Frequencies Analysis
After the PVI, DF mapping during AF in each area was performed using the
fast Fourier transform (FFT) method described previously.10,13,18,19 Recordings at each site for 5 seconds were
performed using a deflectable 20-pole spiral-shaped catheter with a
diameter of 2.5 cm (Reflexion HDTM, St. Jude Medical). Signals were
truncated to 5 seconds at a sampling rate of 1,000Hz, providing 4,096
points for analysis (resolution 0.50Hz). The signals were rectified and
processed by a Hanning window function and filtered from 2 to 20Hz. The
DF analysis was done by an offline FFT analysis using the software
implemented in the polygraph (RMC-5000; Nihon Kohden Co., Tokyo, Japan)
in real-time and then the DF values were input manually into the NavX
system. The DF value was determined as the frequency associated with the
maximum peak power of the spectrum. Only DF points with a regularity
index ≥0.2 were included.10,13,18,19 The high-DF sites
were defined as DFs of ≥7Hz. The highest value of the DF in each mapping
area in the LA was measured and calculated.