2.6. VT burden
The pre-procedure VT burden was defined as the number of VT episodes and
shock therapies up to 2 years from the time of the ablation procedure.
The post-procedure VT burden was determined after 2 years from the day
of ablation procedure. In redo procedures, the pre-procedure VT burden
was defined as the number of VT episodes occurring between the previous
ablation procedure and the when the redo ablation procedure was
performed. VT episodes were defined as continuous VT for 30 seconds
and/or a syncopal events, or as VT that required an appropriate
intervention for termination. We also defined incessant VT that
persisted or immediately reoccurred despite appropriate intervention to
terminate the VT.