Introduction Detail 3D mapping have been useful for effective radiofrequency catheter ablation. Rhythmia system can create the atrio-ventricular dual chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of Rhythmia system for catheter ablation of accessory pathways (AP). Methods From July 2015 to August 2020, 111 patients underwent ablation of APs. The dual chamber mappings were created in 50 patients [median age 15 (10-54), 32 male(64.0%)], while 61 patients underwent the radiofrequency (RF) ablations with conventional single chamber 3D mappings. The background characteristics and procedure details were compared between the dual chamber mapping group and conventional single chamber mapping group. Results The number of RF application [1 (1-3) vs 3 (1-6), p=0.0023], RF time [9.2 (2.0-95.7) vs 95.6 (4.1-248.7), p=0.0023], RF energy [248.4 (58.7-3328.2) vs 2867.6 (134.2-7728.4), p=0.0115] were significantly lower in dual chamber group. Fluoroscopy time [19.9 (14.2-26.1) vs 26.5 (17.7-43.4), p=0.0025], and fluoroscopy dose [52.5 (31.3-146.0) vs 119.0 (43.7-213.5), p=0.0249] were also significantly lower than in single chamber mapping group. Conclusion The dual chamber mappings were useful for effective ablation with reducing the radiation exposure.