Welcome to healthcaremagic. A cardiologist is the best to help your dad & if he advices for other tests it is for the correct diagnosis of your dad. TMT may be positive because of exhertion but if Eco cardiography is normal that says that your dad has no heart problem of major type otherwise doctor would have advised for cardiac angiography
. So relax and keep the decission on treating cardiologist. I hope this helps you.