BOSTON, MA — Results of a landmark study suggest that many women with heart disease don't get a proper diagnosis because they have a form of the disease that doesn't show up on the usual diagnostic tests. The new research shows that heart disease is not one but several disorders and may shed light on why heart disease often behaves differently in men and women, according to the February 2007 issue of Harvard Women's Health Watch.

In the Women's Ischemia Syndrome Evaluation (WISE) study, women with chronic chest pain underwent standard diagnostic procedures, including stress tests and coronary angiograms. Earlier studies had found that among people who show signs of trouble on stress tests, women are far more likely than men to appear free of blockages on follow-up angiograms. This was also true in the WISE study. But newer tests, including ultrasound of the blood vessels, revealed heart problems the angiograms didn't pick up. Many of these women had a condition called vascular dysfunction, in which the blood vessels supplying the heart don't expand properly to accommodate increased blood flow. Vascular dysfunction may affect not only the large coronary arteries, but also the smaller vessels that serve the heart—a problem dubbed microvessel disease.

The WISE results may help explain why women with heart disease are often underdiagnosed and undertreated. In men, the main problem may be a blockage in a large coronary artery, which shows up on an angiogram, while women are more likely to have microvessel disease that can't be seen. With this in mind, the WISE investigators are working to develop a new system for screening women for heart disease.