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 1. 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 2. 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 3. 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 4. 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.

A total of 555 patients were analyzed. Four hundred fifty-one (178 men; 67.6 ± 11.7 years) had at least one risk factor. One hundred four patients (42 men; 64.6 ± 15.1 years) had no risk factor. The appropriateness of the studies is displayed on figure 1. Risk stratification or "check-up" was the main indication for carotid ultrasound study in most patients (55.85%) even in subjects with no risk factor at all, followed by dizziness or vertigo (12.79%). Hypertension was present in 73.8%; dyslipidemia in 55.2%; diabetes in 22.2%; coronary artery disease (CAD) in 15.7%; and current smoking in 14.4%. One hundred twenty patients (21.62%) had carotid plaque: 108 (19.45%) in patients with at least one risk factor and 12 (2.1%) in patients without risk factors. (Tables 1 and 2). The IMT medians were higher in males (0.0280; 95% CI, 00.82 to 0.478; p = 0.0057) and in patients with hypertension (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). (Table 3). (Figure 2). Other risk factors did not influence IMT measurements. Plaque occurrence tended to influence IMT measurement (p = 0.067). Plaque was more present in patients with CAD (p = 0.0002), with diabetes (p = 0.024), and with hypertension (p = 0.036). There was no significant difference in patients with dyslipidemia (p = 0.158) or current smokers (p = 0.766). (Data not shown).

The Mannhein Carotid IMT Consensus 35 and the ASE Consensus Statement 4 recommended IMT measurements for patients at intermediate CVD risk and in subjects with the following clinical circumstances: (1) family history of premature CVD in first-degree relatives; (2) individuals younger than 60 years old with severe abnormalities in a single risk factor who otherwise would not be candidates for pharmacotherapy; (3) women younger than 60 years of age with at least two CVD risk factors; and (4) in all epidemiological and interventional trials dealing with vascular diseases to better characterize the population investigated. However, carotid ultrasound and the assessment of IMT are highly requested today by most physicians, in particular by cardiologists. In the present study, the "check-up" was the main indication for carotid ultrasound study, followed by dizziness or vertigo, even in patients with no risk factors. The risk stratification of an individual patient without clinically apparent atherosclerosis (primary prevention) is oftentimes complex. There are patent scenarios in which an individual is judged to be at low risk of future CV events by traditional risk stratification scoring, however, because of a young age, the presence of a strikingly abnormal single risk factor, or of an emerging risk factor, the incremental information provided by a carotid IMT may more accurately assess this risk 6. The ASE Consensus Statement also recommends the use of a semi-automated border detection program with validated accuracy for assessment of IMT 4, but since most vascular labs do not have an automated system to determine IMT and vascular age, the sonographers regularly use manual reading techniques. In vascular laboratory daily routine, the ultrasonographist easily visualizes a normal and an irregular intima-media layer in carotid vessels or atherosclerotic plaque. (Figure 3). Porter et al 7 showed that dynamic range, gain and probe distance significantly alter lumen diameter and IMT measurements made even using image analysis software. In the present study, we made 5 consecutive measurements for IMT in each common carotid artery in order to minimize the errors. Interestingly, we found atherosclerotic plaque in only 19.45% of patients with at least one risk factor and in only 2.1% of patients without any risk factor. It is clear that the prognostic performance of a method is heavily related to the type of population. The present study included not only patients indicated by a cardiologist but also the general population, referred by other medical specialities such as homeopathic medicine, gerontology and internal medicine, thus including some patients with no cardiovascular risk at all. We also considered cardiac and cerebrovascular events. As in previous studies 189, we found higher values of IMT in hypertensive subjects, however with respect to other risk factors, we did not find any influence on this measurement. The progression of atherosclerotic disease may occur at different rates and as a result of different risk factors in each vascular bed 10. We also found higher values of IMT in males and older patients. In view of all these findings, some questions arise, for example: 1 – What information should we give to the referred physician?; 2 – What will they do in a totally asymptomatic patient with no risk factor? Ultrasonographists, therefore, should be precise in their report regarding the presence or not of plaque and the measurement of IMT. These findings could change risk stratification for asymptomatic subjects and their primary physician should be aware of this possibility. In addition, carotid IMT has proven to be a powerful tool for assessing cardiovascular risk. Atherosclerosis is not a single disease entity, but a process consisting of the responses to numerous insults to the endothelium and smooth muscle cells of the arterial wall. This "response-injury" hypothesis is formulated by numerous observations in humans and animals, and the entire process from the earliest recognizable lesion (fatty streak) to advanced lesions in atherosclerosis (fibrous plaques) is tightly linked to an inflammatory response 71112131415161718. If, in a patient with no risk factor, we find an increased IMT or a small carotid plaque the personal physician should most likely inquire about inflammatory markers. Finally, there are several studies 192021 evaluating the prognoses of increased IMT and raise the question of whether or not one should treat this condition. We hope to soon understand the significance of an increased IMT or the presence of small plaque in healthy subjects.

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.

The authors declare that they have no competing interests.

LAVB participated in the study design, wrote and oriented the manuscript. AO participated in data collection. EAV participated in data collection. GJF participated in data collection. PSDS participated in data collection. AA participated in the study design. DBP participated in the study design. All authors read and approved the final manuscript.