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Viagra Has No Impact On Exercise Capacity For Those With Heart Failure

March 12, 2013
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redOrbit Staff & Wire Reports – Your Universe Online

Taking a popular type of erectile dysfunction drug will not help patients suffering from a specific type of heart failure from increasing the maximum amount of physical exertion that they can withstand, according to a new study published Monday in the online edition of JAMA.

The results of the (RELAX) study, determined that individuals who have heart failure with preserved ejection fraction (HFPEF) — a condition in which the lower chambers of a patient´s heart are unable to fully relax in between beats — did not experience significant improvements in either their exercise capacity or their clinical status as a result of taking sildenafil.

Sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor and erectile dysfunction drug commonly sold under the brand names Viagra and Revatio, had shown encouraging results in smaller-scale trials and in animal models, according to the Mayo Clinic. During the trial, researchers analyzed the medication´s effect on maximum exercise ability (based on peak oxygen consumption and the maximum distance a subject could walk in six minutes) and their heart function, but found no beneficial effects whatsoever.

The RELAX team, led by Dr. Margaret M. Redfield of the Mayo Clinic in Rochester, Minnesota, recruited 216 subjects during a randomized trial that took place at more than two dozen medical centers throughout North America from October 2008 through February 2012. Of those participants, 113 were given slidenafil and 103 were given a placebo — first in 20mg doses, three times per day for 12 weeks, and then in 60mg doses three times per day for 12 weeks.

After the entire 24 week period, the researchers determined that the median change in peak oxygen consumption had not significantly changed in either group of patients. Likewise, there was little significant improvement in the distance traveled during the six-minute walk over the course of the study, nor did either oxygen consumption or walk distance change much at the 12 week period between the treatment groups.

“Contrary to our hypothesis, long-term PDE-5 inhibition in HFPEF had no effect on maximal or submaximal exercise capacity, clinical status, quality of life, left ventricular remodeling, diastolic function parameters, or pulmonary artery systolic pressure,” Redfield and her colleagues wrote, according to a statement discussing the research.

“Renal function worsened more and NT-proBNP, endothelin-1, and uric acid levels increased more in patients treated with sildenafil,” they added.

“Furthermore, there were more (but not significantly more) patients in the sildenafil group who withdrew consent, died, or were too ill to perform the cardiopulmonary exercise test, and patients treated with sildenafil had a higher incidence of vascular adverse events. These findings do not suggest that therapy with the PDE-5 inhibitor sildenafil provides clinical benefit in the general HFPEF population,” they wrote.

The research, which was funded by a National Heart, Lung, and Blood Institute (NHLBI) grant, was also presented Monday during the American College of Cardiology’s 62nd Annual Scientific Session in San Francisco, California.

“It was surprising and a disappointment, and it was contradictory to our hypothesis. There are few options for help for these patients, and we hoped we would find something,” Dr. Redfield told the Mayo Clinic website. “This was a very complex study and criteria for study participants were very strict. 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.”


Source: redOrbit Staff & Wire Reports - Your Universe Online



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