Microvascular disease in women - a real danger often overlooked
Puzzling differences have emerged between men and women with heart disease, making it plain that past studies, mostly on men, do not always apply to women. Researchers have come to realize that to improve diagnosis and treatment for women, they must sort out the differences.
"Every time we turn around, we find more gender differences, so it's important to study," said Dr. C. Noel Bairey Merz, a cardiologist at Cedars-Sinai Medical Center in Los Angeles.
Among the differences:
- Women with chest pain and other heart symptoms are more likely than men to have clear coronary arteries when tests are performed, a surprising result that suggests there may be another cause for their problems.
- When women do have blocked coronary arteries, they tend to be older than men with similar blockages and to have worse symptoms, including more chest pain and disability. And they are more likely than men to develop heart failure (most likely due to age of onset), a weakening of the heart muscle that can be debilitating and ultimately fatal.
- When women have bypass surgery or balloon procedures for coronary blockages, they are less likely than men to have successful outcomes, and they are more likely to suffer from bad side effects.
- Blood tests that pick up signs of heart damage in men do not always work in women.
For symptomatic women without clear atherosclerosis, the underlying problem may be a disorder called microvascular disease, a narrowing or stiffening of the smaller arteries that nourish the heart, vessels too tiny to show up on an angiogram. In microvascular disease, the small vessels lose their ability to dilate and increase blood flow to the heart. The cause does not seem to be fatty deposits such as the ones that can block the coronary arteries. Rather, the muscles in the arterioles thicken, and the walls may stiffen and begin to close in. The result is ischemia, lack of blood flow. Over time, it increases the risk of heart failure and heart attacks.
Three million women in the United States may have microvascular heart disease. Research, begun in 1996, included 936 women who had angiograms because of symptoms such as chest pain. The angiograms found that only a third had blockages in their coronary arteries. In men with similar symptoms, three-quarters or more would have had severe blockages.
Another third of the women had no blockages but did have low blood flow to the heart, most likely a result of microvascular disease. Among those with the disorder, the rate of deaths or heart attacks was 10 percent after four years, much higher than would be expected for women with normal angiograms.
The findings call for a major shift in the treatment of women with chest pain or other symptoms and normal angiograms, said Dr. George Sopko of the National Heart, Lung and Blood Institute. "Instead of tossing aside the angiogram and saying you're OK, let's make sure we are not missing anything."
High cholesterol and blood pressure are almost certainly among the causes of microvascular disease, and it is essential to treat them aggressively in women with chest pain and to urge women to exercise, avoid smoking and lose weight.
Read more on the WISE study and microvascular disease