Characterization of the infarct pattern caused by vulnerable aortic arch atheroma: DWI and multidetector row CT study

Imaging Biomarkers and Prevalence of Complex Aortic Plaque in Cryptogenic Stroke: A Systematic Review

BACKGROUND

Complex aortic plaque (CAP) is a potential embolic source in patients with cryptogenic stroke (CS). We review CAP imaging criteria for transesophageal echocardiogram (TEE), computed tomography angiography (CTA), and magnetic resonance imaging and calculate CAP prevalence in patients with acute CS.

METHODS AND RESULTS

PubMed and EMBASE databases were searched up to December 2022 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline. Two independent reviewers extracted data on study design, imaging techniques, CAP criteria, and prevalence. The Cochrane Collaboration tool and Guideline for Reporting Reliability and Agreement Studies were used to assess risk of bias and reporting completeness, respectively. From 2293 studies, 45 were reviewed for CAP imaging biomarker criteria in patients with acute CS (N=37 TEE; N=9 CTA; N=6 magnetic resonance imaging). Most studies (74%) used ≥4 mm plaque thickness as the imaging criterion for CAP although ≥1 mm (N=1, CTA), ≥5 mm (N=5, TEE), and ≥6 mm (N=2, CTA) were also reported. Additional features included mobility, ulceration, thrombus, protrusions, and assessment of plaque composition. From 23 prospective studies, CAP was detected in 960 of 2778 patients with CS (0.32 [95% CI, 0.24-0.41], I2=94%). By modality, prevalence estimates were 0.29 (95% CI, 0.20-0.40; I2=95%) for TEE; 0.23 (95% CI, 0.15-0.34; I2=87%) for CTA and 0.22 (95% CI, 0.06-0.54; I2=92%) for magnetic resonance imaging.

CONCLUSIONS

TEE was commonly used to assess CAP in patients with CS. The most common CAP imaging biomarker was ≥4 mm plaque thickness. CAP was observed in one-third of patients with acute CS. However, high study heterogeneity suggests a need for reproducible imaging methods.

Aortic Sources of Embolism

Aortic arch atheroma is a frequent finding in ischemic stroke patients. Its role as a source of cerebral emboli or a marker of atherosclerosis is unclear. Transesophageal echography is considered the gold standard for its detection, whereas computed tomography angiography is a good alternative; magnetic resonance and positron emission tomography could be proposed to better analyze plaque vulnerability. Despite the interest in this condition, the optimal antithrombotic treatment remains uncertain, while intensive lipid-lowering therapy should be recommended. This review aims to offer guidance on patients with aortic arch atheroma, about its causal role in stroke, diagnosis, and treatment based on current available evidence.

Effect of Statins on Survival Following Stroke in Patients With Cancer

The objective of this study was to investigate the potential benefits of statin therapy initiation in acute stroke in patients with active cancer. This study was conducted in two parts. First, data from patients who are presented with stroke and active cancer were obtained from prospectively collected multicenter hospital-based stroke registries. Patients were classified into statin user and non-user groups; the statin group was further divided into low-potency and high-potency statin subgroups. The primary outcome was time to mortality. Second, we obtained data from the Korean National Health Information Service-National Sample Cohort (NHIS-NSC) database for external validation and analyzed the effect of statins on mortality, taking compliance into consideration. For the stroke registry cohort, statin use was independently associated with reduced mortality in a multivariable model [hazard ratio (HR) = 0.675, 95% confidence interval (CI) = 0.457–0.996]. There was no interaction between statin use and cancer characteristics, vascular risk factors, or laboratory findings. A dose-dependent relationship between statin use and survival was also demonstrated. Analysis of the NHIS-NSC database found a similar association between statin therapy and reduced mortality (adjusted HR = 0.64, 95% CI = 0.45–0.90) and this effect persisted even after controlling for the adherence of statin use (HR = 0.60, 95% CI = 0.41–0.89). Statin therapy could be associated with reduced mortality in patients with acute stroke and active cancer.

Different infarction patterns in patients with aortic atheroma compared to those with cardioembolism or large artery atherosclerosis

Aortic atheroma is a known cause of ischemic stroke. However, it is unclear whether ischemic stroke is caused by emboli from aortic atheroma or by accompanying atherosclerosis. In this study, we evaluated lesion patterns of patients with complex aortic plaque (CAP) to assume the underlying pathophysiology. Acute ischemic stroke patients who underwent transesophageal echocardiography were included. CAP was defined as a plaque in the proximal aorta ≥ 4 mm thick or with a mobile component. The diffusion-weighted imaging lesion patterns of patients with CAP were compared to those with large arterial atherosclerosis (LAA) or cardioembolism (CE). A total of 64 CAP patients, 127 LAA patients, and 80 CE patients were included. Small cortical pattern was more common in the CAP group (45.3%) than in the LAA (7.9%, p < 0.001) or the CE group (23.8%, p = 0.018). A large cortical pattern was more common in the CE group than in the CAP group (p < 0.001), whereas subcortical only pattern tended to be more common in the CAP group than in the CE group (p = 0.057). In multinominal analysis, the CAP group was more likely to have a small cortical lesion than the LAA group [odds ratio (OR) 14.63; 95% confidence interval (CI) 4.67-45.85] or the CE (OR 3.69, 95% CI 1.19-11.39) group. In conclusion, patients with CAP frequently had small cortical lesions or subcortical single lesion. These findings imply that ischemic stroke in aortic atheroma patients is associated with either small emboli or small artery disease.

An Approach to Working Up Cases of Embolic Stroke of Undetermined Source

Background

From a therapeutic viewpoint, it is important to differentiate the underlying causes of embolism in patients with cryptogenic stroke, such as aortic arch atheroma, patent foramen ovale, and paroxysmal atrial fibrillation. We investigated the clinical and radiological characteristics of these 3 common causes of cryptogenic embolism to develop models for decision making in etiologic workups.

Methods and Results

A total of 321 consecutive patients with acute infarcts from cryptogenic embolism were included. Patients were divided into 3 groups—aortic arch atheroma (n=40), patent foramen ovale (n=153), and paroxysmal atrial fibrillation (n=128)—based on extensive cardiologic workups. We used a multinomial logistic regression analysis to detect the clinical and diffusion‐weighted imaging factors associated with the probability of aortic arch atheroma, patent foramen ovale, and paroxysmal atrial fibrillation. Clinical and radiological features differed among the groups. The patent foramen ovale group had a healthy vascular risk factor profile and showed posterior circulation involvement compared with other groups (P<0.01). In contrast, paroxysmal atrial fibrillation–related strokes had higher initial National Institutes of Health Stroke Scale (NIHSS) scores and larger lesions than the other groups (P<0.001). The aortic arch atheroma group had clinical features similar to those of the paroxysmal atrial fibrillation group but showed small lesions scattered in multiple vascular territories (P<0.001). Multivariate regression analysis revealed that age, initial NIHSS score, lesion size (≥20 mm), multiple (≥3) lesions, and involvement of posterior circulation or multiple vascular territories differentiated the 3 groups (pseudo, R²=0.656). The prediction ability of this model was validated in the external validation cohort (n=117, area under the curve 0.78).

Conclusions

Our data indicate that patients with cryptogenic embolic stroke show distinct clinical and radiological features depending on the underlying causes.

Contributing Mechanisms of Aortic Atheroma in Ischemic Cerebrovascular Disease

In recent years, the correlation between aortic atheroma (AA) and the occurrence and recurrence of ischemic cerebrovascular disease (ICVD) has attracted much attention, but the contributory mechanisms remain controversial. This review analyzes related research on the roles of AA in ICVD, and demonstrates the correlation between the formation and development of AA and abnormal metabolism, inflammation, hemodynamic changes, and other contributory factors. The presence of complex aortic plaque (CAP) in the ascending aorta and aortic arch increases the risk of cerebral embolism and degree of injury, while the association between CAP in the descending aorta and cerebral embolism remains ambiguous. AA also functions as an indicator of atherosclerosis burden as well as hypercoagulability, which may further increase the risk of ICVD. Further study on the relationship of AA to ICVD will improve diagnosis and treatment in clinical practice.

Ischemic lesion burden and characteristics of aortic atheroma

BACKGROUND

To investigate whether ischemic lesion burden including lesion pattern, number, and volume would vary depending on risk stratification of aortic atheroma (AA).

METHODS

Acute stroke patients were enrolled if they had (1) acute ischemic lesions on diffusion-weighted imaging within 5 days of symptom onset, (2) cardioembolic stroke established through extensive workup, and (3) only ascending or arch AA detected by transesophageal echocardiography as an embolic source. AA was classified as complex (protruding ≥4 mm into the aortic lumen or any mobile or ulcerative component) or simple (<4 mm).

RESULTS

Eighty-one patients (male: 65.4% and age: 66.7 ± 11.0 years) were included in the study. Thirty-four patients (41.9%) had complex atheroma. These patients had a greater number of ischemic lesions (median: 2 lesions [range: 1-42] versus one lesion [range: 1-27], P = .017) and a larger infarct size (9.01 cc [range: 3.58-49.14] versus 4.6 cc [range: 2.3-13.28), P = .056) than the simple atheroma group. Multivariable logistic regression analysis showed that ischemic lesion volume was independently associated with complex atheroma (odds ratio: 1.03, 95% confidence interval: 1.002-2.148, P = .035), while multiple lesions were related (odds ratio: 3.03, 95% confidence interval: .88-10.42, P = .079).

CONCLUSIONS

Ischemic lesion burden in patients with AA differed according to AA characteristics, suggesting that the morphological features of AA could reflect an embolic potential of AA.