If you or someone you're with has symptoms that might be a heart attack, call 911 right away. If it is, you're more likely to survive if you get treated within 90 minutes.
While you're on the phone, the person should chew and swallow an aspirin (unless they're allergic) to lower the risk of a blood clot.
Are they unconscious? Hands-only CPR can double their chances of survival.
Key word: immediate treatment heart attack