TUESDAY, Aug. 25, 2009 (HealthDay News) -- Women are more likely to die than men in the 30 days after a heart attack, but that doesn't mean gender is driving the trend, a new study finds.
Rather, "the difference can be attributed to well-known clinical and angiographic characteristics," such as age and the presence of other illnesses, said study lead author Dr. Jeffrey S. Berger, assistant professor of medicine and director of cardiovascular thrombosis at New York University.
He and his colleagues published the findings in the Aug. 26 issue of the Journal of the American Medical Association.
In the study, data on more than 136,000 people (28 percent of them women) from 11 major international studies of acute coronary syndrome showed no significant difference in male-female death rates after adjusting for clinical characteristics such as the amount of blockage in heart arteries and the presence of risk factors such as diabetes and high blood pressure, Berger said.
The analysis was done because "in many prior studies the data had been conflicting about how women do compared to men," he said. "Some would tell you women did worse, others that there were no differences. But the majority of these studies were small, done in single centers and for short periods of time. This study allowed a look at data spanning two decades that occurred all over the world."
The unadjusted data found a 9.6 percent death rate for women versus a 5.3 percent death rate for men in the 30 days after an acute coronary syndrome, which includes events such as heart attack or unstable angina. But that all changed once researchers began adjusting for various co-factors.
For example, the women in the studies were older and more likely to have high blood pressure, high blood cholesterol, diabetes and heart failure, the team noted. On the other hand, the men were more likely to be smokers, to have had a previous heart attack and to have had coronary artery bypass surgery.
When all risk factors were taken into account, "there was no sex-fixed mortality difference among those with acute coronary syndrome," Berger said.
One difference did emerge from the analysis, he said: "Not all acute coronary syndromes can be placed in a single category. There were significant differences based on severity of diagnosis."
The 30-day death rate was higher for women than men who suffered a STEMI myocardial infarction, the most severe form of heart attack. For less severe acute coronary syndromes, such as non-STEMI heart attacks and the acute chest pain called unstable angina, the 30-day death rate was significantly lower for women than men.
The study shows that what physicians call comorbidities -- other illnesses -- play a more important role in determining survival in women than in men, said Dr. Pamela S. Douglas, professor of medicine at Duke University, a member of the research team.
"What we find is that men have a higher mortality from the heart disease event while mortality in women depends more on the heart disease event plus other illnesses," Douglas said.
The finding doesn't mean that women with heart disease should be treated differently than men, but that physicians should remain aware of the importance of other illnesses in women, she said.
A second report in the same issue of the journal described a genetic variant that can limit the effectiveness of Plavix (clopidogrel), the clot-preventing drug that is commonly prescribed after artery-opening angioplasty.
A study led by physicians at the University of Maryland School of Medicine looked at the effect of a gene called CYP2C19 on the activity of platelets, the blood cells involved in clotting, among members of the Old Order Amish community. It found that those who carried one variant of the gene had a significantly lower response to Plavix therapy. Carriers of the gene variant had more than double the incidence of artery blockage or death in the year after angioplasty than noncarriers -- 20.9 percent compared to 10 percent.
The finding could lead to genetic typing to help guide Plavix therapy, the researchers wrote, but they added that "prospective randomized clinical trials will be necessary to determine the efficacy of CYP2C19 genotype-directed therapy in evidence-based clinical decision making."
Advice on heart disease in women is available from the American Heart Association.