Middle-age men are at much greater risk of a heart attack than women their age, but new research suggests the gap may be narrowing.

Some 2.5 percent of men ages 35 to 54 who responded to national health surveys in the late 1980s and early 1990s reported having had a heart attack, compared with 0.7 percent of women the same age. But in more recent surveys, in 1999 to 2004, the percentages for women rose to 1 percent while dropping to 2.2 percent for men.

The researchers acknowledged that the reported increases and decreases might have been due to chance. But the lead author of the study, published in the Oct. 26 issue of The Archives of Internal Medicine, said the changes reflected an “ominous trend.” And the article noted that over the same period, men’s scores on a scale that predicts heart disease risk improved slightly, while women’s scores worsened.

“I think everyone has been complacent that women are not at very high risk at this age,” said the lead author, Dr. Amytis Towfighi, an assistant professor of clinical neurology at the University of Southern California.

A 2007 study by the same authors found that women ages 45 to 54 were twice as likely as men to report having had a stroke, a finding that challenged conventional medical thinking that women were at lower risk for stroke in midlife than men.