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April 27, 2010 -- Long-term use of anabolic steroids appears to weaken the heart, and it is not clear if this weakening is reversible, researchers say.
In a small but alarming new study, middle-aged weight lifters who took steroids for roughly a decade showed evidence of impaired heart pumping function that was not seen in weight lifters who did not take steroids.
The finding suggests that many years of anabolic steroid use weakens the heart more than has been previously recognized, says cardiologist and study researcher Aaron L. Baggish, MD, of Harvard Medical School and Massachusetts General Hospital.
It may also have important public health implications because the use of steroids to improve sports performance is no longer the exclusive domain of a small group of elite athletes.
Steroids use is now common in fighting sports, such as boxing and mixed martial arts, in addition to weight lifting, Baggish says.
Anabolic steroids are synthetically produced drugs that mimic the naturally occurring male sex hormone testosterone, which builds muscle.
"Steroid use in the general public wasn't really an issue until the late 1980s or even the mid-1990s," Baggish tells WebMD. "Even now, when we hear about steroids it's because a professional baseball player or cyclist has taken them. But the vast majority of steroid use is now happening among casual athletes who work 9-to-5 jobs."
In an effort to better understand the impact of long-term anabolic steroid use on the heart, Baggish and colleagues performed heart function testing on 12 weight lifters who took steroids and seven who did not take the drugs.
The average age of the study participants was 40, and the steroid users had taken the drug for an average of nine years. The two groups were similar with respect to duration of weight lifting, total physical activity level, and weight, but the steroid users had more muscle mass than nonusers.
Doppler echocardiography ultrasound was used to examine blood flow through the heart.
In most of the steroid users, the heart's main pumping chamber, known as the left ventricle, showed evidence of weakness during contraction.
A healthy left ventricle pumps 55% to 70% of the blood that fills the heart. This measurement is known as ejection fraction.
Ten of the 12 steroid users had ejection fractions of less than 55%, which has been linked to an increased risk for heart failure and sudden cardiac arrest.
Only one of the seven weightlifters with no history of steroid use had a low ejection fraction.
The steroid users also showed evidence of impaired diastolic function, which is the ability of the left ventricle to relax and fill with blood following contraction.
Left ventricle relaxation was reduced by almost half among steroid users compared to nonusers.