Blood Flow to the Heart Varies during the Menstrual Cycle in Premenopausal Women with Heart Disease

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The summary below is from the full report titled "Menstrual Cyclic Variation of Myocardial Ischemia in Premenopausal Women with Variant Angina." It is in the 4 December 2001 issue of Annals of Internal Medicine (volume 135, pages 977-981). The authors are H Kawano, T Motoyama, M Ohgushi, K Kugiyama, H Ogawa, and H Yasue.

What is the problem and what is known about it so far?

In ischemic heart disease, blood vessels that supply the heart muscle become blocked. If blood flow to an area of heart muscle is blocked for a prolonged period, that area of heart muscle dies and is replaced by scar tissue, a condition commonly known as a heart attack. Blockages in blood flow that do not last long enough to cause the death of heart muscle can cause a type of chest pain known as angina. Before menopause, women are much less likely than men of similar age to have ischemic heart disease. People believe that in premenopausal women, high levels of ovarian hormones such as estrogen reduce the risk for ischemic heart disease. After menopause, these hormone levels decrease, and ischemic heart disease in women becomes more common. In trying to understand how hormones protect premenopausal women from heart disease, scientists have wondered if fluctuations in hormone levels during the menstrual cycle might play some role in heart disease.

Why did the researchers do this particular study?

To find out whether premenopausal women with heart disease are more likely to have ischemic episodes during certain times in the menstrual cycle as levels of hormones such as estrogen change.

Who was studied?

Ten premenopausal women, 33 to 51 years of age, with variant angina. Patients with variant angina get chest pain at rest and during low blood flow to the heart, as indicated on an electrocardiogram. Temporary narrowing of blood vessels due to spasms that narrow the blood vessel causes variant angina.

How was the study done?

By using a wireless device that transmitted data on electrical heart activity to a computer, the researchers collected information on patients' hearts during a complete menstrual cycle. Each patient had special tests to evaluate whether blood vessels dilated (widened) normally in response to increased blood flow. Estrogen and progesterone (another ovarian hormone) blood levels were measured every other day. The researchers then looked to see whether episodes of angina or changes in blood vessel dilation occurred while hormone levels increased or decreased during different times in the menstrual cycle.

What did the researchers find?

Ischemia of the heart muscle was most frequent around the time of menses, when estrogen levels were highest and the blood vessels were least likely to dilate in response to increased blood flow. Ischemia was least frequent in the middle of the menstrual cycle (around the time of ovulation), when estrogen levels were lowest and the blood vessels were most likely to dilate.

What were the limitations of the study?

This study included only 10 women with variant angina.

What are the implications of the study?

Among premenopausal women with variant angina, the risk for blockage in blood flow to the heart is lowest around the time of ovulation, when estrogen levels are high.