May be a little deep for some. Long story short, long covid symptoms do NOT come solely from heart complications, also associated with covid. And just to make sure we're clear here.....this study was done BEFORE vaccines were given. So it's not a vaccine thing either. ALL subjects were unvaccinated, ALL were infected with pre-Omicron covid. ALL "natural" infections, and all had symptoms of long covid.
They tested 700 different protein levels in the body and found consistent abnormalities in people with long covid, whether they had POTS or not. The thinking is, if long covid is a vascular (heart) issue, it can be treated easier than if the virus does some type of systemic damage. It appears to be the latter and there is some type of systemic damage the virus does that often involves the heart, but the heart involvement is not the cause of long covid but a common byproduct of it.