What I would do is to press them for a plan. If they shrug and say 'Live with it...many do, ' I would consider that unhelpful because clearly I am asking for solutions, options, contingencies....ANYTHING but a shrug and the advice to get on with my life, or to make preparations for an untimely death.

You can live for a long time with an arrythmia, most of them, but nobody asked will say it's real living. In fact, it can be so awful that one begins to go downhill. So, one should seek a remedy, and if it isn't forthcoming from one cardiologist or EP, find another who will help...somehow. At some point, it may indeed be the case that there's nothing left, but there is almost one option worth a try rather than to face a slow dying on the vine.