Heart Attack Symptoms, Panic Attacks, Racing Pulse Rate, Stressed. Had EKG. What Is The Reason?

I am a 40 year old female, 145 lbs. 5'6. For 2 years ive been suffering from nocturnal panic attacks, wake up heart racing, feeling like I died and sprung back to life, it goes on for hours, until I get exhausted and fall asleep around 4am. the past 6 months, they've started as I sit at night to rest.. my heart starts to pump,,,then I try to sleep and wake up with a pulse of 120 and I feel like im having a heart attack. I do have an EXTREAMLY stress full life especially the past 5 years. im being treated with .5 clozapam,,,which doesn't seem to work as well nowadays, and I had an ekg at my dr, an another at cardiologist yesterday, both say septal infarst age undetermined. cardiologist does not feel that ive had a heart attack, but is going to run me through some tests. is it possible that the 2 years this has been making my heart race uncontrollably that it may have caused some damage to my heart?