For some years my husband had problems with being tired and fluctuating heart rhythm. (this was some 15 years after having a triple by-pass which was an absolute success). He had the shock treatment mentioned above, three times, and each time the treatment worked, but the heart then went out of rhythm again, resulting in breathlessness and tiredness. Eventually it was decided to cauterize (not sure if that is the right expression) part of the valve that was causing the problem. One or two tests lead to this decision, but it was the ideal solution to what had been an on-going problem. It meant an over-night stay in hospital, not major surgery. This is probably not what you want, but just another angle on what is available.