Susan Fessler was on the evening train headed to Crystal Lake when she experienced a "funny, sickening pain" in her jaw. Then more pain radiated down her left arm.

Fessler remembers feeling especially exhausted that January night, even taking an uncharacteristic nap during the commute home.

"It was unnerving," said the executive assistant and mother of three, who was 45 years old at the time. "I called my husband from the train and told him I didn't feel good."

Her husband rushed her to the hospital, where doctors spent the next two days running tests.

"I remember the cardiologist's exact words: 'Your heart is beautiful; it's perfect,'" Fessler said. Another physician congratulated her for having such low cholesterol.

The doctors chalked up her symptoms to acid reflux and sent her on her way.

One year later, Fessler had a massive heart attack and nearly died.

"I coded right as I got to the emergency room," said Fessler, now 49. "I was down for the count. They had to defibrillate me three times. I woke up two days later on a ventilator."

Fessler is one of an estimated 41.3 million American women with cardiovascular disease. She narrowly escaped being one of the 450,000 of those women who die each year as a result.

Long thought of primarily as a male health problem, cardiovascular disease -- including heart disease, hypertension and stroke -- kills more U.S. women than men. It's been that way since 1984. Even so, only one in five women believe that heart disease is her greatest health threat, according to the American Heart Association.

Cardiovascular disease claims more lives than the next five leading causes of death combined, including all forms of cancer. Consider this: One in 30 American women will die of breast cancer. About one in three will die from cardiovascular disease.

"Most women have a much greater fear of breast cancer," said Fessler's new heart specialist, Dr. John Lopez, interventional cardiologist at Loyola University Health System. "Over the course of a lifetime, the risk of heart- and vascular-related problems are far more likely to affect a woman."

In 2004, the American Heart Association launched its "Go Red for Women" campaign to raise awareness about heart disease in women. What started off as small fund-raising luncheons in Chicago, Los Angeles and San Diego has blossomed into a nationwide program that pumps millions of dollars into medical research, which historically has focused on male heart disease patients.

What doctors now know is that heart disease doesn't always act the same among the sexes. Female heart-attack patients are more likely than men to experience symptoms other than the classic chest pain, such as shortness of breath, exhaustion and pain in the jaw, neck or stomach. Women also tend to develop heart disease later in life -- about 10 years after men, whose symptoms generally start showing up in their 40s.

Educating women about these gender differences and cardiovascular disease in general is a huge component of the Go Red campaign. The Web site GoRedForWomen.org helps them assess their personal risk for heart disease and includes a 12-week nutrition and fitness program modeled on a heart-healthy lifestyle.

Women can use the Web site to ask questions of heart specialists, read about the latest research or order a free red dress pin, much like the pink ribbons worn by breast cancer advocates.

The pins are one way to spread the word about women's No. 1 killer. The campaign also is encouraging all women -- and men -- "to stand up and speak out against heart disease" by adding the color to their outfits during National Wear Red Day this Friday.

Later this month, on Feb. 26, the Palmer House Hilton will hold the annual Chicago Go Red for Women luncheon, a major fund-raiser that features educational sessions, health screenings and inspirational stories. (Call the American Heart Association at 312-476-6667 for details.)

One of the pioneers of the Go Red movement is Dr. Annabelle Volgman, board president of the American Heart Association Metropolitan Chicago. The Rush University Medical Center cardiologist also helped start Rush's Heart Center for Women six years ago.

"We wanted women all over Chicago to know that if they feel they're not being treated well by their doctors, they can come here," Volgman said.

Several studies have suggested that women don't get diagnosed or treated for cardiovascular disease as aggressively as men do, according to the Agency for Healthcare Research and Quality. One study, for example, found that female heart disease patients were less likely than their male counterparts to be on low-dose aspirin therapy. Another showed that females with clogged arteries received less intensive cholesterol management than that given to men.

When statins were introduced in the late '80s, many men were put on the cholesterol-lowering drugs. Meanwhile, legions of post-menopausal women spent the '90s on hormone replacement therapy, largely because the hormones were thought to have a protective effect on the heart. In 2002 researchers discovered the opposite was true.

"Hormone replacement therapy actually increased heart attack and stroke," as well as life-threatening blood clots and breast cancer, Volgman said. "After we stopped giving HRT, there were 17,000 fewer heart attacks among women the following year."

The good news is that cardiovascular deaths among both women and men are on the decline. But experts worry the large number who are obese or have diabetes could reverse that trend.

Recent research also suggests a narrowing of the gender gap that traditionally saw much poorer survival rates for female heart-attack victims. The Archives of Internal Medicine published a study in October that found in-hospital survival rates improved for both genders over the last decade, but women -- especially those younger than 55 -- posted bigger progress in this area than men.

Improvements like this "indicate that we are on the right track," according to an accompanying editorial in the journal. But there's more work to be done.

"Men are still believed to be at greater risk for heart attack and stroke and are thus more aggressively informed, counseled and treated for these diseases," the editorial said.

That disparity aggravates women like Fessler. "You feel like you go to the doctor as a woman, and they write it off as stress or reflux," said Fessler, who has nine stents propping open her arteries. She's on a medicine cabinet's worth of drugs to treat her heart disease, but overall she feels "pretty good." And pretty lucky.

"I almost didn't go to the hospital the night I had my heart attack," she said. "My advice: If you have a feeling in the pit of your stomach that something's not right, it's probably not. Don't ignore what your body is telling you. Listen to it."