Can waking up startled with a racing heart beat give you a heart attack or cardiac arrest? (awful feeling ex: alarm goes off=boom heart jumps) :(

Not in your case: In the absence of advanced heart disease it would be extremely rare. In a young female with no cardiac risk factors (diabetes, high blood pressure, cigarette smoking) not a problem. Try a clock radio with gentle music.

Not likely: Sounds like an anxiety reaction. Unless you are having multiple episodes during the day, it is unlikely to be a major problem. If you have a cardiologist, you may want to check it out with them.