Yes. The physician will find it difficult to identify where, exactly, the node cells have implanted themselves in places near and around the left atrium, but also other places in the heart. Near and around the atrium means the left atrial appendage, the coronary sinus, and in the septum between the two upper chambers, the atria. These are all places where the extra signals that cause chaotic beating may be, and they would have to be ablated where they lie. Most early cases of AF originate in what is called the pulmonary vein ostia....literally the mouths of each of the four pulmonary veins where they empty oxygenated blood returning from the lungs into the left atrium. They are located on the rear wall of the left atrium. So, most EPs expect to have to do an initial, or index, ablation to isolate the pulmonary veins from the tissue around their mouths. In case you're curious and would rather know, the only nerves that carry Sino-Atrial electric current to the left atrium are called the Bachmann's Bundle. These enter the pulmonary veins in some cases, or rather they 'invade' those places....but....so does endothelial tissue that comprises the inner lining of the atrial surfaces. IOW, both the Bachmann's Bundle AND the atrium's endothelial lining find their way into the Pulmonary veins...in some people. The atrium does not contract due to the nerve impulses running into the muscle from tiny nerves issuing from the Bachmann's Bundle. Instead, the electrical impulse runs on the surface of the endothelium and spreads like a rapidly expanding wave. This is what causes the atrial myocytes to contract sequentially, in a wave, and this is what forces the atrium's contents, freshly oxygenated blood, through the mitral valve and into the larger ventricle. So, chances are good, but not 100% that an index ablation will be best done as a PVI to isolate the inner ostia from the atriums endothelium, just cutting off the signal, the unwanted one. This leaves the SA node to continue to determine the contraction rhythm for the atrium. But, maybe it is the left atrial appendage that starts first. Remember 25% of all index ablations fail. Do they fail because the EP didn't completely close off the pulmonary veins? Probably, yes. But it could also be that the newly self-activated nodelette, if I can call it that, is somewhere else. A PVI might be a waste of time.

But also, some people can get by with a single cardioversion and not present at their local ER or doctor's offices for another six years. There is some risk to every invasive procedure, which an ablation surely is. So, if the heart is maintaining itself in NSR (Normal Sinus Rhythm), when go in and zap what it's causing any problems currently? Instead, wait until there's more activity consistently, but get that zapped early after it begins to take place.

The EP performs a 'mapping' procedure to identify where the new electrical signal is entering the atrial endothelium. She can't just being heating and scarring wherever the wand happens to touch your atrial wall. That would be irresponsible, and it's risky for the phrenic, andVagus nerves and for the esophagus. So they use a special wand first to pinpoint the 're-entrant' or focus of the unwanted new signal. THAT is where she needs to apply the thermal heat generated by the RF wand.