A WIDELY used anti-HIV drug could raise heart attack risk by encouraging blood clots to form, according to a new study by Irish scientists that was unveiled at a major international conference in Canada last week.
The Dublin-based researchers showed that patients on the anti-viral drug Abacavir have stickier blood platelets – which can clump to form clots – than patients who are not taking that drug as part of their therapy.
HIV infection itself is thought to increase heart attack risk, but last year a Danish-led study of more than 30,000 HIV-infected patients found that Abacavir appeared to almost double that risk, said Dr Paddy Mallon, consultant in infectious diseases at the Mater Misericordiae Hospital and a lecturer in medicine at University College Dublin.
“It was very unexpected. They saw increased rates of heart attacks in people on this particular drug, and it seemed to be reversible – when people came off the drug it disappeared,” he said, noting that Abacavir is an important drug used worldwide in the long-term control of HIV infection. “It has been the major topic of conversation at the big HIV conferences.”
To investigate further, the Mater group teamed up with scientists from the Royal College of Surgeons in Ireland led by Prof Dermot Kenny.
They compared the reactivity, or stickiness, of blood platelets in 30 HIV-infected patients taking Abacavir and 28 HIV-infected patients who were on other drug therapies.
“Overall, in the patients in the Abacavir group, their platelet reactivity was increased,” said Dr Mallon, who explained that increased reactivity of blood platelets can lead to clots that block blood flow to the heart. “These results are the first snapshot that says this is the potential mechanism underlying .”
PhD candidate Claudette Satchell presented the findings, which came to light only in recent weeks, in a late-breaker session at the influential Conference on Retroviruses and Opportunistic Infections (CROI) in Montréal last Wednesday.
Further and larger studies are now needed to determine the impact of the discovery on patients, to find out whether they can continue to use Abacavir safely or need to switch to alternative drugs, and whether another approach such as taking aspirin could overcome the platelet issue, said Dr Mallon.
“We are really reliant on these [anti-viral] drugs to control HIV, and our goal is to try to find the safest but most effective long-term drug.”
