What Is Coronary Microvascular Disease?
Coronary microvascular disease (MVD) affects the
heart's smallest coronary arteries. Coronary MVD occurs in the heart's tiny
arteries when:
- Plaque (plak) forms in the arteries. Plaque is
made up of fat, cholesterol (ko-LES-ter-ol), calcium, and other substances
found in the blood. It narrows the coronary arteries and reduces blood flow to
the heart muscle. As a result, the heart doesn't get the oxygen it needs. This
is known as ischemic (is-KE-mik) heart disease, or heart disease. In coronary
MVD, plaque can scatter, spread out evenly, or build up into blockages in the
tiny coronary arteries.
- The arteries spasm (tighten). Spasms of the small
coronary arteries also can prevent enough oxygen-rich blood from moving through
the arteries. This too can cause ischemic heart disease.
- The walls of the arteries are damaged or
diseased. Changes in the arteries' cells and the surrounding muscle tissues
may, over time, damage the arteries' walls.
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 nonobstructive CAD.
No one knows whether coronary MVD is the same as MVD
linked to other diseases, such as
diabetes.
Overview
Death rates from heart disease have dropped quite a
bit in the last 30 years. This is due to improved treatments for conditions
such as blocked coronary arteries,
heart
attack, and
heart
failure.
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 diseasesuch as chest
painoften 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.
Outlook
Coronary MVD is thought to affect up to 3 million
women with heart disease in the United States.
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
(ATH-er-o-skler-O-sis) 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:
- Unhealthy
cholesterol levels. This includes high LDL cholesterol (sometimes called
bad cholesterol), low HDL cholesterol (sometimes called good cholesterol), and
high triglyerides (another type of fat in the blood).
- High
blood pressure. Blood pressure is considered high if it stays at or above
140/90 mmHg over a period of time.
- Smoking. This can damage and tighten blood
vessels, increase cholesterol levels, and increase blood pressure. Smoking also
doesn't allow enough oxygen to reach the body's tissues.
- Insulin resistance. This condition occurs when
the body can't use its own insulin properly. Insulin is a hormone that helps
the body convert food to energy.
- Diabetes. This is a disease in which the body's blood sugar
level is high because the body doesn't make enough insulin or doesn't use its
insulin properly.
- Overweight
or obesity. Overweight is having extra body weight from muscle, bone, fat,
and/or water. Obesity is having a high amount of extra body fat.
- Lack of physical activity. Lack of activity can
worsen other risk factors for atherosclerosis.
- Age. As you get older, your risk for
atherosclerosis increases. Genetic or lifestyle factors cause plaque to build
in arteries as you age. By the time you are middle-aged or older, enough plaque
has built up to cause signs or symptoms.
- In men, the risk increases after age 45.
- In women, the risk increases after age 55.
- Family history of early heart disease. Your risk
for atherosclerosis increases if your father or a brother was diagnosed with
heart disease before 55 years of age, or if your mother or a sister was
diagnosed with heart disease before 65 years of age.
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.
It's not yet known whether coronary MVD is the same
as MVD linked to other diseases, such as diabetes.
Who Is At Risk for Coronary Microvascular Disease?
Women at high risk for coronary microvascular
disease (MVD) often have multiple risk factors for
atherosclerosis.
(See "What Causes Coronary Microvascular
Disease?" for a detailed list of these risk factors.)
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 activesuch 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.
Specialists Involved
Doctors who diagnose and treat coronary MVD are most
often specialists in cardiology (heart disease), family medicine, and internal
medicine.
Diagnostic Tests
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:
- Coronary
angiography (an-jee-OG-ra-fee). This test is a special x-ray exam of the
heart and blood vessels. It shows plaque buildup in the large coronary
arteries. This test is often done during a
heart
attack to help locate blockages.
- A
stress
test. This test provides your doctor with information about blood flow
through the coronary arteries to your heart muscle during physical stress.
During stress testing, you exercise (or are given medicine if you're unable to
exercise) to make your heart work hard and beat fast while heart tests, such as
nuclear
heart scanning and
echocardiography,
are performed. If coronary angiography doesn't show plaque buildup in the large
coronary arteries, a stress test may still show abnormal blood flow. This may
be a sign of coronary MVD.
- A magnetic resonance imaging (MRI) cardiac stress
test. This test is being used more widely to evaluate women with chest
pain.
Unfortunately, standard tests for CAD don't always
detect heart disease in women. Standard tests look for blockages that affect
blood flow in the large coronary arteries. However, the
WISE Study showed
that, in women, damage to the heart's smallest coronary arteries may affect
blood flow.
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:
- Statins to improve cholesterol levels
- Angiotensin-converting enzyme (ACE) inhibitors
and beta blockers to lower blood pressure and decrease the heart's workload
- Aspirin to help prevent blood clots or control
inflammation
- Nitroglycerin to relax blood vessels, improve
blood flow to the heart muscle, and treat chest pain (if this medicine has
helped the patient with past symptoms)
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 Microvascular 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:
- Following a heart healthy eating plan. Two heart
healthy eating plans are the
Dietary
Approaches to Stop Hypertension (DASH) diet (for people who have high blood
pressure) and the
Therapeutic
Lifestyle Changes (TLC) diet (for people who have high blood
cholesterol).
- Increasing your physical activity. Aim for at
least 30 minutes of moderate-intensity activity on most, and preferably, all
days of the week. If you're trying to manage your weight and keep from gaining
weight, try to get 60 minutes of moderate-to-vigorous-intensity physical
activity on most days of the week.
- Quitting smoking, if you smoke.
- Losing
weight, if you're overweight.
- Reducing your stress level.
It's also important to learn more about heart
disease and the kinds of habits and conditions that can increase your risk.
- Talk to your doctor about your risk factors for
heart disease and how to control them.
- Know your numbersask your doctor for these
three tests and have the results explained to you.
- Lipid profile. This test measures total
cholesterol, LDL cholesterol (sometimes called bad cholesterol), HDL
cholesterol (sometimes called good cholesterol), and triglycerides (another
form of fat in the blood).
- Blood pressure.
- Fasting blood glucose. This test is for
diabetes.
- Know your body mass index (BMI) and waist
circumference. BMI is an estimate of body fat that's calculated from your
height and weight. You can use the National Heart, Lung, and Blood Institute's
online BMI calculator to figure
out your BMI. To measure your waistline, stand and place a tape measure around
your middle, just above your hipbones. Measure your waist just after you
breathe out.
- Take medicines for lowering cholesterol and blood
pressure and controlling diabetes as your doctor prescribes.
Living With Coronary Microvascular Disease
If you have coronary microvascular disease (MVD),
you can take steps to stop it from getting worse. These steps are the same as
those used to prevent coronary MVD. See "How Can
Coronary Microvascular Disease Be Prevented" for more information.
If you have coronary MVD, see your doctor regularly
to make sure the disease isn't getting worse and to keep track of your
cholesterol, blood pressure, and blood sugar levels. A cholesterol blood test
will show your levels of LDL cholesterol, HDL cholesterol, and triglycerides.
It will show whether you need more treatment. You may need to see a
cardiologist in addition to your primary care doctor.
Talk to your doctor about how often you should
schedule office visits or blood tests. Between those visits, call your doctor
if you develop any new symptoms or your symptoms become more severe. You
should:
- Know your symptoms and how and when to seek
medical help.
- Be able to describe the usual pattern of your
symptoms.
- Know which medicines you take and when and how to
take them.
- Know how to control your symptoms, including
angina.
- Know the limits of your physical activity.
- Learn ways to avoid or cope with stress.
MVD, like traditional
coronary
artery disease, increases your chance for a
heart
attack. Signs and symptoms of a heart attack include:
- Chest discomfort or painuncomfortable
pressure, squeezing, fullness, or pain in the center of the chest that can be
mild or strong. This discomfort or pain lasts more than a few minutes or goes
away and comes back.
- Upper body discomfort in one or both arms, the
back, neck, jaw, or stomach.
- Shortness of breath that may occur with or before
chest discomfort.
- Other signs include nausea (feeling sick to your
stomach), vomiting, lightheadedness or fainting, or breaking out in a cold
sweat.
Call 911 within 5 minutes if you think
you're having a heart attack. Acting fast at the first sign of heart attack
symptoms can save your life and limit damage to your heart. Treatment is most
effective when started within 1 hour of the beginning of symptoms.
Key Points
- Coronary microvascular disease (MVD) affects the
heart's smallest coronary arteries. Coronary MVD occurs when plaque forms in
the arteries, when the arteries spasm (tighten), or when the walls of the
arteries are diseased or damaged.
- In coronary MVD, plaque can scatter, spread out
evenly, or build up into blockages in the small coronary arteries. Plaque
reduces the flow of oxygen-rich blood to the heart muscle. Spasms also prevent
enough oxygen-rich blood from getting to the heart muscle. Changes in the
arteries' cells and the surrounding muscle tissues may, over time, damage the
arteries' walls.
- In coronary MVD, plaque doesn't always lead to
blockages as it does in traditional
coronary
artery disease (CAD). For this reason, coronary MVD is called
nonobstructive CAD.
- Coronary MVD is a new concept. It's currently
being studied as a possible cause of heart disease in women. Many researchers
think that a drop in estrogen levels in women at menopause combined with risk
factors for heart disease causes coronary MVD.
- No one knows whether coronary MVD is the same as
MVD linked to other diseases, such as
diabetes.
- The same cluster of risk factors that cause
atherosclerosis
and CAD may cause coronary MVD. These include
unhealthy
cholesterol levels,
high
blood pressure, smoking, insulin resistance, diabetes,
overweight
and obesity, lack of physical activity, age, and family history of early
heart disease.
- Coronary MVD in women 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.
- Signs and symptoms of coronary MVD often differ
from those of traditional CAD. Typical signs and symptoms of CAD include
angina
(chest pain), feeling pressure or squeezing in the chest, shortness of breath,
excessive sweating, and arm or shoulder pain. Many women with coronary MVD have
angina, but it may not by "typical."
- Women with coronary MVD may also have shortness
of breath, sleep problems, fatigue (tiredness), and lack of energy. In women,
symptoms are often first noticed during routine daily activities and times of
mental stress.
- Medical history and a physical exam are used to
diagnose coronary MVD. Your doctor may also give you tests for traditional CAD.
These may include
coronary
angiography,
stress
testing, and magnetic resonance imaging cardiac stress testing. You also
may be asked to fill out a questionnaire called the Duke Activity Status Index,
which measures how well you're able to do your daily activities.
- If test results show you don't have traditional
CAD, you can still be diagnosed with coronary MVD if evidence shows that not
enough oxygen is reaching the small arteries in your heart.
- Women who have coronary MVD are treated with
medicines to control symptoms and risk factors for heart disease. Women
diagnosed with coronary MVD who have anemia may benefit from treatment for that
condition.
- Women who are diagnosed and treated for coronary
MVD should be checked regularly by their doctors.
- No specific studies have yet been done on how to
prevent coronary MVD. It's not yet known how or in what way preventing coronary
MVD differs from preventing CAD. People can take steps to delay or prevent CAD
by making lifestyle changes, taking medicines, and getting regular medical
care.
- If you have coronary MVD, you can take steps to
stop it from getting worse. These may include lifestyle changes, medicines, and
regular medical care.
- If you have symptoms of heart disease, know how
and when to seek medical help. Be able to describe your symptoms, and know how
to control them. Know which medicines you take and how to take them. Finally,
know the limits of your physical activity and how to avoid or cope with stress.
- If you have signs and symptoms of a
heart
attack, such as chest pain, upper body discomfort, shortness of breath, and
nausea, call 911 right away.
Links to Other Information About Coronary
Microvascular Disease
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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