It is not entirely uncommon to need a pacemaker after some of these interventions. If it so happens, it really is not all bad. I LOVE mine. Compared to all the rest of the stuff- meds, interventions... it's a cakewalk and helps a lot. I hope it turns around soon, but you are not out of options.
Given she is off medications, I'd give her a few more days to see if her pulse comes up to at least the 60s. It is good she is staying on warfarin as AFib can return at any time.
I have gone through similar procedures: mitral valve repair and maze, which did not stop the AFib. And an electrocardioversion, which held me in sinus for only a couple of weeks. Sorry I can share a more successful experience, I share just to help justify the continuation of warfarin. I have had much better results from electrocardioversion in past years when they held for up to 18 months. My experience say AFib is a life-long exercise in control measures. The low PR is not something I have ever experienced. My lowest when in sinus has been approximately 60.