 This was a prospective, multi-center, observational registry study evaluating CARTO XP CFAE Software CFAE Software in subjects with chronic AF requiring CFAE-guided RFCA. Use of the CARTO 3 System including CFAE Software was also allowed. The primary efficacy endpoint was the acute success rate of CFAE-guided radiofrequency catheter ablation RFCA using the CFAE Software. Acute success is defined as the subject achieving sinus rhythm at the end of the procedure without electrical or pharmaceutical cardioversion. Secondary endpoints consisted of measures of efficacy example, performance of the CFAE Software and of safety example, number of procedure-related adverse events. 