Medical researchers have noted that younger women who suffer heart attacks are more likely to die in the hospital than their male counterparts. Now there’s evidence that younger women are also about three times more likely than men to die in the hospital following a procedure often performed to prevent heart attacks: bypass surgery.

That’s the conclusion reached by a team of Emory researchers whose findings will be published in the March issue of Circulation: Journal of the American Heart Association. The research findings are available now in the online version of Circulation, located at http://circ.ahajournals.org/.

“The difference between women and men is particularly striking in those younger than age 60,” said lead author Viola Vaccarino, associate professor of cardiology in the School of Medicine and associate professor of epidemiology in the Rollins School of Public Health.

The Emory scientists reviewed records of 51,187 patients—15,178 (29.7 percent) of them women—in the National Cardiovascular Network database who underwent bypass surgery at 23 medical centers between October 1993 and December 1999. The patients were divided into five age groups: younger than 50, 50–59, 60–69, 70–79 and 80 and older. In patients aged 50–59, women had double the risk of in-hospital death following bypass surgery as men. In patients younger than 50, mortality rates were three times higher among women than men.

“We initially thought the higher prevalence of coexisting conditions might be responsible for the higher rates of in-hospital complications and death in younger women,” Vaccarino said. “For example, diabetes and renal insufficiency were both much more common in women than in men in this age group. However, we concluded that additional health problems and heart disease risk factors accounted for less than 30 percent of the mortality differences between young women and men undergoing bypass.

“In fact,” she continued, “women in all age groups had less severe coronary atherosclerosis, their hearts had better pumping strength and fewer had already suffered heart attacks than their male counterparts. So far, we’ve been unable to determine what was responsible for the mortality difference between young men and women in this study. Clearly, further investigation is needed to find out what factor or factors are responsible.”

Coronary artery bypass surgery, which reroutes blood around clogged arteries to improve the supply of blood and oxygen to the heart, is performed about 571,000 times annually in the United States. Approximately 182,000 women undergo bypass surgery each year.