About 75% of all index ablations (first attempts) are successful. So, about 25% fail. However, the re-dos typically run about 85% successful, so an improvement. I had to have two, seven months apart. Typically, the lesions caused during the first attempt don't let any spurious signal through and the EP team feels you have been completely isolated, so no more AF. Then, six, twelve weeks later, you break into AF one day, or a lot of PACs, and it becomes clear then that the team didn't manage to completely close off the focus (which in about 90% of all initial cases is at the pulmonary vein ostia...the mouths). A second attempt has a higher success rate.
An ablation is not to be feared. It's not very uncomfortable, usually, although everyone experiences it and the aftereffects differently. Most feel very well within a couple of days to a week and then they realize they have their life back! I know several people who have had three, four, five, even six ablations. The idea is to give your first EP another chance, but then you should be looking further afield for a better, or more experienced one. Like chefs, artists, dancers, and fishermen, some are better than others.