Changes in atrial fibrillation cycle length and inducibility during catheter ablation and their relation to outcome

The modification of atrial fibrillation cycle length (AFCL) during catheter ablation in humans has not been evaluated. Seventy patients undergoing ablation of prolonged episodes of AF were randomized to pulmonary vein (PV) isolation or additional ablation of the mitral isthmus. Mean AFCL was determined at a distance from the ablated area (coronary sinus) at the following intervals: before ablation, after 2- and 4-PV isolations, and after linear ablation. Inducibility of sustained AF (> or =10 minutes) was determined before and after ablation. Spontaneous sustained AF (715+/-845 minutes) was present in 30 patients and induced in 26 (AFCL, 186+/-19 ms). PV isolation terminated AF in 75%, with the number of PVs requiring isolation before termination increasing with AF duration (P=0.018). PV isolation resulted in progressive or abrupt AFCL prolongation to various extents, depending on the PV: to 214+/-24 ms (P