According to a new study, testosterone supplements may improve the quality of life for patients who have a certain heart condition.
The researchers used testosterone patches and injections that improved the breathing and exercise abilities of people with heart failure, a chronic inability of the heart to pump enough blood to the rest of the body. Although most of the study participants were men, the researchers said the results would likely apply to women as well, through much smaller doses of testosterone.
Some heart failure patients have symptoms even after standard therapies, such as drugs called beta blockers and ACE inhibitors. “Heart failure is a chronic condition that can be brought on by blockages in the heart, lung disease, diabetes or kidney disease,” said study co-author Justin Ezekowitz, an assistant professor in the department of cardiology at the University of Alberta as well as at the Mazankowski Alberta Heart Institute, both in Edmonton. “It's a clinical syndrome, where the body can not pump enough blood to meet the body's demands for oxygen to do things like exercise properly.” “They physically cannot walk as far or as fast or as much as they could when they were healthy,” Ezekowitz said. “Testosterone appears to be a promising therapy” to improve exercise ability in heart failure patients, the researchers said.
However, Ezekowitz said patients should not start using testosterone supplements based on these results. Larger studies would be needed to confirm the findings and figure out which method of delivery is best and what doses are appropriate.
This study looked at data from four previous studies in which patients were randomly assigned to receive either testosterone therapy or a placebo for 12 to 52 weeks. About 200 patients in total participated; their average age was 67, and 84 percent were men. Patients were also taking standard medical treatments for heart failure.
During a six-minute walking test, patients taking testosterone therapy walked an average of 177 feet farther (54 meters) than those taking a placebo — a greater improvement than what has been achieved with current therapies alone, the researchers said. Patients on testosterone therapy also saw an increase in the amount of oxygen the body used per minute of exercise, a measure known as VO2 max, which is a general indicator of a person's fitness level. No adverse effects on the heart were seen.
Testosterone may help these patients not because it directly affects the heart itself but because it may target the peripheral tissues, such as the skeletal muscles, Ezekowitz said. The hormone has been shown to widen blood vessels, allowing more blood to reach peripheral tissues. It may also increase levels of hemoglobin, a protein in red blood cells that transports oxygen. However, further work is needed to determine exactly how testosterone acts in heart failure patients.
“These studies only looked at exercise function,” Ezekowitz noted. “This is important, because improved function translates into how active a person can be, which can affects a patient's overall quality of life. But it does not say anything about how testosterone therapy might affect a patient's risk for death or hospitalization. That is still uncertain, and we need larger clinical trials to assess that.”
More studies are needed to determine the long-term effects of testosterone therapy. Previous studies have found an association between high doses of testosterone and an increase incidence of prostate cancer, Ezekowitz said.
In the new study, there was a small increase in levels of prostate-specific antigen (PSA) among men who took testosterone therapy. (High PSA levels are associated with prostate cancer.) Patients on testosterone therapy should be monitored for changes in PSA levels, Ezekowitz warned.
Commenting on the findings, Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, stressed the preliminary nature of the studies. “We know that heart failure is characterized by exercise intolerance, muscle wasting, hospitalization and mortality,” he said. “And therefore the use of anabolic steroids could potentially play a beneficial role.” “But at the same time, they can also potentially raise the risk for coronary artery disease and heart failure,” Fonarow added. “So, it's critical to point out that these are small studies, and that no current guidelines recommend the use of testosterone or any other hormonal therapy for heart failure at this time. So this is certainly an area where proceeding cautiously is warranted, while further carefully controlled, larger randomized trials are conducted.”
The study, which received partial funding from the Canadian Institutes of Health Research and from Alberta Innovates-Health Solutions, appears online April 17 in the journal Circulation: Heart Failure.