Lirael
I don't think so, but although I know a lot about the heart I know less about digestion.
It is possible.
What are you doing after eating? If you are running around then your heart is sending blood to different places at the same time and obviously has to work harder.
It can also depend on what you eat / drink, coffee is notorious for causing palpitations.
The menopause is also another factor, hormones can do strange things, and not always the way the textbook says they should eg I get SVT when my thyroxine is too low, it's supposed to happen when it is too high.
Has your cardiologist tried different BBs? 45% for an EF is quite low. But obviously they need to be given time to work.
Beta blockers (well they block the beta receptors but their effect is) slow your heart rate and strengthen the contraction which is why the EF should go up because the heart is not beating as often but the 'beat' is stronger.
Different ones work slightly differently and unfortunately for patients the only option is to try different ones / different doses.
I think I remember earlier posts from you Lirael, if I remember correctly you are more aware of your heart's activity than most people.