i had fluttering early on in menopause..usually when i was excersing, but sometimes for no reason at all.
the dr. sent me for tests, including a sonagram of the heart, and all was well..
the fluttering stopped after about the first year...are you having hot flashes too?
my dr. also checked my thryoid, as a problem with it can cause fluttering..
hrt has been associated w/ fluttering too..
usually not too much of a problem, but certainly can be frightening...
check w/ your dr. for peace of mind...
menopause is not for sissies :-)