2.3 Reproducibility of RR interval variability of VT
We examined the reproducibility of RR interval variability of VT from two perspectives, firstly, reproducibility within an episode (RE), and secondly, reproducibility within an individual (RI).
RE was evaluated when there were two or more VTs in one episode (that is, ATP therapy was performed more than once in an episode). Of the VTs classified on the basis of RR interval variability within an episode, the ratio of the larger number of VTs by type (i.e., regular or irregular) was defined as RE (Figure 1B). If the numbers of regular and irregular VTs were identical in an episode, the episode was assigned according to the variability of the first recorded VT in the episode.
RI was assessed in patients with multiple VT episodes. The ratio of the larger number of VTs by type to the number of total VT episodes in all episodes within an individual was defined as RI (Figure 2).