Objective: To investigate whether switching the ablation catheter between the right and left atria through transseptal puncture site can be accurately performed without fluoroscopy. Methods: Forty patients with persistent atrial fibrillation (mean age, 60.2 +/- 7.4 years; 65% males) got "2C3L" approach were randomized in a 1: 1 ratio to undergo either crossing interatrial septum guided by fluoroscopy (trackless group) or crossing septum guided by track image that was mapped by Carto3 system (track group). Results: The three-dimensional image of the track could be mapped smoothly and shown clearly. No significant differences were found in the success rates between the two groups (100% vs. 100%, p>0.05). However, the procedure of crossing septum was completed without any fluoroscopy use in track group, which showed a shorter procedure time than trackless group (4 +/- 3 s vs. 20 +/- 10 s, p<0.01). Conclusion: Visualizing the track passing through the puncture site using Carto3 system can guide the ablation catheter in safely crossing the intra-atrial septum quickly with zero fluoroscopy.