BOSTON -- Even with state-of-the-art medical treatment, including a key "clot-busting" drug, women are twice as likely to die in the year after a major heart attack as men given the same treatment, a leading cardiologist has told a Senate panel.
While other studies have shown that bias on the part of doctors can result in less aggressive cardiac care for women than men, the new data, expected to be published soon, suggest that misunderstood biological factors may also play a role in women's poorer heart attack survival.
In the new research, both male and female heart attack victims got the best care available and, what is important, both got it within four hours of a heart attack. Yet women still fared far worse in terms of both mortality and subsequent heart attacks, and researchers were at a loss to explain why.
Part of the problem, they said, may be that women react differently from men to some commonly used heart drugs, some of which have been studied primarily in men.
The new data are actually a reanalysis by sex of data from a three-year research project involving more than 3,300 male and female heart attack patients, said Dr. Eugene Braunwald, chairman of the department of medicine at Brigham and Women's Hospital in Boston.
The reanalysis by sex, Dr. Braunwald said, was prompted by growing concern among cardiologists that women's heart disease is much less studied and less understood than men's.
Dr. Braunwald, along with specialists in ovarian cancer, lupus, osteoporosis and other diseases, spoke yesterday at a forum on inequities on women's health care led by Sen. Edward M. Kennedy, D-Mass. Mr. Kennedy said he would continue to urge Congress to fund research on women's health.
For several years, Dr. Braunwald said, doctors have known that women who have heart attacks are about twice as likely to die of them as men, but doctors had hoped this was because women delay longer than men in getting to the hospital, tend to be older at the time of a first heart attack and, as two major studies last year showed, often get less aggressive care for heart disease than men.
The reanalysis makes it clear, however, that even when men and women get identical and extensive care within four hours of a heart attack, including tissue plasminogen activator (known as TPA) and a battery of tests and other treatments, women fare worse than men.
In fact, the reanalysis shows that six weeks after heart attack treatment with TPA, 9 percent of female heart attack victims had died, compared with only 4 percent of the men, said Dr. Braunwald, a co-principal investigator along with Dr. Richard Becker, director of coronary care at the University of Massachusetts Medical Center.
Even one year later, said Dr. Braunwald, women died at twice the rate of men, 12 percent compared with 6 percent, though Dr. Braunwald emphasized that the "good news" is that for both sexes, this is half the death rate that would be expected without clot-busting drugs.
Other studies in Europe, Dr. Becker said, show that this gender disparity persists with other clot-busting drugs, most notably streptokinase, the main alternative to TPA.
Dr. Braunwald said doctors are puzzled by the results. Perhaps women get less benefit than men from clot-busting drugs, he said, because women have more fibrinogen, a clotting substance, in their blood, as other studies have shown.