I had a similar reaction to Moderna (2nd dose). I take Sotalol (80 mg 2x day plus Eliqis 5 mg 2x day). My resting heart rate averages between 57-59 with dips to low 50’s. After 2nd dose of vaccine, resting heart rate went up to 64 with daytime averages up about 10-15 bmp. It only lasted about a week, then went back to normal.