Long-term anabolic steroid use may reduce the heart’s ability to pump blood and relax between beats and cause coronary artery disease, according to new research.

Anabolic-androgenic steroids mimic naturally occurring testosterone, a muscle-building hormone that promotes male sexual characteristics. Since illicit use of these steroids became widespread in the American general population in the 1980s, adverse long-term effects are becoming evident.

Researchers conducted an observational study of 140 male weightlifters: 86 who used anabolic steroids and 54 non-users. Of the users, 58 were on the drug and 28 were off during evaluations. The off-drug users had last used steroids an average 15 months prior to the evaluations. Anabolic steroid users showed higher body- and fat-free mass indexes, consistent with known effects of anabolic steroids.

Using two-dimensional ultrasound imaging, researchers found that the left ventricle, the heart’s main pumping chamber, was significantly weaker during contraction in those taking anabolic steroids compared to the non-steroid users.

Seventy-one percent of the anabolic steroid users who were on-drug during the evaluation had a low pumping capacity (less than 52 percent) and off-drug users had largely normal pumping capacity. In contrast, only two of the non-users had a low pumping capacity.

Diastolic function, which is when the left ventricle relaxes and fills with blood, was impaired for on-drug and off-drug anabolic steroid users. The researchers said this suggests a more permanent heart problem.

“Compared to non-users, anabolic steroid users displayed both higher systolic and diastolic blood pressure as well as a higher prevalence of levels of bad cholesterol in their blood,” said Aaron Baggish, M.D., associate director of the cardiovascular performance program at Massachusetts General Hospital in Boston.

Researchers used coronary CT scans to examine the potential link between anabolic steroid use and coronary artery disease. This portion of the study revealed strong associations between the lifetime duration of illicit anabolic steroid use and the amount of plaque build-up in the coronary arteries.

An estimated 2.9 to 4 million Americans have used anabolic steroids. About a million of them, almost all of whom are male, have developed anabolic steroid dependence.

“Most people relate anabolic steroids to cheating among athletes and fail to realize that there is a large population of men who have developed dependence upon these drugs, but who are not readily visible,” said Harrison Pope, Jr., M.D., professor of psychiatry at Harvard Medical School and director of the Biological Psychiatry Laboratory at McLean Hospital in Boston.

“Clinicians need to know that there may be a marked increase in anabolic steroid-related cardiac pathology as this population moves into later middle age and beyond.”

The study is published in the American Heart Association journal Circulation.