Just a quick note to say hi! I am almost same age and have same issues. Please get your thyroid checked... TSH, FreeT3, Free T4 and get copy of results. I been chasing this "beast of heart issues" for two years. My TSH was normal but VERY low Free T4,T3. I am starting thyroid treatment and it has helped when nothing else did.It is great idea to get your hormones checked too.
Good luck and best wishes.