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FDA Study Finds No Link Between Ziagen and Heart Attacks

March 2011

A US Food and Drug Administration (FDA) analysis of 26 trials comparing Ziagen (abacavir) to other drugs found no evidence that this antiretroviral raises the risk of myocardial infarction (heart attack).1 Ziagen is part of the two-drug combination Epzicom or Kivexa and the three-drug combination Trizivir.


Earlier, a large study of people taking antiretrovirals2 and analysis of SMART trial results3 suggested that Ziagen does raise the risk of heart attack and other heart disease. But the FDA study contradicts that finding. For people with HIV and physicians unsure about how to interpret all these findings, the FDA offers some advice, summarized below in What the results mean for you.

The DAD Study Group analyzed the impact of current or recent nucleosides in 33,347 people taking antiretrovirals.2 Using standard statistical methods, the DAD researchers found no associations between the heart attack rate and total or recent use of Retrovir (zidovudine), Zerit (stavudine), or Epivir (lamivudine). But in an analysis that accounted for 10-year risk of heart disease, recent use of Ziagen raised the heart attack risk 89%, and recent use of Videx (didanosine) raised the risk 49%.

The SMART trial randomized HIV-positive people to take antiretrovirals continuously or to interrupt treatment according to their CD4 count. Analysis of heart disease rates in these people determined that recent Ziagen use almost doubled the risk of major heart disease (heart attack, stroke, or surgery for coronary artery disease).3

Partly because of the DAD and SMART results, experts who write antiretroviral guidelines in the United States removed Ziagen from the list of drugs recommended for a first antiretroviral combination. But several other studies found no link between Ziagen and heart disease. And safety data collected by Ziagen's maker saw no hint that Ziagen makes heart disease more likely. The FDA decided the issue is important enough to examine in a different way -- by comparing heart attack rates in people who took Ziagen in randomized trials with rates in people who did not take Ziagen in those trials.

Heart Attack Risk Factors That Can Be Avoided or Changed

  • Diabetes
  • High blood pressure
  • Smoking
  • Too much fat in your diet
  • Unhealthy cholesterol levels, especially high LDL ("bad") cholesterol and low HDL ("good") cholesterol
  • Chronic kidney disease
Source: US National Library of Medicine, National Institutes of Health. Accesed March 6, 2011. Illustration from the National Library of Medicine.


  1. Ding X, Andraca-Carrera E, Cooper C, et al. No association of myocardial infarction with ABC use: an FDA meta-analysis. 18th Conference on Retroviruses and Opportunistic Infections. February 27-March 2, 2011. Boston. Abstract 808.
  2. D:A:D Study Group, Sabin CA, Worm SW, Weber R, et al. Use of nucleoside reverse transcriptase inhibitors and risk of myocardial infarction in HIV-infected patients enrolled in the D:A:D study: a multi-cohort collaboration. Lancet. 2008;371:1417-1426. Accessed March 6, 2011.
  3. Strategies for Management of Anti-Retroviral Therapy/INSIGHT; DAD Study Groups. Use of nucleoside reverse transcriptase inhibitors and risk of myocardial infarction in HIV-infected patients. AIDS. 2008;22:F17-F24. Accessed March 6, 2011.
  4. "Based on our [statistical] simulations, the power of our study to exclude a relative risk of 1.8 with the observed myocardial infarction background risk (0.45%) was 0.62; however, lack of power does not explain the observed risk difference of 0.008% with a 95% confidence interval of (-0.26%, 0.27%). The simulation to assess the power demonstrates that our study had a probability of 0.95 to find a risk difference greater than 0.1%. Our study's finding is very unlikely if the true risk of [Ziagen] is 1.8 or higher at the observed background myocardial infarction risk (0.45%)."
  5. FDA Drug Safety Communication. Safety review update of abacavir: no statistically significant association seen between myocardial infarction and [abacavir]. March 1, 2011. Accessed March 10, 2011.
  6. Strategies for Management of Antiretroviral Therapy (SMART) Study Group, El-Sadr WM, Lundgren JD, Neaton JD, et al. CD4+ count-guided interruption of antiretroviral treatment. N Engl J Med. 2006;355:2283-2296. Accessed March 6, 2011.

This article was provided by The Center for AIDS. It is a part of the publication HIV Treatment ALERTS!. You can find this article online by typing this address into your Web browser:

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