Three people, three descriptions of a heart attack. Would you recognize one? That's a big question with a critically important answer. Cardiovascular disease remains the No. 1 killer of men and women in the U.S., in part because heart-attack victims often don't recognize the symptoms and delay getting care. Here's how to recognize a heart attack, and what to do if you think you're having one.

What to watch for

"I think I expected a heart attack to be like on TV, with sudden severe chest pain. That's not what I had at all," Shepard says. In real life, heart attacks often start slowly, and many survivors describe them as uncomfortable but not very painful.

Chest discomfort is the most common symptom, but women are somewhat more likely than men to experience others, such as nausea, shortness of breath, and pain in the back or jaw. Women are also prone to an especially deadly reaction—denial. "I have to admit, I was reluctant to call an ambulance and then terribly embarrassed when the EMTs initially said my heart seemed OK," Coldiron says.

So how do you know which symptoms warrant concern? If an area is tender when you push on it or hurts more when you breathe deeply, you're probably not having a heart attack. But if exertion triggers or worsens the discomfort, it might be heart-related chest pain. Symptoms such as cold sweats and difficulty breathing are red flags but can indicate other health problems.

You have to use your judgment, says Kathleen Cowling, D.O., vice president of the American College of Emergency Physicians. "It could be an odd pain in the middle of your back or indigestion that doesn't go away with antacids. But if any of these symptoms is a new problem for you, it could be the beginning of a heart attack."

In general, watch for these signs:

• Chest discomfort, including pain, pressure, squeezing, or a feeling of fullness in the center of the chest. The symptoms may wax and wane.
• Pain or discomfort that radiates to one or both arms, the back, neck, jaw, or stomach.
• Sudden onset of shortness of breath, even without chest discomfort.
• A cold sweat, nausea, or lightheadedness.

Take action

If you suspect you're having a heart attack, call 911 immediately. Then chew and swallow one 325-milligram uncoated aspirin (or four 81-milligram baby aspirins) to help prevent clots from forming in your coronary arteries. Don't even think about driving to the hospital yourself or having someone take you.

If you're with someone who might be having a heart attack, ask whether an automatic electronic defibrillator (AED) is available, in case the person becomes unconscious and doesn't have a pulse. Those easy-to-use devices check heart rhythms and deliver a shock if needed.