coronary microvascular disease
Coronary microvascular disease. Figure A: the small coronary artery network (microvasculature), containing a normal artery and an artery with coronary MVD. Figure B: a large coronary artery with plaque buildup.
Coronary MVD is a new concept. It's different from traditional coronary artery disease (CAD). In CAD, plaque builds up in the heart's large arteries. This buildup can lead to blockages that limit or prevent oxygen-rich blood from reaching the heart muscle.
In coronary MVD, however, the heart's smallest arteries are affected. Plaque doesn't always create blockages as it does in CAD. For this reason, coronary MVD also is called non-obstructive CAD.
No one knows whether coronary MVD is the same as MVD linked to other diseases, such as diabetes.
However, death rates haven't improved as much in women as they have in men. Heart disease in men and women may differ. Many researchers think that a drop in estrogen levels in women at menopause combined with traditional risk factors for heart disease causes coronary MVD. Therefore, coronary MVD is being studied as a possible cause of heart disease in women.
Diagnosing coronary MVD has been a challenge for doctors. Most of the research on heart disease has been done on men.
Standard tests used to diagnose heart disease have been useful in finding blockages in the coronary arteries. However, these same tests used in women with symptoms of heart disease – such as chest pain – often show that they have "clear" arteries.
This is because standard tests for CAD don't always detect coronary MVD in women. Standard tests look for blockages that affect blood flow in the large coronary arteries. However, these tests can't detect plaque that forms, scatters, or builds up in the smallest coronary arteries.
The standard tests also can't detect when the arteries spasm (tighten) or when the walls of the arteries are damaged or diseased.
As a result, women are often thought to be at low risk for heart disease.
Coronary MVD is thought to affect up to 3 million women with heart disease in the United States alone.
Most of the information known about coronary MVD comes from the National Heart, Lung, and Blood Institute's WISE study (Women's Ischemia Syndrome Evaluation). The WISE study began in 1996. Its goal was to learn more about how heart disease develops in women.
The role of hormones in heart disease has been studied, as well as how to improve the diagnosis of coronary MVD. Further studies are under way to learn more about the disease, how to treat it, and its outcomes.
What causes coronary microvascular disease?
The same cluster of risk factors that causes atherosclerosis may cause coronary microvascular disease (MVD) in women. Atherosclerosis is when the arteries harden and narrow due to the buildup plaque on their inner walls. It's one of the key causes of heart disease.
Risk factors for atherosclerosis include:
- In men, the risk increases after age 45.
- In women, the risk increases after age 55.
Coronary MVD may be linked to low estrogen levels occurring before or after menopause. It also may be linked to anemia or conditions that affect blood clotting. Anemia is thought to slow the growth of cells needed to repair damaged blood vessels.
Who is at risk for coronary microvascular disease?
Women at high risk for coronary microvascular disease (MVD) often have multiple risk factors for atherosclerosis, as listed above.
Women may be at risk for coronary MVD if they have low levels of estrogen at any point in their adult lives. (This refers to the estrogen that the ovaries produce, not the estrogen used in hormone replacement therapy.)
After menopause, women tend to have more of the traditional risk factors for atherosclerosis, putting them at higher risk for coronary MVD. Lower than normal estrogen levels in women before menopause also can put younger women at higher risk for coronary MVD. One cause of low estrogen levels in younger women is mental stress. Another is a problem with the function of the ovaries. Women who have high blood pressure before menopause, especially high systolic blood pressure, are at higher risk for coronary MVD. (Systolic blood pressure is the top or first number of a blood pressure measurement).
Women with heart disease have an increased risk for a worse outcome, such as a heart attack, if they also have anemia. Anemia is thought to slow the growth of cells needed to repair damaged blood vessels.
What are the signs and symptoms of coronary microvascular disease?
Signs and symptoms of coronary microvascular disease (MVD) often differ from signs and symptoms of traditional coronary artery disease (CAD).
Many women with coronary MVD have angina (chest pain), but it may or may not be the "typical" chest pain seen in CAD. Typical signs and symptoms of CAD include angina, feeling pressure or squeezing in the chest, shortness of breath, heavy sweating, and arm or shoulder pain.
These signs and symptoms often first appear while a person is being physically active – such as while jogging, walking on a treadmill, or going up stairs. Typical angina is more frequent in women older than 65.
Other signs and symptoms of coronary MVD in women are shortness of breath, sleep problems, fatigue (tiredness), and lack of energy.
In women, coronary MVD symptoms are often first noticed during routine daily activities (such as shopping, cooking, cleaning, and going to work) and during times of mental stress. It's less likely that women will notice these symptoms during physical activity (such as jogging or walking fast).
How is coronary microvascular disease diagnosed?
First, your doctor will take your medical history and do a physical exam to diagnose coronary microvascular disease (MVD). The doctor will check to see if you have any risk factors for heart disease. You will be weighed to check for obesity, and your cholesterol will be tested. You also will be tested for metabolic syndrome and diabetes.
Your doctor may ask you to describe any chest pain, including when it started and how it changed during physical activity or periods of stress.
Other symptoms such as fatigue (tiredness), lack of energy, and shortness of breath will be noted. Women will be asked about their menopausal status. Your doctor may order blood tests, including a test for anemia.
Doctors who diagnose and treat coronary MVD are most often specialists in cardiology (heart disease), family medicine, and internal medicine.
The risk factors for traditional coronary artery disease (CAD) and coronary MVD are often the same. Therefore, your doctor will use tests to help show if you have traditional CAD. These tests may include:
This damage occurs when plaque forms in arteries, when the arteries spasm (tighten), or when the walls of the arteries are damaged or diseased.
In coronary MVD, plaque can scatter, spread out evenly, or build up into blockages in the tiny coronary arteries. Plaque narrows the coronary arteries and reduces blood flow to the heart muscle.
Spasms of the small coronary arteries prevent enough oxygen-rich blood from moving through the arteries.
Changes in the arteries' cells and the surrounding muscle tissues may, over time, damage the arteries' walls.
The standard tests for CAD can't detect these types of problems in the tiny coronary arteries. Therefore, standard tests may show that a woman doesn't have heart disease, even if she does. (Fifty percent of women who have the standard CAD tests show normal coronary arteries compared to 17 percent of men.)
If test results show you don't have CAD, you can still be diagnosed with coronary MVD if evidence shows that not enough oxygen is reaching the small arteries in your heart.
Since symptoms of coronary MVD often first appear during routine daily tasks, you may be asked to fill out a questionnaire called the Duke Activity Status Index (DASI). The questionnaire will ask you how well you're able to do daily activities such as shopping, cooking, and going to work. The results of this survey will help doctors decide on the kind of stress test you should have. It will also give them some information about how well the blood is flowing through your coronary arteries.
Research continues to improve ways to detect and diagnose heart disease caused by coronary MVD.
How is coronary microvascular disease treated?
Women who have coronary microvascular disease (MVD) are mainly treated to control their risk factors for heart disease and symptoms. Treatments may include medicines such as:
Women diagnosed with coronary MVD who also have anemia may benefit from treatment for that condition, because anemia slows repair of damaged blood vessels.
Women who are diagnosed and treated for coronary MVD should be checked regularly by their doctors.
Research is ongoing to find the best treatments for coronary MVD.
How can coronary vascular disease be prevented?
No specific studies have been done on how to prevent coronary microvascular disease (MVD). It's not yet known how or in what way preventing the condition differs from preventing coronary artery disease (CAD). Coronary MVD affects the small coronary arteries in the heart, while CAD affects the large coronary arteries.
You can prevent or delay CAD by taking action to reduce your risk factors. You can't control some risk factors such as age and family history of heart disease. However, you can take steps to lower or control other risk factors such as high blood pressure, overweight and obesity, high blood cholesterol, diabetes, and smoking.
Regardless of your age or family history, you can lower your risk of heart disease with lifestyle changes. These changes include:
It's also important to learn more about heart disease and the kinds of habits and conditions that can increase your risk.
- Lipid profile. This test measures total cholesterol, LDL cholesterol ("bad" cholesterol), HDL cholesterol ("good" cholesterol), and triglycerides (another form of fat in the blood).
- Blood pressure.
- Fasting blood glucose. This test is for diabetes.