Consider this scenario: You are a woman, admitted to a hospital with chest pain, and you undergo an X-ray imaging test called an angiogram to see if you have blockages in the arteries that supply blood to your heart. The test comes back clear, but you have been experiencing chest pain (angina), and another test - called a stress test - finds that portions of your heart are not receiving enough oxygen-rich blood. Both you and your physician know that something is wrong. Now what?
Scenarios such as this are common in women who might have what is called coronary microvascular disease. As the name implies, this is disease of the smaller (micro) blood vessels (vascular) that supply the heart with blood. While microvascular disease can be present in both men and women, it is more common in women, and it is one of the factors that can make heart disease in women harder to diagnose.
What Is Microvascular Disease?
Microvascular disease is a form of heart disease that differs from what you may be used to hearing about. The “classic” description of heart disease is of coronary artery disease, in which the major arteries that supply blood to the heart have one or more blockages. These blockages are formed from the build-up of deposits called plaques that contain cholesterol, fat, and other substances. These blockages may restrict blood flow, causing chest pain, or they may rupture, causing a blood clot to form at the rupture site and resulting in a heart attack.
Microvascular disease, on the other hand, refers to problems in the functioning of the smaller blood vessels of the heart that are 100–200 micrometers in diameter (a human hair is roughly 100 micrometers in diameter). In patients with microvascular disease, blood does not flow properly through these tiny blood vessels and the heart muscle may not have enough oxygen-rich blood, or oxygen may be cut off entirely to portions of the heart muscle.
What medical professionals now know about heart disease in women who do not have blockages in the coronary arteries is thanks to a National Heart, Lung, and Blood Institute study that was started in 1996. Research from this study, called the Women’s Ischemia Syndrome Evaluation (WISE), identified microvascular disease as one reason why some diagnostic tests may not show women’s heart disease.
Today, medical researchers are still working to understand microvascular disease and why it is more prevalent in women. One area that researchers are exploring is whether a drop of the hormone estrogen after menopause may play a role in the development of microvascular disease.
Why Coronary Microvascular Disease Matters
The effects of coronary microvascular disease on women’s health are substantial:
- Two to three million women in the United States have coronary microvascular disease, and there are 90,000 new cases each year.
- Even without evidence of blockages in the major heart arteries, women with ongoing chest pain have high five-year rates of a cardiovascular event such as a heart attack.
- This might be due to the presence of microvascular disease among these women. Further research studies are needed to understand this condition better.
- Nearly 60 percent of women who have chest pain or suspected reduced blood flow to the heart do not have blockages in the major coronary arteries, making their heart disease more challenging to diagnose for the treating heart specialist.
- Women with symptoms of heart disease but no blockages in the major arteries have a higher risk for depression and for a lower quality of life.
- Coronary microvascular disease may contribute to later development of coronary artery disease (blockages in the larger arteries that supply the heart with blood).