Researchers in the Netherlands sought to measure and compare stiffening of the arteries (which is linked to cardiovascular disease) among 1,000 middle-aged people, half of whom were HIV positive. The researchers found that HIV-positive people had increased arterial stiffness. Overall, traditional cardiovascular disease risk factors -- particularly smoking -- were largely responsible for this increased risk. However, among a subset of HIV-positive people, those who had serious immune deficiency (100 CD4+ cells or less) were also at elevated risk for stiffening arteries.
About Stiffer Arteries
Every time the heart pumps blood, a wave-like movement of blood is pushed outward from the heart along the arteries. Flexible arteries are needed to help the wave of blood move. As arteries age they can become stiffer (arterial stiffness). When this happens blood does not travel as well from the heart, and the heart's pumping action intensifies as this organ attempts to compensate by pushing blood more forcefully. Over time, this intensified action can place a strain on the heart. Stiffer arteries have been linked to an increased risk for heart attack and stroke.
Dutch researchers have been trying to understand the impact of HIV on the aging process in a study called AGEhIV. What is very useful about the Dutch study is that it enrolled both HIV-negative and HIV-positive people from the same communities who have similar socio-economic and behavioural factors. This greatly strengthens comparisons made within the study.
Researchers focused their analysis on the following groups:
- 566 HIV-positive people
- 507 HIV-negative people
The researchers made the following summary of the profile of participants when they entered the study:
"... HIV-infected individuals were more often diagnosed with [higher-than-normal blood pressure], had generally less favourable [levels of cholesterol and triglycerides in their blood], and were more often smokers."
Additionally, the average profile of HIV-positive participants upon entering the study was as follows:
- age -- 53 years
- 89% men, 11% women
- 32% currently smoked
The vast majority of participants were taking ART and had an undetectable viral load.
Overall, HIV-positive people had a greater degree of arterial stiffening than HIV-negative people. According to the researchers, this was mainly due to smoking and elevated blood pressure.
Taking into account many factors (including gender, age, smoking), researchers found that some HIV-positive people, particularly those who had endured a high degree of immune deficiency in the past (that is, who had 100 or less CD4+ cells), were significantly more likely to have stiffer arteries.
Why the Link With Immune Deficiency?
Immune deficiency is associated with heightened inflammation and immune activation. Such effects likely injure the arteries and increase the pace at which cardiovascular disease occurs.
It is also possible that, as the Dutch study suggests, having immune deficiency in the past leaves a lasting impact on the health of the arteries.
Researchers were not able to find any HIV-related factors that drove arterial stiffness, so they think that other factors may be continuing to incite inflammation within the arteries. One such possible factor is CMV (cytomegalovirus), a common sexually transmitted member of the herpes family of viruses. Other studies have found an association between CMV co-infection and a risk for increased inflammation in people with HIV.
Overall, the researchers concluded that arterial stiffening played a small role in the increased risk for cardiovascular disease in HIV-positive people. However, the study is important because it adds to the information known about the role of traditional cardiovascular disease risk factors and it has exposed the impact of a history of immune deficiency on arterial health. In this latter regard, the Dutch study provides yet another reason to start ART as early as possible.
HIV and cardiovascular disease -- CATIE fact sheet
Kooij KW, Schouten J, Wit FW, et al. Difference in aortic stiffness between treated middle-aged HIV Type 1-infected and uninfected individuals largely explained by traditional cardiovascular risk factors, with an additional contribution of prior advanced immunodeficiency. Journal of Acquired Immune Deficiency Syndromes. 2016 Sep 1;73(1):55-62.