Ischemic Stroke Patients Demonstrate Increased Carotid Plaque Microvasculature Compared to (Ocular) Transient Ischemic Attack Patients

BACKGROUND

Patients with a recent ischemic stroke have a higher risk of recurrent stroke compared to (ocular) transient ischemic attack (TIA) patients. Plaque microvasculature is considered as a feature of plaque vulnerability and can be quantified with carotid dynamic contrast-enhanced MRI (DCE-MRI). The purpose of this cross-sectional study was to explore the association between plaque microvasculature and the type of recent cerebrovascular events in symptomatic patients with mild-to-moderate carotid stenosis.

METHODS

A total of 87 symptomatic patients with a recent stroke (n = 35) or (ocular) TIA (n = 52) underwent carotid DCE-MRI examination. Plaque microvasculature was studied in the vessel wall and adventitia using DCE-MRI and the pharmacokinetic modeling parameter Ktrans. Statistical analysis was performed with logistic regression, correcting for associated clinical risk factors.

RESULTS

The 75th percentile adventitial (OR 1.97, 95% CI 1.18-3.29) Ktrans was significantly associated with a recent ischemic stroke compared to (ocular) TIA in multivariate analysis, while clinical risk factors were not significantly associated with the type of event.

CONCLUSIONS

This study indicates a positive association of leaky plaque microvasculature with a recent ischemic stroke compared to (ocular) TIA. Prospective longitudinal studies are needed to investigate whether Ktrans or other plaque characteristics may serve as an imaging marker for predicting (the type of) future cerebrovascular events.

Correlation between echo morphological carotid plaque characteristics and neurological symptoms

A group of 72 patients with 111 asymptomatic carotid stenoses (ACS), mean age 65.42 ? 9.21 and of 36 patients with 58 symptomatic carotid stenoses (SKS), mean age 67.63 ? 8.79 were analyzed prospectively during a three-years follow-up period. All patients underwent color duplex scan sonography (CDS), carotid arteriography, computed tomography scan (CT), and neurological examination. The aim of the study was to analyze correlation between echo plaque morphology (degree and plaque quality) and neurological symptoms and objective neurological disorders, as well as value of CDS method to appreciate carotid stenosis characteristics. The results analysis showed significantly higher ACS in the group of 30-49% stenoses, but significantly higher SCS in the group of 70-89% and more than 90% stenoses. Fibrous plaque was more frequent in the ACS group, while exulceration and mix plaque were more frequent in the SCS group. Significantly higher number of clinical CVI cases, deaths, and ischemic lesion registered during CT were reported in the SCS group than in the ACS group. CDS showed 92% sensitivity, 90% specificity, and 92% diagnostic accuracy in the assessment of stenosis growth. Morphological characteristics of carotid plaques, significantly correlated with neurological disorders, were stenoses more than 70%, plaque exulceration, mix plaque, and plaque stenoses more than 50%.

[Early detection of asymptomatic carotid disease in patients with obliterative arteriosclerosis of the lower extremities]

INTRODUCTION

Arterial occlusive disease is a systemic phenomenon frequently coexisting in more than one arterial system. Often in one arterial bed disease is manifested with symptoms, in another is asymptomatic. There are only several reports indicating the prevalence of carotid stenosis in patients with peripheral vascular disease. Asymptomatic carotid stenosis is defined as the presence of internal carotid/carotid bifurcation stenotic or occlusive lesions in patients with no signs or symptoms of cerebrovascular disease. Lesions are important causative factors in unheralded stroke. Two factors are particularly important: severity of stenosis and morphologic characteristics of the stenotic plaque. The recent largest completed clinical trial concerning asymptomatic carotid artery stenosis (completed 1995) ACAS (Asymptomatic Carotid Artery Study) established the benefit of surgical treatment vs. best medical treatment. The reduction in relative risk of stroke was 55% in favor of surgery. Population screening for carotid stenosis is inefficient and expensive. The current interest is focused on the efficacy of screening population at risk.

AIM OF THE STUDY

The aim of the study was to establish prevalence of asymptomatic carotid artery stenosis in patients with symptomatic lower extremities atherosclerosis. Furthermore, possibility for limiting screening to subgroups of patients concerning risk factors, carotid bruit and severity of lower extremities atherosclerosis, was examined.

PATIENTS AND METHODS

Over the study period 109 patients with symptomatic lower extremities atherosclerosis underwent routine carotid duplex examinations (on Acuson 128 XP-10) to detect the presence of asymptomatic carotid disease. Indication for hospitalization was pain at rest in 60% of patients, ulcer or gangrene in 25% and claudication in 15%. Patients with a history of previous carotid endarterectomy or symptomatic cerebrovascular disease, patients who underwent emergency operations, and patients with nonatherosclerotic disease were not included in the analysis. Internal carotid stenosis was determined by duplex ultrasound blood flow velocities according to a criterion of ACAS. Plaque morphology was classified according to Gray-Weale as type I (echolucent) to type IV (echogenic). Plaque surface was graded as smooth, irregular and ulcerated. Secondary analysis was performed to find out a subgroup of patients with symptomatic lower extremities atherosclerosis at significant risk for carotid artery stenosis in order to be maximally effective. We examined the relationship of carotid artery stenosis of 60% or grater or occlusion to the 1st degree of lower extremities atherosclerosis (determined by previous vascular surgery, preoperative ankle-systolic blood pressure index, clinical severity of disease); 2. age and gender; 3. risk factors of atherosclerosis (arterial hypertension, diabetes mellitus, hyperlipidaemia, smoking history, and alcohol consumption); and 4. carotid bruit. Data were analyzed using two-way contingency tables and chi 2 test, two-sample Student's test, and multivariate, stepwise logistic regression analysis.

RESULTS AND DISCUSSION

According to the criterion of ACAS, forty patients (36.69%) had haemodynamically significant carotid artery stenosis > 60% or occlusion, and 32 patients (29%) carotid artery stenosis > 70% or occlusion. These results confirm that patients with symptomatic lower extremities atherosclerosis are at risk for increased prevalence for simultaneous asymptomatic carotid artery stenosis. Using B-mode we assessed carotid plaque characteristics in a group of 40 patients with asymptomatic 50-99% carotid artery stenosis. Distribution of plaque morphology was as follows: type I (echolucent with thin echogenic cap) in 4 patients (9.30%), type II (substantially echolucent) in 10 (23.26%), type III (dominantly echogenic) in 19 (44.18%), and type IV (homogenous echogenic) in 10 patients (23.26%). Plaque types III and IV were more common in asymptomatic patients, but there was no significant association with fibrous component of plaque. Degree of internal carotid stenosis was unrelated to plaque morphology. Plaque surface was as follows: smooth in 8 patients (18.60%), irregular in 25 (58.14%) and ulcerated in 10 patients (23.26%). Presence of ulcerated surface in 6 plaques (14%) with 50-69% of carotid artery stenosis is worth mentioning because these patients could be a subgroup likely to suffer stroke without warning. Secondary analysis examined the relationship of carotid artery stenosis of 60% or grater or occlusion to different patient's characteristics. By multivariant analysis we found that significant carotid artery stenosis was associated with prior vascular surgery, in patients over 60 years of age, arterial hypertension, ASPI < 0.5, and carotid bruit (results were considered significant if p < 0.05). Probability that various factors influenced the prevalence of carotid artery stenosis was assessed by multivariate stepwise logistic regression analysis. Only carotid bruit was associated with carotid artery stenosis > 60% (t = 0.50; p = 0.01), with sensitivity of 67% and specificity of 56%.

CONCLUSION

Prevalence of asymptomatic carotid artery stenosis in patients with lower extremities atherosclerosis is relatively high. Limiting screening of specific subgroups for any demographic or medical characteristics is ineffective. Screening for asymptomatic carotid artery stenosis is indicated in all patients with lower extremities atherosclerosis except in whom prophylactic carotid endarterectomy is not recommended because of comorbid disease or extreme age.

Patterns of cerebrovascular symptomatology associated with carotid atheroma

The aim of this study was to identify ultrasonic tissue characteristics and stenosis of carotid plaques that correspond to amaurosis fugax, hemispheric transient ischaemic attack, and stroke. At total of 146 symptomatic carotid plaques (136 patients) associated with amaurosis fugax, hemispheric transient ischaemic attack, stroke, and having 50-99% stenosis on duplex, were studied. These plaques were imaged on duplex, captured in a computer and their grey scale median was evaluated to distinguish the dark (low grey scale median) from the bright (high grey scale median) plaques. Stenosis was assessed on duplex. The amaurosis fugax group corresponded to carotid plaques with low grey scale median and severe stenosis, as contrasted with the other two groups (hemispheric transient ischaemic attack and stroke) (P < 0.05). These results suggested that amaurosis fugax was dependent only on the instability of carotid plaques, whereas hemispheric transient ischaemic attack and stroke were both dependent on carotid plaques and other pathogenetic factors.