One study that followed 1,400 men for a decade found that while only 2 percent of those in their 40s had ED, almost half of that subgroup went on to develop heart disease. In contrast, it developed in only 1 percent of fortysomething men without ED.
Among men in their 50s, 6 percent had ED, of whom 27 percent subsequently developed heart disease. Only 5 percent without ED developed it.
This link may be explained by the "artery size hypothesis." It assumes that the penile artery, with a diameter of about seven one-hundredths of an inch, is less able to tolerate fatty plaque buildup than a vital heart artery that is twice as wide. Therefore, a man may have signs of reduced blood flow to the penis - namely, ED - before he has any cardiac symptoms.
Primary-care doctors and even cardiologists need to pay more attention to this link, Seftel said.
"Not everyone accepts that ED is a prognostic indicator of cardiovascular disease, especially in younger men," he said. "In the mainstream cardiac literature, ED has never been a big issue."
For sufferers, it may be a big but awkward issue.
"Many men don't want to discuss ED, whether because of embarrassment, fear, or male ego," Seftel said.
Heart disease risk can be cut by weight loss, exercise, cholesterol-lowering drugs, and more. Such healthy behavior may not fix ED (at least, not as effectively as Viagra). But it could still give men a boost in the boudoir, Seftel said, "because they'll feel better."
- Marie McCullough