JERUSALEM — If heart disease is holding tight to its distinction as the No. 1 killer of Western women, it's doing so, in Israel at least, with the active collaboration of the women it attacks.

"Estrogen is probably the most potent cardiac medication available, so the mere fact of being female provides some natural protection against coronary artery disease," says Professor Tova Chajek-Shaul, head of internal medicine at the Hadassah University Hospital on Mount Scopus. "To break through this built-in gender protection against heart disease, women must take more and greater risks with their health than men."

Chajek has recently completed a study in which she compared 400 men and women, ages 45 to 60, suffering from proven coronary artery disease. She not only found the disease more severe and more extensive in the women — who had more arteries involved, and whose arteries were up to 80 percent more occluded than those of their male counterparts — she also turned up startling evidence about exposure to risk factors.

"The risk factors for coronary artery disease are well-known," she says. "As most people are aware, the major ones are smoking, sedentary lifestyle, obesity, cholesterol, hypertension and diabetes. A third of the men we studied had none of these risk factors, and a third of them had only one. Among the women, however, 95 percent had at least one, and fully 70 percent had two or more."

A comparison of the lifestyles of the men and women in the study provided further evidence that the women were neglectful of their health. Chajek found that only 10 percent of them exercised regularly (compared with a quarter of the men), and a staggering 50 percent were smokers, double the number of men.

"The smoking figures are particularly revealing," she says. "Nationwide, only 30 percent of Israeli women smoke, compared with 45 percent of Israeli men. Our figures suggest that for women smoking is one of the major risk factors for coronary artery disease, and that smoking is more devastating to the female vascular system than to the male's system."

These findings, says Chajek, demand that women at risk be identified at least by their 30s, and immediately helped to reduce risk where they can, especially by quitting smoking. That's one of the goals of a new Hadassah institute, the Patricia and Russell Fleischman Women's Health Center, which opened on Mount Scopus in mid-December. The center's mandate is to set new standards for women's health and healing in Israel through a combination of medical care, educational outreach and research.

"Research has already conclusively shown that women require radically different medical care of heart disease than do men," says Chajek. She cites several examples: Standard EKGs and exercise stress tests used to diagnose heart disease in men are inaccurate in women. While total cholesterol level predicts heart disease in men, it doesn't do so in women. While alcohol protects men against heart disease, it's usually deadly for women.

In the past decade, medicine has at last recognized that the differences between men and women go well beyond their reproductive systems. Heart disease, lung and breast cancers, diabetes, depression and physical abuse are all primary health issues among women, and they all differ materially from the established male models of wellness and illness.

Chajek's study, and the educational outreach it will trigger, is a foretaste, she hopes, of a new current in medicine that will make women both visible and equal within the health care system in Israel and beyond.