I've had strep throat 4 times from ages 10-20. Took antibiotics every time. Can I still get heart problems in the future or is that only if untreated?

WOULDN'T WORRY. Those who have untreated strep will have a full natural immune response that creates antibodies. In about 1/200 cases, those antibodies can attack normal body tissue in the heart/brain or kidney, resulting in the damage we want to avoid.Antibiotic treatment within the 1st 10 days of fever stops this from happening.
Unlikely. Since you got treated every time you had strep throat infection and did not have any problem like joint pains ,skin rash or pain in chest /breathing problems after throat infection ,you are not likely to get any problem -heart problem .If you are still worried about get checked up by cardiologist .