They want someone with few other/unmanaged co-morbidities. Diabetes, COPD, as examples, should be managed before attempting ablation. Usually, the same for mitral valve prolapse...get that fixed first because MVP can bring on AF (atrial fibrillation).

They look for sleep apnea, if diagnosed, or suspected, to be controlled. Ideally, weight lose if BMI upwards of 28, not strictly necessary, and a lot depends on the EP involved (electrophysiologist).

Blood pressure...the same. Etc, etc....

Again, some EPs will help when it's a bit risky, or likely to fail due to other problems, but ya gotta find them. Even so, and this is me personally, I would be averse to risking the catheter ablation while still grappling with other serious problems. Those cause stress on the heart, and if you're already in stress due to hypertension, immune compromised, etc, .....your choice as always, but you have to get it past a busy EP.

The other, more closely relevant matters are to do with the heart itself: minimal to moderate left atrial enlargement. If it's walls are too thick, that will cause valve problems, but also invites fibrosis (scarring), which the ablation will only compound. Also, the longer one is in persistent or permanent AF/Flutter, the more difficult it is for the EP to nip it. So, the wisdom, as with most disorders, is to deal with them as soon as possible. The earlier you get an EP to ablate the pulmonary vein ostia, for example, the less likely you are to see that unwanted atrial enlargement, which happens over time as the atrium fibrillates.

Does that help?

(Edit-added) BTW, few EPs will advise you to cease taking an anticoagulant. Even after a successful ablation, there is still a risk of clot formation which only gets worse over time as we age. Metoprolol, sure, no use in taking a channel blocker when you're nicely in NSR, but the anticoagulant becomes more important over time, just especially so if you have small bouts of arrhythmia. Consult your EP for that kind of advice.