Ablation protocol
As previously described,13, 14 encircling pulmonary vein isolation was performed for patients registered in the AF Frontier Ablation Registry who required it through the use of a radiofrequency ablation catheter or cryoablation catheter, depending on the hospital’s preference or type of catheter available at the time of the procedure. The ablation procedure was guided by a circular mapping catheter or a multiple-electrode catheter. The radiofrequency ablation employed an irrigated-tip contact force-sensing catheter or an irrigated-tip standard non-contact force-sensing catheter, and a 3-dimensional mapping system (EnSite NavX/Velocity [St. Jude Medical, St. Paul, MN, USA], CARTO [Biosense Webster, Irvine, CA, USA] or RHYTHMIA [Boston Scientific, Marlborough, MA, USA]). Cryoablation was performed with an Arctic Front Advance cardiac cryoablation catheter (Medtronic, Dublin, Ireland), and any touch-up ablation was performed with a standard irrigated-tip catheter. Some patients were injected intravenously with adenosine triphosphate after pulmonary vein isolation to expose dormant conduction between the pulmonary vein and left atrium. When acute pulmonary vein reconnection or dormant conduction occurred, touch-up ablation was performed. Additional linear ablation, such as tricuspid valve isthmus linear ablation, mitral isthmus linear ablation, and left atrial roof linear ablation, was performed at the physician’s discretion. The residual potentials, including complex fractionated atrial electrograms in the left atrium, were ablated as appropriate.