I have had atrial fibrilation twice and experienced the same symptoms you have had. Having heart disease all my life, numerous operations and procedures I ended up having real bad panic attacks. Even well after I had a cardioversion and my heart rhythm returned back to normal (whats normal for mine anyway) I still thought that there was something dreadful wrong and still had the same symptoms. It was as though suddenly it had hit me all these years that I have heart disease (I was born with it, had op at 12 months old, 8 years of age and 14 years of age. Began to effect me mentally when I was 25, now im 30). I was too scared to do anything in case it was too strenuous for my heart so i ended up very imobile. Since then i have had councelling and I can do virtually anything and i dont get panicky or the sumptoms I had before. Maybe it is maybe more of a mental issue without sounding patronising. It is soooo mad what the mind can do. All I can suggest is that you try to trust the medics and try to see if relaxation techniques help ease any pain. Go and speak to you GP and let him know how you are feeling and how much it is upsetting your life. Do you have a history of heart complaint? Are you under any specific stress in your life at the mo?