MONDAY, May 19 (HealthDay News) -- Findings from two studies of men with diabetes add to the evidence that erectile dysfunction can be a powerful early warning sign for serious heart disease.

A Hong Kong study of 2,306 men with diabetes but no signs of heart disease found that those with erectile dysfunction at the start were 58 percent more likely to have a heart attack or other major cardiac problem over the next four years than those with adequate sexual function.

And Italian physicians who followed 291 men who had diabetes and early coronary heart disease for four years reported similar numbers -- those with erectile dysfunction were twice as likely as men without the problem to have major adverse events, including strokes.

There's a physical connection between male sexual failure and heart disease, involving the effect of diabetes on the nervous system and the blood vessels, said Dr. E. Scott Monrad, a professor of clinical medicine at Albert Einstein College of Medicine in New York City.

"Neuropathy would interfere with the neurogenic responses feeding into proper erection," Monrad said. "And obstruction of blood flow into the arteries reduces the pressure needed to achieve erection."

It has been known that erectile dysfunction shares many risk factors with coronary heart disease, such as high blood pressure, smoking and diabetes, according to Dr. Robert A. Kloner, a professor of medicine at the University of Southern California, who wrote an accompanying editorial on the reports, which were expected to be published in the May 27 issue of the Journal of the American College of Cardiology.

"What is new here is that erectile dysfunction remained a significant risk factor for developing heart disease after controlling for other cardiovascular risk factors," Kloner said in a statement.

"These reports add two things to what we already know," said Dr. R. Parker Ward, an associate professor of medicine at the University of Chicago, who led an earlier study linking erectile dysfunction with heart disease. "One is that they indicate the importance of erectile dysfunction in diabetic patients in terms of predicting future cardiovascular events. These studies suggest that the additional presence of erectile dysfunction places them at incrementally higher risk. Secondly, they show that even when considered in combination with traditional risk factors, erectile dysfunction offers incremental information about the risk of future cardiovascular events."

Cholesterol-reducing statins lowered the incidence of cardiac events by a third, the Italian researchers reported, and Viagra and other drugs for erectile dysfunction also appeared to lower the risk, although the reduction was not statistically significant, meaning that it could be due to chance.

"I strongly caution that we do not have enough evidence at this point that the drugs used for the treatment of erectile dysfunction have any beneficial effects on the development of heart disease," Ward said.

Physicians should be more forward in talking about sexual performance with men, Monrad said, since "this may prove to be a very sensitive marker for all the other things we measure for cardiovascular risk, an early and more sensitive measure if we could get over all our puritanic inhibitions."

Acknowledgment of erectile dysfunction "should prompt us to be even more aggressive about lifestyle change, in diet and exercise," Page said. "It potentially may suggest more aggressive treatment of risk factors such as high blood pressure and cholesterol."

More information

Learn about erectile dysfunction from the National Institute of Diabetes and Digestive and Kidney Diseases.

SOURCES: E. Scott Monrad, professor, clinical medicine, Albert Einstein College of Medicine, New York City; R. Parker Ward, M.D., associate professor, medicine, University of Chicago; May 27, 2008, Journal of the American College of Cardiology

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