Stepdad has A-fib, they tried shock therapy, then tried to place a pacemaker?

but my Mom says they couldn't get the pacemaker to stay in place? I didn't even know that could be a problem. Stepdad has A-fib, been treating it with meds, then the doc decided to try shock therapy today as an outpatient, and they said if that didn't work, they would place a pacemaker. So shock therapy didn't work and neither did placing a pacemaker... Does anyone know the significance of not being able to place a pacemaker? Is that an indication that the heart is worse off than originally thought, or is that common? Just wondering and curious. My Stepdad is a wonderful person and I care very much about his well being, but I know very little about his medical condition. They try not to worry me! LOL