Investigating Source of Women’s Heart Disease

Heart disease in women appears to be vastly different than heart disease in men. Symptoms vary, it strikes later in life, and, most alarmingly, it often goes unrecognized.

Now researchers are beginning to understand why: Women’s hearts simply do not react the same way as men’s.

“The differences between men and women are more than just estrogen and hormones,” said Dr. Noel Bairey-Merz, who chairs a scientific committee of the Women’s Ischemic Syndrome Evaluation.

The federally funded project and other research efforts are shedding light on why current diagnostic tests often fail to detect problems in women with heart disease. The tests, like many treatments, have been designed for men.

“I think for years we had the misperception that women were just like men,” said Dr. Carl Pepine, a University of Florida cardiologist and a researcher with the federal project. “We tried to force them into the same patterns and test findings we had become accustomed to over a century with men.”

Among the most promising developments is the realization that women with chest pain, called angina, often don’t have the clogged arteries found in men with chest pain.

Instead, their heart disease seems to involve other conditions, such as abnormalities in their microvessels. These small arteries generally don’t show up on angiograms, the standard tests used to detect fatty deposits, called plaques, in the arteries.

*

Cardiologists have found that only about 32% of women complaining of chest pain will show obvious signs of artery clogging, or atherosclerosis. That compares, Pepine said, with about 90% of men who undergo the same test.

Often, when these women go to an emergency room complaining of chest pain, they’re tested, told nothing is wrong and sent home. “It can become a source of chronic problems for the women, and it’s expensive for the medical care system,” said Dr. Daniel Pauly, a University of Florida cardiologist.

One explanation for this difference in women’s chest pain may lie in a variation of a particular gene. That gene controls how blood vessel walls expand or contract in response to naturally occurring hormones, including angiotensin, which constricts vessels and raises blood pressure.

When Pauly and his colleagues gave acetylcholine to female chest pain patients without any obvious heart disease, they got surprising results. Normally the hormone makes heart vessels expand, but in women with the genetic variation, the vessels constricted about 5%. The vessels of women without the gene variation reacted as expected and expanded by 16.5%.

The study suggests that when such women are under stress, their heart vessels--instead of expanding to allow more blood flow--actually tighten up.

These findings were recently presented at the American College of Cardiology scientific meeting in Orlando, Fla.

Pepine said a related research finding was that women with chest pain whose arteries tend to tighten up were at greater risk of being readmitted to a hospital for chest pain, heart attack or stroke.

Such research comes amid an increasing awareness among cardiac researchers that women’s symptoms of chest pain are different than what has commonly been associated with men. Whereas men describe crushing pain and pressure in the middle or left side of the chest, women are more likely to describe pain in the shoulder, upper back, neck and jaw, along with shortness of breath.

The difference may account for many women’s heart attacks being missed. But scientists also are learning that the physiological changes in the heart vary.

*

“A heart attack in a man is most often because the plaque ruptures and spews its contents,” in a short period of time, Bairey-Merz said. In contrast, plaques in women who have had heart attacks haven’t exploded or erupted, she said. “They have been eroded or eaten away,” over an extended period when a woman may feel “not quite right.”

Because heart disease is the leading cause of death and disability in women, research leading to better diagnosis and treatments is expected to have a significant impact nationwide.

Looking ahead, Pauly said researchers now will test therapies for women who have chest pain but who don’t have significantly narrowed arteries. Of the chest pain sufferers studied, 42% had no vessel narrowing and 37% had only mild narrowing. Only 21% had arteries narrowed enough to account for their chest discomfort.

The doctors theorize that these women might be in the throes of some hard-to-detect early phase of atherosclerosis that many years from now could produce the classic plaque-lined arteries that have defined coronary artery disease in men.

It’s also possible that they have some other artery abnormality that has yet to be identified, he said.