If you are having cardiovascular and fatigue problems after having COVID, this article may be helpful for your doctor:
“Cardiovascular autonomic dysfunction in post-COVID-19 syndrome: a major health-care burden” by Artur Fedorowski et al
Links aren’t allowed here, but you can find the abstract by copying the title into the search field at the PubMed website. Your doctor or specialist should be able to view the full article through their institutional membership.