Clinical implication
One critical electrophysiologic principle is that ablation is more likely to succeed at the target closer to the origin. The high IA success rate by ipsilateral IA indicated the close relationship of the EVA sites and origins. Currently, no ECG characteristics could distinguish RVOT-type VAs with supravalvular origins from those with subvalvular origins.9,10,16 The widely accepted stepwise strategy is that after one method fails, then consider the other. However, considering the high proportion of supravalvular origins in RVOT-type VAs, activation mapping by single method is not sufficient to reveal the actual EVA sites. One common cause of ablation failure is that the target is not close enough to the origin. A subset of VAs originating from the PSC junction was reported refractory to the reversed U-curve method.17 When using the antegrade method, the earliest activation time beneath PV was 13.2±4.2ms earlier, indicating subvalvular origins. For this reason, the antegrade method had better performance. We defined the VA suppression by contralateral ablation as collateral damage. More ablation applications, prolonged ablation, and higher power were usually needed to achieve success.7 The collateral damage pattern of ablation may impair the outcomes and increase the risk of complication. Our findings suggested complete activation mapping for locating VA origins, then selecting the optimal method to ipsilateral ablation for higher effectiveness.