If you haven't had a heart cath, I would ask your doctor why. I had chest pain and back pain on and off for a long time. Every EKG, stress test and Echo I had always showed I was fine. Finally, a heart cath showed six blockages, three that were over 80%. I'am just one of these people who have problems with heart disease even on the strongest blood thinners. I even went for a second opinion a couple months ago and that doctor wanted to do another cath. He found two more (one 80% and one 90%) blockages. Don't be afraid to ask why a cath hasn't been done. That test could save your life. Unstable Angina could be another cause of your problems. Also, the fluttering you feel could be a sign of A-Fib)