Flat T line waves on a ECG, heart attack?

Ok my mum went to the doctor because she has a almost constant "twinge" as she calls it in her chest and down her left arm. He ordered a ECG and blood test. She hasn't had a chance to get the bloods done yet but had the ECG test done and it indicated flat t line waves... they said it's not good but didn't go into any more detail. What does this mean? Is it bad? She is pretty worried and doesn't know what to do. We have a history of bad hearts in the family with my uncle dying at 55, my grandfather dying at 48 and my grandmother having several heart attacks during her life.