Carotid plaque, intima media thickness, cardiovascular risk factors, and prevalent cardiovascular disease in men and women: the British Regional Heart Study

Comparison of the effects of antihypertensive treatment with angiotensin II blockade and beta-blockade on carotid wall structure and haemodynamics: protocol and baseline demographics

Several systemic factors have been shown to contribute to the acceleration of large vessel atheroma. Correction of these factors leads to a reduction in the progression of plaque formation and associated arterial wall thickness. Atheroma remains, however, a focal disease, developing at characteristic sites within the arterial tree. These sites are typically at areas of vessel branching or marked curvature, and correspond to regions of high tensile stress and low sheer stress, leading to the hypothesis that local haemodynamic factors and vessel wall mechanics potentiate the focal development of atheroma. Current assessment of vascular haemodynamics suffers from an inability to handle complex flow, and does not allow accurate determination of locally varying flow, and shear stress patterns. The application of computational fluid dynamic (CFD) flow simulation techniques to ultrasound and local pressure data, however, allows a comprehensive, non-invasive appraisal of haemodynamic flow parameters to be performed. The Candesartan cilexetil and Atenolol Carotid Haemodynamic Endpoint Trial (CACHET) study compares the effects of two antihypertensive regimens, one b-blocker-based, the other angiotensin receptor blocker based, on carotid intima-media thickness. The collection of ultrasound and pressure data on each subject provides a unique opportunity to apply these data to the CFD model to study the effects of these antihypertensive regimens on local fluid dynamics. This will lead to a greater understanding of the relationship of these factors to atheroma formation and regression.

Carotid intima-media thickness in surgical menopause: women who received HRT versus who did not

OBJECTIVE

The effects of hormone replacement therapy (HRT) in the natural menopausal period have been extensively studied. However, these effects have almost none been studied in purely surgical menopause. The aim of this study was to measure intima-media thickness (IMT) of carotid arteries bilaterally in two groups of surgical menopausal women who received HRT versus who did not.

METHODS

A B-mode ultrasound unit was used for the measurements of the IMTs of carotid arteries in two groups. Measurements of Group 1 (n=65, untreated group) were compared with those of Group 2 (n=70, treated group), in 2-years of follow-up. Patients in Group 2 received daily doses of 0.625 mg of oral conjugated estrogen preparates. Serum estradiol levels, lipid profiles, and blood pressures were measured, pre and postoperatively. For the statistical analyses in terms of differences of IMTs between two groups, general factorial analysis of variation was used.

RESULTS

Among preoperative values of low-density lipoprotein (LDL), high-density lipoprotein (HDL), cholesterol, systolic and diastolic blood pressures, estradiol, and age, only the estradiol values showed significant difference between both groups. The statistical results concerning the postoperative IMT differences for both groups showed that there was a statistically significant difference when comparing both groups, showing an increase in IMT in Group 1.

CONCLUSION

In surgical menopausal women, the direction of the HRT effect is in agreement with evidence from earlier studies on the effects of HRT in natural menopausal women.

Assessment of vessel wall thickness in carotid atherosclerosis using spiral CT angiography

OBJECTIVES

the purpose of this study was to evaluate the amount of vessel wall thickening in the internal and common carotid arteries in patients undergoing spiral CT angiography for the investigation of significant atherosclerotic disease.

MATERIALS AND METHODS

forty-five carotid systems in patients with a 70% or greater stenosis (according to carotid duplex) were imaged with CT spiral angiography using a standardised protocol. The vessel wall thickness of the distal common and mid internal carotid artery was measured using axial CT sections.

RESULTS

vessel wall thickness was greater and more variable within the common carotid artery than within the internal carotid artery. The mean proportion of total vessel diameter constituted by vessel wall thickness was significantly greater in the common carotid artery as compared to the internal carotid artery: 28+/-12% (SD) vs 15+/-6%, respectively (p < 0.001).

CONCLUSIONS

significant and extended wall thickening is commonly present in the internal and common carotid arteries of patients with atherosclerotic disease, but the internal carotid artery is significantly less affected than the common carotid artery. These observations question the validity of using the common carotid artery as a reference vessel for angiographic stenosis measurements.

Ultrasound measurement of carotid plaque as a surrogate outcome for coronary artery disease

Intima-media thickness (IMT) is commonly used as a surrogate marker for coronary artery disease (CAD). However, use of this parameter is a problem because (1) it assumes uniform thickness throughout the blood vessel, and (2) it detects changes primarily in the media, whereas atherosclerosis is a focal phenomenon that is confined to the intima. As an alternative to IMT, we have investigated the use of ultrasound measurements of plaque area and plaque volume as surrogate outcomes for CAD. Plaque area is a sensitive predictor of coronary disease progression and is closely associated with CAD. Clinical studies have shown that the sample size needed to detect atherosclerosis progression is sufficiently small to make this a useful assessment in clinical trials. Plaque volume, as measured by 3-dimensional ultrasound, may offer an even better means of assessing atherosclerosis. Plaque volume assessments are highly accurate and the data can be saved on a compact disc for central reading. Because of the high degree of accuracy and the increased size of plaque volume relative to plaque area or IMT, it is likely that only a small sample size will be required to detect clinically meaningful differences in plaque volume in a clinical trial.

Intima-media thickness: a new tool for diagnosis and treatment of cardiovascular risk

Increased intima-media thickness (IMT) is a non-invasive marker of early arterial wall alteration, which is easily assessed in the carotid artery by B-mode ultrasound, and more and more widely used in clinical research. Methods of IMT measurement can be categorized by two approaches: (i) measurement at multiple extracranial carotid sites in near and far walls and (ii) computerized measurement restricted to the far wall of the distal common carotid artery. Because IMT reflects global cardiovascular risk, its normal value might be better defined in terms of increased risk rather than in terms of statistical distribution within a healthy population. The available epidemiological data indicate that increased IMT (at or above 1 mm) represents a risk of myocardial infarction and/or cerebrovascular disease. Close relationships have been shown between: (i) most traditional cardiovascular risk factors; (ii) certain emerging risk factors such as lipoproteins, psychosocial status, plasma viscosity, or hyperhomocysteinemia; and (iii) various cardiovascular or organ damages such as white matter lesion of the brain, left ventricular hypertrophy, microalbuminuria or decreased ankle to brachial systolic pressure index. Thus, IMT gives a comprehensive picture of the alterations caused by multiple risk factors over time on arterial walls. Prospective primary and secondary prevention studies have also shown that increased IMT is a powerful predictor of coronary and cerebrovascular complications (risk ratio from 2 to 6) with a higher predictive value when IMT is measured at multiple extracranial carotid sites than solely in the distal common carotid artery. Therapeutic double-blind trials have shown that lipid-lowering drugs, such as resin and overall statines, and to a lesser extent antihypertensive drugs, such as calcium antagonists, may have a beneficial effect on IMT progression in asymptomatic or in coronary patients. However, methodological standardization of IMT measurement still needs to be implemented before routine measurement of IMT can be proposed in clinical practice as a diagnostic tool for stratifying cardiovascular risk in primary prevention and for aggressive treatment decision. It can be anticipated however, that the presence of increased carotid IMT in one individual with intermediate cardiovascular risk would lead to his classification into the high-risk category and thus influence the aggressiveness of risk factor modifications.

Validation of in vivo noninvasive high-frequency ultrasonography of the arterial wall layers

To validate estimates of the arterial wall thickness and its separate layers, 19 superficial (7 femoral and 12 cutaneous) arteries were transcutaneously sonographed in 13 anaesthetized pigs with a high-resolution equipment fitted with a 25 MHz frequency probe. Means of ultrasonographic estimates of each wall layer were compared with those obtained from microscopy of the respective arterial specimens taken after the pigs were sacrificed. For all vessels combined, Spearman-rank correlation tests between ultrasonography and histology estimates were significant for total arterial wall thickness (r(s) = 0.78; p =.0001) but not for the separate layers. For the cutaneous arteries, a significant correlation was found for total arterial wall thickness (r(s) = 0.69; p =.01) and media layer (r(s) = 0.76; p =.004). The method seems to give valid estimates of both total arterial wall and media thickness in superficial arteries, but to be less accurate for estimate the adventitia and intima layers.

Antiatherogenic mitochondrial genotype in patients with type 2 diabetes

OBJECTIVE

To evaluate the significance of a longevity-associated mitochondrial genotype (Mt5178A) derived from a C --> A transversion at nucleotide position 5178 of mitochondrial DNA, which causes a Leu-to-Met substitution within the NADH dehydrogenase subunit 2 gene, in type 2 diabetic subjects.

RESEARCH DESIGN AND METHODS

Mt5178 typing was done by polymerase chain reaction-restriction fragment-length polymorphism with the restriction enzyme AluI in 1,148 type 2 diabetic Japanese subjects, and the results were compared with the clinical characteristics. Then, the association of Mt5178 type with early atherosclerotic changes of the bilateral carotid arteries on ultrasonography was assessed in 412 diabetic subjects randomly selected from the original 1,148 type 2 diabetic subjects, while maintaining the same frequency of Mt5178A and Mt5178C.

RESULTS

The frequency of Mt5178A in the type 2 diabetic subjects (454 of 1,148; 40%) was not different from that previously found in healthy blood donors (114 of 252; 45%). Clinical characteristics regarding diabetes were not significantly different between the Mt5178A group (n = 454) and the Mt5178C group (n = 694). However, the mean intima-media thickness (IMT) at six sites in the bilateral carotid arteries was significantly smaller in the Mrt5178A group than in the Mt5178C group (0.906 +/- 0.018 vs. 0.995 +/- 0.021 mm, mean +/- SEM, P = 0.022), and the Mt5178 type was significantly correlated with both the mean IMT and the presence of plaque on multiple regression analysis and discriminant analysis.

CONCLUSIONS

The Mt5178A genotype may be unrelated to the etiology of type 2 diabetes. However, Mt5178A seems to have an antiatherogenic effect, at least in type 2 diabetic individuals.

Association of atrial fibrillation and aortic atherosclerosis: a population-based study

OBJECTIVE

To examine the association between atrial fibrillation (AF) and aortic atherosclerosis in the general population.

SUBJECTS AND METHODS

Transesophageal echocardiography was performed in 581 subjects, a random sample of the adult Olmsted County, Minnesota, population (45 years of age or older) participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. The frequency of aortic atherosclerosis was determined in 42 subjects with AF and compared with that in 539 subjects without AF (non-AF group).

RESULTS

Subjects with AF were significantly older than non-AF subjects (mean +/- SD age, 82+/-10 vs 66+/-13 years, respectively; P<.001) and more commonly had hypertension (28 [66.7%] vs 288 [53.4%], respectively; P=.10). The 2 groups were similar in sex and frequency of diabetes mellitus, hyperlipidemia, or smoking history (P>.10). The odds of aortic atherosclerosis (of any degree) were 2.87 times greater (95% confidence interval [CI], 1.41-5.83; P=.004) and the odds of complex atherosclerosis (protruding atheroma >4 mm thick, mobile debris, or plaque ulceration) were 2.71 times greater (CI, 1.13-6.53; P=.03) in the AF group than in the non-AF group. Age was a significant predictor of aortic atherosclerosis (P<.001). After adjusting for age, the odds of atherosclerosis and complex atherosclerosis were not significantly different between the 2 groups (P=.13 and P=.75, respectively).

CONCLUSIONS

In the general population, AF is associated with aortic atherosclerosis, including complex atherosclerosis. This association is related to age since both AF and aortic atherosclerosis are more frequent in the elderly population.

Assessment of aortic atherosclerosis and carotid atherosclerosis in coronary artery disease

The present study investigated the relationship between aortic atherosclerosis and carotid atherosclerosis, and studied the effects of coronary risk factors for these arteries. The subjects consisted of 78 patients with coronary artery disease (CAD) and 69 patients without CAD. All subjects underwent enhanced computed tomography and B-mode ultrasonography within a short time period to determine the extent of aorta and carotid atherosclerosis. Significant correlations between maximal aortic wall thickness (MAWT) and aortic wall volume (AWV) with carotid intima-media thickness (IMT) were demonstrated. MAWT, AWV and IMT were significantly higher in patients with CAD compared with controls (p=0.009, p=0.024, p=0.001, respectively). Furthermore, there were significant differences in MAWT, AWV and IMT among groups classified by the number of coronary artery stenoses, and no significant differences among groups classified by risk factors, but it was shown that MAWT, AWV and IMT increased gradually as the risk factors increased in number. MAWT, AWV and IMT had positive correlations with age, systolic blood pressure and triglyceride, and a negative correlation with high density lipoprotein-cholesterol. This study demonstrated that both aortic atherosclerosis and carotid atherosclerosis are closely correlated with coronary atherosclerosis, and that the atherosclerosis indices are independently associated with age and hyperlipidemia.

Femoral atherosclerosis in an older British population: prevalence and risk factors

Most estimates of the prevalence of peripheral atherosclerosis have been based on intermittent claudication or lower limb blood flow. The aim of this study was therefore to determine the prevalence of underlying femoral plaque, and to determine its association with other cardiovascular disease and risk factors. Presence of plaque was identified using ultrasound in a random sample of men (n=417) and women (n=367) aged 56-77 years. Coexistent cardiovascular disease, exercise and smoking were determined by questionnaire, blood pressure was recorded, and serum cholesterol and plasma fibrinogen were determined. Of the 784 subjects that were scanned, 502 (64%) demonstrated atherosclerotic plaque. Disease prevalence increased significantly with age (P<0.0001), and was more common in men (67.1 vs. 59.4%, P<0.05). Subjects with femoral plaque had a significantly greater odds of previous ischaemic heart disease (OR 2. 2, 95% CI 1.3, 3.7) and angina (OR 1.7, 95% CI 1.03, 2.7), but not of stroke or leg pain on exercise. Current and ex-smoking, raised serum total cholesterol and plasma fibrinogen levels, but not blood pressure, were associated with an increased risk of femoral plaque, independent of age and sex. Frequent exercise and a high HDL cholesterol were significantly associated with lower risk. In conclusion, therefore, atherosclerotic disease of the femoral artery affects almost two-thirds of the population in late middle age. It is associated with an increased prevalence of ischaemic heart disease and angina, but whether detecting at risk individuals using ultrasound offers advantages over simpler and less expensive risk factor scoring requires evaluation in trials.

Carotid intima-media thickness as a measure of vascular target organ damage

This paper summarizes important investigations published within the past 2 years that use B-mode carotid ultrasound and measurements of intima-media thickness or plaque to elucidate the relationship between traditional or novel risk factors for the development of atherosclerotic or arteriosclerotic disease. This methodology is proposed as an extremely useful, noninvasive tool with proven ability to show cross-sectional associations with cardiovascular risk factors, prevalence of vascular disease, and predictive power. The method appears highly suited to the goal of detecting asymptomatic vascular target organ damage, which may greatly assist with assessment of risk and selection of appropriate, preventive, strategies for management of disease.