ED Medication Didn’t Help Heart Failure Patients

Viagra for heart failure did not improve health or quality of life

/ Author:  / Reviewed by: Chris Galloway, M.D.

(RxWiki News) A commonly prescribed medication for erectile dysfunction (ED) was thought to be a new hope for heart failure patients. But new research suggests otherwise. 

ED is often treated with sildenafil (Viagra), which increases blood flow to the penis and helps with erections. Some small animal and human studies have suggested that sildenafil could help patients with heart failure. 

Sildenafil would work for heart patients much like it does for ED. In theory, sildenafil could increase blood flow in the heart, which would get more oxygen to the heart and improve patients' ability to exercise. 

A recent study found that some patients with certain heart failure conditions did not have improved health, oxygen consumption or quality of life after taking sildenafil compared to a placebo (fake pill). 

"Find out how to keep your heart healthy and prevent heart disease."

Margaret Redfield, MD, of the Department of Medicine at Mayo Clinic in Rochester, Minnesota, and colleagues set out to examine the effects of sildenafil versus a placebo on exercise and health in heart failure patients with preserved ejection fraction. 

Heart failure with preserved ejection fraction is a condition that results when the heart's lower chambers are stiff and unable to relax or fill completely between beats. 

The study included 216 patients with heart failure. Their average age was 69 and 48 percent were women.  Patients were randomly assigned to receive sildenafil (133 patients) or a placebo (103 patients). 

Patients took the medication three times a day for 24 weeks. Sildenafil dosage started at 20 mg for the first 12 weeks and then 60 mg for the last 12 weeks. 

Researchers measured how far patients could walk in six minutes and their peak oxygen consumption while exercising (highest amount of oxygen consumed in the body). Patient's overall health and quality of life were also measured. Measurements were taken at the beginning of the study, at 12 weeks and at the end. 

Results showed no significant differences in peak oxygen consumption or distance walked in six minutes between the patients taking sildenafil versus a placebo. 

At the beginning of the study, patients had the following measures: 

  • Median peak oxygen consumption of 11.7 ml/kg/min
  • Six-minute walk distance of 308 meters

At 24 weeks, patients taking a placebo or sildenafil had the following results: 

  • 0.20 decrease in median peak oxygen consumption for placebo group
  • 0.20 decrease in median peak oxygen consumption for sildenafil group
  • 15.0 meter increase in distance walked in six minutes for placebo group
  • 5.0 meter increase in distance walked in six minutes for sildenafil group

Results also showed no differences between groups in heart-related outcomes:

  • In the placebo group, 78 percent had negative health events and 16 percent had serious negative health events
  • In the sildenafil group, 80 percent had negative health events and 22 percent had serious negative health events

"This was a very complex study and criteria for study participants were very strict," Dr. Redfield said in a press release. "But it's most likely that we didn't see the results we hoped for because this type of heart failure just does not respond to this drug."

There were some limitations to the study. Patients were chosen based on already having a significantly reduced peak oxygen consumption but still being able to complete the six minute walking test. Results may not be generalizable to all patients with heart failure with preserved ejection fraction. 

More patients in the sildenafil group did not complete the study for personal or health reasons compared to the placebo group. However, that there were more drop outs in the sildenafil group was not considered significant.

This study, titled "Effect of Phosphodiesterase-5 Inhibition on Exercise Capacity and Clinical Status in Heart Failure With Preserved Ejection Fraction," was published in The Journal of the American Medical Association

It was funded by the National Heart, Lung, and Blood Institute, the National Center for Advancing Translation Sciences and the National Institute on Minority Health and Health Disparities. Pfizer pharmaceutical companies supplied sildenafil and placebos. Dr. Redfield and colleagues disclosed that all study authors receive fees and/or royalties from numerous pharmaceutical companies.

Reviewed by: 
Review Date: 
March 13, 2013
Last Updated:
March 14, 2013