My Mom Is 68 Yrs Old With Congestive Heart Failure.

My mom is 68 yrs old with congestive heart failure. Heart attack last year and had a sent placed. Today she was complaining of chest pains while in the doctor office. They did a ekg and came back and said she had low voltage. Shes very tired and wasn't feeling good. They sent her home. Without investigating the ekg. She's been in bed since this morning. I keep checking on her because I am scared of complete heart failure. Should I take her to the er and have this investigated or am I just over thinking?