NPPB and atrial fibrillation: In the present study, the AF patients with preserved left ventricular systolic function have been used as subjects to conduct univariate analysis and the results have demonstrated that the variables such as enlarged left atrial diameter and increased pre-procedural plasma NT-proBNP level are significantly associated with the recurrence of AF at one year after RFCA including persistent AF, which is in good agreement with several previous studies[10,11,17].