My Grandmother died of what was said to be a heart attack at the age of 45 in the late 1970's. In 2006 I had an ECG before starting medication and it was noted that I had a borderline QTC of around 450ms at a heart rate of 93bpm. I saw a specialised who said as it was borderline not to worry. However I googled it and since then it's always been on my mind. Fast forward to this February after the loss of my Dad from cancer I started having palpitations. I went to the emergency department twice and both ECG were said to be normal but the QTC thing back in 2006 and the death of my Grandmother still concerned me so I referred myself to the inherited cardiac centre in my city. I had a 72 hour holter and a exercise stress test. I got the results back yesterday and I'm in a panic. The lead electrophysiologist said "the tests were both normal and the corrected QT interval was not significantly prolonged on either test. I hope this is reassuring to you and I don't think we have any clear evidence of long QT syndrome" This all seems a bit uncertain to me. The nurse specialist did look at my previous ECG from the emergency department and she said the QTC was normal with normal T waves. Should I be concerned?