HIV update - 28th March 2018

Heart disease

Heart attack, stroke, angina (chest pains), heart failure, and irregular heartbeat are all forms of cardiovascular disease, an increasingly important cause of illness in people with HIV. Recent studies show that people with HIV are more likely to develop cardiovascular conditions than people who don’t have HIV.

One study looked at the build-up of plaque on blood vessel walls in the arteries which supply blood to the heart. Plaques are deposits of cholesterol and fatty material which can result in a narrowing of the arteries, interfering with blood flow and forcing the heart to work harder.

The researchers recruited American gay men living with HIV and gay men who didn’t have HIV, all of whom were in their forties, fifties or sixties. Plaque was measured when men joined the study and once again five years later. During that time, the amount of plaque increased for four-fifths of men. It was more likely to get worse in men living with HIV than men who didn’t have HIV.

Another study examined peripheral artery disease, in which the arteries supplying blood to the head and limbs become restricted due to a build-up of plaque. Comparing Danish people living with HIV and people in the general population, peripheral artery disease was twice as common in those living with HIV. After adjusting for other factors, having HIV increased the risk of the condition by about the same amount as smoking.

Both sets of researchers commented that more research is needed to understand why people with HIV are at greater risk of these conditions. Part of the explanation may be ongoing activation of the immune system and inflammation in response to HIV. It’s also possible that co-infections such as hepatitis C, herpes or cytomegalovirus (CMV) play a role.

Another study sheds light on a potential explanation of the increased rate of heart attacks that may occur in people taking the anti-HIV drug abacavir.

Abacavir (Ziagen, also in the Kivexa, Trizivir and Triumeq combination pills) is a commonly used nucleoside reverse transcriptase inhibitor (NRTI). Data first released ten years ago showed that people taking abacavir are at greater risk of heart attacks than other people, although the absolute number of heart attacks was still very low.

A recent study collected data on people who had been taking treatment including abacavir and lamivudine. They were randomly allocated to either stay on that treatment or switch to a treatment containing tenofovir alafenamide (TAF) and emtricitabine. Those who changed treatment had less platelet reactivity. Platelets are blood cell fragments that clump together – when this is excessive, it can impede normal blood flow, resulting in chest pains, heart attacks and strokes.

The link between abacavir and heart disease is stronger in people who have other risk factors for cardiovascular disease (such as older age, a family history of heart disease, or smoking). Switching from abacavir is most likely to be beneficial in people with other risk factors.

For more information, read NAM's factsheet 'The heart'.

Women’s risk of HIV infection

Two new studies have given us a better understanding of factors that put women at risk of acquiring HIV.

A study shows that pregnancy and the first six months after giving birth are a period of elevated risk. This is probably due to hormonal changes during pregnancy and breastfeeding.

The researchers calculated the risk of HIV infection per 1000 sex acts for an HIV-negative woman who had an HIV-positive partner with a high viral load. For a woman who was neither pregnant nor post-partum, it was 1.1 infections per 1000 sex acts; during the first 13 weeks of pregnancy, it was 2.2 infections per 1000 sex acts; for the rest of pregnancy, it was 3.0 infections per 1000 sex acts; and during the first six months after giving birth, it was 4.2 infections per 1000 sex acts.

Women with HIV-positive partners who do not have an undetectable viral load may want to use additional prevention tools – such as condoms or pre-exposure prophylaxis (PrEP) – while they are pregnant or breastfeeding.

A second study helps explain why rates of HIV are so high in women in many African countries. Men who have HIV are less likely to be diagnosed and take HIV treatment than women, which puts women at greater risk of having a sexual partner who could pass HIV on. On the other hand, men are protected by women being more likely to have their HIV diagnosed and treated.

The study comes from KwaZulu-Natal in South Africa. Between 2005 and 2015, new HIV infections in men fell sharply, while infections in women slightly increased.

During this time, the proportion of HIV-positive women who were taking treatment increased from 29% to 49%, while the proportion in men increased to a lesser extent, from 26% to 38%. At the same time, the proportion of people with a detectable viral load fell among women while it increased among men.

The researchers say that for women to be better protected from HIV, men – especially young men – need to be tested for HIV regularly and to be better engaged with health care once they are diagnosed. This would mean that they would be less likely to have untreated HIV which they could pass on to their sexual partners.

For more information, read NAM's booklet 'HIV & women'.

News from CROI 2018

The Conference on Retroviruses and Opportunistic Infections (CROI) is one of the most important conferences on HIV treatment and prevention in the world. This year’s CROI was recently held in Boston, USA, and included several studies that are relevant to people living with HIV in the UK.

As a subscriber to HIV update, you should have automatically received our conference bulletins, including summaries of these studies. In case you missed them, here are links to some of the key stories:

• The antiretroviral drug efavirenz significantly reduces the levels of oestrogen and progestin in the vaginal ring contraceptive, potentially reducing its effectiveness.

• Ibalizumab, a long-acting monoclonal antibody, is a novel anti-HIV therapy that has just been approved in the US for people with HIV who have limited options due to extensive prior treatment experience and multidrug-resistant virus.

• People who switched to a single-tablet regimen containing the new integrase inhibitor bictegravir were as likely to maintain an undetectable viral load as those who stayed on their current suppressive regimen containing dolutegravir.

• People with HIV who take statins to lower their risk of heart disease also have a lower risk of cancer, especially cancers which can be caused by viral infections.

• A case of infection with HIV in a person consistently taking pre-exposure prophylaxis (PrEP) has been reported but it is difficult to be 100% certain that this is a case of PrEP failure.

For all our news stories and bulletins from CROI 2018, visit our conference webpages.