THURSDAY FEB 14, 2008 (Foodconsumer.org) -- A study found using anti-retroviral drugs Didanosine and Abacavir increased risk of hear attack and or the formation of blood clots in the heart.   But the adverse effects can be reversed by simply stopping use of these drugs.

The study led by researchers at the University of Copenhagen showed Didanosine raised the heart attack risk by 49 percent while Abacavir increased the risk by 90 percent.

The researchers recommended that patients with high risk of underlying cardiovascular risk should evaluate their risk with their doctors and discuss whether they should use other drugs. But they should not stop taking these drugs before consulting with their health care providers.

The Data Collection of Adverse effects of Anti-HIV Drugs Study initiated in 1999 was meant to examine the side effects of anti-retroviral drugs including a possible increase in the risk of heart attack.

The anti-retroviral drugs evaluated recently were the nucleoside analogues including Stavudine, Zidovudine, Lamivudine, Abacavir and Didanosine, which inhibit the HIV virus by preventing it from multiplying.   But only the last two drugs showed adverse effects on heart health.

The risk increased by Abacavir and Didanosine was most significant in HIV patients who had a serious underlying cardiovascular condition. Abacavir could increase the underlying risk by a factor of 1.9 while Didanosine could raise their risk by a factor of 1.49. For people with low underlying risk, the risk increase was almost negligible while the risk could become serious in people with high underlying risk.

However when patients stopped taking these drugs, no matter how long they had been taking, the risk of heart attack was reversed back to the level the patients had when they did not take these drugs.

These findings were presented at CROI (Conference on Retroviruses and Opportunistic Infections), which is the leading international scientific conference on HIV held in Boston, USA between Feb 3 and 6.