JUST BEING FEMALE HIKES DANGER IN HEART BYPASS.

Byline: Lauran Neergaard Associated Press 

Women are significantly more likely to die after heart bypass surgery than men, even if the men are just as old and sick when they go under the knife, says the author of a massive study released Wednesday.

Concluding for the first time that gender alone is a risk, not just that women are in worse health by the time they reach surgery, doctors now must figure out why.

``I don't know the answer, and I don't think anyone does,'' said study author Dr. Fred Edwards, a cardiothoracic surgeon at the University of Florida who is preparing to research just what kills a higher proportion of women so that perhaps the problem can be prevented.

The risk of death from bypass surgery within days after the operation is very low for both men and women, so the study shouldn't scare anyone away from what often is a lifesaving operation, stressed Dr. Sidney Smith, past president of the American Heart Association.

But the fact that women fare worse is a disturbing finding that must be explored quickly, Smith said. Bypass surgery may not be the only problem: Doctors are finding early signs that women also do more poorly after angioplasties, in which a balloon clears clogged arteries, he added.

``The next step is very much to understand whether the cause of death is different, because that could hold the clue as to why it's occurring,'' said Smith, cardiology chief at the University of North Carolina, Chapel Hill. ``Heart disease in women is an issue we need to take very seriously, and we really need to understand a lot more about it.''

Women's survival from heart bypasses has long been a thorny issue. Some studies indicate they do as well as men. Others conclude women are twice as likely to die because they're older and sicker than the average male patient by the time they have surgery.

While heart disease is the leading killer of U.S. women, they typically are stricken by it 10 years later than men are.

To clear the confusion, Edwards tapped the Society of Thoracic Surgeons' national database for the medical records of 344,000 patients - 97,000 of them women - who had heart bypasses between 1994 and 1996.

After the surgery, 4.5 percent of the women died, compared with 2.6 percent of the men, Edwards reported Wednesday in The Annals of Thoracic Surgery.

Overall, the women were older and had a higher incidence of diabetes, high blood pressure and other complicating illnesses. They were less likely than the men to have undergone bypass surgery on an elective basis - by choice when less invasive treatment was available.

But this study differed from previous research because the database was big enough so that Edwards could test whether any of those risks explained women's vulnerability. When he compared men and women with identical risk factors, there was a higher death rate among the women in each category - sometimes twice as high.

Take one of the least risky groups: people younger than 70 having their first bypass as elective surgery. Edwards found that almost 2.2 percent of the women died vs. 1 percent of the men. In cases where a first bypass was elective surgery for people older than 70, about 3 percent of men and 4 percent of women died.

When a first bypass was required surgery for those older than 70, it was fatal for about 4.4 percent of the women vs. 2.4 percent of the men. In a riskier situation, when an elderly patient required a repeat bypass, 16 percent of women died vs. 14 percent of men.

Even the strength of youth didn't help: 2.4 percent of women under 50 died vs. 1.1 percent of men, the study found.

Smith says the study indicates women should understand the risks of heart disease sooner, so they can take steps to prevent ever needing bypass surgery. The American Heart Association is starting a campaign to do just that.

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Chart: Bypass surgery