I had rheumatic fever, what is the likelihood of contracting endocarditis?

It depends: Becsb, i would recommend you get an echocardiogram (ultrasound) of your heart to assess the valves. If the valves are normal, your risk for endocarditis is minimal and you would not require antibiotics prior to procedures. The acc guidelines recently changed for antibiotic prophylaxis to: anyone with complex congenital heart disease, prior endocarditis, or mechanical heart valves.

Not very: You state you "had" rf. An old infection can cause some permanent issues, but it would be unlikely that you would develop endocarditis after the infection.