10 years ago I had a stent put into my LAD. Everything has been good ever since. In fact for the last 10 years I have been more fit and exercised more than before the stent. I do some very hard cardio work outs. Every once in a while I would feel a hard thump while working out on the treadmill and it would startle me, but that would be it. It was only during a work out. This has been going on for years. Recently I have been getting this thump while not working out, usually while just taking a walk. Has anyone ever heard of this type of thing happening and should I be concerned