The increase in the incidence of CVD in people with HIV and underestimation of the CVD risk through commonly used tools necessitate exploration of new resources to adequately assess vascular risk in these patients. SAT is the pathophysiological basis of CVD. The high prevalence of SAT among the HIV population may explain the greater number of cardiovascular events in people with HIV .
In our cohort, the prevalence of SAT among HIV participants without previous CVD was 62.29%, which is much higher than that published in the literature. In a recent meta-analysis by Liu et al. , a prevalence of carotid SAT between 31.6% and 37% was reported.
The higher frequency of atheromatous plaque recorded in our study can be explained by several factors.
Factors related to the population studied
Our study was developed in Europe, where the prevalence of traditional cardiovascular risk factors (CVRFs), such as smoking, obesity and alcohol abuse, is high . Most of the participants in our study were men (66.6%) and were over 40 years old.
On the other hand, we selected patients with HIV infection with more than 10 years of evolution, which may have influenced the high prevalence of atheromatosis observed in our patients.
Factors related to the type of study
High variability is evident among published reports on the SAT prevalence in the HIV population. These diverse findings can be explained by the heterogeneity of the populations studied and the different criteria used to define atheromatous plaque. A total of 83.32% of the plaques found in our patients were in the carotid territory, and if we exclude the plaques found in the femoral territory, the prevalence of plaque was 52%, which was even higher than published rates. However, the number of territories studied must be considered. In most studies, the estimation of atheromatous plaque is performed on the common carotid , while in our case, we performed this estimation on the common carotid, bulbar, internal carotid, external carotid, common femoral and superficial femoral territories.
HIV infection is related to selective depletion of CD4 lymphocytes and increased expression of CD8, which lead to an inverted CD4/CD8 ratio (< 1) . This ratio has recently emerged as a marker of immunosenescence and is independently associated with risk factors for both AIDS and non-AIDS events and mortality. In addition, it has been independently associated with intima-media thickness (IMT) progression  and SAT . Specifically, a CD4/CD8 ratio < 0.5 or < 0.3 has been determined to be a risk factor for non-AIDS events or mortality, especially when the CD4 count is high (≥ 500 cells/μL) .
A decreased ratio can be maintained despite having achieved viral suppression and normalization of CD4 levels with ART . Among the factors associated with a persistent inversion of the CD4/CD8 ratio are the presence of positive CMV serology, ART initiation before 1997, a low CD4 nadir and a short duration of viral suppression . An inverted CD4/CD8 ratio and a low CD4 nadir have been associated with an increased risk of non-AIDS events .
The CD4/CD8 ratio tends to present greater stability over time than the absolute counts of CD4 and CD8 cells, and its predictive value for events unrelated to AIDS has been described as exceeding that of the absolute CD8 count in individuals with restored CD4 counts (> 500 cells/µL) .
This ratio can be used as a marker of immune dysregulation and as a predictor of non-AIDS events in these patients.
In our cohort, we observed an association between inversion of the CD4/CD8 ratio and the presence of carotid and femoral atheromatosis, which may constitute a parameter to be considered when estimating the risk of CVD in the HIV population without previous events. In addition, the presence of atheromatous plaque was associated with a low CD4 nadir and positive CMV serology, with no differences in viral suppression time found.
Through the use of predictors included in the logistic regression analysis, we obtained a diagnostic yield measured by the ROC curve of 72%.
In our cohort, we observed greater use of PIs in the SAT group. These results must be considered with caution, since patients with HIV follow different therapeutic regimens throughout their disease courses, and within the PI group, the new generations of PIs are very different in terms of side effects and cardiovascular safety.
Although studies related to normalization of the CD4/CD8 ratio with early ART initiation have been published [20,21,22], no differences have been found among the different classes of ART used .
Although the earliest PIs, such as ritonavir, have been associated with an increased risk of CVD , the use of new therapies, such as atazanavir, has been associated with slower progression of atheromatous plaque and a lower incidence of CVD .
Vascular ultrasound of the carotid and femoral territories allows assessment of the presence of atheromatous plaque in these locations and provides information on the extent of atherosclerosis at the systemic level.
This approach is fast and innocuous and may be useful to reclassify the vascular risk of people with HIV , allowing treatment readjustment with the objective of reducing the vascular risk and avoiding CVD in the future.
Performing ultrasound in primary prevention in intermediate-risk patients is relevant since it can permit vascular risk reclassification.
However, despite the high prevalence of plaque in the HIV population, this technique is normally not included in routine check-ups for several reasons, including a lack of ultrasound time and a necessary learning curve.
Identifying the predictive factors for the presence of SAT is essential to be able to reclassify patients and select those who will obtain a greater benefit from evaluations for SAT.
Therefore, the findings obtained in our cohort may be relevant to vascular risk assessments in these patients.
The CD4/CD8 ratio can play a role in comprehensive assessments of vascular risk in people with HIV, constituting a simple and accessible tool.
Through three clinical-analytical parameters easily extracted from the clinical history of participants (CD4/CD8 ratio less than 0.7, age and active smoking), we were able to predict the presence of SAT in HIV patients without previous CVD.
As the sample size was small due to the design of the study, these results should be considered with caution, and additional studies are necessary to confirm the findings.
A tendency towards a greater incidence of traditional vascular risk factors, such as hypertension and diabetes, was evident in the group with atheromatous plaque, although without significance, probably due to the insufficient sample size. We must also consider the greater use of PIs by patients with atheromatous plaque, which have been associated with an elevated vascular risk in people with HIV in other studies.