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Although the research is controversial, some evidence suggests that bursting plaques may not be as important for women as for men. Doctors have long puzzled over the fact that some of their female heart-attack patients--usually those who have not yet gone through menopause--show few signs of artery-clogging plaques on their angiograms. Perhaps their blockages don't occur in the major arteries of the heart, where angiograms are performed and bypasses are most effective. Perhaps blood flow is restricted in the smaller vessels that branch off the coronary arteries. And perhaps the problem isn't plaques at all but the fact that these smaller blood vessels are somehow more prone to spasm, snapping shut at the slightest stress or trigger, cutting off the flow of blood to parts of the heart.
Indirect evidence of just such a possibility was published by researchers at the University of Wisconsin--Madison in the Journal of the American Medical Association last year. By looking at high-resolution images of the blood vessels of the retina--one of the few places where doctors can easily examine the body's vascular system without an invasive test--they found that women with the narrowest arteries were most likely to have heart disease but that the size of the blood vessels made no difference in men.
The small-vessel theory has some flaws. For example, certain drugs called vasodilators, which act to keep blood vessels open, do not appear to prevent heart attacks in women, as you would expect if spasms were the primary problem. Still, there are enough other ways in which small vessels may be involved that researchers aren't yet ready to dismiss their role.
It's also possible that plaques--whether in the main coronary arteries or the smaller vessels--behave differently in women. Unlike men, women tend to distribute all the "garbage" associated with atherosclerosis--such as saturated fat and oxidized waste products--more evenly throughout the arteries. The process is analogous to the way men and women gain weight, says Dr. Noel Bairey Merz of the Cedars-Sinai Medical Center in Los Angeles. "When men get fat, it all goes to their belly," she says. "When women get fat, they tend to get fat all over--fat at the ankles, fat in the sides, fat in the upper arms." So although women generally avoid the monster plaques that kill so many men in early middle age, the continuing buildup in women's arteries may come back to haunt them in their 50s, 60s, 70s and 80s.
Plaques are another reason for women to throw away their cigarettes, as smoking seems to turn stable plaques into unstable ones. "If you look at the plaque [of a woman] under a microscope, it doesn't appear to be the kind of plaque that can become unstable and rupture," says Dr. Robert Bonow of the American Heart Association. "But the surface has become eroded, exposing the material beneath the surface to the blood, which causes blood clots. And it turns out that the women who have this plaque erosion tend to be women who smoked." Those clots can travel through the bloodstream, wreaking havoc in the heart or the brain.