I hope I can help you with your queries.
The changes you have made to your lifestyle are one of the best things you can do to help your heart.
In terms of other drugs such as flecainide these would normally be used as a second line treatment if you were resistant to the bisoprolol. This seems to be working very well for you so no other drugs are indicated at the present time.
In terms of the holistic remedies the arnica is the one that concerns me.
There is some evidence that oral arnica can have an adverse effect on the blood pressure and therefore the heart.
You can read much more about that here:
but as you will see from this article it is banned in some countries.
I hope this helps guide you in your decision making.