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Appropriateness of carotid plaque and intima-media thickness assessment in routine clinical practice
© Baroncini et al; licensee BioMed Central Ltd. 2008
Received: 02 September 2008
Accepted: 16 October 2008
Published: 16 October 2008
To describe the findings and evaluate appropriateness of a carotid artery study including the measurement of IMT, the presence of atherosclerotic plaque, and their correlation with cardiovascular risk factors.
555 patients (220 men; 67.06 ± 12.44 years) were included in the study. 120 patients (21.62%) presented carotid plaque: 108 (19.45%) in patients with at least one risk factor and 12 (2.1%) in patients without risk factors. With respect to appropriateness of the present studies: 65% were appropriate, 22% were uncertain and 13% were inappropriate. The IMT medians were higher in males (0.0280; 95% CI, 00.82 to 0.478; p = 0.0057) and in hypertensive patients (0.391; 95% CI, 0.0190 to 0.0592; p = 0,001). There was a linear increase in mean IMT for each year increased in age (0.0059; 95% CI; 0.0050 to 0.0067). Carotid plaque was more frequent in patients with CAD (p = 0.0002), diabetes (p = 0.024) and hypertension (p = 0.036).
Assessment of carotid arteries identified increased incidence of plaque in patients with CAD, diabetes and hypertension. IMT was increased in older patients, hypertensive patients and males. Forty-five percent of the patients were studied based on uncertain and inappropriate reasons.
It has been proven that the atherosclerotic changes in the carotid artery mirror general atherosclerosis. Ultrasound measurements of IMT and plaque occurrence in the carotid arteries are important not only for the assessment of structural alterations but also because the extent of atherosclerosis in these vessels reflects the severity of arterial damage in other vascular territories . Epidemiological studies and clinical trials have shown that carotid artery intima-media thickness can identify prevalent and incident cardiovascular disease (CVD) events, and progression and regression of atherosclerosis . Intima-media thickness (IMT) of the carotid arteries is increasingly used in clinical trials as an important risk marker to investigate normal aging and preclinical atherosclerosis . Several studies demonstrated that carotid IMT is significantly associated with risk for myocardial infarction, stroke, death from coronary artery disease, or a combination of these events . Interestingly, in daily clinical practice, with the diffusion of knowledge and the education of public opinion, many physicians request carotid ultrasound studies even in patients without cardiovascular risk. We carried out this study to describe the findings and evaluate the appropriateness of carotid artery studies with ultrasound, including the measurement of ITM; the presence or not of atherosclerotic plaque; and their correlation with traditional cardiovascular risk factors in routine exams from our Doppler vascular laboratory.
Patient's baseline characteristics
Patients with risk factors (N/%)
Age (y ± SD)
67.6 ± 11.7
History of hypertension (N/%)
History of dyslipidemia (N/%)
History of diabetes mellitus (N/%)
Cardiovascular history (N/%)
Current smoking (N/%)
Patients without risk factors (N/%)
Age (y ± SD)
64.6 ± 15.1
Indications for carotid ultrasound study (N/%)
Patients with risk factors
Dizziness or vertigo
Transient amnesia or disorientation
Previous carotid artery disease
Patients without risk factors
Dizziness or vertigo
Transient amnesia or disorientation
Previous carotid artery disease
Measurements were made with a high-resolution B-mode ultrasonography (Philips Medical Systems' HD11 platform) with a broadband width linear array transducer L 3–12 MHz. Sonography and readings were carried out by trained and certified sonographers. Measurements of IMT were take on the distal 10 mm of both right and left common carotid artery in the far wall. Five determinations were conducted on each side and the average measurement was used for the IMT. An artery was classified as being affected by plaque if there was a localized thickening > 1.5 mm that did not uniformly involve the whole left or right carotid artery with or without flow disturbance. The vascular ultrasonographist identified plaques on common, internal and external carotids at the time of ultrasound measurement.
Categorical variables were expressed as percentages and continuous variables were expressed as mean ± SD, with a 95% confidence interval (CI) and a significance level of 5%. Multiple linear regression analysis was used to assess the association between cardiovascular risk factors and IMT. Age and sex were used as control variables. Twenty-five IMT measurements identified as possible outliers or influential cases were eliminated using the DFFITS procedure. χ2 test with Yates correction was used to correlate each risk factor and the presence of plaque. The regression logistic model was used to assess all variables with respect to the presence of plaque. Statistical significance was indicated by a value of p < 0.05. Analyses were performed using Statistica/W version 5.1 (StatSoft, Tulsa, Okla.).
Ultrasound measurements (95% CI)
In a routine vascular laboratory the assessment of carotid arteries identified increased incidence of plaque in patients with CAD, diabetes and hypertension. In addition, carotid IMT was increased in hypertensive patients and males. Older patients presented higher values of carotid IMT. Forty-five percent of the studies were categorized as uncertain and inappropriate.
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