A HR of 120 at rest is indeed high,
and you mention a muscle relaxer. You also mention
hypertension and I wonder if you are on a beta blocker, e.g., Metoprolol. The BB family of medications reduce both blood pressure and heart rate and would seem to be in order for you.
On the other hand, I know nothing about the physical heart condition you describe, seems no one else reading your post does either.