My AF has been suppressed for some time by Flecainide with a small amount of Bisoprolol and I have good quality of life and fairly good energy levels - until 3 or 4 days ago. The breathlessness, tight chest, lowered BP and wobbly legs returned but AliveCor repeatedly reported that all was normal. and I could feel no abnormal rhythm. Yesterday I tried to clean a window but had to give up, exhausted.
So, had a glass of water - and realization hit - dehydration?!?! Over the next few hours I guzzled 2 litres of water and gradually the symptoms went away. I assumed my water intake was OK and the weather here has been perishingly cold for weeks, so I was quite surprised.
I've certainly learned to take nothing for granted and thought I would share the experience, in case it can help someone else.