Last night’s trip to the ER for cardiac issues

So I went shopping yesterday around like 3:30 ish and came back 2 hours later after I had gotten all the food I needed for my apartment. I checked my heart rate and it was 160. It was like this for like half an hour to 45 minutes. I called my after-hours doctor and he told me to go directly to the ER because no person’s heart should be beating that fast. He also told me that this was serious and that it could kill me. He told me not to wait so I went, and I got fitted with a Holter monitor today so they can see what is going on. I hope I get some answers soon.