June 3, 2009
There's something about having HIV in your body that may raise your risk for heart disease, say U.S. researchers in a large study published in the June 1 issue of the medical journal AIDS. The study found that this risk even appears to apply to long-term HIV nonprogressors -- people who are able to maintain an undetectable viral load despite never having taken HIV meds.
Research has increasingly shown that people with HIV face a higher risk for developing heart disease. Some experts initially assumed that HIV medications were to blame for the greater risk, and research does indeed suggest that people who take certain kinds of HIV meds are a bit more likely to have a heart attack, though this is really only a concern if those people also have other risk factors for heart disease, such as smoking, high blood pressure or high cholesterol.
At the same time, however, studies have shown that HIV meds are far from the only culprit when it comes to increasing heart disease. In fact, signs are growing stronger that HIV itself plays a previously underestimated role. The theory is that the body's immune system is forced to continually work at fighting off the virus. This may lead to a complication called "chronic inflammation," which has long been thought to increase a person's heart disease risk. (For one example of how inflammation works, think of a mosquito bite. When you get bitten, your skin becomes swollen as your immune system launches its defense against the saliva the mosquito injected to make it easier to extract your blood. That swelling is a type of inflammation.)
In this fascinating study, Priscilla Hsue and other researchers from the University of California-San Francisco conducted tests on 494 people in hopes of determining why HIV-positive people seemed more likely to develop atherosclerosis, a thickening or hardening of the arterial wall that can lead to the development of heart disease. What made this study unique was that, of the 494 study volunteers, 33 were long-term HIV nonprogressors. In addition, 93 of the 494 volunteers were HIV negative.
To determine whether the trial participants had atherosclerosis, the researchers measured carotid intima-media thickness (IMT), or the thickness of the walls of the carotid artery, the main artery that provides blood flow to the head and neck. They also measured C-reactive protein (CRP) levels, a marker for inflammation.
The researchers discovered that HIV-positive volunteers had more atherosclerosis than HIV-negative volunteers. This was the case in every subgroup of HIV-positive people, including those who were on HIV meds, those who weren't on HIV meds and even the long-term HIV nonprogressors.
The greater atherosclerosis was seen even after the researchers took into consideration every atherosclerosis risk factor they could think of -- such as CD4 count, age and other common risk factors, such as smoking (which is more common among HIVers), high cholesterol and family history of heart disease.
At the same time, the researchers found that inflammation (as measured by CRP) was significantly higher among all of the HIV-positive volunteers. Just as with the atherosclerosis, this was found to be true across all subgroups of people with HIV -- in fact, HIV nonprogressors were found to have similar levels of inflammation to all other HIV-positive people, even though they'd never had a detectable viral load.
Based on their findings, the researchers suggest that there are aspects of the body's natural immune response to HIV infection that increase inflammation, which in turn can increase an HIV-positive person's risk of developing atherosclerosis and ultimately heart disease. They noted, however, that their study wasn't able to track these complications over time, and that their findings shouldn't be considered a conclusive link between HIV, inflammation and atherosclerosis.
So what can you do with this new information? As with all studies, it's important to take these results with a grain of salt: Most research is conducted in a bubble in which scientists focus on answering a very specific question -- in this case, whether HIV-positive people are more likely to have hardened arteries and inflammation than HIV-negative people. However, this study didn't compare the impact of HIV itself to, for instance, the impact of smoking cigarettes, taking certain HIV medications or eating too many high-cholesterol foods. So there's no way of knowing from these results where HIV falls on the heart-risk ladder.
That being said, this study provides an important reminder that if you have HIV, it's best to be proactive and take precautions. Many experts say it's critical now more than ever before for people with HIV to become more vigilant about being "heart healthy" -- even if you feel perfectly fine, have a high CD4 count and an undetectable viral load.
What should you do? Among other things, that means exercising regularly, not smoking and eating healthy, lowfat foods. For more on keeping your heart healthy while you're HIV positive, browse through these collections of helpful articles and other resources on TheBody.com: