A century ago, so little was known about heart disease that people who had it resigned themselves to years of bed rest or, worse, an early death. Even less was known about how heart disease affected women – because nobody thought it did.

Heart disease was considered a man's disease. If women had a role to play, it was in taking care of the men in their lives. Even the American Heart Association hosted a conference in the 1960s themed "How Can I Help My Husband Cope with Heart Disease?" and published a nutrition pamphlet titled "The Way to a Man's Heart."

That attitude persisted throughout the 20th century, a time when questions about a woman's health were centered on the parts of her body under her bikini, said Dr. Gina Lundberg, clinical director of the Emory Woman's Heart Center and a professor at Emory University School of Medicine in Atlanta.

"It was, 'Get a pap smear and a mammogram and you're good,'" she said. "We left out all the things we were checking men for, like diabetes and cardiovascular disease. But between a woman's breasts and her reproductive organs is her heart."

Women were believed to have some natural protection from heart disease until their hormone levels dropped during menopause, Lundberg said. After menopause, it was believed that hormone replacement therapy could prolong that protection, a premise since amended to apply only to women who take it during the early stages of this transition.

It wasn't until the turn of the century neared that evidence began to slowly emerge that women, as well as men, faced a substantial risk from heart disease, beginning at a much earlier stage in life and with sometimes differing symptoms than men.

Left out of the research

It wasn't until the mid-1980s when anyone began looking at how heart disease might affect women.

That's when the Framingham Heart Study, the first in-depth, long-term cardiovascular investigation in the U.S., began reporting sex-specific patterns of heart disease, questioning whether the magnitude of this condition in women was being overlooked. The researchers noted that heart attacks were less likely to be recognized in women than in men.

They also pointed out that prior investigations had failed to adequately assess sex differences in heart disease because an insufficient number of women were included in the research. Since heart disease was thought to predominantly affect men, only men were being studied.

This started to change in the 1990s, after Atlanta cardiologist Dr. Nanette Wenger and others led a push for the equitable inclusion of women in National Institutes of Health-funded research. Doing so became NIH policy in 1989 and was written into law in 1993. But Wenger later said the legislation amounted to little more than a directive, falling short of achieving parity. "It had no teeth," she recently told The Fuller Project.

Meanwhile, the prevention and treatment of heart disease in women was based on evidence that came from studies of predominantly middle-aged men, said Dr. Jennifer Mieres, a professor of cardiology and associate dean for faculty affairs at the Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York.

"We thought that you could treat men and women the same," said Mieres, who was the first woman to be a full-time faculty cardiologist at Northwell Health's North Shore University Hospital. "We had great advances in treatment strategies, but we were applying a one-size-fits-all approach and clearly that wasn't working."

A landmark 2001 report from the Institute of Medicine, a nonprofit policy research organization now known as the National Academy of Medicine, highlighted the underrepresentation of women in clinical trials and sex biases in medicine, calling for a better understanding of differences in how men and women were affected by disease.

Mieres said women often failed to meet the criteria for clinical trials because their signs and symptoms didn't match assumptions about what constituted cardiovascular risk. "Our research criteria were customized to men as the gold standard."

This realization led to a push for sex-specific clinical trials, allowing researchers to focus exclusively on how cardiovascular disease develops in women, she said. And that led to the discovery that heart disease caused by narrowed heart arteries is more complex and behaves differently in women than in men.

Beyond the bikini: A new picture of women's health

One of the biggest questions driving the push for more research was why, despite developing heart disease about 10 years later than men, more women were dying from it. And why were women under 65 twice as likely to die from a heart attack as their male peers?

As researchers began to dig, a new picture of women's health emerged.

One problem was health care professionals were doing less to protect women from heart disease, according to a 1999 report from the AHA and American College of Cardiology, the first women-specific clinical recommendations for the prevention of heart disease.

For example, women were less likely to be counseled by health care professionals to reduce their cardiovascular risk factors, such as by losing weight, eating a healthier diet or becoming more physically active. They also were less likely than men to be referred to cardiac rehabilitation following a heart attack or bypass surgery.

Mieres said it became clear that women needed better information so they could take control of their own health decisions. So, the AHA established Go Red for Women, a national campaign to raise awareness of heart disease and stroke as leading killers of women and to advance the science of sex differences in heart disease. It also joined forces with the National Heart, Lung, and Blood Institute, which was developing its own campaign, The Heart Truth. The two campaigns were launched back-to-back in 2003 and 2004.