I hesitate to respond because you are on a beta blocker. I always refused that medicinal because my gut was giving me a big, fat "NO" when my doctor suggested it to me.
Back before 2007 (when I started Iodine supplementation) I was diagnosed with the heart arrythmia called "Long QT Syndrome". I had a hesitation between heartbeats. If it became too long (usually after a sudden scare) and I felt like passing out, then that would be deemed 'life-threatening'...
...even though my heart monitor 'proved' (to the doctor) my condition wasn't life-threatening, I knew my condition WAS because of two very serious episodes that I had.
The bottom line is that I had a somewhat scary 10-minute episode of sped-up heartrate after painting my "original mouth" (surrounding my navel area) with 'detoxified' Iodine that I had purchased (from iodinesource.com).
My in-the-50s heartrate went into the 110-range for those 10 minutes (if memory serves correctly) but afterwards went into the 70s where it stays now most of the time.
I literally have not had an arrythmia since that day in early Feb/2007.
Remember though, I was NOT on a beta blocker, and never was.
What I believe happened, was that Iodine chased the bromides out of my heart, and took its rightful place there.
I call iodine the smart element: it seems to go where the body needs it most for the sake of survival.