for the algorithm (0.80 and 0.84), R1 (0.96 and 0.84), and R2 (0.98 and 0.92), respectively. ICC indicated an excellent (0.98) agreement between the algorithm and the reference standard of the IPH-volumes. The mean DC was 0.82.

Conclusion

The AI-based algorithm reliably assessed the presence or absence of acute ICHs in this dataset and quantified IPH volumes precisely.

Key Points

• Artificial intelligence (AI) is able to detect hyperdense volumes on brain CTs reliably.

• Sensitivity and specificity are highest for the detection of intraparenchymal hemorrhages.

• Interreader reliability for hemorrhage detection shows strong agreement for AI and human readers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08352-4.

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.

Cerebrovascular Contributions to Neurocognitive Disorders in People Living With HIV

BACKGROUND

To investigate a comprehensive array of magnetic resonance imaging (MRI)-based biomarkers of cerebrovascular disease (CVD) in a cohort of people living with HIV (PLWH) and relate these imaging biomarkers to cognition.

SETTINGS

Cross-sectional, community-based study.

METHODS

Participants were PLWH in New York City, aged 50 years or older. They underwent a brain magnetic resonance angiography or MRI to ascertain 7 MRI markers of CVD: silent brain infarcts, dilated perivascular spaces, microhemorrhages, white matter hyperintensity volume, white matter fractional anisotropy and mean diffusivity (measures of white matter integrity), and intracranial large artery stenosis. Participants underwent a battery of neurocognitive tests to obtain individual and global cognitive scores representative of various aspects of cognition.

RESULTS

We included 85 participants (mean age 60 ± 6 years, 48% men, 78% non-Hispanic Black), most of them with well-controlled HIV (75% with CD4 cell count > 200 cells/mm3 and viral load < 400 copies/mL at or near the time of the MRI scan). Silent brain infarcts, intracranial large artery stenosis, and poor white matter integrity were associated with poorer performance in at least one cognitive domain, but the sum of these 3 MRI markers of CVD was associated with lower working memory (B = -0.213, P = 0.028), list learning (B = -0.275, P = 0.019), and global cognition (B = -0.129, P = 0.007).

CONCLUSIONS

We identified silent brain infarcts, intracranial large artery stenosis, and poor white matter integrity as exposures that may be modifiable and may, therefore, influence cognitive decline. In addition, these MRI markers of CVD may help in identifying PLWH at higher risk of cognitive decline, which may be more amenable to targeted therapies.

Determinants and Outcomes of Asymptomatic Intracranial Atherosclerotic Stenosis

BACKGROUND

Intracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide and confers a high risk of stroke recurrence, despite aggressive management of risk factors.

OBJECTIVES

This study identified the role of risk factors and risk of vascular events in subjects with asymptomatic ICAS for improved risk stratification.

METHODS

Stroke-free participants in the NOMAS (Northern Manhattan Study) trial, prospectively followed since 1993, underwent a brain magnetic resonance angiogram from 2003 to 2008. The study rated stenosis in 11 brain arteries as: 0: no stenosis; 1: <50% or luminal irregularities; 2: 50%-69%; and 3: ≥70% stenosis or flow gap. The study ascertained vascular events during the post-magnetic resonance imaging (MRI) period. Proportional odds regression quantified the association of pre-MRI exposures, and proportional hazard adjusted models were built to identify the risk of events in the post-MRI period.

RESULTS

The included sample included 1,211 participants from NOMAS (mean age: 71 ± 9 years; 59% women; 65% Hispanic; 45% had any stenosis). Older age (OR: 1.02 per year; 95% CI: 1.01 to 1.04), hypertension duration (OR: 1.01 per year; 95% CI: 1.00 to 1.02), higher number of glucose-lowering drugs (OR: 1.64 per each medication; 95% CI: 1.24 to 2.15), and high-density lipoprotein (OR: 0.96 per mg/dL; 95% CI: 0.92 to 0.99) were associated with ICAS. The highest event risk was noted among participants with ICAS ≥70% (5.5% annual risk of vascular events; HR: 2.1; 95% CI:1.4 to 3.2; compared with those with no ICAS).

CONCLUSIONS

ICAS is an imaging marker of established atherosclerotic disease in stroke-free subjects, and incidental diagnosis of ICAS should trigger a thorough assessment of vascular health.

Genetic Variants behind Cardiovascular Diseases and Dementia

Cardiovascular diseases (CVDs) and dementia are the leading causes of disability and mortality. Genetic connections between cardiovascular risk factors and dementia have not been elucidated. We conducted a scoping review and pathway analysis to reveal the genetic associations underlying both CVDs and dementia. In the PubMed database, literature was searched using keywords associated with diabetes mellitus, hypertension, dyslipidemia, white matter hyperintensities, cerebral microbleeds, and covert infarctions. Gene lists were extracted from these publications to identify shared genes and pathways for each group. This included high penetrance genes and single nucleotide polymorphisms (SNPs) identified through genome wide association studies. Most risk SNPs to both diabetes and dementia participate in the phospholipase C enzyme system and the downstream nositol 1,4,5-trisphosphate and diacylglycerol activities. Interestingly, AP-2 (TFAP2) transcription factor family and metabolism of vitamins and cofactors were associated with genetic variants that were shared by white matter hyperintensities and dementia, and by microbleeds and dementia. Variants shared by covert infarctions and dementia were related to VEGF ligand-receptor interactions and anti-inflammatory cytokine pathways. Our review sheds light on future investigations into the causative relationships behind CVDs and dementia, and can be a paradigm of the identification of dementia treatments.

Stroke Disparities: From Observations to Actions: Inaugural Edward J. Kenton Lecture 2020

Numerous epidemiological studies have demonstrated stroke disparities across race and ethnic groups. The goal of the NOMAS (Northern Manhattan Study) was to evaluate race and ethnic differences in stroke within a community with 3 different race-ethnic groups. Starting as a population-based incidence and case-control study, the study evolved into a cohort study. Results from NOMAS have demonstrated differences in stroke incidence, subtypes, risk factors, and outcomes. Disparities in ideal cardiovascular health can help explain many differences in stroke incidence and call for tailored risk factor modification through innovative portals to shift more diverse subjects to ideal cardiovascular health. The results of NOMAS and multiple other studies have provided foundational data to support interventions. Conceptual models to address health disparities have called for moving from detecting disparities in disease incidence, to determining the underlying causes of disparities and developing interventions, and then to testing interventions in human populations. Further actions to address race and ethnic stroke disparities are needed including innovative risk factor interventions, stroke awareness campaigns, quality improvement programs, workforce diversification, and accelerating policy changes.

Fox K, Liang Y, Liu L, Zhu J, Pogosova N, Maggioni AP, Avezum A, Piegas LS, Keltai K, Keltai M, Berkowitz SD, Yusuf S. Rivaroxaban for Prevention of Covert Brain Infarcts and Cognitive Decline

Background and Purpose:

Covert brain infarcts are associated with cognitive decline. It is not known whether therapies that prevent symptomatic stroke prevent covert infarcts. COMPASS compared rivaroxaban with and without aspirin with aspirin for the prevention of stroke, myocardial infarction, and vascular death in participants with stable vascular disease and was terminated early because of benefits of rivaroxaban 2.5 mg twice daily plus aspirin over aspirin. We obtained serial magnetic resonance imagings and cognitive tests in a consenting subgroup of COMPASS patients to examine treatment effects on infarcts, cerebral microbleeds, and white matter hyperintensities.

Methods:

Baseline and follow-up magnetic resonance imagings were completed in 1445 participants with a mean (SD) interval of 2.0 (0.7) years. Whole-brain T1, T2 fluid-attenuated inversion recovery, T2* sequences were centrally interpreted by blinded, trained readers. Participants had serial measurements of cognition and function. The primary end point was the proportion of participants with incident covert infarcts. Secondary end points were the composite of clinical stroke and covert brain infarcts, cerebral microbleeds, and white matter hyperintensities.

Results:

At baseline, 493 (34.1%) participants had infarcts. Incident covert infarcts occurred in 55 (3.8%) participants. In the overall trial rivaroxaban plus aspirin reduced ischemic stroke by 49% (0.7% versus 1.4%; hazard ratio [95% CI], 0.51 [0.38–0.68]). In the magnetic resonance imaging substudy the effects of rivaroxaban+aspirin versus aspirin were: covert infarcts: 2.7% versus 3.5% (odds ratio [95% CI], 0.77 [0.37–1.60]); Covert infarcts or ischemic stroke: 2.9% versus 5.3% (odds ratio [95% CI], 0.53 [0.27–1.03]). Incident microbleeds occurred in 6.6% of participants and 65.7% of participants had an increase in white matter hyperintensities volume with no effect of treatment for either end point. There was no effect on cognitive tests.

Conclusions:

Covert infarcts were not significantly reduced by treatment with rivaroxaban and aspirin but estimates for the combination of ischemic stroke and covert infarcts were consistent with the effect on ischemic stroke in the overall trial.

Registration:

URL: https://www.clinicaltrials.gov . Unique identifier: NCT01776424.

Cognitive declines after perioperative covert stroke: Recent advances and perspectives

PURPOSE OF REVIEW

With the aging of the population, there are increasing number of aged patients who require surgical interventions. Perioperative covert stroke is emerging as an important health threat and social burden that could affect patients' long-term neurological outcomes.

RECENT FINDINGS

Recent findings of the association between perioperative covert stroke with long-term cognitive declines of surgical patients highlighted the significance of the silent cognitive function killer-perioperative covert stroke. Considering the devastating long-term consequence of the asymptomatic covert stroke, early diagnosis and prevention are turning out as crucial problems to tackle. The evolving brain imaging techniques, such as multimodel MRI sequences are not only able to detect early, small and subtle injuries of the acute ischemic lesions, but also quite advantageous in capturing the preexisting brain vascular diseases that are considered as important risk factors of covert stroke. However, effective predictive markers are still lacking to identify high risk patients for perioperative covert stroke, rendering an unmet need of investigations in this regard.

SUMMARY

The present review will summarize recent findings in perioperative covert stroke and highlight future perspectives of its early diagnosis and the impact of postoperative cognitive impairments.

Stroke scan agnosia - What radiologists may not see

OBJECTIVE

Neuroimaging helps neurologists make accurate diagnoses. We used a multidisciplinary review system to search for perceptual discrepancies in stroke lesions. We sought to identify recurrent pitfalls in the detection of neuroimaging stroke lesions.

PATIENTS AND METHODS

Patients were selected from a neuroimaging database of second opinions if cerebrovascular lesions had been missed at initial reporting. Patient demographics, scanning modality and stroke type were recorded.

RESULTS

A neuroradiologist second opinion was provided for 1336 patients. Forty-four patients, 18 women and 26 men, mean age 59.9 (SD 14.2) years, were identified in whom a vascular lesion was not detected on initial reporting. The lesions included cerebellar infarcts in 17 patients (bilateral in 7), pontine infarction/ischaemia (n=5), pontine and cerebellar lesions (n=1) and spinal infarction (n=1). Supratentorial infarction occurred in 10 patients of which 3 were thalamic infarcts. Vessel abnormalities were present in 8 patients (hyperdense vessel n=3, dissection n=3, middle cerebral artery occlusion on CTA n=1 and cerebral venous sinus thrombosis n=1). Convexity subarachnoid hemorrhage was missed and a subdural hematoma was not identified in one patient. In 10 (23 %) patients the missed lesions occurred solely on CT brain scanning. The missed lesions were symptomatic in 28 (64 %) patients and presentations were acute in 14 (32 %) patients.

CONCLUSION

Some cerebrovascular lesions are prone to perceptual errors with CT and MRI brain scanning. Radiologists and neurologists should be aware that posterior fossa lesions (particularly in the cerebellum and pons) and hyperdense vessel signs may be missed. Better identification of radiological cerebrovascular lesions should enhance management of acute and chronic stroke patients.