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What Is Coronary Microvascular Disease?

Coronary microvascular disease (MVD) is heart disease that affects the tiny coronary (heart) arteries. In coronary MVD, the walls of the heart's tiny arteries are damaged or diseased.

Coronary MVD is different from traditional coronary heart disease (CHD), also called coronary artery disease. In CHD, a waxy substance called plaque (plak) builds up in the large coronary arteries.

Plaque narrows the heart's large arteries and reduces the flow of oxygen-rich blood to your heart muscle. The buildup of plaque also makes it more likely that blood clots will form in your arteries. Blood clots can mostly or completely block blood flow through a coronary artery.

In coronary MVD, however, the heart's tiny arteries are affected. Plaque doesn't create blockages in these vessels as it does in the heart's large arteries.

Coronary Microvascular Disease

Figure A shows the small coronary artery network (microvasculature), containing a normal artery and an artery with coronary MVD. Figure B shows a large coronary artery with plaque buildup. 

Figure A shows the small coronary artery network (microvasculature), containing a normal artery and an artery with coronary MVD. Figure B shows a large coronary artery with plaque buildup.

Overview

Studies have shown that women are more likely than men to have coronary MVD. Many researchers think the disease is caused by a drop in estrogen levels during menopause combined with traditional heart disease risk factors.

Both men and women who have coronary MVD often have diabetes or high blood pressure. Some people who have coronary MVD may have inherited heart muscle diseases.

Diagnosing coronary MVD has been a challenge for doctors. Standard tests used to diagnose CHD aren't designed to detect coronary MVD. More research is needed to find the best diagnostic tests and treatments for the disease.

Outlook

Most of what is known about coronary MVD comes from the National Heart, Lung, and Blood Institute's Wise study (Women's Ischemia Syndrome Evaluation).

The WISE study started in 1996. The goal of the study was to learn more about how heart disease develops in women.

Currently, research is ongoing to learn more about the role of hormones in heart disease and to find better ways to diagnose coronary MVD.

Studies also are under way to learn more about the causes of coronary MVD, how to treat the disease, and the expected health outcomes for people with coronary MVD.




Other Names for Coronary Microvascular Disease

  • Cardiac syndrome X
  • Nonobstructive coronary heart disease



What Causes Coronary Microvascular Disease?

The same risk factors that cause atherosclerosis (ATH-er-o-skler-O-sis) may cause coronary microvascular disease (MVD). Atherosclerosis is a disease in which plaque builds up inside the arteries.

Risk factors for atherosclerosis include:

  • Unhealthy blood cholesterol levels. This includes high LDL cholesterol (sometimes called "bad" cholesterol) and low HDL cholesterol (sometimes called "good" cholesterol).
  • High blood pressure. Blood pressure is considered high if it stays at or above 140/90 mmHg over time. If you have diabetes or chronic kidney disease, high blood pressure is defined as 130/80 mmHg or higher. (The mmHg is millimeters of mercury—the units used to measure blood pressure.)
  • Smoking. Smoking can damage and tighten blood vessels, raise cholesterol levels, and raise blood pressure. Smoking also doesn't allow enough oxygen to reach the body's tissues.
  • Insulin resistance. This condition occurs if the body can't use its insulin properly. Insulin is a hormone that helps move blood sugar into cells where it's used for energy. Insulin resistance can lead to diabetes.
  • Diabetes. This is a disease in which the body's blood sugar level is too high because the body doesn't make enough insulin or doesn't use its insulin properly.
  • Overweight and obesity. The terms "overweight" and "obesity" refer to body weight that's greater than what is considered healthy for a certain height.
  • Lack of physical activity. Physical inactivity can worsen other risk factors for atherosclerosis, such as unhealthy blood cholesterol levels, high blood pressure, diabetes, and overweight and obesity.
  • Unhealthy diet. An unhealthy diet can raise your risk for atherosclerosis. Foods that are high in saturated and trans fats, cholesterol, sodium (salt), and sugar can worsen other atherosclerosis risk factors.
  • Older age. As you get older, your risk for atherosclerosis increases. Genetic or lifestyle factors cause plaque to build up in your arteries as you age. By the time you're middle-aged or older, enough plaque has built up to cause signs and 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 of 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.

In women, coronary MVD also may be linked to low estrogen levels occurring before or after menopause. Also, the disease 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.

Researchers continue to explore other possible causes of coronary MVD.




Who Is at Risk for Coronary Microvascular Disease?

Studies have shown that women are more likely than men to have coronary microvascular disease (MVD). Women at high risk for the disease often have multiple risk factors for atherosclerosis. (For a detailed list of these risk factors, go to "What Causes Coronary Microvascular Disease?")

Women may be at risk for coronary MVD if they have lower than normal 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 therapy.)

Low estrogen levels before menopause can raise younger women's risk for coronary MVD. One cause of low estrogen levels in younger women is mental stress. Another cause is a problem with the function of the ovaries.

Women who have high blood pressure before menopause, especially high systolic blood pressure, are at increased risk for coronary MVD. (Systolic blood pressure is the top or first number of a blood pressure measurement.)

After menopause, women tend to have more of the traditional risk factors for atherosclerosis, which also puts them at higher risk for coronary MVD.

Women who have heart disease are more likely to have 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?

The signs and symptoms of coronary microvascular disease (MVD) often differ from the signs and symptoms of traditional coronary heart disease (CHD).

Many women with coronary MVD have angina (an-JI-nuh or AN-juh-nuh). Angina is chest pain or discomfort that occurs when your heart muscle doesn't get enough oxygen-rich blood.

Angina may feel like pressure or squeezing in your chest. You also may feel it in your shoulders, arms, neck, jaw, or back. Angina pain may even feel like indigestion.

Angina also is a common symptom of CHD. However, the angina that occurs in coronary MVD may differ from the typical angina that occurs in CHD. In coronary MVD, the chest pain usually lasts longer than 10 minutes, and it can last longer than 30 minutes. Typical angina is more common in women older than 65.

Other signs and symptoms of coronary MVD are shortness of breath, sleep problems, fatigue (tiredness), and lack of energy.

Coronary MVD symptoms often are first noticed during routine daily activities (such as shopping, cooking, cleaning, and going to work) and times of mental stress. It's less likely that women will notice these symptoms during physical activity (such as jogging or walking fast).

This differs from CHD, in which symptoms often first appear while a person is being physically active—such as while jogging, walking on a treadmill, or going up stairs.




How Is Coronary Microvascular Disease Diagnosed?

Your doctor will diagnose coronary microvascular disease (MVD) based on your medical history, a physical exam, and test results. He or she will check to see whether you have any risk factors for heart disease.

For example, your doctor may measure your weight and height to check for overweight or obesity. He or she also may recommend tests for high blood cholesterol, 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. He or she also may ask about other symptoms, such as fatigue (tiredness), lack of energy, and shortness of breath. Women may be asked about their menopausal status.

Specialists Involved

Cardiologists and doctors who specialize in family and internal medicine might help diagnose and treat coronary MVD. Cardiologists are doctors who specialize in diagnosing and treating heart diseases and conditions.

Diagnostic Tests

The risk factors for coronary MVD and traditional coronary heart disease (CHD) often are the same. Thus, your doctor may recommend tests for CHD, such as:

  • Coronary angiography (an-jee-OG-rah-fee). This test uses dye and special
    x rays to show the insides of your coronary arteries. Coronary angiography can show plaque buildup in the large coronary arteries. This test often is done during a heart attack to help find blockages in the coronary arteries.
  • Stress testing. This test shows how blood flows through your heart during physical stress, such as exercise. Even 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.
  • Cardiac MRI (magnetic resonance imaging) stress test. Doctors may use this test to evaluate people who have chest pain.

Unfortunately, standard tests for CHD aren't designed to detect coronary MVD. These tests look for blockages in the large coronary arteries. Coronary MVD affects the tiny coronary arteries.

If test results show that you don't have CHD, your doctor might still diagnose you with coronary MVD. This could happen if signs are present that not enough oxygen is reaching your heart's tiny arteries.

Coronary MVD symptoms often first occur during routine daily tasks. Thus, your doctor may ask you 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 DASI results will help your doctor decide which kind of stress test you should have. The results also give your doctor information about how well blood is flowing through your coronary arteries.

Your doctor also may recommend blood tests, including a test for anemia. Anemia is thought to slow the growth of cells needed to repair damaged blood vessels.

Research is ongoing for better ways to detect and diagnose coronary MVD. Currently, researchers have not agreed on the best way to diagnose the disease.




How Is Coronary Microvascular Disease Treated?

Relieving pain is one of the main goals of treating coronary microvascular disease (MVD). Treatments also are used to control risk factors and other symptoms.

Treatments may include medicines such as:

  • Statins to improve cholesterol levels
  • 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 you're diagnosed with coronary MVD and also have anemia, you may benefit from treatment for that condition. Anemia is thought to slow the growth of cells needed to repair damaged blood vessels.

If you're diagnosed with and treated for coronary MVD, you should get ongoing care from your doctor.

Research is under way 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).

Researchers don't yet known how or in what way preventing coronary MVD differs from preventing coronary heart disease (CHD). Coronary MVD affects the tiny coronary arteries, while CHD affects the large coronary arteries.

Taking action to control heart disease risk factors can help prevent or delay CHD. You can't control some risk factors, such as older age and family history of heart disease. However, you can take steps to prevent or control other risk factors, such as high blood pressure, overweight and obesity, high blood cholesterol, diabetes, and smoking.

Lifestyle changes and ongoing care can help you lower your risk for heart disease.

Lifestyle Changes

Following a healthy diet is an important part of a heart healthy lifestyle. A healthy diet includes a variety of vegetables and fruits. It also includes whole grains, fat-free or low-fat dairy products, and protein foods, such as lean meats, poultry without skin, seafood, processed soy products, nuts, seeds, beans, and peas.

A healthy diet is low in sodium (salt), added sugars, solid fats, and refined grains. Solid fats are saturated fat and trans fatty acids. Refined grains come from processing whole grains, which results in a loss of nutrients (such as dietary fiber).

The National Heart, Lung, and Blood Institute's (NHLBI's) Therapeutic Lifestyle Changes (TLC) and Dietary Approaches to Stop Hypertension (DASH) are two programs that promote healthy eating.

If you're overweight or obese, work with your doctor to create a reasonable weight-loss plan. Controlling your weight helps you control heart disease risk factors.

Be as physically active as you can. Physical activity can improve your fitness level and your health. People gain health benefits from as little as 60 minutes of moderate-intensity aerobic activity per week. The more active you are, the more you'll benefit.

For more information about physical activity, go to the Health Topics Physical Activity and Your Heart article and the NHLBI's "Your Guide to Physical Activity and Your Heart."

If you smoke, quit. Smoking can damage and tighten your blood vessels. It also can raise your risk for heart disease and heart attack and worsen other heart disease risk factors.

Talk with your doctor about programs and products that can help you quit smoking. Also, try to avoid secondhand smoke. For more information about quitting smoking, go to the Health Topics Smoking and Your Heart article and the NHLBI's "Your Guide to a Healthy Heart."

Learn how to manage stress, relax, and cope with problems. This can improve your emotional and physical health. Physical activity, medicine, and relaxation therapy can help relieve stress. You also may want to consider taking part in a stress management program.

Ongoing Care

Learn more about heart disease and the traits, conditions, and habits that can raise your risk for it. Talk with your doctor about your risk factors for heart disease and how to control them.

If lifestyle changes aren't enough, your doctor may prescribe medicines to control your risk factors. Take all of your medicines as your doctor advises.

Know your numbers—ask your doctor for these three tests, and have the results explained to you:

  • Lipoprotein panel. This test measures total cholesterol, LDL cholesterol (sometimes called "bad" cholesterol), HDL cholesterol (sometimes called "good" cholesterol), and triglycerides (a type of fat in the blood).
  • Blood pressure measurement.
  • Fasting blood glucose. This test is for diabetes.

Know your body mass index (BMI) and waist measurement. BMI measures your weight in relation to your height and gives an estimate of your total body fat. You can use the NHLBI's online BMI calculator to figure out your BMI, or your doctor can help you.

In adults, a BMI of 18.5 to 24.9 is considered normal. A BMI of 25 to 29.9 is considered overweight. A BMI of 30 or more is considered obese.

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. A waist measurement of 35 inches or more for women and 40 inches or more for men is a risk factor for heart disease and other health problems.

Know your family history of heart disease. If you or someone in your family has heart disease, tell your doctor.




Living With Coronary Microvascular Disease

If you have coronary microvascular disease (MVD), you can take action to control it. Follow the steps described in "How Can Coronary Microvascular Disease Be Prevented?"

Coronary MVD, like traditional coronary heart disease, increases your risk for a heart attack. If you have signs or symptoms of a heart attack, call 9–1–1 at once.

These signs and symptoms may include chest pain, upper body discomfort, shortness of breath, and nausea (feeling sick to your stomach). For more detailed information about the warning signs of a heart attack, go to the section on warning signs below.

Ongoing Care

If you have coronary MVD, see your doctor regularly to make sure the disease isn't getting worse. Work with your doctor to keep track of your cholesterol, blood pressure, and blood sugar levels. This will help your doctor adjust your treatment as needed.

You may need to see a cardiologist (heart specialist) in addition to your primary care doctor. Talk with your doctor about how often you should schedule office visits or blood tests. Between those visits, call your doctor if you have any new symptoms or your symptoms worsen.

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.

Warning Signs

If you have coronary MVD, learn the warning signs of a heart attack. The signs and symptoms of a heart attack include:

  • Chest pain or discomfort. This involves uncomfortable pressure, squeezing, fullness, or pain in the center or left side of the chest that can be mild or strong. This pain or discomfort often 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 upper part of the stomach.
  • Shortness of breath, which may occur with or before chest discomfort.
  • Nausea (feeling sick to your stomach), vomiting, light-headedness or fainting, or breaking out in a cold sweat.
  • Sleep problems, fatigue (tiredness), and lack of energy.

If you think you're having a heart attack, call 9–1–1 at once. Early treatment can prevent or limit damage to your heart muscle. Do not drive to the hospital or let someone else drive you. Instead, call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room.

Let the people you see regularly know you're at risk for a heart attack. They can seek emergency care if you suddenly faint, collapse, or have other severe symptoms.




Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has helped doctors learn more about heart disease, its risk factors, and ways to prevent and treat the disease.

The NHLBI continues to support research aimed at learning more about heart disease, including coronary microvascular disease (MVD). For example, NHLBI-supported research includes studies that:

  • Examine heart attack risks and recovery in young women (aged 18–55)
  • Explore whether taking daily vitamin D or fish oil (omega-3) supplements reduces the risk of heart disease and other conditions
  • Examine the role that hormones play in women's heart disease risk

Much of this research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.

For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to coronary microvascular disease, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:




Links to Other Information About Coronary Microvascular Disease

NHLBI Resources

Non-NHLBI Resources

Clinical Trials

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November 02, 2011 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.