Men with congestive heart failure and erectile dysfunction can safely use sildenafil (Viagra) to improve sexual function, according to a Brazilian study reported in the August 6th rapid access issue of Circulation.

"Heart failure patients may become noncompliant with their congestive heart failure treatment if they feel it causes or aggravates their erectile dysfunction," says lead author Edimar Alcides Bocchi, M.D. "However, our study suggests that treating the erectile dysfunction may make patients more motivated to take their medicines."

Sildenafil caused no harmful effects and improved exercise performance during treadmill exercise tests in 23 men with congestive heart failure (average age 50 years) and a history of erectile dysfunction, says Bocchi.

Sildenafil blocks the activity of the enzyme phosphodiesterase type 5, which is active in multiple tissues and cells. The effects of enzyme inhibition include increased production of nitric oxide, which is associated with improved function of the cardiovascular system.

Most of the men had moderate or severe heart failure, and each had been referred for treatment of erectile dysfunction. On separate days, the men underwent two exercise treadmill tests, which consisted of a six-minute walk and a maximal exercise test. About an hour before the first test, the men received either 50 milligrams of sildenafil or a placebo. On the second day, the men received the opposite treatment (sildenafil or placebo) before exercise.

Those treated with sildenafil had significantly lower blood pressure and heart rate --- as well as improvement in measures of oxygen consumption and carbon dioxide production --- than those on placebo. Total exercise time also increased significantly. A separate evaluation showed that treatment with sildenafil was associated with higher scores on a questionnaire related to erectile function.

"Frequently, congestive heart failure patients, and especially their wives, are afraid their spouses will have heart failure symptoms or even death during sexual activity," says Bocchi. "Our study shows that the benefits may outweigh harmful side effects of treatment with sildenafil. The successful treatment of erectile dysfunction in congestive heart failure could not only improve sexual relationships but overall quality and success of congestive heart failure treatment."