I was in job Corp in 2006 way back before fitbits existed I had a severe tachycardiac event and I could feel my heart pounding in my chest like I had just got done running 4 marathons. thankfully the doctor and nurse hadn't left yet, I went in there and told them my heart was beating out of my chest and the doctor hooked me up to a EKG and it showed that my heartrate was 180 bpm the doctor left the room for awhile and according to the doctor I passed out cause my heartrate shot up to 280 bpm and they started CPR and shocking my heart to get it beating again, cause it from quivering to my heart just full out stopped beating and it took them two hours to get my heart beating again, they never gave up and from that day on they monitored my heart rate everyday
Posted a pic of what my Fitbit caught while I was sleeping