What are the early signs of heart disease or failure?

I’m just curious because I attended a conference where I learned that I’m at a significant risk for developing heart problems due to family history, anthracycline chemotherapy drugs and chest radiation. The speaker said that people with my risk factors should be having yearly EKGs, Echocardiograms and Holter Monitors… which I am NOT. I am only 18 so while I don’t think heart failure is in my near future, I’d just like to know what warning signs I should be watching for. I already have some weird symptoms that concern me.