Monday April 14 5:57 PM EDT

NEW YORK (Reuters) -- All too often when a heart attack strikes, people ignore the symptoms, hoping they will go away or just turn out to be heart burn. And then, after hours of gradually increasing chest pain, nausea and sweating, they don't call 911 -- but rather choose to drive themselves or be driven to the hospital, according to a new study.

The tragedy is that every minute is crucial during a heart attack. The faster a person is treated with clot-dissolving drugs, the more likely they are to survive with a minimum of damaged heart muscle -- or to survive at all.

"Rapid treatment is very important," said Dr. Thomas Lee, a cardiologist at Partners Community HealthCare, Inc., in Boston. "There is data showing that every hour you get someone to the hospital sooner is valuable -- it's overwhelming," said Lee, who wrote an editorial accompanying the report.

Those most likely to wait? Women, older people, and surprisingly, people with high blood pressure -- who should know they are at greater risk of having a heart attack. In the study of 2,404 people experiencing an acute myocardial infarction, or heart attack, 40% waited more than six hours before going to the hospital, and only 42% called an ambulance or 911 to get there. Women were more likely to delay than men, as were patients over 85.

If the symptoms struck in the evening or early morning -- between midnight and 6 a.m. -- people were also more likely to wait, according to the report in the Annals of Internal Medicine.

"Any reluctance by patients to seek medical care during the evening and early morning hours must be discouraged," wrote lead study author Dr. Jerry Gurwitz, at the university of Massachusetts Medical Center in Worcester.

There are a number of reasons people don't seek treatment early enough, Lee said, including lack of awareness of symptoms, denial that they are occurring, and fear of medical costs.

"It can be genuinely confusing," he said. Some heart attacks can feet like heart burn, an upset stomach or gall stone attack, or even a stiff 'neck or dental pain. But people may also be scared to go to the hospital for financial reasons, because they are uninsured.

"And then there are psychological barriers to keep people from picking up the phone and going in," Lee said. "They just want to wait another hour to see if it goes away."

In the study, people who had had angioplasty or bypass surgery in the past got to the hospital quickly. However, those with risk factors such as high cholesterol, diabetes, a family history of heart disease, or congestive heart failure didn't get there any quicker. And those with high blood pressure were actually less likely to get to the hospital rapidly than those without the condition.

Doctors need to target patients at risk for heart attack, as well as their family members, to teach them to recognize the signs and symptoms and to have a plan if they occur, according to Dr. Kathleen Dracup, a nursing professor at University of California-Los Angeles, and a member of the National Heart Attack Alert Program, sponsored by the National Heart, Lung and Blood Institute in Bethesda, Maryland.

"People should know if they experience chest discomfort -- it doesn't have to be pain -- but a sense of pressure or fullness in their middle chest -- especially if it radiates down the left arm or up the neck, they should call 911 immediately rather than calling their own physician because time is so critical," she said. "Very often people feel that a heart attack should be a dramatic event, but in reality chest discomfort is just that, it's not really a sense of pain, it doesn't knock you off your chair."

People should also realize that if the chest discomfort subsides, but then returns, they could still be having a heart attack.

"I think the fact that it is often not as severe as people think it should be and the fact that it can sometimes be intermittent really fools people," she said.

SOURCE: Annals of Internal Medicine (1997;126:593-598)