Risk Of Carotid Artery Stenosis Research Articles

The prevalence of carotid artery stenosis varies significantly by race

Certain races are known to be at increased risk for stroke, and the prevalence of carotid artery stenosis (CAS) is thought to vary by race. The goal of this report was to study the prevalence of CAS in different races by analyzing a population of subjects who underwent vascular screening examinations. The study data were provided by Life Line Screening. The cohort consists of self-referred individuals who paid for vascular screening tests. Subjects<40 and >100 years of age and those who reported a prior stroke or carotid artery intervention were excluded. Of the remaining 3,291,382 subjects, 3.7% did not self-identify a race. CAS was defined as stenosis in either internal carotid artery ≥50% by duplex ultrasound velocity criteria. The 3,291,382 subjects available for analysis consisted of Caucasian (2,845,936 [90%]), African American (97,502 [3.1%]), Hispanic (75,240 [2.4%]), Asian (60,982 [1.9%]), and Native American (87,757 [2.8%]) individuals. The prevalence of CAS was 3.4% in females and 4.2% in males (P ≤ .001). Controlling for gender and age, there was marked variation in the prevalence of CAS (P< .001) by race. Native American subjects had the highest prevalence of CAS across all age categories and in both sexes. Caucasian subjects had the second highest prevalence of CAS across most age decades and in both sexes. Among males, African American individuals had the lowest prevalence of CAS in nearly all age categories. In contrast to males, Asian females had the lowest prevalence of CAS compared with females of other races in most age groups. Multivariate analysis adjusting for atherosclerotic risk factors in addition to age confirmed race as a significant independent predictor of CAS. Compared with Caucasian subjects, African American (odds ratio [OR], 0.65), Asian (OR, 0.69), and Hispanic (OR, 0.74) subjects had a significantly lower risk of CAS, whereas Native American (OR, 1.3) subjects had a significantly higher risk of CAS. The prevalence of clinically significant CAS varies significantly by race. Native American and Caucasian individuals have the highest prevalence of CAS, whereas African American males and Asian females appear to have the lowest prevalence. This information adds evidence to the hypothesis that the increased stroke rate in African American subjects is likely not related to extracranial cerebrovascular disease. Furthermore, this is a novel report of an extremely high prevalence of CAS in the Native American population.

Prospective analysis of carotid artery flow in breast cancer patients treated with supraclavicular irradiation 8 or more years previously

To the authors' knowledge, the effects of supraclavicular fossa radiation on the carotid artery are not well described. In the current study, the authors performed a prospective study to examine the long-term risk of carotid artery stenosis after supraclavicular irradiation for breast cancer. A total of 46 breast cancer patients who were treated with adjuvant radiation to the supraclavicular fossa with >8 years of follow-up underwent bilateral Doppler imaging of the carotid artery. Two independent cardiologists interpreted each ultrasound study with no knowledge of which side was treated. The median follow-up from the date of diagnosis was 14.6 years and the mean patient age at the time of ultrasound was 55 years. The median prescribed dose to the supraclavicular fossa was 50 grays. Four patients were found to have clinically relevant, asymptomatic carotid stenosis, for which a cardiology referral was necessary. Only 1 of these 4 patients had stenosis involving the irradiated carotid artery only; 1 patient had bilateral stenosis and 2 patients had only contralateral stenosis. There was no difference noted with regard to isolated ipsilateral versus contralateral medial intimal thickening of the carotid artery (5 patients vs 6 patients, respectively). Furthermore, there were no differences noted with regard to ipsilateral versus contralateral peak systolic flow in the internal (83.5 vs 85.6 cm/seconds; P= .522 by the Student t test and P= .871 by the signed rank test) or common (74.4 vs 77.0 cm/seconds; P= .462 by the Student t test and P= .246 by the signed rank test) carotid artery. In this prospective study of breast cancer patients with long follow-up, there was no evidence of late, clinically relevant stenosis, increased intimal thickening, or increased peak systolic carotid artery flow secondary to supraclavicular irradiation.

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

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. 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. 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. 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%. 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.

Hyperhomocysteinemia--a risk factor for development of occlusive vascular diseases

Occlusive vascular diseases take the first places on lists of diseases in general population today. In spite of this, all risk factors which contribute to development of these diseases are not yet known. Recent studies have shown that homocysteine plays a critical role in it and is established as a new risk factor. WHAT IS HOMOCYSTEINE?: Homocysteine is a sulfur containing amino acid formed in the metabolism of methionine. Reference values of homocysteine in circulation and different forms in plasma are described. HYPERHOMOCYSTEINEMIA--A RISK FACTOR: Homocysteine was associated with atherosclerosis and occlusive vascular disease in 1960s for the first time. Since then, many studies--prospective and retrospective, have confirmed the role of hyperhomocysteinemia as a risk factor in 42% of patients with cerebrovascular disease, 28% with peripheral vascular and 30% with coronary artery disease. The Physician's Health Study, a prospective study in which 15,000 male physicians took part, revealed that increase in homocysteine concentration of 1.7 mumol/l above normal values was associated by threefold higher risk for myocardial infarction. The risk for carotid artery stenosis also increases with elevation of homocysteine concentration. Hyperhomocysteinemia is associated with poor prognosis in patients with angiographically established coronary disease. Stroke, venous thromboembolism, and atherosclerosis in chronic renal failure are some of the complications of hyperhomocysteinemia. Hyperhomocysteinemia has numerous genetic and nongenetic etiologic factors. Cystathionine synthase deficiency, methylenetetrahydrofolate reductase deficiency and defects in the synthesis of cobalamin cofactors are genetically determined. Nutritional factors such as B12, folate or B6 vitamin deficiency, cofactors in homocysteine metabolism, lead to hyperhomocysteinemia. Atherogenic propensity of homocysteine is related to endothelial dysfunction, blood thrombocyte aggregation changes in factors of coagulation. Oxidative stress is involved, but the exact mechanism is still unknown. Hyperhomocysteinemia is established as an important risk factor for occlusive vascular diseases. Reduction in homocysteine concentration can be achieved by supplementation of B-group vitamins, cofactors in homocysteione metabolism. Is it going to be effective in reducing cardiovascular risks remains to be seen.