Coronary artery disease, or CAD, claims more lives in the United States, Europe and other developed regions than any other disease. Prompted by symptoms such as chest pain, or angina, more than a half million U.S. women underwent coronary angiography to look for CAD in 2001. But for many of them, that test won't detect their heart disease, leaving them untreated and vulnerable to heart attacks.

Fortunately, a new technology is now available that can show what other tests miss.

Gerald M. Pohost, chief of the division of cardiovascular medicine at the Keck School of Medicine of USC, is pioneering the use a new 3 Tesla Magnetic Resonance Imaging (3T MRI) machine, which has most often been used to diagnose brain problems, for the diagnosis of heart disease.

Until now, "technology has been abysmally poor at determining which women would have cardiovascular disease and which would not," says Pohost.

One of those women is Toni Smith, a 28-year-old from Salt Lake City, Utah, who has suffered chest pains since she was 10. Doctors could not find any evidence of heart disease, and she was told over the years that her pain was caused by stress, psychological problems, or torn cartilage. Nothing they suggested made the pain go away.

She suffered a heart attack when she was 19, but diagnostic tests done the next day only showed her heart was not getting enough oxygen, and could not find the cause of the attack. She had to drop out of school and reinvent her life around her medical problems, she says.

When Pohost scanned Smith in the 3T MRI, he found her problem is actually a condition called cardio microvascular syndrome, in which the blood flow through the tiniest arteries in the heart muscle becomes reduced and fails to supply enough oxygen and metabolites to the heart muscle.

For Smith, it was the answer that she'd been seeking. "I've been waiting 18 years for this picture," she says.

Pohost says the 3T MRI is able to produce clearer pictures of the heart because it has more magnetic coils than regular 1.5T MRIs. "Not only is there better resolution, but the 3T MRI can visualize the wall of the heart muscle, so you can divide the muscle into inner, middle and outer portions."

In addition, 3T MRI measures metabolism - the chemicals like phosphates that make the heart beat. "They are like the food that feed the muscle of the heart. When there's a reduction in that food, it reduces the ability of the heart to contract normally, and that causes chest pain and heart failure," he says.

Research released in February from the National Heart, Lung and Blood Institute of the National Institutes of Health suggested that as many as 3 million women in the U.S. may suffer from cardio microvascular syndrome, which conventional tests fail to detect. Angiography, for instance, which lets doctors see blood flow through the large arteries and is currently considered the standard for diagnosing coronary heart disease, does not detect the plaque that coats inside of the very small arteries, the study said.

The research was part of the Women's Ischemia Syndrome Evaluation (WISE) study, which since 1996 has been tracking almost 1,000 women who have pain or other symptoms, but seem fine in standard tests. The collection of results published in the Feb. 7 issue of the Journal of the American College of Cardiology has highlighted the problem of diagnosing women's heart problems.

"Most studies in the past used findings largely derived from men, but what this shows is that those methods don't frequently work for women," Pohost says.

Although some women are found to have heart disease using diagnostic techniques that work in men, previous WISE results have suggested almost half the women who do not have evidence of CAD on an angiogram are later found to have coronary microvascular syndrome. This helps explain why many women who go on to have heart attacks were previously undiagnosed despite exhibiting symptoms like chest pains, shortness of breath and nausea.

Pohost published a study in 2000 in the New England Journal of Medicine and 2003 in the journal Circulation that suggested magnetic resonance imaging could be widely used to evaluate women complaining of chest pain, and may even reduce the number of women undergoing repeated coronary angiography procedures. For now, the 3T MRI technology is available only at a few select institutions and academic medical centers, including USC.

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