Corresponding Fractionation Analysis

At each EEA site, the primary epicardial deflection or peak and the endocardial primary deflection or peak were compared to the direct opposite electrogram for the presence of fractionation corresponding to the primary deflection/peak. If the FT of a fractionation peak or deflection on the opposite side was ≤7 ms of the LAT, it was labeled as corresponding fractionation (to the primary deflection/ peak) (Fig. ​(Fig.2).2). This cut-off was chosen based on our previous definitions of conduction delay and block [10]. In case of multiple deflections or peaks meeting this criterion, first the closest deflection/peak, otherwise the largest deflection/peak, was selected as fractionation corresponding to EEA. Parameters of the corresponding unipolar deflection or bipolar peak included voltage, SNR and voltage compared to the primary deflection/peak on the same electrogram (in %). In addition, the time difference between the LAT and corresponding FT was analyzed to determine level of time accuracy.