You are not dying ! Picture a stop sign in your mind and tell yourself to Stop the what-if thinking now.
Holter monitoring gives doctors a constant reading of your heart rate and rhythm over a 24-hour period (or longer). The Holter monitor can record heart rate and rhythm when you feel chest pain or symptoms of an irregular heartbeat. While you had the monitor on did you push the button when you felt a fast heart rate or skipped beats?
I would recommend that you see your Dr. and ask to go over each step (event) noted on your Holter monitoring. Sometimes it helps to sit down and have the irregular episodes explained to you in layman's terms.
Remind us, please, what medications are you on? Are you seeing a therapist?
Here is a link to an article re morning anxiety. Read it carefully as it may help you understand how the body works.
and Heart/Cardiovascular Disease. "She Stood in the Storm & When the Wind Did Not Blow Her Away, She Adjusted Her Sails."