Researchers presented several studies at the International AIDS Conference that examined the role of antiretroviral drugs in the development of heart problems in people with HIV. Results from two large studies indicated that other factors play a larger role in determining heart attack risk than taking antiretroviral medications.

Heart disease is the number one cause of death for both men and women in the United States. Some studies have estimated that heart disease causes as many as a fifth of all deaths in people with HIV.

Some previous studies have indicated that antiretroviral drugs contribute to heart problems. In particular, Ziagen (abacavir), a nucleoside reverse transcriptase inhibitor, has been linked to an increased risk of heart attacks. Ziagen is frequently used in combination with other antiretroviral medications. It is also an active ingredient in Epzicom (abacavir/lamivudine).

A study presented at AIDS 2010, however, found that a person’s blood pressure and CD4 count (white blood cell count) contributed most significantly to the risk of heart attack.

An analysis of several previous studies of Ziagen also concluded that the drug was not associated with an increase in heart attack risk compared to other nucleoside reverse transcriptase inhibitors.

However, an additional study found that switching from Ziagen to Viread (tenofovir) reduced arterial stiffness in men already at high risk of heart attack, indicating that in some situations switching medications may be helpful.

High Blood Pressure And Low CD4 Count Are Most Important In Determining Heart Attack Risk In People With HIV

A study examined the relationship between antiretroviral medications, general health, and heart attack rates in people with HIV.

The data encompassed 6,517 HIV-positive adults, 4 percent of whom had a heart attack between 1998 and 2008.

For the study, researchers examined the patients’ medical records to determine risk factors for having a heart attack. They looked at the occurrence of other conditions, such as diabetes and high blood pressure, as well as factors related to the patients’ HIV infections, such as antiretroviral medications, CD4 (white blood cell) counts, and viral loads (amount of virus in the blood).

The researchers found in an initial analysis that the protease inhibitors Crixivan (indinavir) and Viracept (nelfinavir) were linked to an increased risk of heart attack.

However, when they took into account other factors, the scientists found that high blood pressure and low CD4 (white blood cell) counts were the most important indicators of heart attack risk.

Patients with a CD4 count of 200 cells per microliter of blood or less had significantly higher rates of heart attacks.

Older age and being non-Caucasian were also risk factors.

The researchers concluded that these other factors – especially high blood pressure and low CD4 counts – were more important for determining heart attack risk than any individual antiretroviral medications.

Analysis Of Clinical Trials Shows No Connection Between Ziagen Use And Heart Attacks

Researchers who analyzed data from 36 previous randomized clinical trials, both published and unpublished, determined that antiretroviral therapy containing Ziagen did not increase risk of heart attacks or death.

For the analysis, the researchers compared the risk of heart attacks, serious side effects that caused people to discontinue the drug, and death rates in people taking Ziagen versus other nucleoside reverse transcriptase inhibitors.

Results showed no connection between Ziagen use and an increased rate of heart attacks, serious side effects, or death.

Earlier studies suggested Ziagen might increase the risk of heart attacks. However, these studies did not randomly assign people to take Ziagen, which means there may have been a higher rate of patients with preexisting conditions taking Ziagen.

The researchers argued that this latest analysis is more reliable than previous studies because the data came from randomized clinical trials.

They concluded that Ziagen is not associated with an increased risk of heart attack or death.

Switching From Ziagen To Viread May Reduce Arterial Stiffness In Men With HIV

A small pilot study evaluated the effect of switching from Ziagen to Viread on arterial stiffness in HIV-positive men. All of the men had previously been classified as being at high risk of heart attack or death from heart disease.

Stiffness inhibits an artery’s ability to pump blood to the heart, which increases stress on the heart and raises the risk of heart attacks.

The men in the study were designated as high risk status based on their age, sex, total and “good” cholesterol (HDL) levels, smoking, and blood pressure.

The pilot study was 24 weeks long and included 20 men with stable viral loads (amount of HIV in the blood) of 50 copies per milliliter or less.

Researchers found that participants had reduced arterial stiffness after switching from Ziagen to Viread. Participants’ cholesterol levels also dropped, which the researchers hypothesized was actually responsible for the reduced stiffness.

The researchers concluded that men at high risk may decrease their chances of heart attack by switching from Ziagen to Viread.

For more information, please see the AIDS 2010 conference website.