More U.S. women are developing a type of artery disease that raises the risk of death from heart disease and stroke, researchers said on Sunday.

Researchers used U.S. government health surveys to track rates of peripheral artery disease, known as PAD, in people age 40 or older with no outward symptoms of cardiovascular illness. PAD is a circulatory condition in which narrowed arteries cut blood flow to the limbs.

Rates among women rose from 4.1 percent in a nationally representative 1999-2000 survey to 6.3 percent in a 2003-2004 survey. Among men, the rates fell from 3.3 percent to 2.8 percent during the same period, the researchers said.

“In those women with PAD, the increasing prevalence was associated with an increase in the prevalence of obesity,” Dr. Andrew Sumner, medical director of the Heart Station and Cardiac Prevention at Lehigh Valley Hospital in Allentown, Pennsylvania, who led the study, said in an interview.

“It’s a large number of people who are at risk and don’t know it,” Sumner added.

PAD develops when fatty deposits accumulate in the inner linings of artery walls, cutting blood flow and oxygen to the legs, feet, arms and other parts of the body. It raises the risk of developing and dying from heart disease and stroke.

PAD also can be a signal of widespread accumulation of fatty deposits in the arteries, called atherosclerosis, which also may be limiting blood flow to the heart and brain.

The same processes that contribute to the development of atherosclerosis in, for example, the legs also contribute to the development of atherosclerosis in the arteries in the heart and neck that go to the brain, the researchers said.

The findings were presented at an American Heart Association meeting in Orlando.

“Risk of cardiovascular disease is increasing even as mortality due to cardiovascular disease is falling,” said Dr. Jonathan Halperin of Mount Sinai Medical Center in New York, a spokesman for the association.

“We’re getting better with the treatments, but we’re not as effective as we need to be in the area of prevention,” Halperin added.

Because of the increases among women, overall rates rose from 3.7 percent in the 1999-2000 survey to 4.6 percent in the 2003-04 survey, the study found.

The study looked at 5,376 survey participants age 40 and older with no previous history of cardiovascular disease. The researchers identified PAD in these people by examining the ratio of the blood pressure in the arms and legs - known as the ankle-brachial index - to see if it fit the definition for PAD.

“PAD is a marker of sub-clinical coronary artery disease - sort of silent coronary artery disease,” Sumner said.

The condition was most common among those age 70 and older, they found.

The researchers said doctors should be looking for PAD in people with no overt symptoms, and noted that rates are likely to continue to increase as the U.S. population ages.