Last week my 74-year-old mother-in-law had symptoms of a heart attack late at night and dialed 911. Within 4 minutes, there was an ambulance, a fire truck, and two police cars outside her door. She spent 15 hours in the hospital, undergoing EKG, contrast radiography, stress test, enzyme tests, etc. They didn't find a darn thing. They wanted her to stay overnight, but she said no, and got a ride home, even though they brought in a psychologist to check her sanity. She needed a good night's sleep, and she knew she wouldn't get it in the hospital.
She's been fine since and the doctors don't have an explanation.
Same thing happened to wifey a month ago. Docs still can't find anything wrong. We see a cardiologist this week.