Atheroma of the aortic arch: an important and poorly recognised factor in the aetiology of stroke

Aortic tumor or mobile thrombus?

Isolated large mobile mass in the thoracic aorta can be due to thrombus or, rarely, aortic tumor. We report the case of a 61-year-old man with no history of medical problems presenting with neurologic deficits and in whom a large mobile echogenic mass in the distal aortic arch was found with transesophageal echocardiography. Given his few cardiovascular risk factors and absence of other systemic symptoms, he received anticoagulant therapy. Subsequent resolution of the aortic mass suggested a diagnosis of thrombus. This case illustrates an unusual manifestation of aortic arch atherosclerosis and underscores the utility of transesophogeal echocardiography for patients with ischemic stroke.

Atherosclerotic Burden Findings in Young Cryptogenic Stroke Patients With and Without a Patent Foramen Ovale

Background and Purpose— To further determine the mechanisms of cryptogenic stroke or transient ischemic attack in young patients, we evaluated indices of atherosclerosis in patients ≤55 years old diagnosed with cryptogenic cerebrovascular event comparing those with patent foramen ovale (PFO) with those without PFO.

Methods— This was a prospective study including 100 consecutive patients ≤55 years old (mean age, 45±8 years; 56 males) diagnosed with cryptogenic stroke/transient ischemic attack. PFO was identified in 59 of these patients with the use of transesophageal echocardiography with contrast study. The following surrogate markers of atherosclerosis were evaluated in all patients: carotid intima media thickness as measured by carotid ultrasonography and endothelial function as determined by brachial flow-mediated vasodilation. The same measurements were obtained in a control group of 50 age- and sex-matched control subjects.

Results— Patients without PFO were more likely to be current smokers and obese and more frequently had a history of hypertension and dyslipidemia. Carotid intima media thickness measurements were higher ( P <0.0001) in patients without PFO (1.03±0.31 mm) compared with those with PFO (0.75±0.20 mm) and control subjects (0.79±0.17 mm). The absence of PFO was also associated with lower brachial flow-mediated vasodilation (without PFO: 5.04±3.39%; with PFO: 7.16±4.09%; control subjects: 7.33±4.07%; P =0.02). There were no differences in carotid intima media thickness and flow-mediated vasodilation between patients with stroke/transient ischemic attack with PFO and control subjects. The presence of PFO was independently associated with reduced carotid intima media thickness ( P <0.0001) and increased flow-mediated vasodilation ( P =0.019).

Conclusions— In patients ≤55 years old diagnosed with cryptogenic stroke/transient ischemic attack, the presence of PFO was associated with a lower atherosclerotic burden as measured by carotid intima media thickness and endothelial function with no differences compared with a control group without cerebrovascular event. These results suggest that an atherosclerotic-mediated mechanism may be involved in cryptogenic stroke/transient ischemic attack in patients without PFO, whereas a nonatherosclerotic mechanism may mediate the cerebrovascular event in the presence of PFO.

Aortic arch atheroma

Severe atheroma of the aortic arch has now been established as an important risk factor and mechanism for stroke and peripheral embolism. The odds ratio for stroke or peripheral embolism in patients with severe arch atheroma is greater than four, and for mobile atheroma it is greater than 12. The prevalence of severe arch atheroma among patients presenting with acute ischaemic stroke, at over 20%, is in the same order as that of atrial fibrillation and carotid atherosclerosis. In patients with ischaemic stroke for which no cause has been identified, it is reasonable to determine as to whether they have severe arch atheroma by performing a transoesophageal echocardiogram. Recurrent stroke is common in patients with aortic arch atheroma that are thicker than 4 mm or with mobile components, particularly in the elderly, cigarette smokers, and those with hypertension or diabetes. Patients found to have severe atheroma are at high risk of recurrent events (14.2% per year) and may, therefore, need an aggressive secondary prevention strategy. Currently, there is uncertainty as to what this should be, but either combination antiplatelet therapy (aspirin plus clopidogrel) or anticoagulation with warfarin (target INR 2.0-3.0) are commonly used. Which of these is most effective will be evident after the completion of the aortic arch related cerebral hazard trial.

Cryptogenic stroke: time to determine aetiology

Strokes that remain without a definite cause even after extensive work-up are classified as cryptogenic. These constitute about 30-40% of all strokes. Stroke aetiology may remain undetermined for the following reasons: (i) the cause of stroke is transitory or reversible and the diagnostic work-out is not therefore performed at the appropriate time; (ii) all known causes of stroke are not fully investigated; (iii) some causes of stroke remain unknown. Recent studies have challenged the previous view that cryptogenic stroke is a relatively benign cerebrovascular event, and have shown that cryptogenic stroke is associated with a higher rate of recurrence and adverse outcome at long-term follow-up. The determination of stroke aetiology is a valuable procedure to avoid the risk of stroke recurrence, especially in young patients. In this review, we discuss new evidence on the aetiology of cryptogenic stroke, specifically focusing on patients with patent foramen ovale and atheroma of the aortic arch.

Echocardiography in patients with symptomatic intracranial stenosis

BACKGROUND

Echocardiography is often performed in patients with stroke, even when alternative stroke causes are identified. We evaluated the use of echocardiography in patients with transient ischemic attack (TIA) or stroke caused by stenosis of a major intracranial artery.

METHODS

The Warfarin Versus Aspirin for Symptomatic Intracranial Disease (WASID) trial was a National Institutes of Health-funded, randomized, double-blind, multicenter clinical trial in which 569 patients with TIA or ischemic stroke attributed to angiographically proven 50% to 99% stenosis of a major intracranial artery were randomly assigned to warfarin or aspirin. Patients with unequivocal cardiac sources of embolism were excluded. The risk of ischemic stroke, myocardial infarction, and vascular death was compared among patients who had or did not have echocardiography performed before enrollment, and Cox proportional hazards models were used to determine whether echocardiographic abnormalities present in greater than 5% of patients were associated with these outcomes.

RESULTS

In all, 264 of 569 patients in WASID had echocardiograms; 37% were transesophageal. Of these 264 patients, 69 had subsequent ischemic stroke, myocardial infarction, or vascular death. Patients who underwent echocardiography had similar event rates to those who did not (P = .18). Common abnormalities identified on echocardiography were not associated with subsequent risk in this population.

CONCLUSIONS

Among patients with TIA or stroke caused by intracranial arterial stenosis, echocardiography appears to offer limited diagnostic and prognostic value.

Clinical application of transcranial Doppler monitoring for embolic signals

A major advantage of transcranial ultrasound is its suitability for continuous monitoring. Microembolic signals (MES) are brief, high-intensity transients that occur when particulate microemboli or gaseous microbubbles pass through the ultrasound beam. These MES have been detected in several clinical scenarios, but rarely in age-matched controls. The detection of MES provides important pathophysiological information in a variety of disorders, but their clinical importance and possible therapeutic implications are still under debate. The present article summarizes the significance of MES in different clinical settings and outlines some of the problems to be resolved so that transcranial ultrasound can be applied in clinical practice.

Aortic arch atheroma and the risk of stroke

Brain infarction of unknown cause, known as cryptogenic stroke, represents 30% to 40% of all ischemic strokes, or approximately 400,000 cases each year in western Europe. In this category of patients new potential causes, such as aortic arch atheroma in the elderly, have been investigated in the past two decades.

Transient monocular visual loss

PURPOSE

To provide a practical update on the diagnosis and management of transient monocular visual loss (TMVL).

DESIGN

Perspective.

METHODS

Review of the literature.

RESULTS

TMVL is an important clinical symptom. It has numerous causes but most often results from transient retinal ischemia. It may herald permanent visual loss or a devastating stroke, and patients with TMVL should be evaluated urgently. A practical approach to the evaluation of the patient with TMVL must be based on the patient's age and the suspected underlying etiology. In the older patient, tests should be performed to investigate giant cell arteritis, atherosclerotic large vessel disease, and cardiac abnormalities. In the younger patient, TMVL is usually benign and the evaluation should be tailored to the particular clinical setting.

CONCLUSIONS

Specific prevention strategies are tailored to the most likely cause of TMVL and the patient's underlying risk factors. Prevention of a future event should begin in the ophthalmologist's office with education and aggressive treatment of artherosclerotic risk factors.