Heart Failure Support Group
Heart failure is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with or pump a sufficient amount of blood throughout the body. It is often undiagnosed due to a lack of a universally agreed definition and difficulties in diagnosis, particularly when the condition is considered "mild."
It is always a good idea to check with your doctor before starting an exercise routine, however I see no reason you shouldn't. In fact I see no reason you should be worried. I only wish my heart was half that good...
Stop stressing and get on with life. If all you do is worry about dying, you really aren't living.
They will help to evaluate how much activity you can safely tolerate, provide pointers, help you set up your own exercise routines, and perhaps most useful of all provide the sort of community and medical interactions to reduce (if not actually eliminate) your level of FUD (fear, uncertainty, and doubt), thus improving your quality of life.