Study subjects
From October 2014 to December 2018, 518 consecutive patients undergoing initial ablation for persistent AF using Carto 3 (Biosense Webster, Inc., Diamond Bar CA, USA), Ensite NavX (St. Jude Medical, Inc., St. Paul MN, USA) or Rhythmia (Boston Scientific, Boston MA, USA) at our hospital were retrospectively enrolled. Patients who could not undergo voltage mapping were excluded. Other exclusion criteria were age < 20 years, left atrial thrombus, and prior catheter ablation of AF. This study complied with the Declaration of Helsinki. Written informed consent for ablation and the use of data in this study was obtained from all patients, and the protocol was approved by our institutional review board.