You're awake (again) in the middle of the night, worrying about finances, when suddenly you feel a stab of pain in your chest. It's not the first time such chest discomfort has accompanied stress. What's happening?

Answer: You may have small vessel heart disease, or coronary microvascular disease (MVD). By impairing blood flow in the heart's tiniest arteries-the twigs of the arterial trec-MVD can lead to a heart attack or heart failure.

When the Women's Ischemic Syndrome Evaluation (WISE) study began 12 years ago, MVD was found to play a major role in heart disease in women. You may never have heard of MVD-and your primary care physician may know next to nothing about it-even though it affects up to three million American women, most of them over age 45. What women must know about this potentially deadly disease…

Women’s Arteries Are Different

Scientists don't yet know the exact cause of MVD, but they are focusing on several likely factors. Because men are far less prone to MVD, a key to understanding the disease seems to lie in the ways in which arteries differ between the sexes. Women's arteries are…

  • More likely to spasm. Women have much larger variations in hormone levels, day to day and over a lifetime, than men do. Such variations may affect arteries, which have hormone receptors, and lead to vascular reactivity-arteries that are likely to spasm, limiting or halting blood flow.
  • Smaller. It is not only that women, on average, are smaller than men. Even after adjusting for average body area, women have relatively smaller arteries-perhaps because they have less testosterone, a hormone that powers tissue growth. The tinier the blood vessel, the more vulnerable it is to spasm.
  • Prone to smoother plaque. Plaque is a fatty material that builds up on inner walls of arteries, impairing blood flow. In men, plaque typically forms big lumps. Although women may have as much plaque as men, in women it often spreads out smoothly and evenly-which makes it harder to detect.

Difficult To Diagnose

Many women with MVD have the classic signs of heart disease-angina (chest pain) and/or shortness of breath upon minor exertion, such as when walking up stairs. To check for heart disease, doctors typically begin with a stress test, which measures heart function and blood pressure while the patient walks on a treadmill. If results suggest a problem, the patient is given an angiogram-an injection of dye into the arteries which is followed by an X-ray to detect blockages.

Problems: With MVD, the angiogram may not find threatening obstructions in large blood vessels because smooth plaque is not easily detected.. and the test may not be sensitive enough to find abnormalities in small blood vessels.

Result: The woman is assured that she does not have heart disease—though in fact she does. Because she goes untreated, she continues to be at high risk for heart attack or heart failure.

What many doctors don't know: Persistent chest pain and an abnormal stress test are indications of MVD-and sufficient reason for treatment -even when the angiogram is normal.

Many doctors also are not aware that about 50% of women with MVD do not have the typical "exertional" symptoms. Instead, these women have angina when they're upset or stressed even if they are sitting or lying down.

Reason: Anxiety or stress can trigger the release of stress hormones, such as adrenaline, that can affect the small blood vessels and bring on angina. Yet doctors may not recognize the link between this type of "nonexertional" chest pain and heart disease.

Self-defense: If you have persistent chest pain but your doctor says that you don't have heart disease, get a second opinion. This is especially important if your doctor attributes your symptoms to heartburn, hiatal hernia or gallbladder disease even though tests do not confirm any of those diagnoses and treating those conditions does not stop the pain. To find a cardiologist who is knowledgeable about MVD, contact a top medical center for a referral.*

Best: A coronary reactivity test is the gold standard for determining the extent and severity of-and the most appropriate treatment for MVD. First, a wire is inserted into a coronary artery and blood flow is measured...then a substance that dilates small blood vessels is injected, and blood flow is measured again. Currently, the test is available at only a limited number of medical centers. As knowledge of MVD increases, the test should become more widely available. Ask your cardiologist if this test is appropriate for you. Insurance may cover the test.

MVD Treatments

Treatment of MVD aims to ease symptoms and reduce risk factors for heart attack and heart failure. Treatment may include...

  • Lifestyle changes. As with any form of heart disease, follow your doctor's guidelines for eating a heart-healthy diet with no more than 30% of calories from fat...doing aerobic exercise, such as brisk walking, for 30 minutes a day...maintaining a healthy weight...managing stress...and not smoking.
  • Medication. Your doctor may prescribe one or more drugs…
  • A beta-blocker to block the action of adrenaline, thereby slowing heartbeat, lowering blood pressure and easing angina.
  • An ACE inhibitor to reduce heart attack risk by blocking production of angiotensin, a compound that narrows arteries.
  • Baby aspirin, taken at 81 milligrams (mg) daily, to reduce the risk for artery-clogging blood clots.

*Among the top medical centers that treat MVD are Cedars-Sinai Medical Center in Los Angeles. Emory University Hospital in Atlanta...Harvard Medical School's Brigham and Women's Hospital in Boston...Mayo Clinic in Rochester, Minnesota. Stanford University School of Medicine in Stanford, California and University of Florida at Gainesville.

  • Statin medication to lower LDL or "bad," cholesterol.
  • Ranolazine, nitroglycerine and/or a calcium channel blocker to improve blood flow.
  • Enhanced external counterpulsation therapy (EECP). Inflatable pressure cuffs are wrapped around the legs from the calves up to the hips. The cuffs inflate and deflate in time with the heartbeat, improving circulation and blood vessel health.

Drawback: EECP treatment requires a one-hour session, five days a week, for seven weeks. While EECP has not been clinically tested specifically for MVD, it has been proven to be effective for easing angina in cases of heart failure-and many experts say that EECP has helped their MVD patients whose angina was not sufficiently relieved by lifestyle changes and medication.

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