Sept. 4, 2002 -- The heart arteries of Depo-Provera users don't work as well as those of women who don't take the contraceptive shots. A small study suggests that the drug could pose a danger to women at high risk of heart disease.
None of the study's 25- to 33-year-old Depo-Provera users actually had heart disease. But after more than a year's use of the drug, tests showed that their heart arteries weren't working as well as those of similar women who did not use the drug. Cardiologist Dudley J. Pennell, MD, Royal Brompton Hospital, London, and colleagues report their findings in the current issue of the journal Circulation: Journal of the American Heart Association. Abnormal function of the coronary (heart) arteries is an early sign of coronary artery disease.
"The key issue here is for someone who is a long-term user of Depo-Provera -- several years -- and who has a number of risk factors for heart disease: high blood pressure, smoking, a family history of coronary artery disease, or high cholesterol," Pennell tells WebMD. "Such women should consider seeing their doctor to discuss the issues and whether they would be better off switching to another form of contraception for a while to allow their [blood vessel] function to recover. There is no rush; this is not an emergency."
The finding is ironic. Some studies -- but not others -- have suggested that oral contraceptives may increase a woman's risk of heart attack. For that reason, some doctors have prescribed Depo-Provera to women with increased risk of heart disease. Now Pennell's group finds that these are the very women who should not take the long-acting contraceptive injections.
Earlier studies have shown that the female hormone estrogen is good for blood vessels. Depo-Provera results in less estrogen in the bloodstream. Pennell's team worried that long-term use of the drug might hurt blood vessels. Their study used a sophisticated measure of blood-vessel function. They found that Depo-Provera users had significantly lowered test scores.
"People who have this kind of dysfunction tend to have future coronary and cardiac events," Pennell says. "Nobody knows the implications of this for young women, but it is clearly not clever to have a normal function of your body being suppressed. In the longer term this might be associated with cardiac events. Putting two and two together, I don't think people with cardiac risk factors should be taking this long term."
Luisa Iruela-Arispe, PhD, is associate professor of molecular, cellular, and developmental biology at UCLA. An expert on the effects of hormones on blood vessels, she reviewed the Pennell study for WebMD.
"One has to look at the findings with caution," Iruela-Arispe tells WebMD. "It is an important study, it has not been done before, and it has been done with state-of-the-art techniques. There is very little understanding of the effects of hormones on the [blood vessels]. I think it is a well-done study, although it is a little small. One has to be cautious not to jump to conclusions. But this work provides information that we didn't know before. We will see a lot more studies of this now."