By Amy Norton

NEW YORK (Reuters Health) - It is widely believed that elevated estrogen levels protect women from heart disease before menopause. Now a small study suggests that when younger women do develop heart disease, they may be at greater risk for a heart attack during the low-estrogen point in their menstrual cycles.

In relatively young women with diseased heart arteries, blood flow to the heart appears to be more easily obstructed in the week during or right after their periods, UK researchers report. They used exercise treadmill tests to measure heart activity in nine heart disease patients over the course of a month. The women were all in their late 30s or early 40s.

Signs of decreased blood flow to the heart showed up more rapidly when the women's estrogen levels were lowest, according to the report. A reduction in blood flow can trigger chest pain and possibly lead to a heart attack.

Dr. Guy W. Lloyd and his colleagues at St. Thomas' Hospital in London report the findings in the journal Heart.

Estrogen helps increase blood flow in the arteries supplying the heart, Lloyd told Reuters Health. Some animal research, he said, has suggested that low estrogen levels may promote hardening of heart arteries.

In the case of young women with suspected heart disease, doctors may need to consider where they are in their menstrual cycles when administering exercise stress tests, according to Lloyd. Such tests, he said, may miss heart disease if they are given when a woman's estrogen is at its peak.

Although this small study allows no ``sweeping conclusions,'' Lloyd noted, it suggests hormone therapy may help treat chest pain in young women with heart disease.

SOURCE: Heart 2000;84:189-192.

(From Yahoo)