In the United States, more than 300,000 people a year die from a heart attack before they get to a hospital or in the emergency room. Many of those deaths can be prevented by acting quickly.

Some heart attacks are sudden and intense. However, most start slowly, with mild pain or discomfort. Here are some of the signs that can mean a heart attack is happening:

• Chest discomfort. Most heart attacks involve discomfort in the center of the chest that lasts more than a few minutes, or that goes away and comes back. It can feel like uncomfortable pressure, squeezing, fullness or pain.
• Discomfort in other areas of the upper body. Symptoms can include pain or discomfort in one or both arms, the back, neck, jaw or stomach.
• Shortness of breath. This may occur with or without chest discomfort. Other signs. These may include breaking out in a cold sweat, nausea or lightheadedness.

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