It's a health message that doctors have been directing at women for some time, but too often it fails to get through: The classic sign of a heart attack isn't always searing pain in the chest, usually lasting several minutes.

But that's not necessarily the symptom felt by women, who make up 50 percent of America's heart attack victims.

"Women more often than men experience shortness of breath, unusual fatigue, or the pressure is lower down in the chest so it is mistaken for a stomach ailment," said Dr. Nieca Goldberg, a cardiologist with Lenox Hill Hospital in New York City and author of Women Are Not Small Men.

In fact, many aspects of heart disease are different for women than men -- its onset, its progression, its symptoms.

Heart disease is the No. 1 killer of both women and men, according to the National Institutes of Health. But women are less likely than men to believe they're having a heart attack and more likely to delay seeking emergency treatment.

One big reason may be because most don't experience that classic chest pain, a recent study by the College of Nursing at the University of Arkansas for Medical Science found.

Researchers polled 515 women who'd recently had a heart attack regarding their symptoms, and found that fewer than 30 percent complained of chest discomfort.

The most frequent acute symptoms were shortness of breath (58 percent), weakness (55 percent), and fatigue (43 percent). Women also complained of sleep disturbances, back pain, indigestion and anxiety, the survey found.

"Women should be aware of these symptoms, so they can go get help," Goldberg said. "Women are very in tune to their bodies. When they feel different, they should go in and get checked out."

The time frame for greatest heart attack risk for women also is different than men. Women tend to be about 10 years older than men when they have a heart attack, according to the National Institutes of Health.

The typical male profile involves a 50-year-old man with devastating chest pain. But for women, menopause is the time when they enter their danger zone.

"Women, when they enter menopause, they have a much greater risk of high blood pressure and a much greater risk of high bad cholesterol," said Dr. Richard Stein, director of preventive cardiology at Beth Israel Hospital in New York City.

Doctors believe this could be due to the falling estrogen and progesterone levels that women experience during menopause, Stein said.

But studies have shown that hormone-replacement therapy actually increases heart attack risk for women rather than lowering it, he added.

"The typical time for a woman to have a heart attack is about 10 years after menopause," Goldberg said, placing it around age 60.

Women also tend to exhibit more risk factors for heart disease than men, Goldberg said. These factors include:

• Diabetes.
• Smoking.
• Lack of exercise.
• Obesity.

"Two-thirds of women who have their first heart attack die suddenly," Goldberg said. "They have complications because they come into the health-care system late. Women as a whole tend to take care of everyone but themselves."

To head off heart disease, post-menopausal women should undergo regular blood pressure and cholesterol checks -- and do them with greater frequency than men do, Stein said.

For example, a man at risk of a heart attack should have his blood pressure checked once a year.

But because women's heart attack risk increases so dramatically following menopause, Stein recommends they have their blood pressure tested at least twice a year and their cholesterol tested at least once a year.

Women also should pay attention to how they feel when exerting themselves, Goldberg said.

"When the situation gets more serious, the person will get symptoms with less and less exertion, or even at rest," she said. "So that's a big clue. Six weeks before they have an actual heart attack, they will have exertion symptoms."

Women should also cut back on smoking and drinking, and watch their diet, Stein said.

Regular aerobic exercise and a high-fiber, low-fat diet can be the two best ways to head off a heart attack, he said.

"Diet and exercise are critical parts of prevention for women," Stein said.

And women can't start taking care of themselves soon enough, Goldberg added.

"We can actually see the earliest buildup of plaque in a woman's late teens and 20s," she said. "The groundwork starts early. It's important to adapt to a healthy lifestyle when you're young."