Mayo Clinic study shows no adverse heart effect for sildenafil (Viagra®)

ROCHESTER, MINN. -- Using ultrasound images of the heart during exercise, Mayo Clinic researchers have shown for the first time that sildenafil citrate (Viagra®) does not adversely affect blood flow to the heart in men with stable coronary artery disease who are not taking nitrates. The findings appear in this week’s Journal of the American Medical Association (JAMA).

The study, which was funded by the American Heart Association and by Mayo Clinic, involved administering two exercise echocardiograms to 105 men with known or probable coronary artery disease. The testing was done on a reclining exercise bicycle to allow continuous ultrasound imaging of the heart, and it was combined with an electrocardiogram (ECG) to monitor the heart’s electrical activity. One stress test was given an hour after taking sildenafil and the other after taking a sugar pill. Both the patients and the researchers were blinded to when they were testing the drug and when they were using the placebo.

"In these patients, sildenafil had no adverse effect on symptoms or how long the men were able to exercise," says Patricia Pellikka, M.D., a Mayo Clinic cardiologist and the lead investigator for the study. "We expected and saw that echocardiograms of these heart disease patients would show evidence of inadequate blood supply to the heart muscle during exercise. The key finding, however, is that the problem was not made worse by sildenafil."

Because previous studies have shown that nitrates combined with sildenafil can lead to serious decreases in coronary blood flow and blood pressure, the men were required to stop taking nitrates at least three days before participating in this study.

Dr. Pellikka says the study has important implications for patients and physicians. "While 105 patients is not a large enough number to absolutely predict cardiac events, especially among particular subgroups, the overall message is that sildenafil does not increase oxygen deprivation to the heart, says Dr. Pellikka. As a cardiologist, these findings increase my confidence in prescribing sildenafil, which can have important quality of life benefits for patients. For men with coronary artery disease who are not taking nitrates, the study should provide reassurance that sildenafil is not likely to increase their heart attack risks."