Aortic arch atherosclerosis in ischaemic stroke of unknown origin affects prognosis

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.

Prevalence of high-risk aortic arch atherosclerosis features on computed tomography angiography in embolic stroke of undetermined source

INTRODUCTION

Embolic stroke of undetermined source (ESUS) comprises a heterogenous group. There is a need to further identify etiologies within this group to guide management strategies. We examined the prevalence of aortic arch atherosclerosis (AAA) on CT angiography (CTA) in patients with embolic stroke of undetermined source (ESUS) to characterize high-risk plaque features.

METHODS

All patients from two prospective multicenter acute ischemic stroke studies (INTERRSeCT and PRove-IT) were included if the CTA adequately imaged the proximal aortic arch and the stroke etiology was recorded. Three readers blinded to stroke etiology analyzed the following AAA plaque features on baseline CTA at the time of stroke: 1) thickness in millimetres (mm); 2) morphology (none, smooth, ulcerated, or protruding); 3) location within the aortic arch (proximal, transverse, or distal); and 4) calcification (none, single small, multiple small, single large, or diffuse extensive).

RESULTS

We included 1063 patients, of which 293 (27.6%) had ESUS (mean age 67.5 years; 46.4% men; median NIHSS 12; 80.6% large vessel occlusion). Mean AAA thickness was significantly larger in ESUS patients (3.8 mm) compared to non-ESUS patients (3.0 mm; p<0.0001) and to a subgroup of patients with large artery atherosclerosis (2.9 mm; p=0.003). ESUS patients had a significantly higher proportion of ulcerated or protruding plaques (17.4% vs 10.3%; risk ratio 1.7, 95% C.I. 1.2-2.4, p=0.002). The location of AAA in the ESUS group was the ascending aorta in 37.9%, transverse arch in 42.3%, and descending aorta in 84.6%. Although AAA was mostly located in the distal aortic arch, ulcerated or protruding plaques were least common in the distal arch (p=0.002). There was no difference between ESUS and non-ESUS patients in plaque location (p=0.23) or calcification grade (p=0.092).

CONCLUSION

ESUS patients in our study had thicker AAA and a higher prevalence of ulcerated or protruding plaques located more proximally within the aortic arch. High-risk plaque features may suggest a causal role of AAA in the ESUS population with visible intracranial occlusions.

Detection of Cardioembolic Sources With Nongated Cardiac Computed Tomography Angiography in Acute Stroke: Results From the ENCLOSE Study

BACKGROUND

Identifying cardioembolic sources in patients with acute ischemic stroke is important for the choice of secondary prevention strategies. We prospectively investigated the yield of admission (spectral) nongated cardiac computed tomography angiography (CTA) to detect cardioembolic sources in stroke.

METHODS

Participants of the ENCLOSE study (Improved Prediction of Recurrent Stroke and Detection of Small Volume Stroke) with transient ischemic attack or acute ischemic stroke with assessable nongated head-to-heart CTA at the University Medical Center Utrecht were included between June 2017 and March 2022. The presence of cardiac thrombus on cardiac CTA was based on a Likert scale and dichotomized into certainly or probably absent versus possibly, probably, or certainly present. The diagnostic certainty of cardiac thrombus was evaluated again on spectral computed tomography reconstructions. The likelihood of a cardioembolic source was determined post hoc by an expert panel in patients with cardiac thrombus on CTA. Parametric and nonparametric tests were used to compare the outcome groups.

RESULTS

Forty four (12%) of 370 included patients had a cardiac thrombus on admission CTA: 35 (9%) in the left atrial appendage and 14 (4%) in the left ventricle. Patients with cardiac thrombus had more severe strokes (median National Institutes of Health Stroke Scale score, 10 versus 4; P=0.006), had higher clot burden (median clot burden score, 9 versus 10; P=0.004), and underwent endovascular treatment more often (43% versus 20%; P<0.001) than patients without cardiac thrombus. Left atrial appendage thrombus was present in 28% and 6% of the patients with and without atrial fibrillation, respectively (P<0.001). The diagnostic certainty for left atrial appendage thrombus was higher for spectral iodine maps compared with the conventional CTA (P<0.001). The presence of cardiac thrombus on CTA increased the likelihood of a cardioembolic source according to the expert panel (P<0.001).

CONCLUSIONS

Extending the stroke CTA to cover the heart increases the chance of detecting cardiac thrombi and helps to identify cardioembolic sources in the acute stage of ischemic stroke with more certainty. Spectral iodine maps provide additional value for detecting left atrial appendage thrombus.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04019483.

Acute Thromboembolic Ischemic Stroke From Complex Aortic Arch Plaque

Atherosclerosis is a systemic pathologic process, may involve aorta and is important cause of systemic embolization. The risk of embolism is increased for mobile and complex aortic plaques that are >4 mm thick. The most common manifestations are stroke, transient ischemic attack (TIA) and peripheral embolization. Imaging modalities used include transesophageal echocardiogram (TEE), CT angiography and magnetic resonance angiography (MRA). The mainstays of medical treatment are antiplatelets and statin. The role of anticoagulation is reserved for plaques with thrombotic component.

There were two patients who presented with large acute ischemic stroke with high grade, floating aortic arch thrombus and complex aortic arch plaques. In one of cases, after 10-day follow-up CT aortic angiography showed completely resolved thrombus after being treated with IV tissue plasminogen activator (TPA) followed by low molecular weight heparin (LMWH). The risk of embolism depends on size of aortic plaques and mobility. TEE is modality of choice for thoracic aortic plaques. Aortic plaques >4 mm are independent predictors of recurrent ischemic stroke. There are limited data available for off-label use of intravenous thrombolysis and mechanical thrombectomy (MT) in presence of aortic arch thrombus in acute ischemic strokes. These two case reports help in recognition of aortic arch complex plaques as independent risk factor for recurrent stroke. The right patients may consider about the use of intravenous alteplase and MT performed via trans-brachial access after excluding aortic dissection and aneurysm. In future, multicenter, randomized controlled trials will be required for safety of IV TPA and MT.

Association of Embolic Sources With Cause-Specific Functional Outcomes Among Adults With Cryptogenic Stroke

Importance

It is unknown whether poststroke outcome varies between different potential causes in patients with cryptogenic stroke.

Objective

To investigate whether functional outcome differs according to potential embolic sources after cryptogenic stroke.

Design, Setting, and Participants

This multicenter, hospital-based, prospective stroke registry cohort study investigated potential embolic sources on admission and assessed 3-month outcome in patients with ischemic stroke hospitalized at 7 stroke centers in the Fukuoka Stroke Registry. This registry enlisted 9866 consecutive patients with acute ischemic stroke who were enrolled from June 11, 2007, to May 31, 2016, in Fukuoka, Japan. Patients with small vessel occlusion (n = 3130), extracranial and intracranial atherosclerosis causing at least 50% luminal stenosis in arteries supplying the area of ischemia (n = 2011), and other specific uncommon causes of stroke identified (n = 301) were excluded. Potential embolic sources were diagnosed in patients with embolic stroke of undetermined source (ESUS) based on the following criteria proposed by the Cryptogenic Stroke/ESUS International Working Group: minor-risk potential cardioembolic sources (MCS) (n = 209), covert paroxysmal atrial fibrillation (CPAF) (n = 43), cancer associated (CA) (n = 79), arteriogenic emboli (AE) (n = 522), paradoxical embolism (PE) (n = 190), and undetermined embolism (unidentified or ≥2 potential embolic sources) (UE) (n = 1120).

Main Outcomes and Measures

The association between potential causes and functional outcome was evaluated in reference to cardioembolic stroke (CE) caused by major-risk cardioembolic sources after adjusting for age, sex, National Institutes of Health Stroke Scale score on admission, and reperfusion therapy using logistic regression analysis. Functional dependency (modified Rankin Scale score, 3-5) was evaluated at 3 months after onset.

Results

The study enrolled 2261 patients with CE (mean [SD] age, 78.4 [10.7] years, 51.8% male) and 2163 patients with ESUS (mean [SD] age, 72.4 [12.6] years, 57.1% male). Compared with CE (median National Institutes of Health Stroke Scale score, 8 [interquartile range {IQR}, 3-17]), baseline neurological deficits did not differ in MCS (median, 7 [IQR, 2-18]), CPAF (median, 6 [IQR, 2-18]), and CA (median, 5 [IQR, 2-13]) but were less severe in AE (median, 2 [IQR, 1-4]), PE (median, 2 [IQR, 1-4]), and UE (median, 3 [IQR, 1-7]). Multivariable-adjusted odds ratios of functional dependency significantly increased in CA (3.61; 95% CI, 1.52-8.54 vs CE) but decreased in PE (0.33; 95% CI, 0.16-0.71 vs CE).

Conclusions and Relevance

Potential causes are associated with poststroke outcome in patients with cryptogenic stroke. Embolic sources potentially underlying cryptogenic stroke should be considered significant variables associated with outcome.

A Novel Evaluation for Predicting Aortic Complicated Lesions Using Calcification on Chest X-ray

BACKGROUND

The aorta is a significant source of cerebral thromboembolisms. Aortic complicated lesions (ACLs) are key findings on transesophageal echocardiography (TEE) for assessing aortic sources of emboli to the brain. TEE is sometimes avoided due to its invasiveness. However, few reports have examined alternative methods for predicting ACLs. We investigated relationships between aortic arch calcification (AAC) on chest X-ray and ACLs.

METHODS

Participants comprised 300 patients with acute ischemic stroke or transient ischemic attack who underwent TEE for the evaluation of the aortic arch and heart. A postero-anterior plain chest X-ray in the recumbent position was evaluated on admission for each patient. AAC was evaluated using 4 grades (0-3) and "AAC thickness" defined as the distance from the inner margin of the most distant AAC to the outer margin of the aortic vessel wall. ACLs were defined by intima-media thickness (IMT) ≥4.0 mm or presence of ulcerated or mobile plaques. Carotid maximum IMT on ultrasonography was also evaluated. Comparison of the diagnostic ability to predict ACL was performed between AAC grades and AAC thickness or AAC thickness and carotid maximum IMT using the Delong method.

RESULTS

ACLs were identified in 71 patients (23.7%), including ACLs with ulcerated plaques in 24 (8.0%) and ACLs with mobile plaques in 9 (3.0%). Plaque thickness was greater in higher AAC grades or higher quartiles of AAC thickness (p for trend <0.001 each). The Cochran-Armitage test showed that both higher AAC grade and higher quartile of AAC thickness were significantly associated with the presence of ACLs, as well as the presence of ulcerated or mobile plaques (p for trend < 0.001 each). Receiver-operating characteristic (ROC) analysis showed optimal cut-off values for AAC thickness of 5.6 mm for ACLs and 6.0 mm for ulcerated or mobile plaques. Multivariate logistic regression revealed a higher grade of AAC (grades 2-3) and AAC thickness (≥6 mm) as significantly associated with ACLs and ulcerated or mobile plaques (p < 0.001 each). ROC curve comparisons showed that AAC thickness offered a better marker of ACLs than AAC grade (p = 0.019), although no significant difference was evident between AAC thickness and carotid maximum IMT (p = 0.567).

CONCLUSIONS

AAC on chest X-ray, evaluated by both AAC grade and AAC thickness to the outer aortic vessel wall, was significantly associated with ACLs on TEE. AAC thickness was suggested as more useful than AAC grade and equivalent to carotid IMT in predicting ACLs.