Hello, My Father Is In The ER, Has Been Waking

Hello, My father is in the ER, has been waking up with abnormal heart palpitations. Today the strange rhythm caused him to cough. These palpitations would come and go he would feel fine. No other symptoms besides that. He had an EKG and results read normal sinus rhythm, t-wave abnormality consider inferolateral ischemia. They are keeping him overnight for observation and doing an echo. My grandfather died from a heart attack. What can these results mean so far? Thank you so much.