1. Introduction
Cardiovascular diseases (CVDs), primarily coronary artery disease (CAD) and stroke, are the predominant causes of death worldwide and a principal contributor to disability [
1]. Hypertension remains one of the cornerstones of the cardiovascular risk (CVR) assessment [
2].
Coronary angiography is of key importance in the imaging diagnosis of coronary artery disease. However, coronary angiography is an invasive method. In recent years, the importance of noninvasive imaging methods in the diagnosis of coronary artery disease has been increasing, primarily as complementary methods, and in selected groups of patients as optional methods compared to coronary angiography [
3]. Cardiac computed tomography enables assessment of the risk of significant coronary disease (assessment of the coronary artery calcium score (CACS)) and assessment of the presence of atherosclerotic plaques in coronary arteries and the degree of coronary artery stenosis (computed tomography angiography), as well as assessment of reversible myocardial ischemia (perfusion with the administration of adenosine or regadenoson) [
3,
4]. Numerous studies are underway to develop the CCTA-derived fractional flow reserve (FFR-CT) technique [
5]. Magnetic resonance imaging also enables the assessment of reversible myocardial ischemia in functional tests. Moreover, it allows the differentiation of ischemic myocardial injury from nonischemic causes, as well as the assessment of myocardial viability in patients with ischemic myocardial damage [
3].
Ultrasonography is a simple, noninvasive technique that does not require radiation or intravenous contrast and is effective for risk prediction in atherosclerotic vascular disease [
6]. The carotid arteries, being superficially situated and not obscured by bone, are particularly well suited for examination through ultrasonography. The ultrasound assessment of atherosclerotic plaques in the carotid arteries can be used to stratify cardiovascular risk in patients with arterial hypertension [
7,
8]. Taking into consideration the accessibility to carotid duplex ultrasound (CDUS) and its cost effectiveness [
9], it seems important to search for the relationship between the presence and severity of atherosclerotic lesions in the carotid and coronary arteries.
3. Materials and Methods
3.1. General Characteristics of the Performed Study
The inclusion criteria for the study were age ≥ 18, arterial hypertension pharmacologically treated ≥5 years, and clinical indication to CCTA according to the recommendations of the European Society of Cardiology. The exclusion criteria were CACS value exceeded 800, insufficient quality of the coronary CT angiography, secondary hypertension, previous coronary interventions, previous myocardial infarction, previous stroke, chronic kidney disease, and hyperthyroidism or hypothyroidism.
Group size was determined using a sample size calculator. The selection conditions were as follows: population size 2.8 million (the size of the population from which patients were recruited for the study—the population size of the Lower Silesian Voivodeship in Poland), fraction size 0.3 (approximate prevalence of hypertension in the Polish population shown in population studies), maximum error 10% (standard level of maximum error used in scientific research), and confidence level 95% (standard level of statistical significance). The required minimum size of the study group was 81. We enrolled 83 patients with hypertension to the study: 37 (44.6%) men and 46 (55.4%) women; the average age of the subjects was 71.3 ± 8.5 years.
All subjects underwent ultrasound of the carotid arteries and CT of the coronary arteries. The studied group was divided into two subgroups: a subgroup with the carotid plaque score equal to or less than one and a subgroup with carotid plaque score equal to or greater than two.
3.2. Computed Tomography
The cardiac computed tomography (CCT) was performed using the standard coronary CT angiography (CCTA) protocol with dual-source 384-slice CT scanner SOMATOM Force (Siemens Healthcare, Erlangen, Germany). The obtained images were assessed by a certified radiologist with EACVI Cardiac Computed Tomography Exam and over 10 years of clinical experience. The coronary artery disease severity was determined based on the Coronary Artery Disease—Reporting and Data System (CAD-RADS), where 0—documented absence of coronary artery disease (CAD), 1—minimal nonobstructive CAD (maximal stenosis: 1–24%), 2—mild nonobstructive CAD (maximal stenosis: 25–49%), 3—moderate CAD (maximal stenosis: 50–69%), 4—severe CAD (maximal stenosis: 70–99%), and 5—total coronary artery occlusion.
3.3. Carotid Duplex Ultrasound
The ultrasound examination with carotid plaque score assessment was performed using a FUJIFILM Arietta 850 (FUJIFILM Healthcare Americas Corporation, Lexington, MA, USA) by the same experienced ultrasonographist in the case of all patients. The carotid plaque score was assessed in accordance with Recommendations for the Assessment of Carotid Arterial Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk: From the American Society of Echocardiography [
10]. The carotid plaque score is a semiquantitative approach where the total number of carotid arteries segments containing plaque along the common carotid arteries, carotid bulbs, and internal carotid arteries are visualized and summed. Only the lesions seen in easily identified segments of the carotid arteries are considered for the assessment of the carotid plaque score. Therefore, lesions limited to the distal 1 cm of the common carotid arteries, the carotid bulb, and the proximal 1 cm of the internal carotid arteries were included in the evaluation. As a result, the assessment obtained carotid plaque scores ranging from 0 to 6.
3.4. Statistical Analysis
The statistical evaluations were conducted using “Dell Statistica 13” software (Dell Inc., Round Rock, TX, USA). Quantitative data were summarized as mean values ± standard deviations. The Shapiro–Wilk test was utilized to assess the distribution of the variables. Hypotheses testing for variables that followed a normal distribution was carried out using the t-test, whereas the Mann–Whitney U-test was applied for variables not normally distributed. Qualitative data were represented as percentages. For qualitative variables, the maximum likelihood chi-square test was used for further statistical analysis. To determine the relationship between the studied variables, correlation and regression analyses were performed. In the case of quantitative variables with a normal distribution, Pearson’s correlation coefficients were determined, in the case of quantitative variables with a non-normal distribution—Spearman’s coefficients, and in the case of ordinal variables—Kendall’s coefficients. The parameters of the model obtained in the regression analysis were estimated using the least squares method. Statistical significance was attributed to results with a p-value of less than 0.05.
5. Discussion
In our study, it was observed that the subjects with a carotid plaque score equal to or greater than two had a significantly higher coronary artery calcification index and more severe atherosclerotic changes in the coronary arteries based on the CAD-RADS system in comparison to the subgroup of patients with a carotid plaque score equal to or less than one. Furthermore, we showed that the carotid plaque score and the patient’s age are independent risk factors for the severity of atherosclerotic lesions in the coronary arteries.
CCTA serves as a first-line imaging method to evaluate CAD in patients with stable chest pain [
11]. It is capable of reliably excluding significant obstructive CAD with a high degree of luminal narrowing (≥50%) with high negative predictive value. It is widely acknowledged that this approach can indicate clinical treatments and reduce the incidence of myocardial infarction in comparison to conventional stress testing [
12]. There are, however, some flaws. Firstly, CCTA is relatively expensive, and it demands the supply of contrast. Secondly, the performance of CCTA in patients with obstructive CAD is suboptimal due to its poor specificity. Severe calcific plaques forming luminal stenosis may be the reason for overestimation due to calcium blooming [
13].
In a cohort of middle-aged individuals recruited from the general population, the carotid plaque score turned out to effectively predict the occurrence of stroke and major adverse cardiovascular events, surpassing the performance of SCORE2 in risk prediction [
6]. According to the 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes [
14], however, carotid ultrasound intima media thickness (IMT) for cardiovascular risk assessment is not recommended in the general population [
15]. Screening for CAD in asymptomatic subjects should base on a risk-estimation system such as SCORE2 scale. Total risk estimation is recommended for asymptomatic adults aged >40 years without evidence of CVD, diabetes, CKD, or familial hypercholesterolemia [
14]. Recently, however, there has been performed a systematic review that supported the thesis that pictorial presentation of silent atherosclerosis using carotid US screening has a contributory role in CV risk stratification and prevention of CVD [
16]. According to the meta-analysis performed by Gupta et al. [
7], the presence of ultrasound-determined carotid plaque echolucency provides predictive information in asymptomatic carotid artery stenosis beyond luminal stenosis. Yet, the level of increased risk is inadequate by itself to pinpoint patients who would significantly benefit from surgical revascularization [
7].
Carotid plaque, coronary artery calcium, or abnormal ankle pressures appear to be reliable markers for the existence of subclinical atherosclerosis and could be utilized as biomarkers [
17]. The occurrence of cerebral ischemic incidents in patients with asymptomatic carotid stenosis is a significant concern. Plaque progression and contralateral stenosis are key factors in predicting these cerebral ischemic events [
18]. Our results suggest that ultrasound assessment of the carotid plaque score in patients with arterial hypertension can be used as a prognostic indicator of the occurrence and severity of atherosclerotic changes in the coronary arteries. With plaque-RADS, the recently published standardized system of reporting carotid plaque composition and morphology via different imaging techniques, the efficient communications between both scientists and physicians of different specialties seems more reachable [
19].
Our study contains several important limitations that should be mentioned. Firstly, the study was performed on a small group of patients. The group size is, indeed, sufficient, as confirmed by the sample size calculator, and the patients were properly qualified from the point of view of radiological protection for computed tomography (only 6% of patients with the final documented absence of coronary artery disease). However, for a more reliable analysis, a study on a larger group of patients would be justified. Secondly, subjective inclusion and exclusion criteria were adopted, e.g., at least 5 years of hypertension or CACS > 800 as a criterion for withdrawing from the angiographic phase of CCTA. It was possible to simply include additional patients with hypertension in the study and then include all variables potentially influencing the results in statistical analyses. However, the principles of radiological protection were followed when qualifying patients for CCTA. In terms of the study group, our group is also characterized by an overrepresentation of women and the older age. Moreover, the study included only a few patients with a high degree of coronary artery disease according to the CAD-RADS classification (CAD-RADS > 3 in only 12% of patients). In terms of research methodology, a significant limitation is the lack of data on the results of further diagnostics in patients classified as having CAD-RADS 3 based on CCTA. A limitation in the way the study is presented may be the fact that the indications for CCTA examination in
Table 2 are presented based on the entries of doctors referring patients for CCTA examinations on referrals to the computed tomography laboratory. Furthermore, it should be remembered that this is an observational study and, hence, a snapshot of the characteristics of the study population. Based on such studies, no conclusions can be drawn regarding long-term clinical outcomes.