Time is often the critical factor in heart attack survival. Once heart muscle starts to die, there isn't much time for doctors to intervene and prevent death.

Yet the average victim waits three hours before deciding to seek help, says the American Heart Association.

"They don't come to the hospital straightaway, and that is a problem, says Dr. Alan Guerci, director of cardiology at Johns Hopkins Hospital. "Often the patients don't known what is happening to them. They feel bad, and because of denial and confusion, they think, 'Gee, I'll sit down and in a few minutes I'll feel better.' "

Pain is the classic first warning of a heart attack. It can be an uncomfortable pressure, a fullness, squeezing or plain sharp pain in the center of the chest which lasts for two minutes or longer. The pain may spread to the shoulders, neck or arm and may be accompanied by dizziness, nausea, sweating, shortness of breath and even fainting.

But pain is not always present. Among the atypical -- but frequent -- signs are an upset stomach, pulled muscle or sudden sweat. People at high risk of getting a heart attack include those who: are male; are older than 40; smoke cigarettes; have high blood pressure; have high concentrations of fats and cholesterol in their blood; are diabetic.

Other factors may contribute to the risk of having a heart attack, including obesity, lack of exercise and a stressful life style or occupation.

If any of the heart attack symptoms occur, the patient should immediately go, or be taken, to the nearest hospital emergency room.

Family members of those with risk factors should learn the life-saving technique called cardiopulmonary resuscitation (CPR).

People interested in learning CPR may call the the D.C. Chapter of the American Heart Assocation at 337-6400 or the D.C. Chapter of the American Red Cross, 728-6585.