lots of us have cardiac complications - myself included
typically its some form of "heart block" or arrhythmia - often variable - so not always showing up on tests when tested - but often very obvious at other times to the person themselves
mine was pretty scary a few months back esp as i was starting to ramp up treatment - especially at night when my heart would essentially stop for several beats and or do periods of very very fast beats - like 4-5x normal rate - and periods of very slow super heavy beats that moved my whole chest
3 days of IV is unlikely to be enough to resolve a long standing infection
nor is single antibiotic therapy -i'm afraid - multiple abx longer term are likely needed
finding a good LLMD is a good course of action
i have read a little into it and it is suspected to be caused by interruption of the nerve signals in the heart tissue due to inflammatory change sin that tissue - driven i think by white blood cell infiltration an inflammation.
i see this is often present in patients with bartonella as well as lyme - so you may want to look into that
this is the single best place i have come across - as a place to start
https://www.youtube.com/watch?v=njywmmpjikui take a lot of herbs to help with inflammation - and i have read that COQ10 is supposed to help protect the heart - and some people think high doses help with this
also the famous herbalist Stephen Buhner advocates hawthorn berry tincture to protect the heart
mine and others i have spoken with have experienced improvement during treatment - but often after a few weeks of initially worsening heart symptoms
this is consistent with more inflammation from herx like reactions initially - then settling down