Role of rapid focal activation in the maintenance of atrial fibrillation originating from the pulmonary veins

Most episodes of focal atrial fibrillation (AF) can be initiated by prematu re beats originating from the pulmonary veins (PV). However the role of rap id focal activation in the maintenance of AF is unclear. Thirty-two patient s with, focal AF who underwent focal ablation of triggering ectopic beats w ere studied. Bipolar electrograms from all four PVs were recorded sim ultan eously. The cycle length (CL) of RFA at sites that triggered AF was measure d at AF onset, after 5 minutes of sustained AF, and just before the spontan eous termination of 32 episodes of nonsustained AF. Fifteen episodes of sus tained AF (> 10 minutes) and 17 episodes of nonsustained AF (5-120 seconds, mean 56 +/- 59 seconds) were analyzed. In sustained AF, the mean CL of RFA in the PV from which it originated was not significantly different than in the other PVs, and RFA was continuously observed. In nonsustained AF, the mean CL of RFA in a PV from which it originated was significantly shorter t han in other PVs and, when RFA disappeared, AF terminated. RFA in 1 PV indu ced RFA in another PV. In conclusion, widespread conduction of RFA from a P V at ifs source to the other sites may be necessary for the sustenance of A F. A PV interaction, a RFA triggering another, may be involved in the maint enance of AF. RFA arising from PVs is important not only as a trigger of on set, but also in the maintenance of AF.